ICE, the most crucial part of flow restriction is at the intake and exhaust
valve. Well designed valve can be a major factor in decreasing the air flow
resistance into the combustion chamber. The lifting of the intake valve must be
enough to allow air suck into the cylinder with minimal resistance and
restriction. Valve lift is one of the significant parameter that can affect the
engine performance 5.
intake cam profile diagram 5.
of the best way to increase engine torque and power is pair the effect of
variable valve timing with valve lift. Variable valve timing and lift have
proven to increase power output in high engine speed and good stability in low
engine speed 13. A study conducted by James, Mckee and
Russel (2006) shows that the variation of valve timing and valve does have
significant effect on the engine torque. The engine use for the study is a DOHC 600cc inline 4 Yamaha YZF R6 engine for Formula
SAE application. The objected of the simulation study is to develop an engine
that can deliver the maximum torque as possible over a wide range of engine
speed. The study invovle in designing a new intake camshaft to be tested on the
engine and compare the result with the standard ones. Maximum engine torque ca
be achieve by combining the effect of valve timing and valve lift 14. The study also involved in modifying the
plenum and runners. The simulation was performed and the data comparison
between the standard camshaft and the modified camshaft parameter is as shown
in Table 2.2.
Table 2.2: The design
variable comparison of the standard and modified engine 14.
comparison between the standard and modified intake cam 14.
Figure 2.11: The result
of modified and standard intake camshaft on torque 14.
Based on Figure
the modified intake camshaft with higher valve lift and different valve timing,
the engine torque increases with the engine speed. Although the result is based
on the combination of other modified parameters, but still the valve lift can
be considered as one of the parameters that can affect engine performance. A
study done by Kutaeba shows that at a certain engine speed, the valve lift can
affect the engine torque 15.
Figure 2.12: The
variation of valve lift on brake power at 2500rpm of engine speed 15.
Based on Figure
the higher the valve lift, the more brake power the engine will produce. The
increase in valve lift is proved to be beneficial to the engine performance 15. The increasing valve lift also increases the brake
power. Therefore, from the findings of the studies, it is confirmed that with
variable valve timing and lift, maximum brake power and brake torque can be
Engine Simulation Software
is a software commonly used in the automotive industry by car manufacturers and
Original Equipment Manufacturers (OEM) companies. It is an engine performance simulation
software enable user the built engines, run simulations, and display results
based on what they have built. User can build their own 1D engine block can
specify the parameters needed to build a complete engine. The simulation is
then performed and the results can be displayed. Various result can be selected
depend on the desire of the user. In term of engine performance, the results
that can be shown is brake power, brake torque, thermal efficiency, volumetric
efficiency and fuel consumption.
the analysis and simulation of this case study, GT-Power software will be used.
The 1D engine block diagram is constructed based on the standard parameters
provided by the manufacturer. The engine that will be used in this study is
Proton Iriz 1.6L VVT engine. The engine with standard parameters will run and
the results of the engine performance is recorded. The engine performance will
be analysed based on brake torque, brake power, volumetric efficiency, brake
mean effective pressure, brake specific fuel consumption and residual gas. Then,
the result will be compared with the engine performance after the modification
of the parameters mention above, which are plenum volume, intake runner length,
valve timing and valve lift.