Ok so if I use lower compression pistons it will increase long-term reliability but, decrease torque. Right?

And by using lower compression pistons it will be better suited for a turbo aplication. Why?

 

low compression is good for turbo because youre adding more pressure into the combustion chamber. i dont know about long-term reliabilty though. and yes it will decrease hp which in turn decrease torque.

 

But how is lower compressiom adding more compression? I could just turn up the boost.

Is lower compression more or less air volume in the engine?

 

A lower compression is not necessarily "better" for turbo applications. A higher compression engine will make more power, howerver it is more difficult to tune.
For example, if you had a 11:1 engine running 5lbs, you could make say 300hp. If you had a 8.5:1 engine you could run 15lbs and make 300hp. However, it is much more difficult to tune 5-6 psi than it is to tune 15-20psi.

 

You want to lower compression if you go turbo, bucause our gas octane isn't high enough. If you run 12:1 CR and 10psi on race gas, it's fine. But you can't do the same with 92 octane gas. So yes, you are sacrificing off-boost hp, but lower CR allows you to run more boost on crappy gas.

 

There was a brief debate about high compression/low-boost versus low compression/high-boost sometime ago. A higher compression engine + forced induction will make detonation more likely to occur. The higher the compression, the more difficult it is to tune, and the less room for error.

There's also the argument of throttle response and power curve characteristics, but I won't open that can of worms.

Shingo

 

I dont know what compression my b20b pistons are but say if I run a lower compression with out turbo I will loose torque but gain longility on my engine right? And if I decide to run turbo later it will be easier to tune?

 

oh I'm building a frankenstien w/ b20b bottom stock crank still deciding on pistons 95 gsr head, intak and T/B. Hopefully some Toda cams?