Bracket Talk
figuring compression formulas

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November 09, 2024, 09:18 AM
wideopen231
figuring compression formulas
Just a info post. It seems lots of way to figure compression. Looking threw internet info.

The one I have always used and probably amost impossible tihe chevy.
It uses pored cc' rather than calculating each piece. It does so with assmebled engine. Thats why works wiuth Hemi but not many others.

I Leve engine on stand fron to rear and head surface side to side with engine rotated head up. Put piston TDC and measure amount to fill to bottom of plug hole;

Formula is. ( 1/2 x b) squared x 51.48 time stroke= swept volume SV plus cc's poured / cc's poured = compression.

It can be used to figure stuff like gasket ccs too and few other things.

I know with chevy you normally figure gasket,combustion chamber, deck hight and dome voulme. Man thats lot of work,LOL

So what formula do you use?




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November 10, 2024, 11:36 AM
Goob
Don't make it harder than it needs to be.

Gasket cc's are listed in the catalogs.

Most piston manufacturers give you the dome cc's, or dish cc's.

The only unaccounted for volume with these calculators is the space to the top ring.

Intractive calculator


"Despite the high cost of living, it remains popular."
Dave Cook
N375
November 10, 2024, 02:05 PM
wideopen231
Along with deck height. Valve seat depth which will effect chamber volume.

Not making hard here its chevy guys that have it hard. Hell I just b olt together and take a measurment of total volume and done. Well I do it two or 3 times just to check me.




America home of free. Brought to you by 2nd amendment.
November 10, 2024, 04:26 PM
Goob
quote:
Along with deck height. Valve seat depth which will effect chamber volume.


Deck is in the calculations, you pour check the head cc's.

Did you look at the link?


"Despite the high cost of living, it remains popular."
Dave Cook
N375
November 11, 2024, 08:41 AM
Greg Kelley
I use the one on Diamond Pistons web site.


GK - www.MotorSportsInnovations.com
609-265-2110 GKelley@MotorSportsInnovations.com