360 Advice Needed - Autocross / Street Engine Build
Yeah I don't know how you get a different SCR. I can understand the DCR a little because of how the intake closing is calculated, different calculators use different figures. I was using the UEM calculators ABDC @ .050" +15*, which may give the DCR a little high with the fast ramps. If you use advertised duration and do the intake duration (276) divided by 2, add the lobe separation (110), subtract the ground in advance (4) and subtract 180 you get 64 for the ABDC and get a DCR of 7.845.
But all the numbers are right here for the SCR. I contacted KB directly to work out the numbers for the pistons because of the over the deck pistons and valve reliefs, that's where the 7.3 for the piston head volume and 0 for the deck clearance numbers come in, and it doesn't matter what calculator you use if you plug in those numbers you get 9.8 for the SCR.
The cranking pressure is about 10 to 15 psi higher than what most of the calculators say, but that's a crapshoot anyway. Cranking speed changes the cranking pressure, temperature, ring sealing, humidity, gauge, etc. Too many variables. To be within 10-15 psi of the calculation is no big deal, no reason to suspect anything at all beyond standard variation. You're getting too wrapped up in the calculators, cranking pressure as measured isn't a perfect indicator of SCR or DCR, there's too many variables at play.
Yeah I don't know how you get a different SCR. I can understand the DCR a little because of how the intake closing is calculated, different calculators use different figures. I was using the UEM calculators ABDC @ .050" +15*, which may give the DCR a little high with the fast ramps. If you use advertised duration and do the intake duration (276) divided by 2, add the lobe separation (110), subtract the ground in advance (4) and subtract 180 you get 64 for the ABDC and get a DCR of 7.845.
But all the numbers are right here for the SCR. I contacted KB directly to work out the numbers for the pistons because of the over the deck pistons and valve reliefs, that's where the 7.3 for the piston head volume and 0 for the deck clearance numbers come in, and it doesn't matter what calculator you use if you plug in those numbers you get 9.8 for the SCR.
The cranking pressure is about 10 to 15 psi higher than what most of the calculators say, but that's a crapshoot anyway. Cranking speed changes the cranking pressure, temperature, ring sealing, humidity, gauge, etc. Too many variables. To be within 10-15 psi of the calculation is no big deal, no reason to suspect anything at all beyond standard variation. You're getting too wrapped up in the calculators, cranking pressure as measured isn't a perfect indicator of SCR or DCR, there's too many variables at play.
