I dont like how so many new cars, including the evo take so long to settle back to idle after blipping the throttle to give it a rev.
For example, the 4 cyl. streetbikes have a nice quick rev - the motor spins up fast and settles right back to idle quickly.
What is responsible for that difference? Is it the compression ratio? Stroke?

Is there anything we can do in terms of tuning that would improve this on the evo?

Thanks!

 

without really knowing the answer i was told it has to do with emissions.

with that being said, i know now that i have a lightweight flywheel the car seems to rev, and settle back down a bit quicker than stock

 

The difference is due to several things:

(1) Inertia - the flywheel/clutch mass of a superbike weighs very little, which enables the engine to accelerate/decelerate very quickly when revved in neutral. A superbike can get away with this because it weighs very little, and does not need much rotating mass to get it moving from a stop the way your heavy EVO does.

(2) Throttle body - any engine with individual throttle bodies can be tuned to deliver much quicker response than an engine with a single TB. ITBs are actuated right at the port, so things happen instantly. A single TB setup has a plenum that acts as a buffer, and that reduces the quickness of the response.

(3) Tuning - OEMs tend to tune engines to decelerate more slowly to minimize the chance of stalling if the car is shifted into neutral at speed, which would cause a loss of power steering and braking.

 

The major difference with the bike is #1 your referring to an engine thats 1000cc which is 1/2 our engine.. or a 600cc which is near 1/3 our engine.. next is piston and rod weight.. The pistons and rods weigh so much less and the crank is probably 1/2 the weight of an evo crank.. Rotational mass is why bikes rev up so quick.. Also, being all motor is a huge difference.. I have heard K series hondas that rev almost as quick as bikes..

 

I really dont think it has much to do with engine size.
In terms of size, what about old v8's.... alot of those settle back to idle very quick....I had a carbureted chevy 350 that would act like this... it was nothing special, and didnt have a high compression come to think of it. I think its rotational mass is much greater than our evo's....

I really feel like it has something to do with computer control of engines somehow...could it be emissions related?

 

lighter flywheel will make the engine rev faster, but on the highway if you are cruising, if you let go the throttle, speed will drop faster with lighter flywheel.

 

thats only 1/2 of what he asked though.. he said, how quick a bike revs and then settles down.. V8's hardly rev anything like a bike.. As far settling down it could be a # of reasons including the emissions related parts we have on the car.. I was focusing more on why a bike revs so quick and snappy compared to a 2.0L motor..

 

If you hear some of the 2nd and 3rd generations RX7 built in Puerto Rico you will be very impressed and amazed at how the rotary engines rev. If you are mechanically incline and willing to take the challenge of maintaining a rotary engine and fitting it with the best Apex seals available in the market every so often you will find yourself with one of the fastest revving engines in the market ever.