Part 2: Cummins/Allison swap into 2001 F-250 Super Duty
Big Three Blend: Part 2
In our first report, we outlined the necessary procedures for “destroking” an ’01 Ford F-250 by replacing its powertrain with a 5.9L Cummins engine and an Allison 1000 six-speed automatic transmission, using special adapters and parts offered by DeStroked and GOS Performance. The technicians at Mobile Diesel Service in Oakland, Oregon, took on the task of blending the best of the Big Three’s diesel pickups when the owner of the F-250 lost faith in the 7.3L Power Stroke engine and the 4R100 four-speed automatic transmission after a catastrophic failure occurred hundreds of miles from home.
The truck’s owner decided to invest in a hybrid swap rather than rebuilding the 7.3L. His dream combo: keep the roomy and comfortable Ford body/chassis but replace the engine and transmission with a setup similar to what moves many big rigs down the road—a Cummins engine backed by a six-speed Allison automatic.
And so began our journey, following along as the blend of the best of the Big Three is merged into one strong, reliable, smooth-running diesel performance package that’s well suited for street and towing.
Cummins CleanupOnce the ’01 24-valve 5.9L Cummins engine Shawn Smalley found for the swap was stripped down and the grime was washed away with a power washer, we determined it was in surprisingly good condition. Shawn pulled the cylinder head for inspection and smiled when he could still see the hone marks in the cylinder walls and the lack of carbon buildup on the pistons and valves. The rod and main bearings looked brand-new as well. The $3,500 engine looked like it had just been rebuilt, so all we did was install new front and rear main seals and add a set of ARP studs before setting the head back in place.
MSD also primered the used engine and sprayed on a few coats of high-heat red paint to make the block stand out in its new home. They also added a PDM kit that includes polished O-ring–sealed freeze plugs under the turbocharger tappet cover and intake plate.
Phat Power ModsOne of the beautiful qualities of the 235hp 5.9L Cummins is that it responds really well to small increases in fuel and air. So, in addition to talking with the folks at Industrial Injection Diesel Performance in Salt Lake City about the shiny parts, we also picked their brains for information about the best injector and turbo package for a Cummins destined for a Super Duty, which will be used as a daily driver and tow rig.
“Our PhatShaft 62/70 turbo and Race2 X4 120hp injectors provide a really good air-to-fuel ratio for the 24-valve 5.9Ls,” says Alec Hembury, who handles a lot of Industrial’s specialty sales. “The 62mm PhatShaft is a great replacement for the 58mm stock Cummins turbo. The larger inlet and housing on the compressor side flow considerably more air, and the turbo starts spooling up within that engine’s stock rpm range and on through the entire rpm curve.”
“Pair that with our 120hp Race2 Bosch injectors, which are supplying about 40 percent more fuel than stock, and you have a great combination that is very efficient at boosting power without the smoke,” adds Brett Williams, one of the family members who owns Industrial Injection and is an active part of the sales team. “The Cummins you guys are putting in the F-250 should be making between 480 and 520 hp with this setup, with double those numbers in torque.”
What makes Industrial’s Race2 X4 injectors different from many others on the market are the brand-new Bosch injectors that are put through a state-of-the-art Extrude Hone machine so each injector in a set flows exactly the same. The injectors in this particular Cummins are fed by a stock VP44 injection pump that was basically remanufactured and blueprinted by Industrial Injection.
“You’ll find this package will allow the 5.9L to spool quickly yet be very efficient in terms of fuel economy and manageable EGT with minimal smoke output,” Alec says. “It’s an ideal combination for the best balance of street performance and towing.”
Allison RebuildShawn isn’t as fortunate when it comes to the quality of the salvage-yard Allison 1000 six-speed automatic transmission he found for $1,500. When the specialists at GOS tore down the unit, they found it had been ridden hard and put away wet before coming to rest at Mobile Diesel’s doorstep. The clutches were burned up, the wiring had been spliced in several places, and someone left a screwdriver smashed between the filter and the pan. And there was more.
“This unit was burnt up from C1-C5, which tells us it was either used for extreme pulling, high horsepower, high mileage, or a combination of all three,” says Kelly Bergsing, the lead transmission technician and the brains behind all of the builds at Automatic Transmission Specialists. “The front pump was destroyed when a little chunk came off one of the planetaries and went through it. It wasn’t catastrophic, but this transmission had been previously hurt.”
Kelly went through the Allison with a fine-tooth comb, cleaning and replacing every part that could possibly be a weak link when handling up to 800 hp. That includes replacing the pump and electrical components with the newest updated Allison parts, and then loading the clutch packs, valvebody, and other moving parts with high-performance replacements from SunCoast Diesel Transmissions.
The rebuild kit includes SunCoast’s proprietary C3/C4 alto carbonite frictions and Raybestos GPZ frictions that don’t have center slots. These pieces utilize a waffle pattern in the material to help retain oil, keeping the clutches cool. It also includes performance frictions and steels for C1, C2, C5, and C6, as well as redesigned apply pistons with improved rubber compounds that are proven to hold more heat.
“The custom pistons allow us to use a thicker spring apply plate, which replaces the thin OEM version and in turn causes an uneven apply surface,” says GOS’ Aden McDonnell. “SunCoast’s custom apply plate redirects fluid to better lubricate frictions from the inside out, which lubes the entire friction, rather than OEM style that lubricates from the center out, leaving the inner half of the clutch burnt.”
“We also replaced the bushings and thrust washers, along with the pressure manifold,” Kelly explains. “The Allison’s pressure manifold tells the computer what the pressure in the transmission is doing per which gear is commanded or which gear the customer manually engages. We find a lot of the stock units full of friction material and our luck just cleaning them has not been the best, so we just replace the manifold. We also replaced the speed sensors and internal harness. These are just normal upgrades we do with every unit. We feel this ensures the best long-term reliability possible.”
Adapting Ford Transfer CaseWith the engine and transmission handled, Mobile Diesel’s Mat Johnson turned his attention to modifying the manually shifted NP271 Ford transfer case to match and function properly with the Allison, eliminating the need to have custom driveshafts made.
Fortunately, DeStroked makes that job easy with its Ford-to-Allison (#DS-TCase-Adapter) kit that includes new input and output shafts, a “clocking ring” to position the NP271 in a flatter position for the Allison, and a “reluctor wheel” so the output sensor on the Allison works as it should.
Installation took Mat about two hours, with the hardest part being installing the press-fit reluctor wheel on the input shaft. A hot plate, patience, and good gloves are essential for this part of the job. With those parts in place, shifting this Super Duty into Hi/Low range functions just like it did with the stock OEM configuration.
Ready to GoWith the Cummins cleaned and prepped for bigger power, the Allison completely rebuilt, and the Ford transfer case modified to work seamlessly with the new transmission, we can finally focus our attention on the actual swap.
The next installment of our Big Three Blend will cover the wiring and plumbing hurdles this swap creates. Actually, “hurdle” is too harsh a word. It’s more like “steps,” as the combination of DeStroked and GOS Performance’s parts make the final leg of this interesting powertrain swap easier than many Ford owners would imagine.
What’s our summation of the project thus far? Is it time consuming? Yes. Is it something a backyard, DIYer can tackle? Definitely not. Is it a great alternative to rebuilding an old workhorse Ford 7.3L Power Stroke? Die-hard Ford fans will argue it isn’t. But it certainly is a viable option. Having the best of the Big Three’s diesel components in one heavy-duty rig is going to be really sweet.
Industrial InjectionSalt Lake City, UT 84104
BD Diesel PerformanceSumas, WA 98295
DestrokedWheat Ridge, CO 80033
FuelabLitchfield, IL 62056
Mobile Diesel Service541-459-8939
Automatic Transmission Specialists406-222-3992