LT1 Pistons and compression ratio question
Thread Starter
Racer
Joined: May 2005
Posts: 497
Likes: 1
From: Casa Grande Az
LT1 Pistons and compression ratio question
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!
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!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
RACE ON!!!
