Racingjunk Forums

Racingjunk Forums (https://www.racingjunk.com/forums/index.php)
-   Engine Tech (https://www.racingjunk.com/forums/forumdisplay.php?f=9)
-   -   compression ratio (https://www.racingjunk.com/forums/showthread.php?t=23917)

gasalley 04-18-2009 06:40 PM

compression ratio
 
can anyone tell how to figure compression ratio without taking the heads off?
I have a sbford 302,stock pistons w/.030 overbore, `78 351W heads w/ 202 intake valves, milled(don't know how much). :?

JimmySmith 04-19-2009 06:40 AM

CR
 
You would have to know what piston and what chamber CC you have to figure this. Later J.Smith 4621 racing

desoto30 04-19-2009 10:24 AM

the only way I'd imagine that this could be done would be to fill the cylinder @ tdc & bdc with fluid & calc from that,though sealing may present a problem

Jordan1984 04-19-2009 10:49 AM

You can buy a compression gauge from an auto parts store that you put in place of the spark plug and bump the engine over. It has a reset on it that locks it in place while you are bumping the engine from the driver seat, or you could have a buddy do it while you watch it. Put it in every cylinder and write it down on paper, then add them all together. Take that number and divide it by the number of cylinders, and you will get a round about compression ratio.

MEMRACING62 04-19-2009 12:27 PM

??? :shock: :shock:

suicidebomb 04-19-2009 02:52 PM


Originally Posted by MEMRACING62
??? :shock: :shock:

Confused? me too :shock: :?

MEMRACING62 04-19-2009 02:57 PM

must some kinda new math!! :lol: :lol:

wrightway 04-19-2009 03:41 PM


Originally Posted by Jordan1984
You can buy a compression gauge from an auto parts store that you put in place of the spark plug and bump the engine over. It has a reset on it that locks it in place while you are bumping the engine from the driver seat, or you could have a buddy do it while you watch it. Put it in every cylinder and write it down on paper, then add them all together. Take that number and divide it by the number of cylinders, and you will get a round about compression ratio.


:shock: All that will get you is an average cranking psi :roll:

Tod74 04-19-2009 05:15 PM

Holy Cow My compression ratio is 245 to 1!!!!

BEAST477 04-19-2009 05:18 PM


Originally Posted by Tod74
Holy Cow My compression ratio is 245 to 1!!!!

WOW Tod, where do you get fuel for that? :shock:


All times are GMT -8. The time now is 11:58 PM.