To Smoke A Muscle Car: 6.4L Power Stroke Edition

• October 2, 2020
• Story By
  Mike McGlothlin

Picture this: It’s fall and you’ve decided to hit your track’s year-ending Midnight Madness to have a little fun with the local street cars. While you’re waiting your turn to race the car next to you, you see it—the big, dopey-looking Super Duty you saw lumbering around the staging lanes a few moments ago just turned in a 12-second pass. And not only that, it gapped the late-model Mustang GT it was up against from wire to wire. How the hell did that happen? Surprisingly, we’ve seen this scenario play out many times before. With a couple simple mods and the help of four-wheel drive, an ’08-’10 Ford Super Duty equipped with the 6.4L Power Stroke V-8 can be a real menace at the drag strip. Below, we explore just how easy it is to hunt down pony cars in one.

Unmatched Out-of-the-Box Potential

We know the 6.4L Power Stroke has its reliability issues, but if you’re after raw horsepower and utmost performance value per dollar spent, it is unrivaled in the modern diesel era. With two simple mods, the factory compound turbocharged, common-rail diesel V-8 can be awakened in a big way. In fact, so much power can be unlocked from the 6.4L that it hardly matters it’s one of the heaviest engines ever offered in what was also the domestic truck market’s heaviest pickup.

Custom Tuning

On any late-model diesel engine, common-rail technology means that electronic controls are everywhere, but so are lightning-quick injection events and super high injection pressures. When you tap into the control system and command more injector duration, add timing and raise rail pressure, huge gains can be had without changing anything else on the truck. The 6.4L Power Stroke is no different. In fact, aggressive custom tuning for the 6.4L has long been known to add more than 300-rwhp over stock. In some cases, even as much as 350rwhp can be unchained. Of course, in addition to custom powertrain control module (PCM) tuning for the engine, it should always be accompanied by custom transmission control module (TCM) tuning in order to keep the stout 5R110 TorqShift transmission alive.

Exhaust

In conjunction with custom PCM and TCM tuning, a free-flowing exhaust system is the only other thing you need to get a 6.4L Ford into 600rwhp territory or beyond. While 5-inch systems are popular, 4-inch piping suffices just fine in diesel applications under 800 hp. Combined with the factory variable geometry turbo, a restriction-free exhaust gives you the “hair-dryer” effect that a stock turbo’d 6.4L is notorious for.

The Rest Can Be Left Stock (Like Stock-Stock)

The rest of the 6.4L can be left 100-percent stock. That means stock injectors (the efficient piezoelectric units are extremely fast-firing), factory high-pressure fuel pump (the Siemens K16, which outflows a comparable Bosch CP3 by 20-percent) and an untouched OEM compound turbocharger system (the 52mm/65mm arrangement that spools lightning quick and also pulls hard up top). It also means stock transmission (the 5R110 was designed to handle 1,100 lb-ft of twist), stock transfer case (these never brake, at least not at this power level) and bone-stock axles. The only real con is that the front-end may hop if launched with more than 15-psi of boost on tap, but it’s not usually a big deal on the drag strip, and at this power level. Hooking to a sled is a different story.

The Boosted 4x4 Launch: Making Diesels Fun Since The ‘90s

On the track, four-wheel drive eliminates virtually any traction issues a diesel might have, even when launching under considerable boost. If the burnout didn’t warm up the street radials enough on your car or you end up spinning on the line, good luck reeling the truck back in. A diesel that’s tethered to an automatic transmission has the unique advantage of being power-braked while staging in order to build boost pressure. When that happens, an immense amount of torque is stored in the converter, and it hits all at once at go-time, hence the 1.7-second 60-foots you see from these 8,000-pound behemoths. Four-wheel drive provides the traction and boost provides the low-end explosion of torque that catapults them off the line.

Standard Cab Super Duty’s Aren’t Exactly Lightweights

This was the workhorse we did our testing with. The XL trim, regular cab ’08 F-250 was the lightest Super Duty we could find, yet still tips the scales at 7,300 pounds! Aside from a set of wheels and tires, it was treated to a tune and exhaust and promptly driven to the local test ‘n tune. As for the weight, don’t let the heft of these trucks scare you. We’ve seen tune-only crew cabs squeak into the 12’s over the years. And if you have plans to play around with a small stage of nitrous like we did, you can easily dabble with bottom 12’s in the quarter-mile or mid 7’s in the eighth.

8.0’s in the Eighth

At our local eight-mile facility’s test ‘n tune, the truck responded with an 8.07 at 84.59 mph, which calculates out to 617 hp at the wheels and converts to 12.8 at 105 mph through the quarter, if you trust the online Wallace Racing calculators thousands of gearheads swear by. Other quarter-mile conversions list the truck as being capable of 12.60s at just under 106 mph. Either way, we were moving, and never saw the truck in the other lane.

Mid 7’s On A Tune, Exhaust and N2O (750+ HP)

Getting a little sneaky with a single stage Nitrous Express system, we returned to the track to see what a little giggle gas could do. The 6.4L liked it—a lot. Picking up roughly 150 more horsepower, the truck went 7.55 at 91.08 mph in the eighth-mile. Wallace says that’s a 12.00 at 113 mph in the ‘1320. Also notice the 60-foot in the 1.6’s on that hit…the truck left hard yet smooth and was aided in the effort by a set of NT420S Nittos, which had no problem sticking to the track.