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Yes, I hope to get those posted tonight in hopes that some of you can help me make sense of the data. I'm not unhappy at all about the power on the pump tune, the car runs awesome and pulls hard. I'm just really surprised I don't see a bigger difference on the race tune. Aside from the dyno charts, the car runs almost the exact same 1/4 mile times on either profile.
Looks like race gas vs. pump gas while both HP and torque start up at higher RPM they go up quicker and remain higher and flatter with the race gas.
The drop off at higher RPMs could be the race gas might be a bit stale. A fuel test in EVO some years ago found race gas in a stock turbo-charged car was ok at lower RPMs but really came alive at higher RPMs and just blew the pump fuels into the weeds.
Data might shed some light on the drop off too.
So far this is the only explanation that makes sense in my head as to why the race gas profile isn't showing better times in the 1/4 mile. Additionally, if you compare the two lines at the top of the rpm range, once I hit about 6,000 rpm, the race profile drops off significantly. When running a 1/4 mile, a good chunk of that time is spent in that high rpm range, and then when I shift from 3rd to 4th (or 2nd to 3rd), the rpms drop down just below that area and then are quickly in the drop-off range again.
Here's a quick snapshot of my data. The pump gas info is on the left and race gas info on the right. Unfortunately some of my data was corrupt but hopefully this helps.
As a side note, I did 3 runs on race gas and 3 runs on pump gas, and when the lines from each set of runs were viewed together, it was indistinguishable and looked like a single line. The guy running the dyno said he's never seen anything NEAR this level of consistency between runs.
As an aside, the dyno at TiC reads low usually. They use it more for seeing improvement/loss than for sheer power numbers.
Makes sense, with some drivetrain loss through AWD and Automatic transmission I would think his numbers are accurate for his ET and trap speeds at the track.
I agree 100% which is why I wanted to get some numbers on the dyno. I was running right around 11.1-11.2 with the pump profile and about the exact same with the race gas profile. This session confirmed my suspicion that I wasn't really making any more power on race gas. From about 5700 rpm's and up, I'm making more power and torque on the pump gas profile. I'm hoping the durametric numbers will help answer why.
Hey John,
Here are my results from earlier this year. Given my altitude, I was close with my mind number.
The reason for my dyno post is, Your curve is so different in comparison to mine. Is it the tip causing this?
I'd be interested to hear Kevin's take or one of the guy's who really understand these tunes inside and out.
I'm just a backyard mechanic that tries my best to understand all of this stuff, but here are my thoughts.
But with those data plots and my limited knowledge of how things work, it all pretty much matches up. Given the same boost and just adjustments in timing you're not going to see huge power jumps...esp when the increase in timing at the peak of the power band is around 5 degrees on average. Where you get larger timing deltas in the 3500-5k RPM range you see a much larger spread on the dyno graphs.
As I mentioned earlier, I think the car is maximizing timing on the 93 tune given you've got 100+ in the tank for those runs. I'd like to see the 93 tune with 93 actually in the tank to see if there's a much larger spread and see where the timing numbers are in that situation.
Have you run the car on the pump gas tune at the track, with 93 in the tank and still had the same 1/4 mile results, or have all of those passes been on 100+ the whole time?
I get where QuadCammer is going too. Knock retard would better tell the story of why there is a large separation in timing in the middle of the power band and not as large of a gap at the top...
Given I've seen duty cycle data for cars tuned on E85, I doubt that's an issue that you are seeing here though it'd be nice to see as well...
I'm a little lost on why the race gas tune quits at the top. IAT is missing on that run, I think IAT and knock retard would be good info to have there.
Were there fans on the intercoolers during the runs to help keep IAT's under control?
12-15-2015, 05:26 PM
