Blimey’s Dyno Tune

Jan Brueggemann Rocks. There, I said it. Call me a fanboi. I don’t care.

Thanks to Joe for arranging a tuning party at Speedwerks in Thomasville (right around the corner from Grassroots Garage). Several folks from THMMC, along with others from between DC and Charleston and Atlanta and Tennessee, showed up over a Friday and Saturday for their hour or so of magic on the dyno.

Jan uses DimSport tuning software and hardware to modify the MINI’s ECU maps, to optimize performance. This has an impact even on stock cars, but is especially impactful on cars that have aftermarket mods like pulleys, heads, headers, exhausts, intakes, camshafts, injectors……. you get the idea. The dyno applies a load to the front hubs of the car, and measures the torque and RPM generated, as well as analyzing exhaust gasses for air/fuel ratios.

Here’s Blimey on the SpeedWerks Dynapack chassis dyno:

blimeydyno

Note that the front wheels are removed, and the car is hooked up to the Dynapack load units on each side. The big fans are used to provide radiator, engine and intercooler airflow to similar driving conditions on the street. In reality, you can’t move nearly as much air with a decent sized fan as you really get when driving, but every little bit helps. You also spray the intercooler with water between runs to reverse heat soak and create as much consistency across runs as possible.

Here’s Jan at work on his computer, tuning the ECU maps before uploading them to the car.

janatwork

The automatic transmission is VERY challenging to dyno and tune. You can’t “bog” the auto… it will automatically downshift, even when in “manual” mode. Likewise, if you floor the accelerator past the “kickdown point”, it will downshift automatically. The dyno pull has to be done in third gear, so you have to set the dyno to start reading at about 3000 RPM, then very carefully modulate the throttle to get the RPMs just below 3000 in 2nd so you can upshift to 3rd, then floor it to (but not past) the kickdown point and hold until the car builds to max RPM and the run is over. It takes a LOT of trial and error to get this technique down.

Even when you’re done, the auto is harder for Jan to tune. The torque converter prevents clean transmission of power from the engine to the axles. So there’s a weird dip in the middle of the torque curve until the torque converter “locks” then torque jumps up suddenly.

Even with all these challenges, big gains are possible with work. Here’s my melted dyno sheet (the ink got wet on the way home… and Jan didn’t save the files so I couldn’t have a reprint done)…

dynochart_melted_200807183

You can’t assume much from the left end of the charts… but on the right end, note the blue line is higher than the red line… those are significant torque gains… that you can immediately feel on the street. Jan tuned the car a tad rich to allow for my cam install later, or gains would have been even greater.

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