Compression ratio calculators??

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.

Dave Casey · 11-23-2009, 11:17 PM

13.54 to 1

I look at as the volume with the piston at bdc divided by the volume with the piston at tdc

convert all values to cc's is easiest for me

16.387 cc's per cu inch

bore and stroke volume + deck volume + chamber volume +gasket volume-dome volume
divided by
deck volume + gasket volume + chamber volume - dome volume

art leong · 11-23-2009, 11:27 PM

Quote:

Originally Posted by Dave Casey

13.54 to 1

I look at as the volume with the piston at bdc divided by the volume with the piston at tdc

convert all values to cc's is easiest for me

16.387 cc's per cu inch

bore and stroke volume + deck volume + chamber volume +gasket volume-dome volume
divided by
deck volume + gasket volume + chamber volume - dome volume

Thats the way i thought it was calculated. But why are the calculators on line so far off? It seems like simple math to me. I just wasn't sure of the formula.

Adger Smith · 11-25-2009, 09:08 AM

In doing a little number movement with most of the on line calculators I think they are not figuring the dome vol. + or - properly in the formulas.
Art,
Daves formula was the one I had at the shop that I said I would PM to you.

12-01-2009, 09:19 AM

I have a compression ratio calculator on my website that seems to be very accurate. www.racingenginetechnologies.com/services
Please let me know what you think.

Thanks,

Chris Hardy

Dave Gantz · 12-01-2009, 01:03 PM

A couple of the ones that I tried consider piston dome as a positve number, some consider it a negative number.

art leong · 12-01-2009, 01:46 PM

Quote:

Originally Posted by Dave Gantz

A couple of the ones that I tried consider piston dome as a positve number, some consider it a negative number.

Yes but even when entered correctly they vary by a lot. The one thing I have figured out is my new motor has about 1 more in the compression ratio.

11-22-2009, 11:23 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?? 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	#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 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	#4
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

11-23-2009, 11:17 PM	#5
Dave Casey VIP Member Join Date: Dec 2002 Location: Hampden, MA Posts: 1,201 Likes: 233 Liked 774 Times in 164 Posts	Re: Compression ratio calculators?? 13.54 to 1 I look at as the volume with the piston at bdc divided by the volume with the piston at tdc convert all values to cc's is easiest for me 16.387 cc's per cu inch bore and stroke volume + deck volume + chamber volume +gasket volume-dome volume divided by deck volume + gasket volume + chamber volume - dome volume __________________ Dave Casey 1330 STK

11-25-2009, 09:08 AM	#7
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?? In doing a little number movement with most of the on line calculators I think they are not figuring the dome vol. + or - properly in the formulas. Art, Daves formula was the one I had at the shop that I said I would PM to you. __________________ Adger Smith (Former SS)

12-01-2009, 09:19 AM	#8
Chris Hardy Guest Posts: n/a	Re: Compression ratio calculators?? I have a compression ratio calculator on my website that seems to be very accurate. www.racingenginetechnologies.com/services Please let me know what you think. Thanks, Chris Hardy

12-01-2009, 01:03 PM	#9
Dave Gantz Senior Member Join Date: Nov 2005 Location: Verrry South Jersey Posts: 537 Likes: 134 Liked 251 Times in 125 Posts	Re: Compression ratio calculators?? A couple of the ones that I tried consider piston dome as a positve number, some consider it a negative number.

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