Tonight I performed four acceleration runs in back-to-back pairs going opposite directions. The first two runs were in a fully automatic mode, letting the tranny shift itself. I brake-torqued the transmission as much as possible, which turned out to be about 2600rpm max. After the first two runs I put it in manual mode and shifted myself, using the same style of brake torquing for the launch. The results of the acceleration runs were 14.5 and 14.8 seconds in automatic mode, and 14.2 to 14.4 seconds in manual mode.
Due to the automatic transmission my launches weren't as hard as they could have been since the engine wasn't near its torque peak. My best 0-60mph was 6.1 seconds, with the worst at 6.6 seconds. Manual mode offered two significant benefits: I could pick a better shift point, and apparently less slop in the torque converter locking up. More information below...
The highest power output was 200bhp @ 6200rpm. This figure is about 10-20bhp lower than I expected and the performance figures suggest, but since I did not weigh the car I could only estimate its weight, which throws off power calculations. After atmospheric corrections my calculated net power is 253-259bhp. Since that the calculated power of the 2005 G35 matches up well against my G35's calculated power and performance it appears the driveline on the G35 is absorbing slightly more power than my transmission loss estimates adjust for (which is not unexpected -- they are very rough estimates due to the variables involved.) From this data it does look like my G35's calculated 275-280bhp after modifications is right on.
Well, I have to say that launching automatic transmission cars can be pretty boring. Turn off traction control, pin the brake to the floor, nail the throttle, wait until the RPMs to level off, and release the brake. The combination of the torque converter and lower RPM level meant that each launch was accompanied by a foot or two of tire tread and little other drama. However, there was a marked difference between automatic and manual modes in both the launch and shift points. As you can see from the launch RPMs and Gs comparison, the manual mode allowed the torque converter to lock up harder and gave a bit more wheelspin and RPMs. This helped the engine get into the powerband quicker and shaved a couple tenths off the 0-60mph time!
The other thing I noticed was that the auto tranny wanted to shift itself at 6500rpm. In theory that makes sense since it's just past the 6200rpm power peak and it drops the RPMs pretty much on top of the 4800rpm torque peak. However, I noticed that the torque peak actually came on a bit after 5000rpm, and the power held up pretty well to the redline. When you look at the shift RPMs and acceleration comparison you can see the benefits from the later shifts. A good three or four tenths difference in the quarter mile, plus another 3-4 mph trap speed! Woo-hoo!
Corrections and Other Factors:
Once again I've corrected the quarter mile results to the weight of a single person, quarter tank of fuel, and SAE J1349 standards. I used the manumatic tranny runs since they were a better showing. You can see the correction spreadsheet for both the best run and both manual runs averaged together:
|Recorded Data||Corrected Data|
|Averaged Runs||0-1/4 mile in 14.3secs @ 99mph||0-1/4 mile in 14.5secs @ 98mph|
|Best Run||0-1/4 mile in 14.2secs @ 99mph||0-1/4 mile in 14.4secs @ 99mph|