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turbo pistons

1K views 15 replies 4 participants last post by  boredandglued 
#1 ·
im looking to purchase a set of forged pistons for an engine im slowly building. 4.125 bore, 3.75 crank, 6" rod. this engine will be turbocharged. so my question is what are the main factors i should take into consideration when purchasing pistons for a turbocharger? ex: im shooting for around 8.5:1 cr should i go with dished or d-dished pistons? when it comes to compression height is more better or is less better? should i look for a piston with the top ring closer to the top of the piston or further away? ive done a little math and if im correct a piston with a 1.125 compression height with a 6" rod and 3.75 crank should put me right at 9". is there an ideal quench area ( i think thats what its called) for a turbo setup? thanks for any and all advise!
 
#2 ·
These fellows say it better than I could.....
Piston Tech Tips from Kennedy's Dynotune

Squish is said to be not quite as critical in a blown application because the mixture is homogenized by the blower on the way into the cylinder. I, however, would still build with a 0.035" to 0.045" squish.

Moving your cursor over "Tech Info" on this home page will yield a drop-down with all the information you could possibly want....
Blowers : Blower Drive Service, We Deliver Horsepower
 
#5 ·
Depending on boost levels a tight squish can create more problems than it solves- some purpose built turbo race engines run have .100" squish to slow down the mixture.

It's that old "if some is good then more is better" way of thinking that can sometimes lead to trouble.

With 8,5:1 compression I assume he'll be running at least 15psi.
 
#4 ·
heres what i came up with JE pistons part #242885-8, 6" rod, 3.75 crank,4.125 bore...... if my math is correct i can deck my block to 9.015, use a 72cc head, use a 4.125/.030 (compressed) head gasket...this should give me real close to 8.5:1 c/r with a squish area of .045. does this sound correct? also are these pistons a good choice for a turbocharged motor?
 
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