What differences are there between these two motors, what accounts for the 15 hp gain in the RS but identical torque to the GT3? I know the RS has 12.2:1 compression versus "only" 12:1 in the GT3; anything else? With torque being the same, can you really feel the difference in power?

Is there any good way to improve power and torque in these engines without tearing them apart and rebuilding them; ecu flashes make only a small difference as compared to the differences a flash in the turbo models?

 

The intake might be different, the exhaust is titanium in the RS. The main difference as far as engine feel is the single mass flywheel and the shorter gearing in the RS.

 

The RS intake manifold/plenum is different......I believe that is where a majority of the difference came from as I have read for
the HP/TQ differences in the engine itself. Looking at the doc, it looks as-if they altered the -13% by just a different final ratio
change and altered 6th gear alone. (Not sure on that one)

 

how much of a job is it to change the 3 flywheel to the 3rs set up? with parts and labor does it even become worth it for the 15 hp?

 

^to my knowledge the flywheel doesnt add any power, just lets the engine Rev quicker.

You could get the RS intake with matching decklid(has 2 scoop intake and a bigger scoop on the decklid) , but it does seem the extra power mainly comes from the higher compression ratio.

 

I don't think the intake manifold is different, rather just the intake. I think that's where the delta comes from. A light weight flywheel will give you a few ponies if measured on a chassis dyno (measured @ the wheels). Technically the motor isn't making any more power, but you are reducing the drivetrain loss by a small factor. I think the .2 GT3 all have the .1 RS light weight crank pulley so no difference there.

 

if you are talking about the .2 gt3's

intake
exhaust
gearing is shorter on the RS, more like the cup cars

 

yea i know it wont get you the 15 hp, was typing the post and got side tracked and didnt realize what i posted. it will get you less spun wieght and maybe a few hp to the wheels ( freed up due to the less mass to be spun ) but how much faster are you going to be able to rev and will it make much a difference with out the gearing changes?

 

How did they raise the compression ratio? Are the pistons different?

 

I may be incorrect, but I do not believe that altering the flywheel weight affects measured power output. Nor does altering gear ratios.
The simplest way to look at the former is to imagine an infinitely light flywheel. Would the power climb proportionately, approaching infinity? Probably not. Moreover, if power was so sensitive to rotating mass (including flywheel), car companies would be doing a lot more than the occasional titanium connecting rods to lighten mass.
Re the gear ratios, I believe that dynos are not affected by such changes though ensuring that the car remains in the center of it's powerband contributes to a good 'run'.

 

That may be true, but a light flywheel should allow you to spin up a chassis dyno roller more quickly due to less mass to move, which would result in higher measurable horsepower than the same car with a heavier flywheel. Unless I'm missing something of course.

 

Probably a thinner head gasket. The displacement remains the same.