This 1,000HP Compound-Turbo, Gen 3 Hemi Swapped Grand Cherokee is Absolutely Insane

10 min read

This 1,000HP Compound-Turbo, Gen 3 Hemi Swapped Grand Cherokee is Absolutely Insane

10 min read

“My first project car was a ’76 Jeep Wagoneer,” recalls Greg Huizenga, a mechanical engineer from Middleville, Michigan. “We did a full restoration on it, pretty much back to stock. But then I decided I wanted clean it up a bit under the hood, and then I thought I should pull the engine out to make it easier. Then I figured I might as well rebuild the engine, and then I figured I might as well build a bigger engine. Then it kind of snowballed from there.”

The Wagoneer ended up being the first in a succession of hot-rodded vintage Jeep builds for Huizenga. It eventually led to a six-year ’83 Cherokee Wide Track project that he completed in 2016, but just a year after he put the finishing touches on the project, the Jeep was totaled by a drunk driver. That left Huizenga wondering what to do next.

“I sort of consider this ’75 to be a continuation of the ‘83,” he explains. “I hesitate to call it a pro touring build because it doesn’t really have all of those creature comforts, but it’s a similar concept. I wanted to build something that would be reliable and do a lot of different things pretty well, and I think I’ve achieved that – I drove it 500 miles to MoParty, beat the crap out of it at the event, and drove it back home without issue.”

For most of us, seeing a full-sized vintage Jeep being flogged on the autocross or sent down the drag strip is a pretty unusual sight. Huizenga’s build takes that notion to the next level by virtue of the fact that this Cherokee can truly hold its own in either setting: Huizenga took the top spot in the Truck class for both the Speed Stop and Autocross events at MoParty and then proceeded to run in the mid-10s on strip using the same set of tires.

As you might expect, the Cherokee is anything but stock underneath the skin. The Jeep sits on a second-generation Chevy C10 chassis that’s been shortened by seventeen inches in the middle, while the front framerail has been moved down by four inches. “I did that to get the suspension mounting points where I wanted them to get the right geometry,” Greg says. “And with the frame down, the whole engine kind of sits above the frame, so it’s super easy to work on.”

The suspension consists of a Wide Ride IFS setup from No Limit Engineering with Ridetech coilovers up front, while the rear is modified version of the factory C10 hardware with custom coilovers and an adjustable track bar. “The rear axle is an old Yates Racing Cup car unit, so it’s a full floater 9-inch,” he notes. “And I’m using a 3.70 gear with a Detroit Locker.”

At Holley MoParty, Huizenga competed in the Grand Champion competition and took home the win in the truck class. His Jeep was wickedly fast at the drag strip and on the autocross course!

On the powertrain front, Huizenga rows through the gears with a modern Tremec TR6060 six-speed manual transmission that he sourced from a late-model Dodge Challenger. Greg made a few tweaks of his own here as well.

“It’s kind of a hodge-podge – I’m using the gear set from an R/T for gears 1-4 and the close-ratio 5th and 6th gears from a Hellcat. I didn’t want to use the Hellcat first gear – it’s really hard on clutches when you’re trying to do the drag stuff. On a slick, the 2.97 first gear from the R/T works really well. I can leave at like 5400 RPM off of the two-step on seven pounds of boost.”

Speaking of boost – the engine is another area where Greg shrugged off convention. Power comes from a thoroughly warmed-over 5.7-liter Gen III Hemi, but Huizenga quickly dispels any notions that this is some kind of exotic, high-buck build. “There’s actually not a whole lot to say about the engine itself – it’s got the stock crank, bearings, and camshaft. To handle the boost I’m using Molnar connecting rods and Mahle pistons, along with upgraded valve springs and injectors.”

Beyond killer looks and performance, the Jeep is a real driver. Huizenga drove it 500mi to Holley MoParty 2020 and has put 37,000mi on the Gen 3 hemi engine since installing it.

He originally built a single turbo setup for the Cherokee, but soon decided he wanted more. “I have a friend that works at Bullseye Power Turbochargers, and he had an idea that he wanted to try. I wanted a really smooth power curve that started really low in the rev range for the autocross stuff, so he wanted to try a really small turbo on there. We put one of their S366 66mm turbos on it and it made 720 horsepower to the tires, and it was great for autocross. But it just didn’t make quite enough power – I could get to 10.30s in the quarter mile on slicks, and I wanted to go 9s. But I also didn’t want to go to a bigger single turbo and lose the low-end response.”

The solution was a compound turbo setup. “I left the small turbo on there and added an 80mm S480 on top of that,” he tells us. “So the small turbo basically spools up immediately like it always has, and that helps the big turbo spool up quicker as the revs climb. I’m also using a dual wastegate setup – one of them bypasses the small turbo while the other works like a regular wastegate, controlling the total boost – and with the bypassed one, I can change the characteristics of how each turbo comes in. By playing around with that, I was able to get an extremely linear power curve out of it. It’s almost like an electric motor.” The current combination is good for 875 rear-wheel horsepower by Huizenga’s calculations.

To help corral all the grunt, a Holley HP EFI system handles boost control and launch control as well as throttle position control. “The throttle position modifier is useful for the autocross because it prevents the pedal from working like an on/off switch and frying the tires,” he says. “I have really good control at low throttle openings, and it snaps open past half-throttle. It’s a great setup – literally all I changed to go autocrossing at MoParty from previously running high 9s at the drag strip was the tires.”

After his success at MoParty, you might think Huizenga would be content to leave well-enough alone, but he’s already got his sights set on the next step in the Cherokee’s evolution.

“This 5.7 is running pretty well, but it’s got a ton of miles on it,” he says. “I’ve put 37,000 miles on it on boost, and it already had 56,000 miles on it when I pulled it from the junkyard. So I’ve got a 6.4-liter Hemi that’s slowly coming together. I’ve been getting parts for it here and there, but Holley keeps adding on more ideas to my project; I was going to build an intake for it because nobody made what I’ve been wanting for it, and then all of a sudden they come out with a Hi-Ram!”


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