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I have a new LSX 454 finished block, Wiseco Pistons 4.850 bore, LS7 Crank 4" Stroke, 6.125" rods. This should net me a 440 ci build but when I plug numbers into Compression Calc. I get screwed up #s. like 4.3:1. I cant figure out where I am screwed up. Can anyone help?
If my calcs are correct, you need a 4.185 bore to get to 440 cid with a 4" stroke. Here's the static/dynamic compression calculator I use https://www.jeepstrokers.com/forum/calculator/ There are others out there that work just fine. This is just the first one I played with and learned how to use.
You are correct, however that was a dyslexic typo on my part. I have been using the correct 4.185 bore when calculating. Some of the calcs are difficult to get if you don't already have some values like piston compression height or piston dome cc.
I have a new LSX 454 finished block, Wiseco Pistons 4.850 bore, LS7 Crank 4" Stroke, 6.125" rods. This should net me a 440 ci build but when I plug numbers into Compression Calc. I get screwed up #s. like 4.3:1. I cant figure out where I am screwed up. Can anyone help?
As you have realized you need a lot information about components before you can calculate compression ratio.
You can make assumptions until you have known values. For piston deck clearance you can use the stock below deck of .007. If you surface the block this will likely change depending on the zero deck of your pistons, but can give you an approx.
Also, when looking into this for you I've realized I've been entering my domed pistons into this calculator as -2.8 but the negative is for dished pistons. So my CR is about .5 higher than I thought, lol. Oops.
Help with new 440 build
