Khoo, Aik Soon
(2014)
Simulation And Experimental Studies Of Intake And Exhaust Tuning For Automotive Engine Low-End Torque
Enhancement.
Masters thesis, Universiti Sains Malaysia.
Abstract
Modern passenger car engines have been “down-sized” for improved fuel
consumption, resulting in high speeds to obtain good performance. Consumers,
however, are demanding improved low-end torque for improved drivability. The
target engine; a 4 valve per cylinder, 1.6L engine with two intake cam profiles and 2
intake runner lengths, was modeled and correlated with measured engine
performance characteristics (power, torque, etc.); and pressure traces from
combustion chamber, intake and exhaust manifolds to establish the confidence level
in the model's prediction. The model was then optimised for low-end torque by
manipulating exhaust manifold configuration, exhaust runner length, intake diameter
and intake runner length. It was found that the original exhaust system is too short
and gives uneven exhaust cross-charging among the cylinders. Simulation result
indicated that a 2.7-5.6% improvement in torque could be realised with an evenly
cross-charged and longer exhaust runner. A 2% torque improvement was predicted
by changing the intake manifold geometry to smaller diameter. The target engine
was subsequently modified with new set of exhaust manifold and intake runner.
Result showed a torque improvement of 2.7-4.5% at lower engine speed over the
base design by exhaust tuning. Effect of intake tuning was not significant but it
showed a similar trend as indicated by simulation.
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