Late-model transmission have come a long way in performance. Not only do we have more gears to improve fuel mileage, but they are also capable of handling the greater power coming from modern powertrains. Unfortunately, the internal designs that make them great in stock applications sometimes become the weak point when the power level goes up, and the rigors of racing only exacerbate the issue. Then it’s time to step up to a racing transmission for durability and reliability.
With a TKM-built 5.0-liter Coyote engine, Brett Barber-ported cylinder heads, a 3.8-liter Whipple supercharger, and a stock ECU tuned by Rob Shoemaker, Leticia Hughes’ 2018 Mustang GT makes over 1,300 horsepower to the rear wheels and was in need of a more durable transmission option. (Image courtesy of NMRA)
NMRA racer Leticia Hughes has been steadily improving the performance of her 2018 Mustang GT and has been racing it in various classes over the last few years. The 5.0-liter Coyote engine in her Mustang has been upgraded over that period and horsepower has gone from the mid 400 range at the crankshaft to over 1,300 at the rear wheels. She had been using the original 10R80 10-speed automatic transmission and despite having it built to its fullest capability, Hughes eventually found that it wasn’t reliable for the power level of the engine and the racing she was doing. As she intended to compete in the NMRA’s 8.60 Street Race category for the entire season, she approached her sponsors about moving to a Turbo 400 transmission.
Step one in building a top-shelf Turbo 400 transmission involved using a Reid Racing Super Hydra 400 case. These are SFI-certified and often required by racing sanctions depending on the class and e.t. a vehicle may be running.
“We needed the most reliable option with moving the NMRA 8.60 class,” Hughes explained. “Anything beyond 1,000 and the 10R80 becomes really unreliable. I went a personal best on one pass, ran again and ate the transmission. At my horsepower level, the Turbo 400 is the superior transmission.”
The 10R80 did well and Hughes had it fully built to ensure it was durable. Her car is still registered and capable of street driving, so the overdrive was a good choice, but the car’s power level and increased track presence was pushing in the opposite direction.
“The combination of the physical nature of the 10R80 and the software in the stock ECU that controls it are the main issues. The computer can override the tuning…
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