The combination of a Ford chassis with a Chevrolet powerplant may make the purist cringe, but the marriage of these two opposites has become a go-to setup for many budget-minded racers. Karl Pritz of K.P. Tuning has brought this ideology to a whole different level. After shooting the breeze with friends at his shop, he laid out plans to test the horsepower boundaries of a 4.8-liter engine, which he recently pulled out of a Chevrolet pickup truck at his local junkyard.
Pritz knew full well that this unsuspecting small-displacement, LS-based engine is a formidable combination once boost is introduced into the equation. But Pritz wasn’t just looking for cheap way to make a blistering quick 1/4-mile monster. After scouring the internet, he realized this would be a chance to break the factory long block L20 record.
According to this LS1tech forum thread, the quickest pass made on a stock long block 4.8-liter was made by user Lavoy, who claims his 2,800 pound vehicle traversed the 1/4-mile in 8.85-seconds at 153 mph with the assistance of a 74mm turbocharger.
In this Youtube video, by user TalonTSi97 Videos, we witness firsthand the fall of the factory long block 4.8-liter record. When this turbocharged Mustang rolls up to the staging beams you know it’s ready to create a bit of LS history. After letting go of the transbrake, Pritz makes the 8.284-second pass at 164.53 mph look easy, despite the fact that the hood departs itself from the car at the end of the run.
During the second pass of the day, the front end caught an extensive amount of hang time. The saying is, what goes up must come down. Once he aborted the run, the nose came crashing down to the racing surface and made contact with the cast aluminum oil pan, rendering the rest of the day a bust. The critical first pass may be the pinnacle of this story, but it is by no means the entire saga. We caught up with Pritz to discuss what inspired him to pursue this particular LS-record.
“This entire build was an extensive test for me, something I’ve wanted to do for quite a while now,” stated Pritz. “While everyone seem to head towards the 6.0 and 5.3-liter builds I’ve always felt drawn to the 4.8, due to its unique square bore to stroke ratio.”
He began this venture by acquiring a Fox body roller, and then proceeded to transplant a 2007 Chevrolet Silverado junkyard engine; that was pulled with 150,000 miles on the odometer. According to Pritz, they only modifications performed to the long block is the introduction of Brian Tooley Racing valve springs and pushrod, a custom ground Comp Cam, ARP head studs, and a new set of head gaskets. The addition of a stout Rossler Powerglide transmission and PTC torque converter was attached to this little engine, in order to control the chaos that was about to ensue.Now down to the nitty-gritty of what woke up this 300 horsepower factory-rated L20 and became its driving force.
A Borg Warner s484 turbocharger with a custom billet 84mm Forced Inductions compressor wheel feeds this small displacement bullet. Every bit of turbo piping was custom fabricated by JM Fabrication out of Sellersville, Pennsylvania. They also threw together the custom top hat for the Holley high ram intake manifold. The intake charge is cooled down drastically by an air-to-water intercooler before hitting a steady supply of VP Racing Fuel C16. While a Holley EFI HP ECU controls the intense potential of 30 pounds of boost, in conjunction with a Leash Electronics Boost Leash.
“I was going to turn the car down and run it in 8.50-index, but I’ve already decided to build another engine,” said Pritz. “The next time she heads out to the track, I’m going to turn her up until she comes apart. After that last run, it also seems like I’m going to need limiters to control the front end. I’ll also be shooting to break the 7-second barrier this next outing.”
We’ll be catching back up with the K.P. Tuning crew after their next outing with this gnarly little Fox body. If everything goes well, Karl Pritz will be talking to us with a 7-second time slip in hand.