Dynamic Compression Q
03-20-2005, 12:11 PM
#1
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Dynamic Compression Q Can you calculate dynamic compression without .006 numbers? I plugged the info from my cam card into a 'calculator' I found off google, I'm not sure how accurate it is. It says my dynamic compression ratio is 9.54:1 and dynamic cranking pressure is 199psi
My numbers with 11.1:1 heads would be 10.38:1 with a dynamic cranking pressure of 221.92. Isn't that a lot?
My numbers with 11.1:1 heads would be 10.38:1 with a dynamic cranking pressure of 221.92. Isn't that a lot?
03-20-2005, 06:52 PM
#2
Yeah, those numbers seem a little bit high, but not way out of line. With my TR224-114 and stock heads I had ~165 psi cranking pressure with 7 of 8 sparkplugs still in.
DCR is a the effected compression ratio multiplied by the volumetric efficiency. The 9.54 you have (which seems high to me) is probably the ECR and not the DCR since the ECR is usually ~8.5:1 and the DCR is usually 85% of that.
Do you know what the VE of your engine is?
Do you know what the intake valve closing angle is?
DCR is a the effected compression ratio multiplied by the volumetric efficiency. The 9.54 you have (which seems high to me) is probably the ECR and not the DCR since the ECR is usually ~8.5:1 and the DCR is usually 85% of that.
Do you know what the VE of your engine is?
Do you know what the intake valve closing angle is?
03-21-2005, 11:08 AM
#3
If this is the DCR calculators that I see all the time and you get some stupid high number then you need to put in the actual IVC not the IVC @ .050"
Here are a few examples from the last few days....
http://web.camaross.com/forums/showthread.php?t=351113
http://web.camaross.com/forums/showthread.php?t=350863
Bret
Here are a few examples from the last few days....
http://web.camaross.com/forums/showthread.php?t=351113
http://web.camaross.com/forums/showthread.php?t=350863
Bret
03-31-2005, 09:51 AM
#4
Originally Posted by 99ssleeper
DCR is a the effected compression ratio multiplied by the volumetric efficiency. The 9.54 you have (which seems high to me) is probably the ECR and not the DCR since the ECR is usually ~8.5:1 and the DCR is usually 85% of that.
DCR is the cylinder volume determined at the point where the intake valve closes, ABDC. Take that volume and divide it by the compressed volume and you have the DCR. Volumetric efficiency has nothing to do with it.
