92ZR1WANNABE

Hello all.

I am currently building a 355 LT1 and have a quick question about pistons.

I currently have the following:

Speed Pro Z345NP - Federal Mogul Cast Pistons

These were in the motor when I bought it, so they cost me nothing. They are nothing special however I was a little confused by the fact that they have a 1.540 in. compression distance.

I plan on buying these to use instead:

Speed Pro ZH345NCP30 - Speed-Pro Hypereutectic Pistons

These are hypereutectic , with the skirt coatings. They also have the proper 1.560 in. compression distance that I was looking for.


Is there any reason to not use these pistons? I am looking to build a good solid street motor that will see only occasional trips to the track. Keeping that in mind I do not see the need to spend $400+ on forged pistons, as a set of the ZH345NCP30s cost approx $115 bucks (no rings).

As far as compression ratio goes I am looking at the following:

Bore: 4.030
Stroke: 3.48
Head gasket: .039
Deck Height: .020
Piston Top Volume: 5 cc
Combustion Chamber: 54cc

It all leads to approx 11.19:1 compression. Is this going to be pump gas happy? (93 octane out here in the southwest).

If I keep the other pistons i'm looking at approx 10.63:1 compression (cast pistons).

Thanks again!

CFI-EFI

More than likely. There are other variables that play a part. Your cam timing has more to do with cylinder pressures than the CR.

RACE ON!!!