Compression ratio math?

art leong · 01-17-2012, 01:05 AM

I've just measured my motor. And would like to see what compression ratio others come up with?
Here are my specs.
Bore 3.480
Stroke 3.976
Flat of piston is .010 out of the bore
Head volume 49 cc
Head gasket thickness .077
Head gasket bore 3.50
Volume of cylinder with piston .355 down the bore is 47 cc
I believe that will give me a dome volume of 8.33 cc's
Head gasket volume is 12.14 cc's
Cylinder volume is 619.7 cc's

art leong · 01-17-2012, 01:20 AM

Sorry meant to post this in the tech section.
I've used some of the online calculators and I get some quite different answers.
Numbers vary from 11.7 to 1 to 13.0 to 1

NORMAN BARNARD · 01-17-2012, 01:23 AM

Art. My compression ratio program useing your info. Say's it's 13.1:1 normally aspirated at sea level. I also get the same cylinder volume as you do 619.7 cc's.....hope this helps.....norm

Alan Roehrich · 01-17-2012, 02:04 AM

Using the compression ratio calculator on my copy of Larry Meaux's PipeMax software, I get 13:1.

race watcher · 01-17-2012, 08:44 AM

Google compression ratio calculator. A nice site comes up with a number of different tools.

Ed Wright · 01-17-2012, 10:29 AM

Art, you should buy Pipemax. Very usefull.

01-17-2012, 01:05 AM	#1
art leong VIP Member Join Date: Dec 2001 Location: Richmond Hill, Georgia Posts: 2,003 Likes: 0 Liked 1 Time in 1 Post	Compression ratio math? I've just measured my motor. And would like to see what compression ratio others come up with? Here are my specs. Bore 3.480 Stroke 3.976 Flat of piston is .010 out of the bore Head volume 49 cc Head gasket thickness .077 Head gasket bore 3.50 Volume of cylinder with piston .355 down the bore is 47 cc I believe that will give me a dome volume of 8.33 cc's Head gasket volume is 12.14 cc's Cylinder volume is 619.7 cc's __________________ Art Leong 2095 SS Last edited by art leong; 01-17-2012 at 01:10 AM.

01-17-2012, 01:20 AM	#2
art leong VIP Member Join Date: Dec 2001 Location: Richmond Hill, Georgia Posts: 2,003 Likes: 0 Liked 1 Time in 1 Post	Re: Compression ratio math? Sorry meant to post this in the tech section. I've used some of the online calculators and I get some quite different answers. Numbers vary from 11.7 to 1 to 13.0 to 1 __________________ Art Leong 2095 SS Last edited by art leong; 01-17-2012 at 01:23 AM.

01-17-2012, 01:23 AM	#3
NORMAN BARNARD Member Join Date: Mar 2006 Location: EL PASO, TEXAS Posts: 156 Likes: 0 Liked 2 Times in 2 Posts	Re: Compression ratio math? Art. My compression ratio program useing your info. Say's it's 13.1:1 normally aspirated at sea level. I also get the same cylinder volume as you do 619.7 cc's.....hope this helps.....norm

01-17-2012, 02:04 AM	#4
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,097 Likes: 1,542 Liked 1,775 Times in 404 Posts	Re: Compression ratio math? Using the compression ratio calculator on my copy of Larry Meaux's PipeMax software, I get 13:1. __________________ Alan Roehrich 212A G/S

01-17-2012, 08:44 AM	#5
race watcher Junior Member Join Date: Nov 2006 Posts: 50 Likes: 5 Liked 1 Time in 1 Post	Re: Compression ratio math? Google compression ratio calculator. A nice site comes up with a number of different tools.

01-17-2012, 10:29 AM	#6
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 390 Times in 170 Posts	Re: Compression ratio math? Art, you should buy Pipemax. Very usefull. __________________ Ed Wright 4156 SS/JA