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September 22, 2005
Live ECU tuning at the track, and a trophy
Last night I got my first drag racing trophy. It wasn't much of a trophy, just sort of a big mug with the Sacramento Raceway logo and graphic. And I was only runner-up, losing the final bracket race by 8/1000th of a second to a much slower but extremely consistent automatic. But it felt sooo good to get that silly trophy.
This was one of the last Wednesday drags of the season, so about 250 cars showed up. We only got two time trials, which was bad news for me as I had just installed a new pulley on my supercharger and needed to adjust the Hondata K-Pro calibration for it. I had done some street tuning, but the track is different. I always datalog all of my runs.
On my first attempt I did a 13.9 at 104mph, but my air-fuel ratio went into the low 13s above 7700 rpm. Boost was lower than expected, mostly in the high 7s with an occasional rise into the 8s. Anyone who has seen a Comptech boost curve knows that it is difficult to read because of some internal buffeting that makes the MAP sensor show peaks and valleys with amplitudes of up to 0.8 psi. I also noticed fairly substantial knock. None in second, 6 at high rpm in third, and another 12 all through 4th. Not good. I wasn't going to remap my entire ignition tables sitting in a line of cars, not knowing when my next time trial run would be, so I decided to try ignition compensation by gear. I quickly glanced at the K-Manager documentation: "To retard the ignition, enter a negative value." Retard... Retard.. okay, so that probably means a lower number, which I needed. So I entered -1 for third, and -2 for fourth and fifth. I also adjusted fuel, wondering if I was making a mess of things doing it all on the fly, and also what temperature compensation had already done with my starting line IATs in the mid-120s.
Anyway, I really blew my second run when I couldn't get it into 2nd, but the rest of the way it was fine. Datalog showed that total knocks were down substantially, and that gear ignition compensation had actually worked.
Then we got into tropy runs which I both love and hate. I am still on a quest for lower ETs, but since I also want to win, I usually get off the gas when an opponent is obviously beaten. First trophy run: 13.9 coasting through the finish line since my opponent, a nice E36 M3, had apparently misjudged his dial-in. Second trophy run: a twin turbo 280ZX who had a reaction time of 0.001, then ran under by almost half a second. I had an average run, but beat him because he ran under. Third run against a Prelude who also couldn't even come close to his dial-in, so I got off the gas early and did another 13.9 as I coasted through the line at 90mph. Semi-final against an Acura who had beaten me before. He ran a near-perfect run, but I beat him with a 13.8 on a 0.08 reaction time and went off the gas early. The runs now had no more knock and AF in the high 11s. Boost, however, was only in the mid to high 7s and actually decreasing a bit after 8000 rpm. Could it be that my belt was slipping a bit with Ryan at Comptech torqueing it the way he thinks is right as opposed to what the instructions say?
For the final run I lowered my dial-in to 13.7 because it was cooler now, in the 90s, and I did not want to break out. I got to race the dreaded middle-aged lady from Folsom who drove that 18.0 second Kia and generally ran 18.05s like clockwork with near-perfect reaction times. Needless to say, she didn't have wheelspin problems. The 4.3 second headstart was a bitch, I spun the wheels (as I did on every launch yesterday, despite the Falken 615s), caught her at the finishing line, inches too late. 13.8, 105 mph trap.
Fun evening all in all. Tuning the car majorly while waiting to stage is a handful. The knocks, AF problems, lower-than-expected boost and sky-high IATs kept me busy. My inability to find the proper launch infuriating as it probably added half a second to each run. The only other RSX there, I/H/E/Hondata with a good driver, did 14.6-14.8. The winner in the other import class was a S2000 who did 14.2s and beat a E46 M3 (the new one) who did 13.9s in the finals. Maybe Sac Raceway just isn't a very fast track.
So now it's back to the drawing board. My 3.3 inch pulley only does mid 7s to low 8s in boost. My launches bite; still in the 2.3s 60 foot. The calibration needs some real work; no way can the official Comptech Stage 2 calibration be used for the 3.3-inch pulley without drastic changes.
Posted by conradb212 at September 22, 2005 2:03 PM