Quote:
Originally Posted by Reaper
I think its not worth buying another turbo when he can just put pistons in it and achieve his result at a lower psi and will make more usable torque.
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The pistons aren't the problem. The rods are.
Clearly he just wants to buy a built block. One that comes in at 9.0:1 . What I am saying is that a 2L at that static comp using a gtx2867r is a great combination; because the motor running at that comp means the turbo will be boosting harder; and it's more efficient when boosting harder. So that comp and a gtx2867r end up being a great combo.
Run high static comp, the motor is more efficient. Because the motor is more efficient it means it's less of a restriction. Because it's less of a restriction it can ingest more air. This means to make the same power the turbo is operating at a lower boost level. This isn't necessarily a good thing.
Look at any modern turbo and note where the choke line is at given pressure ratios. Where the choke line extends it's furtherst to the right should be the target pressure ratio. This means that running lower static comp so that the turbo is operating at its ideal pressure ratio will result in optimum power.
That's why people running a gtx28 at 7psi will say the turbo will choke in the top end. Look where the choke line and therefore the efficentcy zones at that pressure ratio on the comp map and you'll see why. Now if they ran lower static comp, then the turbo can operate at a more ideal pressure ratio; and the setup will make more power with the same turbo.