“A nitrous car will leave with more power than any other car in Pro Mod,” he boasts, standing next to his ’70 Duster with a 940ci Pat Musi bullet under the hood scoop. “A turbo car will make power at the other end. Obviously it’ a challenge to get the car to leave and go down the track with more power. But the turbo cars are playing catchup.”
EngineLabs caught up with Lepone at the NMCA West race at Fontana where he posted the third-quickest qualifying time of 5.405 (1,000 feet) but lost in the first round to the eventual runnerup, Andrew Berry.
Lepone burns almost 10 pounds of nitrous oxide, and he makes sure there’s plenty of available juice by mounting a pair of 25-pound bottles on board the D Bar D Racing doorslammer owned by Derrol Hubbard with Bob Wooten serving as crew chief and Greg Hollman and John Beckner helping in the pit. Last year the car won the NMCA West event at Pomona.
“This engine makes around 1,800 horsepower without nitrous, and anywhere from 2,800 to 3,000 with nitrous,” says Lepone. “It’s gone 243 (mph) in the quarter.”
The team relies on an Edelbrock 4-stage nitrous system team with Edelbrock EFI and MSD Grid ignition controls.
“We leave with one kit,” explains Lepone, “and roughly six to eight tenths into the run we turn on the second kit.”
Right after shifting into second gear, a third stage of nitrous is fed into the runners.
“At most tracks we got all four kits in the middle of second gear,” adds Lepone. “At this track, it was one in first, one in second and one in third.”
Lepone didn’t reveal much about the Pat Musi mountain motor, other that to say it had a 6-inch stroke crank and canted valve heads.
“It’s not a hemi. A hemi is actually too efficient for nitrous,” he says. “You want inefficiency for nitrous so the nitrous can pick it up more.”
Lepone cools down the engine to around 60 degrees before the race.
“We try to run the engine as cold as possible from the start. It’ll make less power, so we can put more nitrous at the start,” explains Lepone. “Then when you get heat in the engine at half track, it starts making power and it won’t hurt itself as you add more nitrous.”
Eventually, heat is the enemy and Lepone has to start pulling timing out to avoid detonation. The one downside to nitrous is that the engine tune is completely predetermined in the pit.
“It’s an open-loop system. The O2 sensors can’t keep up with the resolution,” says Lepone, noting EFI still gives him more tuning options than carburetors. “And the engine will make more torque with EFI.”