Acceleration:

Today Duane and I made three acceleration runs, since our first drive-thru was to check out a truck pulled off the side of the road at "Test Site North". It turned out to be a bow hunter, so the truck was empty and we were good to go!

Duane's fastest run was his first, netting a 0-1/4 mile time (unadjusted) of 14.5 seconds @ 97 mph. His second two runs were slower, between 14.6 and 14.8 seconds, mainly due to some, err... shifting difficulties. You see, Duane's shifter knob is normally held on the shaft by a small lip. However, the previous owner of the M3 raced it quite a bit, so the knob is currently somewhat detachable.

In fact, it detached twice... both times during the 1-2 shift where Duane had to shift the fastest. On the second run I noticed Duane's arm recoiled pretty far back, but I was rather surprised when he threw the shifter knob to me and continued with the run! The third run was even slower, as he and I were both giggling hard enough that he just chucked the shifter into the door pocket -- but then ran into his RPM limiter. Doh! The limiter cut the legs off the engine and stopped the acceleration dead.

Duane's 0-60 times varied between 6.7 and 6.8 seconds, which is a bit higher than expected. This is primarily due to him launching fairly softly by releasing the clutch slowly. I've compared his runs to one of mine, and you can see his acceleration curve climbs quite a bit slower. I'm sure that visions of expensive Bimmer clutches were dancing in his head... :)

Power:

The highest power output recorded today was 181bhp @ 6100rpm, and his torque peak was about 160lb-ft @ 4800rpm. Using my correction worksheet, that calculates to about 222-226bhp. This is quite close to the 240bhp rated power, especially since his car has a few miles on it. Since we did not do a power run we didn't get a full RPM range power curve, but I'm sure that the M3's torque figure would be higher and occur closer to the rated 3800rpm torque peak. Normally I would have recommended one, but Duane and I were still laughing over the detachable shifter knob. ;)

Technique:

Well, in this case the most obvious place for improvement is shifting... specifically keeping the shifter attached! Once Duane's replacement shifter knob is in I'd expect more reliability, if less humor, in his launches. Also, by slowly releasing the clutch Duane slowed down his 0-60 times by at least a half second. Since his car's torque peak is at a fairly low 3800rpm, I'm sure a more brisk declutch would offer a lot harder launch.

Duane's launch RPMs varied between 2500rpm and nearly 4000rpm, but the first launch was marginally better overall (even though it was at a lower RPM) because he let the clutch out faster, especially at the end. This caused some light wheelspin but gave a pretty hard launch. Dropping the clutch faster at 2500-3000rpm should ensure the fastest launch, especially since he's running very sticky Pilot S03s - P245/45ZR17 in the rear.

Finally, Duane varied his shift points a bit between the runs. By looking at all of the shift points, you can see that Duane shifted from third to fourth 500rpm later in his first run, which gave him a distinct power advantage in the first run, which translated into better acceleration. Since his engine power peaks at 6100 and doesn't fall off until after 6300rpm, shifting at any less RPM will slow things down.

Corrections and Other Factors:

Since Duane's M3 is OBD-compliant my CarChip was able to deliver data on the intake air temperature, and combined with my DNS Pro for weather data, I have a fully corrected set of data for the runs. Here is the data from the best run in original and corrected form:

	Recorded Data	Corrected Data
Best Run	0-1/4 mile in 14.5 secs @ 97mph	0-1/4 mile in 14.2 secs @ 99mph

Not bad! The published figures are usually about 14.0seconds @ 99mph, so since his trap speed is right on the money, and the power is clearly there. With a bit different launch and shift technique Duane should be able to drop a couple tenths from his ET.