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Old 10-08-2012, 10:43 AM
TDIwyse TDIwyse is offline
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Location: Midwest
Join Date: Sep 2010
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Mein Auto: 4 diesels
Spent some time this weekend with the GTech device to analyze launching traction issues that seemed potentially helpful to others. Also, there was some additional tweaking on the above car this weekend. The progressive JBD mod was further tweaked (to reduce low rpm distortion to below "0" level to minimize peak low rpm torque, and push the distortion further into the rpm and take the peak distortion to the ~100% level to further enhance top end power) as well as running 50/50 water/methanol (recently added an AEM flow meter and the car is sucking ~650ml/min at peak fueling).

The GTech device shows some very interesting effects on the launching procedures. Below is 4 seperate runs with various brake boosted launching rpm's and fueling procedures. Additonally two runs had the rear street tires at 41psi and two at 33psi. 3 had DCT on, 1 had all traction control off.

It's neat to see the impact of these variables on the G forces and speeds. Obviously the lower psi on the tires helps with traction, and it also appears this car needs to not be floored immediately as the tires can't handle the traction at the two psi settings that were examined. Further reduction in psi, or using drag radials should improve the traction to a point where more fuel can be applied sooner for better 60' launches.

Also thought the Black vs Green run was interesting. The green had a better 60' time, but because the tires lost traction, and no traction control algorithms were used to cut back pwr, the 330' time was actually worse.

Also, used the Black run (3rd gear portion) to compare to the earlier recorded hp/tq curves using the previous JBD/H2O injection setup. The torque curve is pushed further into the rpm range and provides for nearly 20more hp from 3400-4400 rpm. It's probably not quite that much as the temps were a lot cooler this weekend, although it was into a 10mph headwind . . .
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2011 335d 11.8 sec 120 mph 1/4 mile NHRA certified track

2004 Ram Cummins with lots-o-mods
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