A Nitro Street Car? This Drag-And-Drive Hot Rod Makes It Possible

Reliability is one of the most important traits to have in a drag-and-drive car, but it is not a word typically associated with nitro.

Brian Kohlmann still holds the honor of being the only madman to compete at a drag-and-drive event with nitromethane in the tank. His ‘31 Chrysler CM6 Coupe is essentially a street driven fuel altered, which has been into the sixes over the quarter-mile.

There was once a 392-style Hemi riding up front, but Kohlmann switched to a late model Hemi, mainly for the dual plug head. 

“By going to a twin plug head I was able to increase the amount of timing I could put into the engine,” he explained. “A normal Hemi would run 36, maybe 38 degrees of timing, but with nitro you generally run 45 to 50 to get the power out. We couldn’t start the car with all that timing in it because it would knock the starter off. The guys with the fuel cars have those big starters on the blower, but we can’t do that kind of thing. So I start this engine on the EFI side with the gas and I use the running engine as a starter for the nitro.” 

Brian’s Chrysler coupe is almost a century old, but he has turned it into something spectacular.

Kohlmann believes he has the only car in the world with such a set up, and it wasn’t easy.

“I don’t have the luxury of watching a YouTube show to tell me how to build this thing. We are figuring it out step by step on our own. I have also had some good people who have lent some advice over the years and I appreciate their expertise. Some of them had their doubts but they liked the sound of the project.”

He is still at pains to remind anyone who looks at the car that he keeps it period correct where possible.

“It still has a lot of the features those cars would have had back then, like the Hilborn scoop and injection,” he said. 

Definitely not period correct, but absolutely necessary to make this a street car, is the dual fuel system. The nitromethane burns on the track and the Hemi gets gasoline for the roads. There is an EFI system for the gas and a mechanical fuel system for the nitro, and Kohlmann is able to make the switch with controls inside the cabin.

The system actually serves two functions. There’s the obvious impracticalities of nitro on the street, but Kohlmann also wanted the motor to be its own starter when he makes the switch to nitro.

Even a full tank of nitro won’t take long for this hot rod to burn.

The mechanical fuel pump for the nitro has two pinch bolts that Kohlmann can loosen for the street, ensuring it isn’t constantly running. Once he is at the track, he only has to engage the pump and plug in the coil for the mag to get the car ready to pop. While the engine looks like a dual mag arrangement, the second magneto is actually gutted and contains a distributor.

The car might look short, but this hot rod has a 125-inch wheelbase – relatively long compared so some of its fuel altered cousins.

“The car is balanced right where it doesn’t look like it is stretched in the front,” Kohlmann said. “The number one cylinder is 16 inches behind the front axle and that makes a huge difference. It has a legit 55% of weight on the rear axle. My driving position is pushed back too, so we have done as much as we can to get weight back.”

In terms of driver and passenger comfort, the windshield and cowl vents can still open to allow air flow through the car, as can the rear window.

Just like the engine bay, inside is all business, with just a few artistic touches.

The last time we saw Kohlmann at a drag-and-drive event was at the 2021 running of Summit Midwest Drags. There all hell broke loose mechanically. It was clear things were not right in the burnout, with the motor idling very high, and Kohlmann chose to roll the car down track instead of taking the beams. A few seconds later came the pop of the burst panel and a brief fire aboard the hot rod.

“I think it rolled the number four cam bearing,” he said. “Look at the rockers, it’s starting to push the bushings out and everything is all burnt. It lost all the lash caps, knocked out the burst panel, and cut all the nitro wires on the driver’s side. I have a lot of parts and pieces to fix it all, I just don’t have the time as we have to take the heads off.”

The fire went precariously close to burning through the lines to the nitro tank, but thankfully Kohlmann lived to fight another day. 

“In the world of nitro cars this is just a flesh wound. Big show cars do it every pass, it’s kind of what happens. When everything works it is a lot of fun, but these things can and do happen. The baddest hot rod on the planet is the fuel altered.”

Not every day is a good day on nitro. Here Brian holds up a blown burst panel and some fire-damaged material.