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i heard that the IS 300 engine is de-tuned version of the GS 300. it this true and if so, what is envolved in re-tuning the engine to make it as fast as the GS 300.
thankx for any help.
 

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I believe the only reason why the engine is slightly detuned from the GS300 is due to exhaust constraints... I assume they mean the headers or something, because they said it was because of space.
 

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I really won't call it de-tuned, rather I would say the power lost is due to a limitation. The reason it lost power is because it went to one exhaust pipe instead of two as seen in GS. This means you have restricted the amount of air going out of the engine which resulted in higher back-pressure. You can easily gain those power back by going to an aftermarket exhaust system that will reduce the back pressure to that of GS300. But remember, this is not a turbo car, you still need some back pressure to help the compression in the cylinder, so don't go too big on the pipe.

Daniel
 

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About the pipe diameter, if your going to be super or turbo charging your car you might want to look into bigger piping. I think for super charging they figure a 2.5" pipe is good(i think) but for turbo's the bigger the better...just not too big you don't want to scrape the piping on the road. I know for turbos the reason why you don't have to be concerned about the back pressure is because the turbo (or something) is creating the back pressure before it hits the headers. So when the turbo spools up you want a system that will get all that exhaust gases out asap. I think super's might work that way also...but I have no clue

[From TEG: I think the whole "backpressure" issue is a little more complicated than that]


[This message has been edited by TEG (edited July 15, 2000).]
 

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supercharger does not have to with exhaust since its compressor is mechanically driven (or electrically, depends). For supercharger, you should follow the same rule as N/A engine, i.e. tune the exhaust pipes so you will get a resonance wave that goes the opposite of the exhaust flow. This wave will act as a shock wave and help compressing the air/fuel mixture of the engine. This maybe hard to do for IS and most street cars since the only part you are allow to change is after the catalytic converter, so you will have a much more complex flow to consider. But this is how you tune a racecar exhaust, so try it if you think you are good fluid dynamicist, you will gain significant amount of power.

Daniel
 
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