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  • What Happens When a 600hp Cummins and an Allison Transmission Come Together in an 2004 Ford Excursion

What Happens When a 600hp Cummins and an Allison Transmission Come Together in an 2004 Ford Excursion

Fumminstein Lives!

Jason Sands
Jun 17, 2015
Photographers: Jason Sands
Marshall Davis had what seemed like a simple problem: He wanted a diesel SUV. Unfortunately, the vehicle he was looking for in terms of power, capability, and size just wasn't out there. Sure, there were the older Chevrolet Suburbans, but he was none too excited about their twisty frames or 6.5L indirect-injection diesels.
Photo 2/22   |   2004 Ford Excursion Side
There were also Volkswagen Touaregs for Marshall to consider. But, with their V-10 engines making “only” 310 hp and because there were only a limited assortment of performance upgrades available for those powerplants, Marshall’s options were slim.
It was around this time that he connected with Scott Countryman, owner of Destroked.com. Together, they came up with a plan for building the best SUV for meeting Marshall’s needs, using parts from Ford, Dodge, and GM trucks. The frame needed to be solid, so the vehicle they selected was a tough ’04 Ford Excursion. The gas-powered SUV lacked power and fuel economy, however, which is where the Cummins part of the equation came into play.
Photo 3/22   |   At the heart of this awesome swap is a 6.7L Cummins engine that was pulled from a donor vehicle with only 30,000 miles on it. The heavily modified powerplant makes an estimated 600 hp, all the while knocking down 17 to 18 mpg on the freeway.
One of the most capable diesel engines on the planet is the 6.7L Cummins, which is the engine Marshall chose for his build. He wanted more than double its rated horsepower, though, so the engine received a host of upgrades. Since the 6.7Ls are very strong from the factory, a set of ARP head studs is all that was added to the long-block to help keep the head properly clamped under high boost pressures.
Speaking of boost, the Cummins’ compound turbocharger system makes a whopping 70 psi, thanks to a 64mm BD turbo fed by a 75mm BorgWarner S400 atmospheric ’charger. Air is then funneled through a Banks Power intercooler designed for a 6.0L Ford. Fuel has also been tinkered with via an ATS Performance Diesel Twin Fueler CP3 kit, Dynomite Diesel 120hp injectors, and tuning from MADS Smarty Performance.
Photo 4/22   |   A big contributor to the engine’s impressive power is this compound turbocharger setup, which was built by Destroked.com. The smaller of the two turbos is a 64mm ’charger, which is fed by a 75mm S400. Capable of up to 70 psi of boost, the turbos spool just fine in high altitude, thanks to the 6.7L’s extra cubic inches.
With Colorado being a state with just a few “small hills” to climb and descend, Marshall also wanted a five- or six-speed transmission. The best gearbox for the job turned out to be a GM product: the Allison 1000 six-speed automatic transmission. Built by Destroked.com, the unit can handle the extra power thanks to upgraded clutches, a Precision Industries triple-disc torque converter, and a stand-alone controller to manage the shifting.
With bucket loads of engineering and a conservatively estimated 600 hp, it should come as no surprise that Marshall couldn't leave the stock suspension alone, either. Custom springs from Deaver on all four corners support the Cummins engine and give the truck a 3-inch lift, while providing an awesome ride for a daily driver.
Photo 5/22   |   Monitoring of the drivetrain is done through a single Edge CTS monitor, which most of the time is set to display boost, EGT, fuel pressure, and engine coolant and oil temperatures.
So, with a Ford frame, Cummins engine, and Allison transmission, did Marshall get the SUV he finally wanted? Interior space isn't lacking in a big rig like an Excursion, the engine makes more horsepower than a Porsche Cayenne S Turbo, and the suspension can tackle the tough Colorado winters.
With almost five years and thousands of miles on this combination, we'd say Marshall finally has the ride he was looking for.
Photo 6/22   |   2004 Ford Excursion Rear Three Quarter
Fast Facts
Year/Make/Model: 2004 Ford Excursion
Owner: Marshall Davis
Hometown: Denver, Colorado
Odometer: 126,893 miles
Engine: 6.7L Cummins I-6 with ARP head studs
Fuel: AirDog 165-gph lift pump, Dual CP3s from ATS Performance Diesel with a Destroked.com pulley, Dynomite Diesel 120hp injectors, and MADS Smarty Performance tuning
Air: Destroked.com intake with AFE filter, BD 64mm turbo over a 75mm BorgWarner S400, and Banks Power intercooler
Exhaust: 4-inch exhaust built by Destroked.com
Transmission: Allison 1000 six-speed automatic built by Destroked.com, Precision Industries torque converter, and Destroked.com stand-alone controller.
Horsepower: 600 hp
Torque: Est. 1,100 lb-ft
Tires: 285/75R18 Nitto Terra Grappler A/T
Wheels: 18x10 KMC wheels
Suspension: Custom front and rear springs from Deaver Spring, King shocks, and Firestone airbags
Axles: Stock, with 3.73:1 gears
Fun Fact: If you're wondering about the orange paint on an otherwise understated build, it turns out Marshall is a huge Denver Broncos fan.
Photo 7/22   |   2004 Ford Excursion Front Three Quarter

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