The wild, four-digit Hurst/Kenne Bell Mustang project recently hit the dyno at GTR High Performance to see if it lived up to its mission.
There’s plenty more to come, but the immediate news from Kenne Bell is the company’s 1,100-horsepower street car project has hit the chassis dyno rollers with 951 rear-wheel horsepower in its first quickly tuned session. Call that 1,119 ponies at the crankshaft — or right on target. Plus, there is much more boost and tuning in the future.
A Hurst/Kenne Bell Mustang in the making, the 1,100-horsepower car is owned by a smiling Darroll Myers. He will publically debut it at the Fabulous Fords Forever show at the end of this month. While still plain white with only 17 miles on the odometer, the S550 will be in full Hurst/Kenne Bell regalia at the famed Knott’s Berry Farm gathering on April 30.
With any luck you saw our build story documenting this Kenne Bell 4.2-liter supercharged topped 5.2-liter engine, which is based a Shelby GT350 5.2 block and cylinder heads but runs a traditional cross-plane crankshaft.
Getting to the dyno was the usual two-steps-forward, one-step-backward progression for a new combination, but posed no fundamental engineering challenges. The engine is a Vooyote crossbreed using the Shelby GT350’s Voodoo cylinder heads and block, but a Coyote derived (90-degree) custom stroker crankshaft and a massive 4.2-liter Kenne Bell screw blower.
It took awhile for Gil Nevarez to assemble the engine and GTR High Performance to perform the metal surgery required to shoehorn the tall and long engine into the 2017 Mustang GT’s engine compartment and have Ken Christley at Kenne Bell get engine, fuel system, chassis and computer thinking alike.
With time in short supply and Knott’s on the horizon, Ken was able to do little more than get the mega-powered street machine running before taking it off the dyno and handing the project over to Larry Weiner of Performance West Group for paint, interior and trim conversion to Hurst/Kenne Bell specs. Power development with the car will resume at Kenne Bell post-Fab Fords, and we’ll be there to document it.
Ken did extract one important bit of hot rodding during the first dyno session. Convinced by 15 years of testing mega-powered Mustangs that the Ford exhaust system—cats and all—is far more capable than it’s typically given credit for, Ken and Kenne Bell principal, Jim Bell, ran the heavily huffed Vooyote with the stock Mustang exhaust. As the dyno graph shows, all was well until at “just” 24.2 pounds of boost and 6,500 rpm where the engine laid down at 864 rear-wheel horsepower.
As you can see, the new combo crested 951 rear-wheel horsepower in initial testing, which already puts it well over 1,100 horsepower at the crank. Once the car makes it show debut, it will return for more boost and tuning, which should result in even more power.
Then Ricardo Topete at GTR replaced the stock Ford exhaust system in its entirety with a complete American Racing Headers system of long-tube headers, midpipes and mufflers. With no other changes, including tuning, the engine dropped 1.8 pounds of boost, a.k.a. backpressure, and gained 87 rear-wheel horsepower to reach the test’s peak of 951 horsepower at the tire.
It appears the modern Ford exhaust is no impediment to at least 800 rear-wheel horsepower and offers little real-world loss at 850 rear-wheel horsepower. But it’s also a complete cork above that threshold.
We’ll close by noting this combination is not working hard at just over 1,100 crankshaft horsepower. The big 4.2-liter blower turned only 13,800 rpm to make 22 pounds of boost through the free-flowing Voodoo heads, so simple pulley changes could easily deliver another 8 psi. Stay tuned.