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Discussion Starter #1
Hey All,

I have been recently trying to figure out compression for my 351W build, so I have been using the Compression Calculator at www.JeepStrokers.Com
The direct link is here... Just input our engine specs and you will have static and dynamic compression ratios. As best as I can tell, the specs for my 88 block are...

8 cylinders
4.0" bore (stock)
3.5" Stroke (stock)
combustion chamber depends on your head, I used 60cc for gt-40 cobra heads
.023" Deck Clearance
Gasket Thickness depends on your gasket
Gasket Bore Same as above
Dome/Dish/Valve Relief depends on your pistons
5.956" connecting rod length
your cam specs

Check it out, I have found it very useful...:thumbup

I also own a 2001 Jeep GC with a 4.5 Stroker that I built, thus the Jeep Strokers website reference:brownbag.


TTB for short
2,189 Posts
GT40 (not P heads) run around 64-66cc with Cobra heads leaning more toward 64cc. Explorer heads vary more, most Cobra/Lightning/Ford Motorsports heads fall on the smaller side of that range and don't seem to vary as much between cylinders. FWIW Exploder GT40P's run 59-61cc but every set of Ford Motorsports GT40P's I've cc'ed are dead nuts 59cc.

Deck Clearance should be .0145 according to my book, but I've heard the .023 number thrown around a lot so there might be some truth to it. My book says '77 and up were .0145 but maybe they changed the compression height with the EFI pistons.

regular old head gaskets should be 4.10 bore and .041 thick

stock pistons are 15cc dish

For comparison I just put together a stock rebuilt '83 bottom end with gt40P's (12.85cc pistons, .41 gaskets, 59cc chambers, .0145 deck Clearance, wimpy SD cam) and I have a static compression ratio of 9.75:1 and 190psi cranking pressure. Pushing the limits of pump gas, but it runs strong for what it is.
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