FULL BILLET

A LOOK INSIDE DORSEY DIESEL’S STAGE 4 4R100 TRANSMISSION

Tuning, turbo, and injection system technology has come a long way for the 7.3L Power Stroke in recent years. The amount of horsepower that can be gleaned from Navistar’s dinosaur V8 is constantly on the rise, and at the present time it’s not uncommon for a 7.3L-powered Ford to be making 600 to 650 hp at the wheels. However, pushing the 7.3L platform to new heights has had its downside: a lot of dead E4OD and 4R100 transmissions. In many cases, the parts used in the built transmissions of yesteryear no longer suffice in today’s highpower environments. The sub-500hp 7.3L days are over.

After testing various parts combinations on his 7.3L over the years and perpetually ramping up power along the way, the built 4R100 in Jake Enos’s ’02 F-350 was on the verge of calling it quits. As the owner of Irate Diesel Performance—a company that specializes in all areas of 7.3L performance—enos regularly uses the truck to showcase just how fast a 7,900-pound 7.3L Super Duty can be (12.40s on fuel, 11.70s on spray). He not only wanted the truck back on the racing circuit as soon as possible, but he needed a transmission that could hold up to the rigors of competition and the stress of 800-plus horsepower.

For the ultimate race-ready 4R100, the truck was dropped off at Dorsey Diesel in Park Hills, Missouri, for one of that company’s Stage 4 builds. Once the four-speed had been torn down, cleaned up, and its case re-surfaced, it was fitted with a host of billet and precisionmachined hard parts, upgraded clutches, steels, a high-flow pump, modified valve body, and a few trade secrets. A Precision Industries triple-disc converter and Mishimoto 37-row transmission cooler would round out the long list of improvements.