Compression Ratio Estimate
Thread Starter
Joined: Mar 2007
Posts: 1,698
Likes: 3
From: NE Pennsylvania
Car: 85 Iroc-Z
Engine: 383 TPI Procharger D1SC
Transmission: TKO600
Axle/Gears: Strange S60 3.73
Compression Ratio Estimate
I am going to be building a 383 shortly and am wondering around what my compression ratio will be. It will be a 383 (4.030 bore 3.75 stroke) with 65cc cylinder heads, +5cc pistons, and probably a .035 head gasket. I have tried calculating it but usually get different estimates, most of them being around 10.7:1. Does this sound correct? And I will be using a summit 383 block, so I believe the block has a stock deck height.
Supreme Member
Joined: Sep 1999
Posts: 7,072
Likes: 13
From: Philly, PA
Re: Compression Ratio Estimate
You're talking about flattops with 5cc worth of valve reliefs? If so, then yes, you'll be somewhere in the mid 10s.
I ran your combo with the pistons sitting .025" in the hole at TDC plus a FelPro .039" head gasket (~9cc) and got 10.31:1. Same same but using a .028" GMPP head gasket and it's 10.65:1.
I ran your combo with the pistons sitting .025" in the hole at TDC plus a FelPro .039" head gasket (~9cc) and got 10.31:1. Same same but using a .028" GMPP head gasket and it's 10.65:1.
Thread Starter
Joined: Mar 2007
Posts: 1,698
Likes: 3
From: NE Pennsylvania
Car: 85 Iroc-Z
Engine: 383 TPI Procharger D1SC
Transmission: TKO600
Axle/Gears: Strange S60 3.73
Re: Compression Ratio Estimate
Yeah I meant 5cc worth of valve reliefs. Thanks
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