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Jeep Horsepower And Torque Numbers

Posted in Features on May 5, 2014
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Horsepower and torque. If you are obsessed with cars or Jeeps, chances are that you are obsessed with horsepower and torque. All of us have a cousin or uncle whose college roommate had a diesel truck that made 5,000hp at the rear wheels. Or maybe you (or we) “used to have” a muscle car that had more power than a Bugatti Veyron. Sure, sounds like some of the fishing stories we’ve all heard. These cars, trucks, and Jeeps get way stronger and faster with time, much like that fish grows. Well, one way or another, our obsessions that are Jeeps also make horsepower and torque. How much, you ask? Well, it literally depends on the weather, but why don’t we look into this a little further and see what some fairly typical Jeeps get for horsepower and torque numbers. Sounds good, right? How ya gonna pull that one off, Jp? A smart phone app and a back road? Well, we have friends…no, not many, but still one or two. One such friend, or rather business, that tolerates our presence is Airaid, the company that builds and sells air filters and air intake systems out of Phoenix, Arizona. Airaid has a Mustang chassis dynamometer that we are allowed to use occasionally between 1,000hp fuel-injected and blown Oldsmobile street cars and next year’s production cars.

That works for us, and it allows us to give you a real-life idea of what a few fairly typical Jeeps (some of which you may recognize) make when it comes to power and torque numbers. Are we gonna start running every Jeep we have in the book on the dyno? No. Are we gonna start testing every part we bolt on our Jeeps on the dyno? No way. Are we overly concerned with what our 2.5L four-banger puts to the ground? Not really, but we do hope this will give you an idea of what numbers these Jeeps make at the rear wheels, what you can expect from a similar build, and some plain old fun reading entertainment. And if you like this article, let us know and we’ll set up a few more dyno runs with some different rigs. Special thanks to Airaid, Trent McGee, and Donovan Shafer for helping this story happen.

Mike’s Super-Clean CJ-7
Our buddy, Mike, is a life-long Jeep nut. With several Jeeps to pick from we twisted Mike’s arm and got the keys to his recently restomoded ’76 CJ-7. The Jeep has a fresh AMC 360ci V-8 with 9:1 compression built for torque and a little bit of extra power. Fortunately for us, the Jeep put down some good numbers just before something in the T-case went pop as the rollers slowed down locking the rear wheels (so we don’t have enough good data for a dyno graph). As of this writing, we don’t know what happened, probably a bearing seized, but all involved agree (including Mike, who is, remarkably, still speaking to us) that it was good that it happened on the Dyno and not the highway.

Vehicle: ’76 CJ-7
Engine Displacement: AMC 360ci V-8 with 9:1 compression on premium fuel
Cam: Comp Cams XE256H
Induction: Edelbrock Performer non-EGR intake manifold, Holley 670 Truck Avenger, 14-inch Airaid air filter in open-element housing
Ignition: Davis Unified Ignition HEI
Exhaust: Stock AMC manifolds, Dual exhaust with 2.25-inch tubing and Thrush mufflers.
Heads/Head Work: Older AMC 360 heads with screw-in studs, TRW roller rockers, mild porting
Transmission: TH400 auto
Axle Gears: 3.54:1
Tire/Wheel Size: 33x12.50R15 BFG KMs on 15x8 alloys
Miles: 7,500 since full restomod.
Max Horsepower: 211hp @ 4,300 rpm
Max Torque: 284 lb-ft @ 3,400 rpm

Verne’s CJ-3A
This Willys has been in several tech articles in Jp since the ’00s in one form or another. It’s Feature Editor Simons’ one true keeper car that he has owned since ’99, while others have only lasted a year, two, maybe three. A ’49 Willys CJ-3A now powered by a GM rebuilt even-fire Buick V-6. Simons bought the engine from a junkyard in ’02 from a wrecked Oldsmobile that had a GM Goodwrench engine installed just before the Grandmamobile had a tree jump in front of it. It has a GM rebuild plaque on the block telling about the overbored cylinders and machined crank. The Jeep was run in Third gear with the Saturn Overdrive engaged, effectively turning the 5.38 axle gears to about 4.10s.

Vehicle: ’49 Willys CJ-3A
Engine Displacement: GM-rebuilt even-fire Buick 231ci V-6 bored 0.40 over, 87-octane
Cam: Stock
Induction: GM/Howell 4.3L TBI, 10-inch round Airaid filter in open element housing
Ignition: ’79 even-fire Buick HEI
Exhaust: Novak shorty headers, full length 2-inch true dual exhaust by Chapelle’s Exhaust and Kustom with Thrush mufflers
Heads/Head Work: Stock
Transmission: Ford T-18
Axle Gears: 5.38
Tire/Wheel Size: 35x12.50R15 BFG KM2 on 15x8 Champion Beadlocks
Miles: 4,700 in the Willys, fewer than 40,000 total
Max Horsepower: 115 hp @ 3,800 rpm
Max Torque: 194 lb-ft @ 2,000 rpm

Trent’s TJ
Consummate Jeeper and freelance writer Trent McGee moonlights at Airaid, helping out at shows and with tech calls. He’s at least a large part of why this story happened. We talked him and the dyno operator and engineer extraordinaire Donovan Shafer into running Trent’s ’97 TJ-based buggy on the dyno. “Trent’s Super Hoopty,” “The Buggy,” “Ol’ Blue,” no matter what you call it, the Jeep can go just about anywhere, including down heavy rock trails or the highway. The Jeep has seen 20,000 tough miles since being completed. This includes three Petersen’s Ultimate Adventures and a Vegas-to-Billings-in-January frozen road trip. Trent’s buggy has lots of cool parts, including an Atlas four-speed and some bulletproof, yet heavy, heavy wheels. What does that do to the torque and power numbers—apparently, not much? Trent’s buggy put down some pretty solid numbers for a 4.0L.

Vehicle: ’97 TJ Wrangler-based buggy
Engine Displacement: 4.0L, 87-octane
Cam: Stock
Induction: Airaid UBI system with 3.5-inch tubing and 7-inch SynthaFlow filter
Ignition: Stock
Exhaust: JBA header, 2.5-inch tube with Magnaflow catalytic converter and 40-Series Flowmaster
Heads/Head Work: Stock
Transmission: AX15 five-speed
Axle Gears: 4.88
Tire/Wheel Size: 37x12.50R17 Nitto Trail Grapplers on 17x9 Spyderlock wheels
Miles: 120,000
Max Horsepower: 172hp @ 4,600 rpm
Max Torque: 225 lb-ft @ 2,100 rpm

Shrink Ray TJ
You probably recognize our shortened and beaten TJ, sometimes known as the Shrink Ray TJ. If not, know that it has been a pretty budget build with a few tricky spendy parts. Simons beats on the poor little four-banger TJ with abandon and generally drives it to and from the trail—or from Phoenix to Moab and back. The engine has about 120,000 miles on the ticker just like Trent’s buggy and the Airaid stock TJ, only Shrinky has a 2.5L and an AX5, making it the low-power beater of the bunch. This thing gets less love than a prostitute with leprosy, but thanks to the steep approach and departure angles and flat belly, it can go places where only much larger rigs venture.

Vehicle: ’97 TJ SE
Engine Displacement: 2.5L, 87-octane
Cam: Stock
Induction: Airaid UBI intake with 3-inch tubing and SynthaFlow Filter, 4.0L throttle body
Ignition: Stock
Exhaust: Stock manifold, possible 2.25 after-cat exhaust, Dynomax muffler, dump in front of the rear axle
Heads/Head Work: Stock
Transmission: AX5
Axle Gears: 4.88
Tire/Wheel Size: 35x12.50R15 Pro Comp MT2 on 15x8 Weld wheels with OMF beadlocks
Miles: 122,000
Max Horsepower: 116hp @ 5,000 rpm
Max Torque: 139 lb-ft @ 1,700 rpm

The Stock TJ
Occasionally, Airaid plays with an employee’s daily driver and then foolishly allowed us to run it on the dyno for this article. One such Jeep is this ’98 TJ that is fairly stock compared to the rest of the pack we are testing in this article. With 31s, a hard top, and some aftermarket tricks, this TJ is what our Jeeps used to be and probably what many of your Jeeps were, too. Still with an odometer reading right around that of Trent’s buggy but running an auto tranny, comparisons can be made between this TJ, Trent’s, and even our very own 4-cylinder-powered shrunken TJ.

Vehicle: ’98 TJ Sport
Engine Displacement: 4.0L, 87-octane
Cam: Stock
Induction: Airaid CAD Cold Air Intake System and Airaid PowerAid throttle body spacer
Ignition: Stock
Exhaust: Flowmaster header, Flowmaster cat-back exhaust
Heads/Head Work: Stock
Transmission: TF999 auto
Axle Gears: 3.55
Tire/Wheel Size: 31x10.50R15 Goodyear Duratrac on stock 15x8 Outlaw Jeep wheels
Miles: 102,000
Max Horsepower: 171hp @ 4,700 rpm
Max Torque: 214 lb-ft @ 3,900 rpm

Installing Airaid’s Universal Air Kit
You’ve probably noticed that all of the Jeeps in this article are running Airaid intake parts. From a filter to a fully engineered cold air kit, Airaid has intake and air cleaning for pretty much any Jeep in a headlock. That includes a you-build-it style system for very custom Jeeps such as Trent’s Buggy and our very own Shrink Ray, where the stock engine bay may not still be present. That comes in the form of Airaid’s UBI kit. Just for smiles, we talked Airaid into letting us test it to see if their UBI (short for you build it) custom intake system helped Shrink Ray make more power and torque than with the old bulky stock air tubes and box. Bravely, they let us try it, and hey, we made more power and torque with the simple UBI kit we built and installed in about 30 minutes. That’s pretty cool, especially since dedicated intake kits usually undergo many hours of digital design and flow optimization. With the UBI installed, we picked up 5hp and about 4 lb-ft of torque.


Phoenix, AZ 85050

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