compression ratio

[cumminsram]

Is there any way to determine say if you take x amount of thousanths off the top of a piston it gives you x compression ratio. Im looking for 14 or 15 to 1. Or x amont in valve relief equals x compression ratio?

 

[LReiff]

If you're tech enough!

 

[loganp]

I know that a .020" over stock thickness head gasket takes your compression down to 16.4:1.

 

[cumminsram]

thank you both,anyone chime in on valve relief and compression ratio

 

[brushpuller]

If you're tech enough! [/QUOTE

An i missing somthing here, just looked at that web site and that calculater for compression doesn't take in the piston volume... If so, that's no good for calculating compression!!!

 

[CL2000]

You just use the head chamber for that, but it dosent have piston to deck height

 

[White Knight]

Jerrod Glover explained it in a thread a couple of days ago:

Good idea, before anyone can figure the cr there are a few things that need to be measured:
Bore, is it standard, I think so.
Head Gasket thickness, you will want the crushed measurement.
Piston potrusion, how far above the deck is the piston on your motor.
Valve pocket cc's, Time to get the burette out tell us how many cc's there are with the valves in since they add to the cylinder volume.
Valve relief Diameter, How big of a valve do you want to run and how much over that do you want to cut the opening.
If I remember correctly you have Mahle #286110 piston with 47.1 cc bowls

Displacement = (Bore ÷ 2)2 x 3.14 x Stroke x 16.387
Head Gasket space = (Bore ÷ 2)2 x 3.14 x Gasket thickness x 16.387064
Deck Height space = (Bore ÷ 2)2 x 3.14 x Deck Height x 16.387064
Compressed Volume = Head Gasket space + Deck Height space +
Piston Top volume + Combustion chamber volume
Uncompressed Volume = Compressed Volume + Displacement
Compression Ratio = Uncompressed volume ÷ Compressed volume

(16.387 is a number than converts cubic inches to cc's.)

 

[brushpuller]

Jerrod Glover explained it in a thread a couple of days ago:

Yep...thats more like it!!!