So I did some more playing with my GTech device this weekend. I’ve measured some interesting things.
First, wanted to verify the flatness of the terrain. Below is GPS altitude data for the area I’m doing the runs. The two plots are recorded data from both directions. Elevation appears to be essentially flat within the margin of error of the altimeter.
http://www.flickr.com/photos/10201173@N06/4515850049/I can get the best results (0-60, 1/8 ml, ¼ ml) if I launch in 2wd with the OD off and ESP off with just a bit of brake boost for the launch. If I do too much boost then tires spin and traction control turns on and sucks power to the ground to keep the wheels from slipping. If I do just a little brake boost the wheels only slip a minimal amount and no flashing TC lights and the power gets to the ground with minimal interference. See picture link below which compares last weeks ¼ ml run to this weeks. I’m a little shocked and feel this needs to be duplicated because the results seem too fast.
http://www.flickr.com/photos/10201173@N06/4516457020/After about 2-3 back-to-back-to-back full fuel runs the performance starts to degrade. This is either from heat soak of the intercooler or transmission fluid temps or fuel temps. The G-Tech definitely shows this to be true because the measured hp/tq/G forces become less and less after several of these full fuel runs with minimal recovery time (I’ve been basically mashing it, braking it, turning around, mashing it, braking it, turning around, etc.).
I also did some lower rpm torque/hp curves to fill in the results at rpm’s closer to peak torque. I found it really tricky to get a good low rpm data curve without the torque converter unlocking .
http://www.flickr.com/photos/10201173@N06/4516457156/It should be noted that the hp/tq plots had a weight of 4800 lbs for the vehicle and me. Upon further review of this thread (
viewtopic.php?f=5&t=24628&p=326898&hilit=weigh#p326898) I think I’ve over estimated the weight. I weigh about 170 with shoes/clothes so I’m guessing my vehicle (with the spare tire for the Saturday runs) was about 4550 instead of 4800. So the hp/tq numbers should be reduced by 4550/4800~0.95 (5%).
I’ve also recorded the following hand calculated mpg’s for the last several fillups:
30.5 mpg: ~50% back and forth to work, ~50% a 50 ml trip to Cedar Falls Famous Daves and back with mostly 75 mph interstate.
27.0 mpg: Mostly 75 mph interstate. ½ into a head wind, ½ with tail wind but in rain. And several hrs in 4x4 with a trailer hauling fresh chain sawed oak from my dads forest to the barn.
28.4 mpg: Mostly back and forth to work with some city driving.
23.5 mpg: Mostly full fuel runs from Saturday.