Coffman Starter 24-Valve 5.9L Cummins Engine - Engine Builder Magazine

Coffman Starter 24-Valve 5.9L Cummins Engine

This 24-valve 5.9L Cummins is your average workhorse build for pulling trailers... until you learn about the Coffman-inspired starter James Crutcher built for this engine.

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“I’ve done everything with a Cummins that you can do, I think,” says James Crutcher. “I’ve built them for customers, for myself, and it’s really a big passion of mine.”

James Crutcher has been working on diesel trucks for over a decade now, and quite a few trucks have entered and exited his garage over that time. Crutcher is a former oil field worker, which is where he got most of his early automotive experience. Before that, his grandfather, who had turned wrenches for General Motors for nearly 50 years, initially got the ball in motion for him.

Now, James does diesel work from his home, and occasionally from the mobile shop he runs out of his Toyota Tacoma. Most of the jobs are light, but Crutcher plans on upgrading to a bigger space in the future and getting a lift to be able to get jobs done easier. Having a small space doesn’t mean he isn’t able to build a cool engine, though.

In fact, Crutcher’s current project is sure to catch a few builders off guard with what he’s doing. On the surface, it’s a simple 24-valve 5.9L Cummins. But, take a closer look and you’ll find that he’s added some unique touches to have the Cummins stand out from the crowd.

“It all started a few years back when I bought an ‘02 BMW 325xi off a guy I worked with for $300,” Crutcher says. “A little later, I was at a sheriff’s auction and I traded the BMW for another guy’s ’02 24v Cummins. It had 260,000 miles on it and when I opened the door, there was no interior whatsoever – no seats, carpet, door paneling, nothing.”

Crutcher parted out his other trucks and made the interior serviceable, then started daily driving it. The VP44 inside remarkably made it to just over 400,000 miles before it quit. The new P-pumped engine is just about finished, and although Crutcher has made performance engines in the past, this is strictly a mild build to be used as a workhorse and daily driver. It hasn’t been dyno’d, but Crutcher believes the 5.9L is making around 400 horsepower.

“She’s 100% mechanical and you see P-pumped 24-valves popping up all the time now. It’s not as unique as it used to be, but mine is.”

At the moment, Crutcher is trying to perfect his very own Coffman engine starter system for the truck. History buffs will recognize the Coffman starter as a staple system used in piston engines for aircraft, armored vehicles, and some agricultural vehicles in the 1930s and 1940s.

Initially, the Coffman starter system incorporated a sizable casing which resembled a shotgun shell that contained cordite explosives. Upon ignition inside the breech, the swift and high-pressure gas discharged onto the engine piston surface would prompt the engine to initiate rotation. Subsequently, the starter ring gear, firmly linked to the engine crankshaft, becomes interlocked and allows the engine to spin while the ignition system takes over and commences the engine’s operation.

“It would be great for oil and gas applications because I’ve pretty well figured out how to start the engine with its own compression – and it will restart the starter I built, so next time you just have to hit the plunger and the compression will literally reset itself,” he says. “Right now, I’m using the springs I cut off of a muskrat trap for it, and I cut down the cylinder for the starter off of the hydraulic cylinder from an old Bobcat.”

Despite the engine not being super powerful, Crutcher says it’s bulletproof and more than capable of towing his trailers or doubling as a hunting buggy.

As for other additions to the engine, Crutcher added a single upgraded BorgWarner HX40 turbo that provides about 25-lbs. of boost. He stepped down the fuel injector ladder and recently put on smaller, 50% over injectors, and changed his delivery valves down to Bosch .024s.

“The Industrial Injection-built P-pump is probably the largest performance upgrade,” he says. “I’ve also got 4K governor springs on it, and good studs throughout.”

Diesel of the Week is sponsored by AMSOIL. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected].

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