Series8217 wrote:Show us your math, Mr. I'm-A-Better-Engineer-Than-The-SAE-Guys.
OMFG Steven. It is basic fucking math. We learned this shit in high school.
Sea level = 14.69psi
Colorado Springs = 11.7 (That is the cells that my piggyback is at with ign on, engine off).
First of all, just found this interesting. 14.69 / 11.7 = 1.255. Look familiar?
Anyways, we lose about 3psi due to altitude. For an N/A car, this is a 20.4% loss in air pressure, which would equate to a 20.4% loss in power.
Back in high school, I had a friend who moved here from Texas, on the coast, who had a modded GTP. Via his data-logging software, he saw dead on 15psi. Added to the 14.69, he had 29.69psia. However here, due to how a positive displacement blower works, he only saw 12psi. Combined with the lower atmospheric pressure, he only got 23.7psia. He saw a 20.2% drop in psia, equating to a rough 20.2% drop in power, near identical to the N/A numbers.
However, things are different for a turbocharger, since boost (Pressure above ambient), is kept equal at your peak power. So for me, it was 14psi. Added to the 14.69, at sea level, I'd have 28.69psia. Up here, that drops to 11.7 + 14 = 25.7psia. A 10.4% loss in power, roughly half that of the N/A and SC cars.
Thanks Stimpy, I've already dropped the boost back down to 8.7. The car is still scary fast at that, and more than I'll ever need.
Billybo455 wrote:enlighten me on what i'm going to tell you on how to make your car spool faster?
The same thing you've said like 4 times now, that's common fucking sense int he tuning world. Rich, retard timing. I ran it rich, and I pulled 20* of timing. Car ran like shit. It was too much of a change too soon for my engine to like. For some reason, my engine wants smooth adjustments to the cells. For example, under vacuum, my cells are 10 (The FTC1 value for neutrality, no change to the MAF signal). However, at full boost, the values are 9.1 across the RPM board. I initially tried going right from 10 at 11.7psia, to 9.1 at the 12.2 mark (Meaning as soon as boost came on, I went to a 9.1 multiplier, and held this throughout the pressure/rev range). The engine hated the vacuum/boost gateway. So for each bump in pressure (.5psi), I dropped the multiplier by .1 or .2. So now my cells go 9.9, 9.7, 9.5, 9.3, then 9.1. The engine loves it. Well, at 3,000-3500rpm, I made the multiplier 15, which causes it to go pig rich, and pulled 20* of timing in the same cells. The engine would spool nice, but it was overall really poor performance. I'd get bucking, a lot of smoke, and a poor transition back to normal fuel/timing. Maybe it's my motor, maybe it's the piggyback, but whatever it is, I'd need to fade into the rich/timing retard, and fade back out, and that isn't practical. Maybe if I could make adjustments every .1psi and 100rpm, but that's not how my piggyback works.
If I really cared about the spool time, I could trigger a 20-50shot of nitrous at 2,000rpm. But it isn't bad, I just have to rev it. So I need to wait until 3500-4000rpm for boost, but I can run to 7200rpm. What's the point in having boost at 2k? If I wanted off idle boost, I would have swapped a 3800.
