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Old 04-10-2009, 08:05 AM   #4
S14DB
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Originally Posted by HYPNOTIK View Post
I think that is a horrible idea. You're not going to make anymore power. With higher compression your just going to have to pull timing to keep it from knocking. That's why most people replace there stock head gasket with a thicker one to lower the compression ratio. Compression has nothing to do with how much power a turbo can make anyway. A particular turbo will only support a certain amount of power no matter what motor you put it on or what the compression ratio of said motor is. Stock SR turbine will still only support ~300hp even if you put it on a V8. I think you need to read up on turbines and compressor maps.
Huh?


Forced induction raises your effective compression ratio. I don't know the PLAN numbers on the SR. But an cylinder can only hold so much pressure. You can increase cylinder pressure with a change in C:R, Cam Timing or adding forced induction.

The engine is going to produce the same power at the same effective C:R. Whether it is a high C:R engine and low CFM turbo or a Low C:R engine, high CFM turbo.

The advantage to running a high C:R is that it is always a high C:R. You don't have to wait on a turbo to spool up to raise the cylinder pressure. The exhaust velocity's will be faster and the turbo will spool faster.

The benefit is also the problem. With a high C:R it is harder to tune cause your margins are much closer and the effective C:R raises faster with boost. It is a lot easier and safer to run low C:R, high boost.


If you are going to build a high C:R motor for boost. Make sure you are getting bottom end parts designed for forced induction. Some of the high C:R stuff is designed for NA. Light weight to reduce rotating mass not hold increased cylinder load. I know a guy that got some nice 11:1 pistons that were designed for NA and he blew the ring lands out on them cause they were high on the skirt for ring seal. Didn't shroud them from the pressure. I'm sure the dome top vs a dish didn't help ether.
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