Quote:
Originally Posted by enkeivette
Some math for fun:
432/315 = 1.3714
.31714/5 = .07429 addition hp per lb over NA
.07x13 = .9657 theoretical percentage increase at 13lb over NA based on 5lb increase
1.9657x315 = 619.2 whp
But, I've found that cooling the air can drop the pressure 3lbs as tested. So doing the math at 10lbs I get:
549 whp (like you guys are guessing)/ 83 = 661 bhp
I'll bet there is a much better way to do this if you know the common compressor outlet temp and can use the temp difference from the inlet temp to find out the pressue increase. Then use that to find the realistic 02 increase, then subtract pumping loss as a percentage. Then add 30-50hp for the AFR which we haven't been doing, and rightfully so because I'm sure the above mentioned will subtract more than 30-50hp. |
According to my tuner Steve, who has measured outlet temps on setups like my Cobra that don't have an intercooler, the outlet temps range between 250 and 300 degrees at the 11-12psi my engine sees. Notice in the tests that without an intercooler the outlet temp was 199.2 degrees at 8.2psi and they had the timing pulled back to 22 degrees. With an intercooler the temp was only 120 with the same 8.2psi and they were able to run 30 degrees. By increasing the psi to 11.5 the outlet temp rose just under 20 degrees or roughly 14% with an intercooler. See where I'm going with this? Do you still think you can run 26 degrees with 13psi, no intercooler and 91? Remember, this was testing on a dyno, not a car that is sitting in traffic and then being gunned to get on the freeway.
Also, notice in the tests that it took 58hp to turn the P600B at 8.2psi measured at the manifold and 74hp on the same blower to make 11.5psi. That's roughly 21%. Assuming it would take that same 21% to make another 2 psi the blower would be consuming about 90hp.