Compression ratio calculators??

art leong · 11-22-2009, 04:21 PM

I've used a few different sites that come up with 3 different numbers.
Specs are 3.484 bore, 3.976 stroke, 10.2 cc dome, deck height 0, gasket thickness .074
gasket bore 3.51. Cylinder head volume 48 cc's
The sites I've found vary by as much as 2 full points (13 to 1 up to 15 to 1) Using the same input data (some of the sites don't ask gasket bore size) I would think it shoulkd be within half a point.

Adger Smith · 11-22-2009, 06:07 PM

You have a PM
You have more than enough

jmcarter · 11-22-2009, 06:08 PM

Art, did you try Wallace Racing calc?

http://www.wallaceracing.com/cr_test2.php

Jeff Lee · 11-22-2009, 08:39 PM

I find this site is real simple for numerous race calculations:
http://users.erols.com/srweiss/index.html

art leong · 11-22-2009, 10:26 PM

What gets me is I get 15.70 on one site 14.62, 16.30 on another
This is with putting the same numbers in Some take in to account the head gasket bore others don't. But it shouldn't come to 2 full points. I think there is a formula in an old rule book I can do on paper.

Ed Fernandez · 11-22-2009, 10:44 PM

Quote:

Originally Posted by art leong

What gets me is I get 15.70 on one site 14.62, 16.30 on another
This is with putting the same numbers in Some take in to account the head gasket bore others don't. But it shouldn't come to 2 full points. I think there is a formula in an old rule book I can do on paper.

Artie,make sure you bolt that hood down good and tight.............................................

art leong · 11-22-2009, 11:00 PM

Quote:

Originally Posted by Ed Fernandez

Artie,make sure you bolt that hood down good and tight.............................................

Ed I have my front mounted parachute on that hood

Adger Smith · 11-22-2009, 11:23 PM

Art,
I think there is a formula in both the How to Build Books. Both Small Block and Big Block. I have it on my shop computer and will PM it to you tomorrow. It will come out with in a .00 of what I sent you.
Adger

NORMAN BARNARD · 11-22-2009, 11:36 PM

Useing your info. Above i got 13.540:1, normally aspirated at sea level........this is an older computer program i use with sprint car
motors.

art leong · 11-23-2009, 09:05 AM

I'm going to run the motor the way it is. But I was perplexed at the variation in the different programs. I wonder if the calibations are done by nhra in different divisions LOL.

11-22-2009, 04:21 PM	#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 calculators?? I've used a few different sites that come up with 3 different numbers. Specs are 3.484 bore, 3.976 stroke, 10.2 cc dome, deck height 0, gasket thickness .074 gasket bore 3.51. Cylinder head volume 48 cc's The sites I've found vary by as much as 2 full points (13 to 1 up to 15 to 1) Using the same input data (some of the sites don't ask gasket bore size) I would think it shoulkd be within half a point. __________________ Art Leong 2095 SS

11-22-2009, 06:07 PM	#2
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Compression ratio calculators?? You have a PM You have more than enough __________________ Adger Smith (Former SS) Last edited by Adger Smith; 11-22-2009 at 06:24 PM. Reason: SP

11-22-2009, 06:08 PM	#3
jmcarter VIP Member Join Date: Dec 2008 Location: Richmond Hill GA (and Port Ludlow WA) Posts: 4,295 Likes: 2,378 Liked 3,174 Times in 971 Posts	Re: Compression ratio calculators?? Art, did you try Wallace Racing calc? http://www.wallaceracing.com/cr_test2.php __________________ Jim Carter 2340 Super Stock 2340 SST/2340 Stock Set another place at the table

11-22-2009, 08:39 PM	#4
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: Compression ratio calculators?? I find this site is real simple for numerous race calculations: http://users.erols.com/srweiss/index.html __________________ Jeff Lee 7494 D/S '70 AMX

11-22-2009, 10:26 PM	#5
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 calculators?? What gets me is I get 15.70 on one site 14.62, 16.30 on another This is with putting the same numbers in Some take in to account the head gasket bore others don't. But it shouldn't come to 2 full points. I think there is a formula in an old rule book I can do on paper. __________________ Art Leong 2095 SS

11-22-2009, 11:23 PM	#8
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Compression ratio calculators?? Art, I think there is a formula in both the How to Build Books. Both Small Block and Big Block. I have it on my shop computer and will PM it to you tomorrow. It will come out with in a .00 of what I sent you. Adger __________________ Adger Smith (Former SS)

11-22-2009, 11:36 PM	#9
NORMAN BARNARD Member Join Date: Mar 2006 Location: EL PASO, TEXAS Posts: 156 Likes: 0 Liked 2 Times in 2 Posts	Re: Compression ratio calculators?? Useing your info. Above i got 13.540:1, normally aspirated at sea level........this is an older computer program i use with sprint car motors.

11-23-2009, 09:05 AM	#10
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 calculators?? I'm going to run the motor the way it is. But I was perplexed at the variation in the different programs. I wonder if the calibations are done by nhra in different divisions LOL. __________________ Art Leong 2095 SS

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