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difference between turbo and NA pistons?
Posted: Wed Sep 15, 2004 6:43 am
by douglas vincent
A- is the stock turbo piston built/made stronger than the stock NA piston?
B- is the stock turbo piston "smaller" than the NA piston? as in is the turbo piston "shorter" than the NA piston so therefore lower compression?
Posted: Wed Sep 15, 2004 6:48 am
by evolutionmovement
IIRC what the turbo piston looked like, the turbos have a more dished surface.
Steve
Posted: Wed Sep 15, 2004 3:33 pm
by entirelyturbo
That's for a decreased CR right?
Posted: Wed Sep 15, 2004 5:37 pm
by Matt Monson
You would be surprised how little material needs to be removed from the top of the piston to make significant changes in CR. This is part of why really high end forged pistons get hand finished. I am guessing withouth looking up the specs, but I bet the NA and Turbo pistons are dimensionally the same and that the difference is only in the dish...
Posted: Thu Sep 16, 2004 3:04 am
by morgie
bore is the same, build process not the same..
you don't want na pistons into a turbo engine. I asked the Director of Quality insurance of Subaru Canada and he strongly recommended not to do so.
Posted: Thu Sep 16, 2004 7:41 am
by douglas vincent
I was looking for turbo pistons into the NA engine
Posted: Thu Sep 16, 2004 8:37 am
by 94L_wagon
Why?
Are you planning on using some kind of forced induction on said NA engine?
Just being nosey - its none of my business so feel free to be rude or ignore
.
EDIT : Ignore that - I assume that the supercharger has something to do with it!
Posted: Thu Sep 16, 2004 5:28 pm
by Matt Monson
douglas vincent wrote:I was looking for turbo pistons into the NA engine
I've been thinking of doing the same with my "spare" NA EJ22. I figure with the lower CR, even with the open deck block, an old NA EJ22 could probably hold 15psi of boost out of a VF-11, TD04, or similarly sized turbo...
Posted: Thu Sep 16, 2004 6:04 pm
by professor
You are right that it takes very little change to lower or raise the compression ratio. See this article where they explain not only how to measue it, but how they raised the compression ratio from 9:1 to 9.5: just by fitting thinner head gaskets. Explains why the "head shave" technique for class-illegal "stock" engines works so well.
It would not surprise me if the same pistons are just dished to lower the ratio, surely someone must have an old turbo piston to send you to compare.
Posted: Thu Sep 16, 2004 6:05 pm
by professor