Need help calculating compression ratio
Thread Starter
On The Tree
Joined: Jan 2011
Posts: 107
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From: Middle of Nowhere, IL
Need help calculating compression ratio My engine is a 5.3L block that has been bored to 3.8" and has the stock 3.622" stroke. The pistons are aftermarket Wiseco flat tops with -2.2cc valve reliefs in them. I have a deck height of exactly 0.000", the pistons at TDC sit completely flush with the block. I will be using a GM MLS gasket which I believe is 0.054" compressed. Heads are 243 castings that currently are 63cc and I am considering going down to 59cc so I can get my compression ratio closer to 10.5:1 or 11:1. Any help with the calculation will be appreciated and thanks in advance. If u am leaving any measurements out let me know and I'll post them as soon as possible.
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Thread Starter
On The Tree
Joined: Jan 2011
Posts: 107
Likes: 1
From: Middle of Nowhere, IL
Thanks. I just thought the wiseco paperwork said 10.25:1CR and with my milled heads to 59cc I thought I should have more then 10.46:1CR if the stock 62cc heads would give those pistons a 10.25:1CR. Especially since I'll be using the same stock head gasket.
Thread Starter
On The Tree
Joined: Jan 2011
Posts: 107
Likes: 1
From: Middle of Nowhere, IL
So I did calculate it correctly because my builder told me the same compression basically as the links you guys listed. So with my 59cc heads I'll be at 10.5:1CR so I'll be good for n/a or nitrous if I add some. Or I can throw some 317 heads on with stock chambers and be close to 9:1CR and could turbo the setup later.
