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FINAL YEAR PROJECT REPORT ON THE PERFORMANCE OF
HONDA’S I-VTEC ENGINE

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ACKNOWLEDGMENT

Firstly I thank none but one Almighty Allah for showering His mercy and blessing on me and being with me
always, and He is with me hence only I can finished my work successfully. Our debts are many
and we acknowledge them with much pride and delight.

We would like to express our deep sense of gratitude and respect to our guide MR.
IMTIAZ KHALID KHAN (Assistant Professor, Mechanical Department, UOL Islamabad),
for his encouragement and valuable advice. We convey our deep sense of gratitude for him. It
was great privilege to get his constant inspiration and guidance during our work.

In fact, it is very difficult to acknowledge all nature and help and encouragement we have
received from our friends in the preparation of report work.

Last but not least, we would like to present a special thanks to our families, for their love,
understanding, encouragement, and confidence in us.

Thankful I ever remain………..

ABSTRACT

The most important challenge which is faced by the car manufacturers today is to make the vehicles
that deliver excellent fuel efficiency and superb performance while maintaining cleaner emissions
and driving comfort. In this report we actually studied the different performance characteristics of
the Honda I-VTEC engine and their variations based on one another. We can analyze the effects
of performance characteristics on one another by plotting the graphs between them. Our main
objective of the research is to study the variations of different engine parameters of I-VTEC engine.

This report deals with I-VTEC (Intelligent-Variable Valve Timing and Lift Electronic
Control) engine technology which is one of the advanced technology in the IC engine. I-VTEC is
the new trend in Honda’s latest large capacity four cylinder petrol engine family. The name is
derived from ‘intelligent’ combustion control technologies that match outstanding fuel economy,
cleaner emissions and reduced weight with high output and greatly improved torque characteristics
in all speed range. The automotive industry is continuously developing technologies and strategies
for increasing the efficiency in Fuel consumption and reducing the emissions of pollutants. The
variable valve timing system provides such a solution for internal combustion engines.

The design cleverly combines the highly renowned VTEC system, which varies the timing and
amount of lift of the valves with Variable Timing Control (VTC). VTC is able to advance and
retard inlet valve opening by altering the phasing of the inlet camshaft to best match the engine
load at any given moment. The two systems work in concern under the close control of the engine
management system delivering improved cylinder charging and combustion efficiency, reduced
intake resistance, and improved exhaust gas recirculation among the benefits. I-VTEC technology
offers tremendous flexibility since it is able to fully maximize engine potential over its complete
range of operation. In short Honda’s I-VTEC technology gives us the best in vehicle performance.

TABLE OF CONTENTS

CHAPTER # 01: INTRODUCTION………………………………………………..06
CHAPTER # 02: NEED OF I-VTEC TECHNOLOGY……………………………..09
CHAPTER # 03: HISTORY…………………………………………………………10
? DOHC VTEC……………………………………………………10
? SOHC VTEC……………………………………………………11
? VTEC-E………………………………………………………….12
? 3 STAGE VTEC…………………………………………………13
? I-VTEC ………………………………………………………….14
o (K Series ; R Series)
? I-VTEC WITH VARIABLE CYLINDER MANAGEMENT ….16
? IVTEC-I …………………………………………………………16
? AVTEC…………………………………………………………..17
? VTEC TURBO …………………………………………………..17
? VTEC IN MOTORBIKES……………………………………….17

CHAPTER # 04: I-VTEC MECHANISM……………………………………….….18
? VTEC ENGINE…………………………………………19
? BASIC VTEC MECHANISM……………………………19
? DIFFERENT VARIANTS OF VTEC……………………20
? I-VTEC DOHC…………………………………………..20
CHAPTER # 05: I-VTEC SYSTEM LAYOUT………………………………………22

CHAPTER # 06: TYPES OF I-VTEC ENGINE……………………………………..24
CHAPTER # 07: I-VTEC IMPLEMENTATION……………………………………..25
CHAPTER # 08: ADVANTAGES AND DISADVANTAGES………………………27
CHAPTER # 09: ENGINE PERFORMING PARAMETERS………………………..28
CHAPTER # 10: METHODOLOGY…………………………………………………29
LIST OF EXPERIMENTS PERFORMED
SINGLE CYLINDER ENGINE TEST BED………………………………………………….30
? TEST PROCEDURE………………………………33
? IMPORTANT FORMULAE USED………………35
? CALCULATIONS…………………………………37
? GRAPHS…………………………………………..44
HONDA VTEC ENGINE DYNO TEST……………………………………………………….49
? TERMS OF
ENGAGEMENT………………………………….50
? FORMULA SHEET……………………………..52
? CALCULATIONS……………………………….55
? GRAPHS…………………………………………59
CHAPTER # 11: CONCLUSIONS………………………………………………….66

CHAPTER # 01

INTRODUCTION

I-VTEC:-

I-VTEC is the acronym of ‘intelligent’ VTEC. VTEC (Variable valve timing ; lift electronic
control) is a valve train system developed by Honda. The VTEC system uses two camshaft profiles
and electronically selects between the profiles. VTEC is an electronic and mechanical system in
some Honda engines that allows the engine to effectively have multiple camshafts. As the engine
moves into different rpm ranges, the engine’s computer can activate alternate lobes on the camshaft
and change the cam’s timing.

I-VTEC engine works by controlling the timing and lifting of the camshafts depending upon the
engine speeds. The valves open smaller during low engine speed to achieve maximum fuel
efficiency.

The valves will open bigger at higher engine speed to achieve higher performance.

The basic mechanism used by the VTEC technology is the simple hydraulic actuated pin. The pin
is hydraulically pushed horizontally to link up adjacent rocker arm. A spring mechanism is used
to return the pin back to its original position. To start on the basic principle, examine the simple
diagram below. It comprises a cam shaft with two cam lobe side by side. These lobes drive to side
by side valve rocker arms.

As we know the price of fuel is increasing day by day, hence the proper fuel utilization in engine
is very important. As in other cars, power with mileage is not possible but due to this technology,
it is possible to get both in one car. The latest and most sophisticated VTEC development is I-
VTEC, which combines feature of all various previous VTEC systems for even greater power band
width and cleaner emissions. The demanding aspects of fuel economy, torque and clean emissions
can all be controlled and provided at a higher level with VTEC and VTC combined.

VTEC does Honda complete range of engine speed to provide good top-end output develop a
system. The principle of a VTEC system is to optimize the amount of air/fuel charge entering, and
the amount of exhaust gas leaving, the cylinders over the together with low and mid-range

flexibility. The VTEC system provides the engine with valve timing optimized for both low and
high RPM operations.

The older approach to timing adjustments is to produce a camshaft with a valve timing profile that
is better suited to low-RPM operation. The improvements in low-RPM performance, which is
where most street-driven automobiles operate a majority of the time, occur in trade for a power
and efficiency loss at higher RPM ranges. Correspondingly, VTEC attempts to combine low-RPM
fuel efficiency and stability with high-RPM performance. In basic form, the single cam lobe
and follower/rocker arm of a conventional engine is replaced with a locking multi-part rocker arm
and two cam profiles:

? One optimized for low-RPM stability and fuel efficiency.
? The other designed to maximize high-RPM power output.

The switching operation between the two cam lobes is controlled by the ECU which takes account
of engine oil pressure, engine temperature, vehicle speed, engine speed and throttle position. Using
these inputs, the ECU is programmed to switch from the low lift to the high lift cam lobes when
certain conditions are met. At the switch point a solenoid is actuated that allows oil pressure from
a spool valve to operate a locking pin which binds the high RPM rocker arm to the low RPM ones.
From this point on, the valves open and close according to the high-lift profile, which opens the
valve further and for a longer time. The switch-over point is variable, between a minimum and
maximum point, and is determined by engine load.

Honda I-VTEC (Intelligent-VTEC) has VTC continuously variable timing of camshaft phasing
on the intake camshaft of DOHC VTEC engines. The technology first appeared on Honda’s K-
series four-cylinder engine family in 2001. In the United States, the technology debuted on the
2002 Honda CR-V.

VTC controls of valve lift and valve duration are still limited to distinct low- and high-RPM
profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees,
depending upon engine configuration. The electro-hydraulic actuated variable valve timing system
is a new power train technology that allows a fully flexible control of the opening/closing transient
phases of the intake valves in a diesel engine. In the conventional engine, the in-cylinder air flow
is controlled by the rotation of the camshaft through a mechanical actuation and a throttle.

Phasing is implemented by a computer-controlled, oil-driven adjustable cam gear. Both engine
load and RPM affect VTC. The intake phase varies from fully retarded at idle to somewhat
advanced at full throttle and low RPM. The effect is further optimization of torque output,
especially at low and midrange RPM.

CHAPTER # 2

NEED OF I-VTEC TECHNOLOGY

? In this modern world of car, everybody wants great mileage in his/her car, so to produce
such a car which has mileage and great power the I-VTEC technology is used in engines.

? As we know the price of fuel is increasing day by day, hence the proper fuel utilization in
engine is very important. As in other cars, power with mileage is not possible but due to
this technology, it is possible to get both in one car. The latest and most sophisticated VTEC
development is I-VTEC, which combines feature of all various previous VTEC systems
for even greater power band width and cleaner emissions. The demanding aspects of fuel
economy, torque and clean emissions can all be controlled and provided at a higher level
with VTEC and VTC combined.

? The proper fuel utilization in engine is very important. As in other cars, power with mileage
is not possible but due to this technology it is possible to get both in one car.

? We need I-VTEC engine for:
o Better fuel efficiency,
o Lower emissions,
o Strong performance,
o Ample torque

? The demanding aspects of fuel economy, ample torque, and clean emissions can all be
controlled and provided at a higher level with VTEC (intake valve timing and lift
control) and VTC (valve overlap control) combined.

CHAPTER # 03

HISTORY

VTEC, the original Honda variable valve control system, originated from REV (Revolution-
modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.

I-VTEC was invented by Engr. LKOU KAJITANI. In the regular four-stroke automobile engine,
the intake and exhaust valves are actuated by lobes on a camshaft. The shape of the lobes
determines the timing, lift and duration of each valve.

? Timing refers to an angle measurement of when a valve is opened or closed with respect
to the piston position (BDC or TDC).
? Lift refers to how much the valve is opened.
? Duration refers to how long the valve is kept open.

Due to the behavior of the working fluid (air and fuel mixture) before and after combustion, which
have physical limitations on their flow, as well as their interaction with the ignition spark, the
optimal valve timing, lift and duration settings under low RPM engine operations are very different
from those under high RPM.

Optimal low RPM valve timing, lift and duration settings would result in insufficient filling of the
cylinder with fuel and air at high RPM, thus greatly limiting engine power output. Conversely,
optimal high RPM valve timing, lift and duration settings would result in very rough low RPM
operation and difficult idling. The ideal engine would have fully variable valve timing, lift and
duration, in which the valves would always open at exactly the right point, lift high enough and
stay open just the right amount of time for the engine speed in use.

DOHC VTEC:-
Introduced as a DOHC (Dual overhead camshaft) system in Japan in the 1989 Honda Integra XSi
which used the 160 bhp (120 kW) B16A engine. The same year, Europe saw the arrival of VTEC
in the Honda CRX 1.6i-VT, using a 150 bhp (110 kW) B16A1 variant. The United States market
saw the first VTEC system with the introduction of the 1991 Acura NSX, which used a 3-litre
DOHC C30A V6 with 270 bhp (200 kW). DOHC VTEC engines soon appeared in other vehicles,
such as the 1992 Acura Integra GS-R (150 bhp (110 kW) B17A1), and later in the 1993 Honda
Prelude VTEC (195 bhp (145 kW) H22A) and Honda Del Sol VTEC (160 bhp (120 kW) B16A3).
The Integra Type R (1995–2000) available in the Japanese market produces 197 bhp (147 kW;
200 PS) using a B18C 1.8-litre engine, producing more horsepower/liter than most super-cars at

the time. Honda has also continued to develop other varieties and today offers several varieties of
VTEC, such as i-VTEC and i-VTEC Hybrid.

SOHC VTEC:-
Honda also applied the system to SOHC (single overhead camshaft) engines such as the D-
Series and J-Series Engines, which share a common camshaft for both intake and exhaust valves.
The trade-off was that Honda’s SOHC engines benefited from the VTEC mechanism only on the
intake valves. This is because VTEC requires a third center rocker arm and cam lobe (for each
intake and exhaust side), and, in the SOHC engine, the spark plugs are situated between the two
exhaust rocker arms, leaving no room for the VTEC rocker arm. Additionally, the center lobe on
the camshaft cannot be utilized by both the intake and the exhaust, limiting the VTEC feature to
one side.
Examine the diagram of a standard SOHC cam assembly below. Note that the pair of intake
rocker arms are separated but adjacent to each other.

In the SOHC VTEC implementation (diagram above), Honda put a wild-cam lobe for the intake
valves in the space between the two rocker arms. Note that the two exhaust rocker arms are
separated by the two intake rocker arms and the “tunnel” for the sparkplug cable connector. This
is the reason why Honda implemented VTEC on the intake valves only.
The primary exhaust rocker arm contacts a low-profile camshaft lobe during low-RPM engine
operation. Once VTEC engagement occurs, the oil pressure flowing from the exhaust rocker shaft
into the primary exhaust rocker arm forces the VTEC switching piston into the secondary exhaust
rocker arm, thereby locking both exhaust rocker arms together. The high-profile camshaft lobe
which normally contacts the secondary exhaust rocker arm alone during low-RPM engine
operation is able to move both exhaust rocker arms together which are locked as a unit. The same
occurs for the intake rocker shaft, except that the high-profile camshaft lobe operates the primary
rocker arm.

VTEC-E:-
A novel implementation of VTEC in SOHC engines is the VTEC-E implementation (E for
Economy). VTEC-E uses the principle of swirling to promote more efficient air-and-fuel mixing
in the engine chambers. VTEC-E works by deactivating one intake valve. Examine the diagram
below.

In the SOHC VTEC-E implementation, only one intake cam-lobe is implemented on the camshaft.
Actually it is really a flat “ring”. In operation this means the relevant rocker arm will not be
activated causing the engine to effectively work in 12-valve mode. This promotes a swirl action
during the intake cycle. VTEC is used to activate the inactive valve, making the engine work in
16-valve mode in more demanding and higher rpm conditions. Honda was able to implement air-
fuel mixture ratios of more than 20:1 in VTEC-E during the 12-valve operating mode. The SOHC
VTEC-E engine EG-series Civic ETI is able to return fuel consumptions of as good as 20km/litre
or better!!
SOHC VTEC implemented for power is often mistaken as SOHC VTEC-E which is implemented
for economy. It is worthwhile to note that the 1.5l SOHC VTEC-E used in the JDM Honda Civic
ETI produces 92ps. This is in fact less than that produced by the standard 1.5l SOHC engine’s
100ps which uses dual Keihin side-draft carburetors. SOHC VTEC in the D15B produces 130ps.
This is 30% more than the standard SOHC implementation.
3-STAGE VTEC:-
Examine the SOHC VTEC and SOHC VTEC-E implementations. The clever Honda engineers saw
that it is a logical step to merge the two implementations into one. This is in essence the 3-stage
VTEC implementation. 3-stage VTEC is implemented on the D15B 1.5l SOHC engine in which
the VTEC-E mechanism is combined with the power VTEC mechanism.
Many of us probably has laughed at the poor ignorant layman who said “I want power AND
economy from my Honda”. We know of course that power and economy are mutually exclusive
implementations. Honda decided not to abide by this rule. Now, with 3-stage VTEC, we
get BOTH power and economy. The diagram below illustrates the 3-stage VTEC implementation.
The intake rocker arms have two VTEC pin actuation mechanisms. The VTEC-E actuation
assembly is located above the camshaft while the VTEC (power) actuation assembly is the
standard wild-cam lobe and rocker assembly.

Below 2500rpm and with gentle accelerator pressure, neither pin gets actuated. The engine
operates in 12V mode with very good fuel combustion efficiency. When the right foot gets more
urgent and/or above 2500rpm, the upper pin gets actuated. This is the VTEC-E mechanism at work
and the engine effectively enters into the ‘2nd stage’. Now D15B 3-stage works in 16V mode (both
intake valves works from the same mild cam-lobe).
Stage 2 operates from around 2500rpm to 6000rpm. When the rpm exceeds 6000rpm, the VTEC
mechanism activates the wild cam-lobe pushing the engine into the ‘3rd stage’, the power stage.
Now the engine gives us the full benefit of its 130ps potential.
The 3-stage VTEC D15B engine is used on the current EK-series JDM Civic/Civic FERIO VTI/Vi
together with Honda’s new Multimatic CVT transmission. Stage-1 12V or “lean-burn” operation
mode is indicated to the driver by an LED on the dashboard. The 2500rpm cutover from lean-burn
to normal 16V operation in fact varies according to load and driver requirements. With gentle
driving, lean-burn can operate up to 3000rpm or higher. Stage-3 may not always be activated. The
Multimatic transmission has a selector for Economy, Drive, and Sports mode. In Economy mode
for eg, the ECU operates with a max rpm of around 4800rpm even at Wide-Open-Throttle
positions.
The essence of 3-stage VTEC is power AND economy implemented on a 1.5l SOHC PGM-Fi
engine. Many people mistakes 3-stage VTEC as a “superior” evolution of the power oriented
DOHC VTEC implementation, describing DOHC VTEC as “the older 2-stage VTEC” and
implying an inferior relationship. This is totally wrong because DOHC VTEC is tuned purely for
high specific output and sports/racing requirements. 3-stage VTEC is in truth an evolution of
SOHC VTEC and VTEC-E, merging the two implementations into one.
I-VTEC:-
Honda I-VTEC (intelligent-VTEC) is a system that combines VTEC with Honda’s VTC (Variable
Timing Control), a continuously variable camshaft phasing system used on the intake camshaft of
DOHC VTEC engines. The technology first appeared on Honda’s K-series four-cylinder engine
family in 2001 (2002 in the U.S.). In the United States, the technology debuted on
the K24A1 engine in the 2002 Honda CR-V.
VTEC controls of valve lift and valve duration are still limited to distinct low- and high-RPM
profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees,
depending upon engine configuration. Phasing is implemented by a computer-controlled, oil-
driven adjustable cam sprocket. Both engine load and RPM affect VTEC. The intake phase varies
from fully retarded at idle to somewhat advanced at full throttle and low RPM. The effect is further
optimization of torque output, especially at low and midrange RPM. There are two types of i-
VTEC K series engines which are explained in the next section. Honda’s J-Series SOHC engines
use an entirely different system also, confusingly, marketed as i-VTEC. Honda J-Series Engines
using I-VTEC combine SOHC VTEC operation with Honda VCM (Variable Cylinder
Management) variable displacement technology to improve fuel economy under light loads.

K-SERIES:-
The K-Series engines have two different types of I-VTEC system implementations. The first type
is for performance engines like the K20A2 or K20Z3 used in the 2002-2006 RSX Type S or the
2006-2010 Civic Si and the second type is for economy engines like the K20A3 or K24A4 used in
the 2002-2005 Civic Si or 2003-2007 Accord. The performance i-VTEC system is basically the
same as the DOHC VTEC system of the B16A’s. Both intake and exhaust cams have 3 cam lobes
per cylinder. However, the valve train has the added benefit of roller rockers and VTC
continuously variable intake cam timing. Performance i-VTEC is a combination of conventional
DOHC VTEC with VTC (which operates for intake valves only). The VTC is available in the
economy and performance I-VTEC engines.
The economy i-VTEC used in K20A3/K24A4 engines is more like the SOHC VTEC-E in that the
intake cam has only two lobes, one very small and one larger, as well as no VTEC on the exhaust
cam. At low RPM only one valve on the intake opens fully, promoting combustion chamber swirl
and improved fuel atomization. This allows a leaner air/fuel mixture to be used, improving fuel
economy. At higher RPM, both intake valves run off the larger intake cam lobe, improving total
air flow and top-end power. The two types of engines are easily distinguishable by the factory
rated power output: the performance engines make around 200 hp (150 kW) or more in stock form,
while the economy engines do not make much more than 160 hp (120 kW).

R-SERIES:-
The I-VTEC system in the R-Series engine uses a modified SOHC VTEC system consisting of
one small and two large lobes. The large lobes operate the intake valves directly while the small
lobe is engaged during VTEC. Unlike typical VTEC systems, the system in the R-Series engine
operates in a ‘reverse’ fashion engaging only at low to mid RPMs. At low RPMs, the small lobe
locks onto one of the larger lobes and keeps one of the intake valves partially open during the
compression cycle, similar to the Atkinson Cycle. The ability for Honda to switch between
Atkinson cycle and normal cycle allows excellent fuel efficiency without sacrificing too much
performance.
I-VTEC with Variable Cylinder Management (VCM):-
In 2003, Honda introduced an I-VTEC V6 (an update of the J-series) that includes Honda’s cylinder
deactivation technology which closes the valves on one bank of (3) cylinders during light load and
low speed (below 80 km/h (50 mph)) operation. According to Honda, “VCM technology works on
the principle that a vehicle only requires a fraction of its power output at cruising speeds. The
system electronically deactivates cylinders to reduce fuel consumption. The engine is able to run
on 3, 4, or all 6 cylinders based on the power requirement, essentially getting the best of both
worlds. V6 power when accelerating or climbing, as well as the efficiency of a smaller engine
when cruising.” The technology was originally introduced to the US on the 2005 Honda
Odyssey minivan, and can now be found on the Honda Accord Hybrid, the 2006 Honda Pilot, and
the 2008 Honda Accord. Example: EPA estimates for the 2011 (271 hp SOHC 3.5L) V6 Accord
are 24 mpg combined vs. 27 in the two 4-cylinder-equipped models.
I-VTEC VCM was also used in the 1.3-liter LDA engine used in the 2001-2005 Honda Civic
Hybrid.

I-VTEC-I:-
A version of I-VTEC with direct injection, first used in 2004 Honda Stream. Direct injection
2.0L DOHC I-VTEC I gasoline engine. The 2-litre DOHC i-VTEC I integrates the i-VTEC
system which uses the VTEC and VTC which uses a direct injection system for an air-fuel ratio
of up to 65:1 for an unprecedented level of ultra-lean combustion. Stable combustion is achieved
by using less fuel than conventional direct injection engines which have an air-fuel ratio of 40:1.
•Combustion control through the use of high-precision EGR valves and a newly developed high-
performance catalyst enable the 2.0 litre DOHC I-VTEC I lean-burn direct injection engine
which qualify as an Ultralow Emissions Vehicle.

AVTEC:-
The AVTEC (Advanced VTEC) engine was first announced in 2006. It combines continuously
variable valve lift and timing control with continuously variable phase control. Honda originally
planned to produce vehicles with AVTEC engines within next 3 years. Although it was speculated
that it would first be used in 2008 Honda Accord, the vehicle instead utilizes the existing I-VTEC
system. As of late 2017, no Honda vehicles use the AVTEC system.

VTEC TURBO:-
The VTEC TURBO engine series were introduced in 2013 as part of the Earth Dreams Technology
range and include new features such as gasoline direct injection, turbochargers, and Dual Cam
VTC. VTEC Turbo engines come in three displacement capacities: a 1.0 liter 3-cylinder, a 1.5 liter
4-cylinder, and a 2.0 liter 4-cylinder. Initial implementation for European vehicles included 2-litre
4-cylinder engine used in Honda Civic Type R, which included Euro 6 emissions compliance.

VTEC in motorcycles:-
Apart from the Japanese market-only Honda CB400SF Super Four HYPER VTEC, introduced in
1999, the first worldwide implementation of VTEC technology in a motorcycle occurred with the
introduction of Honda’s VFR800 sports bike in 2002. Similar to the SOHC VTEC-E style, one
intake valve remains closed until a threshold of 7000 RPM is reached, then the second valve is
opened by an oil-pressure actuated pin. The dwell of the valves remains unchanged, as in the
automobile VTEC-E, and little extra power is produced, but with a smoothing-out of the torque
curve. Critics maintain that VTEC adds little to the VFR experience, while increasing the engine’s
complexity. Honda seemed to agree, as their VFR1200, a model announced in October 2009, came
to replace the VFR800, which abandons the VTEC concept in favor of a large capacity
“UNICAM”, i.e., SOHC, engine. However, the 2014 VFR800 reintroduced the VTEC system from
the 2002-2009 VFR motorcycle.

CHAPTER # 04

I-VTEC MECHANISM

The latest and most sophisticated VTEC development is I-VTEC (“intelligent” VTEC), which
combines features of all the various previous VTEC systems for even greater power band width
and cleaner emissions.

With the latest I-VTEC setup, at low rpm the timing of the intake valves is now staggered and
their lift is asymmetric, which creates a swirl effect within the combustion chambers.
At high rpm, the VTEC transitions as previously into a high-lift, long-duration cam profile.

The I-VTEC system utilizes Honda’s proprietary VTEC system and adds VTC (Variable Timing
Control), which allows for dynamic/continuous intake valve timing and overlap control.

The demanding aspects of fuel economy, ample torque, and clean emissions can all be controlled
and provided at a higher level with VTEC (intake valve timing and lift control) and VTC (valve
overlap control) combined.

The I stands for intelligent:

I-VTEC is intelligent-VTEC. Honda introduced many new innovations in I-VTEC, but the most
significant one is the addition of a variable valve opening overlap mechanism to the VTEC system.

Named VTC for Variable Timing Control, the current (initial) implementation is on the intake
camshaft and allows the valve opening overlap between the intake and exhaust valves to be
continuously varied during engine operation.

This allows for a further refinement to the power delivery characteristics of VTEC, permitting
fine-tuning of the mid-band power delivery of the engine.

VTEC ENGINE:-

VTEC (standing for Variable valve Timing and lift Electronic Control) does Honda Motor Co.,
Ltd. develop a system .The principle of the VTEC system is to optimize the amount of air-fuel
charge entering, and the amount of exhaust gas leaving, the cylinders over the complete range of
engine speed to provide good top-end output together with low and mid-range flexibility.

VTEC system is a simple and fairly elegant method of endowing the engine with multiple camshaft
profiles optimized for low and high RPM operations. Instead of only one cam lobe actuating each
valve, there are two – one optimized for low RPM smoothness and one to maximize high RPM
power output. Switching between the two cam lobes is controlled by the engine’s management
computer.

As the engine speed is increased, more air/fuel mixture needs to be “inhaled” and “exhaled” by the
engine. Thus to sustain high engine speeds, the intake and exhaust valves needs to open nice and
wide. As engine RPM increases, a locking pin is pushed by oil pressure to bind the high RPM cam
follower for operation. From this point on, the valve opens and closes according to the high-speed
profile, which opens the valve further and for a longer time.

BASIC V-TEC MECHANISM:-

The basic mechanism used by the VTEC technology is a simple hydraulically actuated pin. This
pin is hydraulically pushed horizontally to link up adjacent rocker arms. A spring mechanism is
used to return the pin back to its original position.

To start on the basic principle, examine the simple diagram below. It comprises a camshaft with
two cam lobes side-by-side. These lobes drive two side-by-side valve rocker arms.

The two cam/rocker pairs operate independently of each other. One of the two cam-lobes are
intentionally drawn to be different. The one on the left has a “wilder” profile, it will open its valve
earlier, open it more, and close it later, compared to the one on the right. Under normal operation,
each pair of cam lobe/rocker-arm assembly will work independently of each other.

VTEC uses the pin actuation mechanism to link the mild-cam rocker arm to the wild-cam rocker
arm. This effectively makes the two rocker arms operate as one. This “composite” rocker arm(s)
now clearly follows the wild-cam profile of the left rocker arm. This in essence is the basic working
principle of all of Honda’s VTEC engines.

DIFFERENT VARIANTS OF V-TEC:-

I-VTEC DOHC (Double Overhead Cam):-

The last evolution of Honda’s VTEC system was back in 1995 where they introduced the now-
famous 3- stage VTEC system. The 3-stage VTEC was then designed for an optimum balance of
super fuel economy and high power with drivability.

For the next 5 years, Honda still used the regular DOHC VTEC system for their top power models,
from the B16B right up to the F20C in the S2000. Now Honda has announced the next evolution
of their legendary VTEC system, the I-VTEC.

CHAPTER # 5

I-VTEC SYSTEM LAYOUT

Diagram explains the layout of the various components implementing i-VTEC. I have intentionally
edited the original diagram very slightly – the lines identifying the VTC components are rather
faint and their orientation confusing. I have overlaid them with red lines. They identify the VTC
actuator as well as the oil pressure solenoid valve, both attached to the intake camshaft’s sprocket.
The VTC cam sensor is required by the ECU to determine the current timing of the intake camshaft.
The VTEC mechanism on the intake cam remains essentially the same as those in the current
DOHC VTEC engines except for an implementation of VTEC-E for the ‘mild’ cam.

1:-Best fuel economy (idle/lean burn range):-

Using the low speed cam, one intake valve is mostly resting, which results in a strong swirl.
Overlap is minimal and exhaust gases are kept separate from intake air for more stable combustion.

2:-Fuel economy + power:-

Using the low speed cam, one intake valve is mostly resting, which results in a strong swirl. With
large overlap, clean emissions and improved fuel efficiency can be achieved.

3:-Optimum low end torque:-

The intake valve closing timing is controlled to optimize torque.

4:-Optimum mid/high end torque:-

When switched over to the high rpm cam, both intake valves open, and valve closing angle is
optimized for maximum torque.

CHAPTER # 06

TYPES OF I-VTEC ENGINES

The new 1.3L I-VTEC engine is agile and intelligent: at low engine speeds one of the two intake valves is
idled. The engine sips gasoline, using a lean fuel mix at low engine speeds for further improved combustion
efficiency.

The two intake valves of the new 1.5L i-VTEC engine switch modes in accordance with engine speed,
opening a small amount at low engine speeds and fully opening at high engines speeds, achieving both high
power and low fuel consumption.

CHAPTER # 07

I-VTEC IMPLEMENTATION

The I-VTEC system was implemented into more modern K series engine, as opposed to the VTEC
system of the older B series engines. There is a performance i-VTEC system, and an economy i-
VTEC system. The performance variant allowed three cam lobes per cylinder for both intake and
exhaust, whereas the economy I-VTEC system only possesses two lobes on the intake cam, and
no VTEC control on the exhaust cam. The performance version resulted in an additional 40
horsepower in the K series engines.

AT LOW ENGINE SPEED- Valves are opened only a small amount for lower fuel consumption.

AT HIGH ENGINE SPEED- Valves are wide open for maximum power.

CHAPTER # 08

ADVANTAGES AND DISADVANTAGES OF I-VTEC

ADVANTAGES:-

? Class-leading power and fuel efficiency
High performance and low fuel consumption in a single engine.
? I-VTEC: high power + low fuel consumption
? I-VTEC regulates the opening of air-fuel intake valves and exhaust valves in accordance
with engine speeds.
By regulating valve opening to match engine speed, the I-VTEC engine adjusts its
characteristics to realize both superior power and low fuel consumption.

DISADVANTAGES:-

? I-VTEC engines are very expensive.
? The mechanism of I-VTEC engine is very complicated.
? It decreases the life of the engine because the power of the engine is increased but the
torque which is produced is not sufficient.

APPLICATIONS OF I-VTEC ENGINE:-

Currently I-VTEC technology is available on three Honda products;
? 2002 Honda CRV
? 2002 Acura RSX
? Honda Civic 2006
? 2010 Honda City i-VTEC

CHAPTER # 09

ENGINE PERFORMANCE PARAMETERS

Following are the engine performance parameters.

? Fuel Power.
? Indicated Power.
? Brake Power.
? Indicated Mean Effective Pressure.
? Brake Mean Effective Pressure.
? Friction Power.
? Indicated Thermal Efficiency.
? Brake Thermal Efficiency.
? Mechanical Efficiency.
? Combustion Efficiency.
? Relative Efficiency.
? Volumetric Efficiency.
? Specific Fuel Consumption.
? Air/Fuel (A/F) ; Fuel/Air (F/A) Ratios.
? Specific Power.
? Output per Displacement.
? Engine Specific Volume.
? Engine Specific Weight.

CHAPTER # 10

METHODOLOGIES

Here is the list of experiments which are performed on the engine in our project.
First these experiments are performed on the single cylinder 212cc engine in the university in
the IC Engines lab and then performed on the VTEC engine.

-:EXPERIMENTS:-

? Determination of indicated power of an IC Engine from an Indicator diagram.
? Evaluation of torque and brake power by mechanical absorption dynamometer.
? To study torque vs engine speed at various throttle setting.
? Evaluation of brake thermal efficiency of an engine.
? Evaluation of the engine volumetric efficiency.
? Behaviour of brake thermal efficiency against engine speed.
? Variation of volumetric efficiency with engine speed.
? Engine characteristics of A/F ratio against engine speed.
? Brake specific fuel consumption against engine speed.

MT501M SINGLE CYLINDER ENGINE TEST BED, Mechanical Brake
Absorber.

Installation:-

Normally the Engine Test Bed is shipped in two main parts, Engine Test Bed and Control
Panel. These two parts are connected as per above diagram. The engine test bed should be firmly
attached to the floor or else it may move during the test due to vibrations.
The test bed itself should be located in a well-ventilated room. If it is to be located in a closed
room, an adequate size ventilation fan must also be installed. The engine exhaust should be
connected to outside the building.
An air flow measuring device is normally installed in the back of control panel and the
panel is located next to the engine. The flexible hose between the airflow measuring devise and
the engine should be as short as possible to maximize volumetric efficiency.

Once the two main parts are put in place, connection should be made as;
? Water lines
– From outside water supply to the dynamometer
– From the dynamometer outlet to drain

? Connect control cables from the control panel to the test bed.
? Connect air inlet line from the air flow measuring device to the engine.
? Connect the fuel line from control panel to the engine.
? Connect throttle cable between the control panel and the engine.

The Engine Test Bed is equipment of an engine performance. The engine output is measured by
an engine speed and a torque using dynamometer. The input calculated from fuel consumption
(Fuel Rate).
Normally the air flow rate is measured to obtain an air fuel ratio and to determine volumetric
efficiency. A simple schematic diagram for an engine test bed is as per below.

Outside water supply

Control

Drains

Control Panel
Engine
Dynamo
meter
Fuel Speed
Air Torque

Dynamometer

Engine

Dynamometer:-
The dynamometer is connected to the engine shaft and provides a mean for measuring engine
power output. There are several types of dynamometer e.g. Hydraulic, Eddy Current, Friction or
Mechanical Brake. The dynamometer used for this test bed is mechanical brake dynamometer.
Air Flow Measuring Devices:-
There are three types of air flow measuring device to be used with MT501M; inclined manometer,
differential pressure sensor and the air flow sensor. The inclined manometer and differential
pressure sensor give the result of differential pressure from the air box which yields the result of
the air flow rate.
Fuel Flow Rate:-
There are two types of fuel flow measuring device for the MT 501; a graduate cylinder and a stop
watch and a fuel flow sensor. The graduate cylinder and a stop watch is a standard for measuring
device. The fuel flow rate of the graduate cylinder is calibrated at the factory against a standard
pipette and a stop watch.
If the fuel flow sensor (optional) is to be used with MT501M, the fuel flow sensor will be installed
in series with the graduate cylinder.
Speed Measuring Device:-
There are two types of the speed measuring device for the MT501M, a tachometer and a speed
sensor (optional). If the speed measuring sensor used, it will be installed next to the rotating shaft.
Torque Measuring Device:-
There are two types of the torque measurement device for the MT501M, the mechanical
dynamometer and the torque (optional) Torque measurement is measuring a force exerted by the
dynamometer arm. The length of the arm is set and calibrated at factory. MT501M, use a spring
balance as a standard for force measurement. Normally a spring balance provides a direct reading
of the turning force.
Temperature Measuring Device:-
The temperature sensor is type K thermocouple. The temperature indicator is calibrated at the
factory.
0 Degree centigrade for ice water.
100 Degree centigrade for boiling water in the atmosphere.

Test Purposes:

The purpose of the test is to study characteristics of engine performance such as power, torque vs
speed at various load conditions or at the various positions of throttle opening. The test begins with
the startup of the engines, warming it up to a normal working temperature, adjusting the
dynamometer to take small load, open the throttle, and record the fuel consumption and the turning
torque of the engine. Next step is to increase the load to the engine step by step until the engine is
stalled by excessive load.
From the recorded data, calculate power, A/F ratio, Brake thermal efficiency, volumetric
efficiency specific fuel consumption, and engine torque and use the results to plot a graph showing
relations between brake thermal efficiency, volumetric efficiency, specific fuel consumption,
power, torque and speed.

Before the Test:

o Install the engine dynamometer on the floor and adjust the supports for leveling.
o Connect domestic tap water line to the dynamometer.
o Connect water drain pipe line from the dynamometer to the draining conduit
o Open the cooling water outlet valve and adjust the valve to control the water temperature
of the dynamometer at a constant temperature within a maximum limit of 80 Degree
centigrade
o Connect fuel line from the engine to the fuel tank
o Close fuel supplies valve V1, fill up the fuel tank
o Fill up the graduate cylinder by opening valves V1, V2, and V3, then close valves V2, V3
o Purge air from the fuel line
o Prepare to start the engine
o Open valve V2
o Turn ON the start switch
o Wait about 5 minutes to warm up the engine to operating temperature.

Salient features of Engine installed on the test bench is as under:

Dynamometer

– Type ; Water cooled stainless steel mechanical brake absorber with anti-splashing
system.
– Capacity : Up to 20 kW at 5000 rpm.

Engine measuring
instruments.

– Torque

: Spring balance at the dynamometer.

– Speed : Portable tachometer.
– Fuel flow rate : Graduated cylinder and a stop watch.
– Air flow rate : Air box with orifice plate and inclined water manometer.

Sensor with digital
display
: Temperatures for ambient air and exhaust gas.

Power supply : 220 V, 50 Hz. Other power supply is available on request.

No. of Cylinder : 1
Torque Arm (Constant) L : 200 mm

FORMULA SHEET:-
When we find the speed and torque of the engine, the other performance parameters of the engine
can be calculated using some formulas and the formulas for different engine performance
parameters are given below.

Fuel consumption:-
Fuel consumption is measured by a graduated cylinder and a stop watch.

Air flow rate:-

Volumetric efficiency:

CALCULATIONS:-
Here are the calculations of different engine performance parameters.
Knowing the engine speed, torque and fuel flow rate, we can fine the other engine parameters as
given below in the calculations.
The speed is measured by the tachometer, torque by the dynamometer and fuel consumption by
the graduated cylinder. Further readings are calculated by using the formulas.
Let us calculate for 3077 rpm speed and 4.8975 Nm torque, as we know;
Ambient air temperature : 27.1 degree centigrade
Absorber water outlet temperature : 30 degree centigrade
Atmospheric pressure : 950217 Pa
Specific gravity : 0.85 kg/L
Heating value : 11320 kcal/kg
Fuel type : Gasoline
Exhaust gas temperature : Varies with the engine speed.
Air flow rate of air box (?P) : 6.0 mmH2O=58.839 Pa
No. of cylinders : 01
Speed of engine, N : 3077 rpm
Torque, T : 4.8975 Nm
Orifice diameter : 300/25 mm
Engine : Yamano 212 cc

When we get the engine speed, torque at different RPM and fuel flow rate, the other parameters
can be calculated by calculation.

Brake power:-

;#55349;;#56439;=;#3627409358;.;#3627409359;;#3627409358;;#3627409362;;#3627409365;;#3627409360;;#55349;;#56443;;#55349;;#56463;=(;#3627409358;.;#3627409359;;#3627409358;;#3627409362;;#3627409365;;#3627409360;)(;#3627409362;.;#3627409366;;#3627409367;;#3627409365;;#3627409363;)(;#3627409361;;#3627409358;;#3627409365;;#3627409365;)=;#3627409359;;#3627409363;;#3627409365;;#3627409366;.;#3627409359;;#3627409359;;#55349;;#56446;=;#3627409359;.;#3627409363;;#3627409365;;#3627409366;;#55349;;#56460;;#55349;;#56446;

Air Flow rate through orifice:-
;#3627408452;;#3627408483;;#3627408462;=;#3627409148;?;#3627409163;;#3627408465;2
4?(2??;#3627408451;
;#3627409164;;#3627408462;)
12

Calculate the diameter ratio;
;#3627409149;=;#3627408476;;#3627408479;;#55349;;#56406;;#3627408467;;#55349;;#56406;;#3627408464;;#3627408466; ;#3627408465;;#55349;;#56406;;#3627408462;, ;#3627408465;
;#3627408436;;#55349;;#56406;;#3627408479; ;#3627408463;;#3627408476;;#55349;;#56421; ;#3627408465;;#55349;;#56406;;#3627408462;, ;#55349;;#56375;=25
300=0.0833
Thus ?=0.60, obtained from graph between ? ; ?.
Differential pressure ratio=?P/Pa=58.839
950217=0.06192257

From the graph of € ; ?P/Pa, we get €=0.999

From the graph of density of air vs temperature, at the temperature 27.1 degrees, air density is
;#3627409164;=1.175 kg/m3.
The air volume flow rate is:
;#3627408452;;#3627408483;;#3627408462;=(0.6)(0.999)(3.14?0.0252
4)(2?58.839
1.175)
12
=0.002895;#3627408474;3
;#3627408480;=10.42229;#3627408474;3
?
The air mass flow rate is:
;#3627408452;;#3627408474;;#3627408462;=;#3627409164;;#3627408462;?;#3627408452;;#3627408483;;#3627408462;=(1.175?0.002895)=0.003401;#3627408472;;#3627408468;
;#3627408480;=3.401;#3627408468;
;#3627408480;

Fuel consumption:-
Fuel consumption,
;#3627408452;;#3627408483;;#3627408467;=10 ;#3627408474;;#3627408473;
21 ;#3627408480;=0.000476;#55349;;#56383;
;#3627408480;=1.71428;#55349;;#56383;
?
;#3627408452;;#3627408474;;#3627408467;=;#3627408452;;#3627408483;;#3627408467;?;#3627409164;;#3627408467;=(0.000476;#55349;;#56383;
;#3627408480;)(0.85;#3627408472;;#3627408468;
;#55349;;#56383;)=0.0004047;#3627408472;;#3627408468;
;#3627408480;=0.404;#3627408468;
;#3627408480;

Air/Fuel ratio:-
The air fuel ratio can be determined from,
;#3627408436;
;#55349;;#56377;=;#3627408452;;#3627408474;;#3627408462;
;#3627408452;;#3627408474;;#3627408467;=3.401
0.404=8.404 :1

Heat input to the engine:-
;#3627408452;;#3627408467;=;#3627408452;;#3627408474;;#3627408467;?;#55349;;#56383;;#55349;;#56379;;#3627408457;=(0.0004047)(11320)(4.184)=19.16;#3627408472;;#3627408458;

Brake specific fuel consumption:-
;#3627408437;;#3627408480;;#3627408467;;#3627408464;=3600;#3627408452;;#3627408474;;#3627408467;
;#3627408451;=(3600)(0.0004047)
1.5781=0.9233447;#3627408472;;#3627408468;
;#3627408472;;#3627408458;?

Brake Thermal efficiency:-
;#55349;;#57090;;#3627408481;?=;#3627408451;
;#3627408452;;#3627408467;=1.5871
19.16=0.08232=8.232%

Volumetric efficiency:-
;#3627408452;;#3627408481;?=;#3627408466;;#3627408475;;#3627408468;;#55349;;#56406;;#3627408475;;#3627408466; ;#3627408481;;#3627408476;;#3627408481;;#3627408462;;#3627408473; ;#3627408465;;#55349;;#56406;;#3627408480;;#3627408477;;#3627408473;;#3627408462;;#3627408464;;#3627408466;;#3627408474;;#3627408466;;#3627408475;;#3627408481; ;#3627408483;;#3627408476;;#3627408473;;#3627408482;;#3627408474;;#3627408466;?;#3627408475;
120=212;#3627408464;;#3627408464;?3077
120=19.56972;#3627408474;3
?=0.005436;#3627408474;3
;#3627408480;
;#55349;;#57090;;#3627408483;=;#3627408452;;#3627408483;;#3627408462;
;#3627408452;;#3627408481;?=0.002895
0.005436=53.25 %

Now we will make the graphs of different performance parameters with the engine speed.

1-ENGINE SPEED vs BRAKE POWER:-

The graph shows the variation of the engine brake power at different engine speed. The engine
speed is in rpm and the brake power is calculated in kW. The graph shows the variations in brake
power when the engine speed is increased. When the engines starts and rpm is increased from 1616
rpm to 3077 rpm, the power produced is increased and maximum power is produced at 2886 rpm
and then will decreased slowly.

Maximum power produced : 1.776kW @ 2886 rpm (maximum engine speed)
Minimum power produced : 1.312kW @ 1616 rpm (minimum engine speed)

The graph shows that the power produced will increase first and then will decreased to its minimum
value at higher rpm. The minimum power is produced at maximum engine speed.

0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0500100015002000250030003500
power (kW)
engine speed (rpm)
engine speed vs power

2-ENGINE SPEED vs TORQUE:-

The above graph shows the variation of torque with the increase in the engine speed. The graph
shows that the torque (Nm) decreases with the increase in the engine speed (rpm).

Maximum torque produced : 7.93 Nm @ 1616 rpm (min engine speed)
Minimum torque produced : 4.89 Nm @ 3077 rpm (max engine speed)

With the increase in the engine speed, the torque is decreasing as shown in the graph above. At
2124 rpm, the torque produced is 7.05 Nm and at 2886 rpm, the torque produced is 5.87 Nm. This
shows that the torque is decreasing with the increase in the engine speed.

0
1
2
3
4
5
6
7
8
9
0500100015002000250030003500
torque (Nm)
engine speed (rpm)
engine speed vs torque

3-ENGINE SPEED vs BRAKE SPECIFIC FUEL CONSUMPTION:-

The above graph shows the relation between the brake specific fuel consumption and the engine
speed that how the specific fuel consumption of the engine varies with the increase/change in the
engine speed. The brake specific fuel consumption of the engine is increased with the increase in
the engine speed. The brake specific fuel consumption is more at higher rpm of the engine and less
at lower rpm of the engine.

Minimum brake specific fuel consumption : 0.373 kg/kWh @ 1616 rpm (min engine
speed)
Maximum brake specific fuel consumption : 0.923 kg/kWh @3077 rpm (max engine speed)

The graph shows that when the engine starts and the rpm is increased, the brake specific fuel
consumption increased and there is maximum brake specific fuel consumption at higher rpm.
When the engine speed is maximum, there will be more brake specific fuel consumption. When
the engine speed is minimum, there will be low brake specific fuel consumption,

0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0500100015002000250030003500
bsfc (kg/kWh)
engine speed (rpm)
engine speed vs bsfc

4-ENGINE SPEED vs BRAKE THERMAL EFFICIENCY:-

The graph shows the relation between the brake thermal efficiency of an engine at different speed
of an engine. Brake thermal efficiency indicates how well an engine converts the heat from a fuel
to mechanical energy. The graph shows that there is less brake thermal efficiency at higher rpm
and high brake thermal efficiency at lower rpm.

Maximum brake thermal efficiency : 20.34 % @ 1616 rpm (min engine speed)
Minimum brake thermal efficiency : 8.23 % @ 3077 rpm (max engine speed)

The graph shows that at higher rpm, the brake thermal efficiency is very low as compared to brake
thermal efficiency at low engine speed. It means that this engine doesn’t convert the heat of the
fuel into mechanical energy very well at higher rpm as compared to lower rpm. The performance
of heat conversion at lower rpm is good that it converts the heat of fuel into mechanical energy
very well as compared to high rpm.

0
5
10
15
20
25
0500100015002000250030003500
BTE (%)
engine speed
engine speed vs BTE

5-ENGINE SPEED vs VOLUMETRIC EFFICIENCY:-

The graph shows the relation between the engine speed and the volumetric efficiency. The shows
the effect on volumetric efficiency of engine by changing the engine speed. Volumetric efficiency
refers to the efficiency with which the engine can move the charge of fuel and air into and out of
the cylinders.
Maximum volumetric efficiency : 83.29 % @ 1616 rpm (min engine speed)
Minimum volumetric efficiency : 53.25 % @ 3077 rpm (max engine speed)
The calculation shows that the volumetric efficiency is higher at lower rpm and lower at higher
rpm. It means that the charge doesn’t enter into the cylinder efficiently at higher rpm when the
engine speed is maximum, i-e; produces less volumetric efficiency. The charge enters into the
cylinder very efficiently at lower rpm when the engine speed is minimum, i-e; produces high
volumetric efficiency up to 83.29 %. The graph shows that when the engine speed in increased,
the volumetric efficiency is decreased and vice versa.

0
10
20
30
40
50
60
70
80
90
0500100015002000250030003500
Volumetric eff (%(
engine speed (rpm)
engine speed vs VE

-:HONDA I-VTEC ENGINE PERFORMANCE ON THE CHASSIS DYNAMOMETER:-

Now the performance of different parameters of Honda VTEC engine against the engine speed.
CHASSIS DYNAMOMETER:-
A Chassis dynamometer, sometimes called a rolling road is a device used for vehicle testing and
development. It uses a roller assembly to simulate a road in a controlled environment, usually
inside a building. A chassis dynamometer measures the power from the engine through the wheels.
It is a device for measuring the force, moment of force (Torque) or power. For example, the power
produced by an engine, motor or other prime mover can be calculated by simultaneously measuring
torque and rotational speed.
Chassis dynamometers are very popular to run some quick tests for installed power and check out
the chassis and drivetrain. They are quick to use but have some problems that should be made clear
before you start down that direction. If you plan on testing a few sets of exhaust components or
any bolt-on parts that might take more time than if the testing was done on an engine dyno, so do
some planning and think about what you want to accomplish.

Chassis dynamometers come in all sorts of designs and configurations but there are some things
that are common to all. Most designs test a vehicle that powers a roll or rolls for all wheel drive
types. Most can provide some common numbers for horsepower but not all measure torque to do
so. Basically there are two general types of chassis dynos – inertia only and those that measure
torque with either an electric load or even a mechanical brake. All have to get rid of the heat from
the vehicle and the dyno as well.
Road load simulation principle on chassis dynamometer:-
Vehicle do not behave the same way on chassis dynamometer as on the road. For example,
aerodynamic shape of the vehicle does not matter. Sum of all forces on the vehicle on a real road
are simulated through tires on chassis dynamometer. Increasing air drag with the speed on the road
manifests as increasing braking force of the vehicle wheels. The aim is to make the vehicle on the
dynamometer accelerate and decelerate the same way as on a real road. First you need to know the

parameters of the “behavior” of the vehicle on a real road. In order to get “road parameters”, vehicle
must be driving on ideal flat road with no wind from any direction, gear set to neutral and time
needed to slow down without braking is measured in certain intervals i.e. 100–90 km/h, 90–
80 km/h, 80–70 km/h 70–60 km/h etc. Slowing down from higher speed takes shorter time mainly
due to air resistance.
Those parameters are later set in dynamometer workstation, together with vehicle inertia. Vehicle
is restrained and so called vehicle adaptation has to be performed. During vehicle adaptation
dynamometer automatically slowing down from set speed, changing its own “dyno parameters”
and trying to get same deceleration in given intervals as on real road. Those parameters are then
valid for this vehicle type. Changing of set simulated inertia it is possible to simulate vehicle ability
to accelerate if fully loaded, with setting gradient it is possible to simulate force if vehicle going
downhill etc. Chassis dynamometers for climatic chamber does exists, where it is possible to
change temperature in give range i.e. -40 to +50 °C or altitude chamber where it is possible to
check fuel consumption with different temperatures or pressure and to simulate driving on
mountain roads.
WORKING OF CHASSIS DYNAMOMETER:-

TERMS OF ENGAGEMENT:-
The terms as torque, horsepower, speed, roll speed, heat load, power capacity, speed capacity, and
many others can easily roll off of the tongue or rattle from a keyboard.
Torque:-
Torque is a twisting motion and is typically expressed in lbs-ft. Notice this is not ft-lbs! Although
everyone commonly uses incorrect units for description of this very important item, the proper
reference is indeed pounds-feet (lbs-ft).

Horsepower:-
1 horsepower is equivalent to 2546 BTU/hr or 550 ft-lbs of work per second. The most interesting
is from the calculation of Hp= (T x RPM) / 5252 and in that equation the torque value is in lbs-ft
as described previously. Speed – Most common references in the US for speed is miles per hour
(MPH). Speed can also be in feet per second such as 88 ft/sec = 60 MPH.
Roll Speed:-
Refers to the speed of the roll(s) on the chassis dynamometer and can be directly related to the
vehicle speed or simply given as roll RPM. Because of the friendly relationship of round things to
? or 3.1416, it is easy to calculate the circumference of the roll by measuring the diameter and
multiplying that by ?. That gives us the opportunity to verify some dyno basics.
Speed Capacity:-
Often a mechanical limit set by the manufacturer such as 150MPH or some other number that
should not be exceeded for safety’s sake.
Power Capacity:-
Also a number set by the manufacturer that is fundamental to the capability of the drive tires. This
capacity number is quite often higher than most vehicles can even contest. The term is also
normally associated with a speed such as 500 Hp at 120 MPH or something similar.

SCHEMATIC DIAGRAM:-

FORMULA SHEET:-

Air flow rate:-

Volumetric efficiency:

-:CALCULATIONS:-

Here are the test results which are performed on the Honda’s VTEC engine.
The engine speed, torque and Air/Fuel ratio are taken from the dynamometer and other
values can be calculated by using the formulas as shown earlier in the single cylinder
engine.

? Piston stroke = L= 89 mm = 0.089 m
? Engine speed = N = 1409 rpm
? Torque produced = T = 75 ft-lbs = 101.68 Nm
? ?;#3627408451;=126 ;#3627408451;;#3627408462;
? ;#3627408436;;#3627408481;;#3627408474;;#3627408476;;#3627408480;;#3627408477;?;#3627408466;;#3627408479;;#55349;;#56406;;#3627408464; ;#3627408477;;#3627408479;;#3627408466;;#3627408480;;#3627408480;;#3627408482;;#3627408479;;#3627408466;=94350 ;#3627408451;;#3627408462;
? No of cylinders = 04
? Room temperature = T1 = 35 degree centigrade
? ;#55349;;#56372;;#55349;;#56406;;#55349;;#56415;
;#55349;;#56377;;#55349;;#56418;;#3627408466;;#3627408473;=;#55349;;#56388;;#3627408474;;#55349;;#56398;
;#55349;;#56388;;#3627408474;;#3627408467;=16.9
? Engine type : Honda Civic 1.6 VTEC ? 01 (81kW)
? Air Density (kg/m3 ) : 1.1365
? Heating value (kcal/kg): 11320
? Fuel Type : Gasoline

;#55349;;#56391;?;#3627408479;;#3627408476;;#3627408481;;#3627408481;;#3627408473;;#3627408466; ;#3627408465;;#55349;;#56406;;#3627408462;=;#3627408465;=5.7;#3627408464;;#3627408474;+0.01;#3627408464;;#3627408474;=5.71;#3627408464;;#3627408474;=0.0571;#3627408474;

;#55349;;#56391;?;#3627408479;;#3627408476;;#3627408481;;#3627408481;;#3627408473;;#3627408466; ;#3627408462;;#3627408479;;#3627408466;;#3627408462;=;#3627408436;;#3627408481;?=3.14?0.05712
4=0.00256;#3627408474;2

;#3627408453;;#3627408482;;#3627408475;;#3627408475;;#3627408466;;#3627408479; ;#3627408465;;#55349;;#56406;;#3627408462;=;#3627408465;=5.25;#3627408464;;#3627408474;?3.26;#3627408464;;#3627408474;

;#3627408453;;#3627408482;;#3627408475;;#3627408475;;#3627408466;;#3627408479; ;#3627408462;;#3627408479;;#3627408466;;#3627408462;=;#3627408436;;#3627408479;=;#3627409163;?2.625;#3627408464;;#3627408474;?1.63;#3627408464;;#3627408474;=(3.14?0.02625?0.0163)
=0.001344;#3627408474;2=0.001344?4=0.005376;#3627408474;2

;#3627409149;=0.00256
0.005376=0.4762
;#3627409149;=0.00256
0.005376=0.4762

From the graph of ? ; ;#3627409149;, we get ? = 0.5989

Air Flow rate through orifice:-

;#3627408452;;#3627408483;;#3627408462;=;#3627409148;?;#3627409163;;#3627408465;2
4?(2??;#3627408451;
;#3627409164;;#3627408462;)
12

Differential pressure ratio=?P/Pa=126
94350=0.001335453

From the graph of € ; ?P/Pa, we get €=0.999

From the graph of density of air vs temperature, at the temperature 35 degrees, air density is
;#3627409164;=1.1365 kg/m3.

The air volume flow rate is:
;#3627408452;;#3627408483;;#3627408462;=(0.6)(0.999)(3.14?0.05712
4)(2?126
1.1365)
12
=82.15580011;#3627408474;3
?

The air mass flow rate is:

;#3627408452;;#3627408474;;#3627408462;=;#3627409164;;#3627408462;?;#3627408452;;#3627408483;;#3627408462;=(1.1365?0.02282)=0.02593613;#3627408472;;#3627408468;
;#3627408480;=25.93;#3627408468;
;#3627408480;

Fuel consumption:-

;#3627408436;
;#55349;;#56377;=;#3627408452;;#3627408474;;#3627408462;
;#3627408452;;#3627408474;;#3627408467;=14.5

;#3627408452;;#3627408474;;#3627408467;=;#3627408452;;#3627408474;;#3627408462;
14.5=0.0259361
14.5=0.001788699kg
s=1.78;#3627408468;
;#3627408480;

Heat input to the engine:-

;#3627408452;;#3627408467;=;#3627408452;;#3627408483;;#3627408467;?;#55349;;#56383;;#55349;;#56379;;#3627408457;

;#3627408452;;#3627408483;;#3627408467;=;#3627408452;;#3627408474;;#3627408467;
;#3627409164;;#3627408462;=0.001788699
1.1365=0.002104351L
s

;#3627408452;;#3627408467;=;#3627408452;;#3627408483;;#3627408467;?;#55349;;#56383;;#55349;;#56379;;#3627408457;=(0.002104351)(11320)(4.184)=84.717 ;#3627408472;;#3627408458;

Brake specific fuel consumption:-

;#3627408437;;#3627408480;;#3627408467;;#3627408464;=3600;#3627408452;;#3627408474;;#3627408467;
;#3627408451;=(3600)(0.002104351)
14.99=1.812855018;#3627408472;;#3627408468;
;#3627408472;;#3627408458;?

Brake Thermal efficiency:-

;#55349;;#57090;;#3627408481;?=;#3627408451;
;#3627408452;;#3627408467;=14.99
84.717=0.17757=17.57%

Volumetric efficiency:-
;#3627408452;;#3627408481;?=1972?N?3600
120?1000000=83.35 m3/h

;#55349;;#57090;;#3627408483;=;#3627408452;;#3627408483;;#3627408462;
;#3627408452;;#3627408481;?=82.155
83.35=98.55%

From the above calculations, we made a table of different performance parameters of an
engine depending on the engine speed. The table is shown in the next page.
From the calculations, we noticed that volumetric efficiency is above 100% due to the forced
induction.

Volumetric efficiencies above 100% can be reached by using forced induction such
as supercharging or turbocharging. With proper tuning, volumetric efficiencies above 100%
can also be reached by naturally aspirated engines. The limit for naturally aspirated engines is
about 130%; these engines are typically of a DOHC layout with four valves per cylinder. This
process is called inertial supercharging and uses the resonance of the intake manifold and the
mass of the air to achieve pressures greater than atmospheric at the intake valve. With proper
tuning (and dependent on the need for sound level control), VE’s of up to 130% have been
reported in various experimental studies.

From the above calculations, we will make the graphs of engine’s different performance
parameters against the engine speed. Here are the graphs given below.

1-ENGINE SPEED vs TORQUE:-

This graph shows the relation between the engine speed and the torque. The torque is in Nm and
the engine speed is in rpm. The graph shows that the torque produced is increasing with the
increase in the engine speed.

Maximum torque produced : 210.15 Nm @ 6404 rpm (higher rpm)
Minimum torque produced : 101.68 Nm @ 1409 rpm (min engine speed)

The graph shows that the torque will increase first with the increase in the engine speed and then
there will be a small decrease in the torque at higher rpm.

0
50
100
150
200
250
0100020003000400050006000700080009000
Torque (N m)
Engine Speed (rpm)
engine speed vs torque

2-ENGINE SPEED vs POWER:-

This graph shows the relation between the engine speed and the brake power. The graph shows
that the brake power is increasing by the increase in the speed of the engine. At lower rpm, the
engine produces less power, increasing the fuel economy of the engine. But at higher rpm, the
valves open wider to increase the power of the engine.

Maximum power produced : 161.71 kW (216.85 hp) @ 8258 rpm (max engine speed).
Minimum power produced : 14.9 kW (19.98 hp) @1409 rpm (min engine speed).

The above value shows that the VTEC engine will produce more power at higher rpm increasing
the A/F ratio, because more fuel will be burnt when the valves are opened wider and maximum
power output will be achieved.

0
20
40
60
80
100
120
140
160
180
0100020003000400050006000700080009000
power (kW)
engine speed (rpm)
engine speed vs power

3-ENGINE SPEED vs A/F RATIO:-

This graph shows the relation between the engine speed and A/F ratio. The graph shows that the
A/F ratio is low at higher rpm and higher at lower rpm. A ‘Stoichiometric’ AFR has the correct
amount of air and fuel to produce a chemically complete combustion event. For gasoline engines,
the stoichiometric, A/F ratio is 14.7:1, which means 14.7 parts of air to one part of fuel. The
stoichiometric AFR depends on fuel type– for alcohol it is 6.4:1 and 14.5:1 for diesel.

Maximum A/F ratio : 16.9 @ 1409 rpm (min engine speed)
Minimum A/F ratio : 12.4 @ 8258 rpm (max engine speed)

This shows that at higher rpm, the A/F ratio is low. It means that at higher rpm, more fuel than the
air is entered into the engine cylinder for combustion giving the lower A/F ratio.
VTEC engine gives the high fuel economy at lower rpm. The valves open wide at higher rpm to
get the maximum power.

0
2
4
6
8
10
12
14
16
18
0100020003000400050006000700080009000
A/F
Engine speed(rpm)
Engine speed vs A/F

4-ENGINE SPEED vs BSFC:-

The graph shows the relation between the engine speed and bsfc. The graph shows that the brake
specific fuel consumption of the VTEC engine is decreased with the increase in the engine speed.
As here in the graph, when the speed is increased, the bsfc is started to low down. At low rpm, the
bsfc is more than that of the higher rpm.

Maximum bsfc : 1.89 kg/kWh @ 1409 rpm (min engine speed)
Minimum bsfc : 1.1 kg/kWh @ 2200 rpm (normal speed)

The graph shows the different variations of bsfc with the change in the speed of the engine. When
the engine speed is increased, the bsfc decreased immediately at first and then adjusted at higher
rpm

0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0100020003000400050006000700080009000
BSFC (
kg/kWh)
ENGINE SPEED (rpm)
E N G I N E S P E E D V C B S F C

5-ENGINE SPEED vs BRAKE THERMAL EFFICIENCY:-

The graph shows the relation between the engine speed and the brake thermal efficiency. Brake
thermal efficiency indicates how well an engine converts the heat from a fuel to mechanical
energy. As shown in the graph, it shows that at low rpm of the engine, brake thermal efficiency
is low (about 17%) and when the speed is increased, the efficiency is also increased but in a very
small value.

It means that at different rpm of the engine, the engine converts almost an equal amount heat
from fuel into mechanical work (a very little change in efficiency).

0
5
10
15
20
25
30
35
0100020003000400050006000700080009000
BTE (%)
ENGINE SPEED (rpm)
E N G I N E S P E E D V S B R A K E T H E R M A L E F F.

6-ENGINE SPEED vs VOLUMETRIC EFFICIENCY:-

Volumetric efficiency (VE) in internal combustion engine engineering is defined as the ratio of
the mass density of the air-fuel mixture drawn into the cylinder at atmospheric pressure (during
the intake stroke) to the mass density of the same volume of air in the intake manifold.
Volumetric efficiencies above 100% can be reached by using forced induction such
as supercharging or turbocharging. With proper tuning, volumetric efficiencies above 100% can
also be reached by naturally aspirated engines. The limit for naturally aspirated engines is about
130%; these engines are typically of a DOHC layout with four valves per cylinder. This process is
called inertial supercharging and uses the resonance of the intake manifold and the mass of the air
to achieve pressures greater than atmospheric at the intake valve. With proper tuning (and
dependent on the need for sound level control), VE’s of up to 130% have been reported in various
experimental studies.

Minimum volumetric efficiency : 98% @ 1409 rpm (min engine speed).
Maximum volumetric efficiency : 130 % @ 4109 rpm (normal speed).

The graph shows the relation between the volumetric efficiency and the engine speed. When VTEC
engine is started, its volumetric efficiency is 98% and when the speed is increased and the engines
in at higher rpm, the volumetric efficiency passes 100% due to the variation of the VTEC. At
higher rpm, the VTEC engine valves opens widely and the more volume of air is burnt.

0
20
40
60
80
100
120
140
0100020003000400050006000700080009000
VOL EFF (%)
ENGINE SPEED (rpm)
E N G I N E S P E E D V S V O L E F F

CHAPTER # 11

CONCLUSIONS

From the above graphs and results, let us compare both engines, one having a single cylinder
without VTEC and other VTEC 4 cylinder engine.

-:COMPARISON OF NON-VTEC SINGLE CYLINDER ENGINE vs HONDA’S VTEC
ENGINE:-

ENGINE SPEED vs BRAKE POWER:-

Non-VTEC:-
Maximum power : 1.776 kW @ 2886 rpm
Minimum power : 1.312 kW @ 1616 rpm
VTEC:-
Maximum power : 161.71 kW @ 8258 rpm
Minimum power : 14.9 kW @ 1409 rpm

From the above observation, we have noticed that in the single cylinder Non-VTEC engine,
maximum power is produce at 2886 rpm and the drop off from 1.776 kW to 1.578 kW when the
speed is increased from 2886 rpm.
0
20
40
60
80
100
120
140
160
180
0100020003000400050006000700080009000
power (kW)
engine speed (rpm)
engine speed vs power
VTEC POWERNON VTEC POWER

But in VTEC engine, the power is continuously increasing from lower rpm to higher rpm.
Maximum power is produced at higher rpm and minimum power is produce at lower rpm. There
is no drop off power in the VTEC engine. Maximum power is produced (161.71 kW) at 8258 rpm
and minimum power is produced (14.9 kW) at 1409 rpm.

ENGINE SPEED vs TORQUE:-

Non-VTEC
Maximum torque : 7.93 Nm @1616 rpm
Minimum torque : 4.89 Nm @ 3077 rpm
VTEC
Minimum torque : 101.68 Nm @1409 rpm
Maximum torque : 210.15 Nm @6404 rpm

From the above calculations, we noticed that in the single cylinder non VTEC engine, the
maximum torque is produced (7.93 Nm) at lower rpm and when the speed increase, the torque
decrease. The minimum torque (4.89 Nm) is produced at higher rpm.
On the other hand, in VTEC engine the minimum torque is produced (101.68 Nm) at lower rpm
and when the engine speed increase, the torque also increase and maximum torque (210.15Nm) at
6404 rpm and after this point, there is a drop off in the torque and when the speed is increased
above 6404 rpm, the curve of the torque starts dropping and the torque is decreased with the further
increment in the engine speed.

0
50
100
150
200
250
0100020003000400050006000700080009000
TORQUE (NM)
ENGINE SPEED (RPM)
E N G I N E S P E E D V S TO R Q U E
VTEC torquenon vtec torque

ENGINE SPEED vs BRAKE SPECIFIC FUEL CONSUMPTION:-
Non-VTEC:-
Minimum bsfc : 0.373 kg/kWh @ 1616rpm
Maximum bsfc : 0.923 kg/kWh @ 3077rpm
VTEC:-
Minimum bsfc : 1.121 kg/kWh @2644 rpm
Maximum bsfc : 1.812 kg/kWh @1409 rpm

From the above calculations, we noticed that in single cylinder engine, there is a minimum bsfc at
lower rpm and maximum bsfc is at higher rpm. The bsfc is continuously increasing when there is
an increment in the engine speed.
But on the other hand, in the VTEC engine there are variation in the curve of engine speed and
Bsfc. There is maximum bfsc at lower rpm and there is a sudden drop in the curve when the speed
is increased, further the bsfc is increased behave differently on different rpm. There is no constant
increase in the Bsfc like the other engine which are Non-VTEC.

0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0100020003000400050006000700080009000
bsfc (kg/kWh)
engine speed (rpm)
engine speed vs bsfc
VTEC bsfcnon VTEC bsfc

ENGINE SPEED vs BRAKE THERMAL EFFICIENCY:-
Non-VTEC:-
Maximum BTE : 20.34 % @ 1616rpm
Minimum BTE : 8.23 % @ 3077 rpm
VTEC:-
Maximum BTE : 28.69% @ 2644 rpm
Minimum BTE : 17.75% @ 1409 rpm

The above calculations shows that in a single cylinder there is maximum brake thermal efficiency
at lower rpm and minimum brake thermal efficiency at higher rpm. When the engine speed is
increased, the brake thermal efficiency start decreasing and there will be minimum brake thermal
efficiency at higher rpm.
On the other hand, in the VTEC engine, there is a minimum brake thermal efficiency at lower rpm
and a sudden increase in the curve of brake thermal efficiency, when the speed is increased and
there are variations and the curve shows that different behavior at different engine speed. The
curve is not constant, there are different variations in the curve at different rpm.

0
5
10
15
20
25
30
35
0100020003000400050006000700080009000
?th (%)
engine speed (rpm)
engine speed vs BTE
VTEC BTEnon VTEC BTE

ENGINE SPEED vs VOLUMETRIC EFFICIENCY:-
Non-VTEC:-
Minimum volumetric efficiency : 53.25% @ 3077 rpm
Maximum volumetric efficiency : 83.29% @ 1616 rpm
VTEC:-
Maximum volumetric efficiency : 130% @ 4109 rpm
Minimum volumetric efficiency : 96.3% @ 1409 rpm

The above calculations shows that, in the single cylinder engine, there is maximum volumetric
efficiency at lower rpm and minimum volumetric efficiency at higher rpm. When the engine speed
is increased, the volumetric efficiency starts decreasing and at the higher rpm, there is a minimum
volumetric efficiency.
On the other hand, in the VTEC engine, the volumetric efficiency exceed 100 %. The maximum
volumetric efficiency is 130% as per calculations. At lower rpm, the volumetric efficiency is low
as 98.55% and when the speed increases, the volumetric efficiency also increases. Volumetric
efficiency exceed 100% due to the variations of VTEC. At higher rpm, the engine valve open
widely and the more volume of air is enter.

0
20
40
60
80
100
120
140
0100020003000400050006000700080009000
vol eff (%)
engine speed (rpm)
engine speed vs vol eff
VTEC vol effNON VTEC vol eff

From the research and calculations, we conclude that VTEC system is more sophisticated than
earlier variable valve timing systems, which could only change the time both valves are open
during the intake/exhaust overlap period on the transition between the exhaust and induction
strokes.

By contrast, the I-VTEC setup can alter both camshaft duration and valve lift. I-VTEC technology
gives us:

? The best in vehicle performance.
? Fuel economy is increased.
? Emissions are reduced.
? Derivability is enhanced.
? Power is improved.

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

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