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Jeep TJ 4.0L Power Up

Engine Installing Air Intake0
Christian Lee | Writer
Posted October 22, 2002

AEM's Brute Force Cold Air Intake

Advanced Engine Management (AEM) Inc. wasn't messing around when its engineers set out to design the Brute Force Air Intake System for '97-'02 Jeep TJs. Using the technology behind its established street systems, AEM already had a good basis for what type of performance gains it expected to get out of the Jeep 4.0L engine. One difference, however, is that in the search for horsepower, the engineers still paid close attention to maintaining and increasing low-end torque. This resulted in a very trail- and street-friendly intake system and easier breathing for the Jeep TJ.

The AEM Brute Force Air Intake System features a CNC mandrel-bent 6061 aluminum intake pipe that's individually tuned in both length and diameter for maximum power, is powdercoated, and uses TIG-welded fittings and brackets. Efficient air filtration is achieved through use of AEM's lightweight urethane four-layer cotton-gauze filter that features a redesigned air horn that's said to make an additional 1-3 hp when used with an AEM system.

The Brute Force system is pending C.A.R.B. exemption (50-state legal) and comes with complete installation hardware, detailed instructions, and an AEM decal and license plate frame. The system is manufactured in the U.S.A and requires no drilling or modification of factory components for installation.

We installed one of the first Brute Force systems manufactured on our Project TJ and were immediately impressed with the increase in performance. Highway and commuter driving benefited greatly, offering a 75 mph cruising speed at 3,200 rpm with plenty of pedal left to bring it to 80-85 mph while still under 3,500 rpm.

Low-end performance also hopped up a good deal, with excellent pedal response for planting extra torque to the ground for bumping over trail obstacles and steep hill climbs. AEM promised a better breathing engine with its Brute Force Air Intake System. Not surprisingly (and thankfully), it has provided.


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  • The Brute Force Intake System from AEM is available for '97-'02 4.0L Jeep TJs. The system uses AEM's specially designed Power Spacer to maximize performance.

  • In addition to the Power Spacer, the AEM system includes a CNC mandrel-bent 6061 aluminum tube, a one-piece, four-layer cotton gauze AEM air filter, an aluminum heatshield, a rubber reducer, installation hardware, and detailed instructions.

  • The stock cold air intake system might cut it on a stock vehicle, but not so much when you're rolling 35s and weighing in a bit heftier.

  • Removal of the stock system is a simple process. We first removed the air tube and upper portion of the air filter box, then unfastened the box base and inlet from the wheelwell.

  • The throttle body was then unbolted from the intake manifold so the AEM Power Spacer could be set in place. It was installed using the provided gaskets and longer bolts.

  • With the throttle body bolted atop the Power Spacer, the rubber reducer was secured to it with a hose clamp.

  • A custom aluminum heatshield -- designed to ensure the intake receives the coolest air possible -- bolts in place on the wheelwell. No drilling is required.

  • The mandrel-bent aluminum air tube was then secured to the rubber reducer using a provided hose clamp. A soft mount to the wheelwell helps keep the intake system well stabilized, even on the bumpiest of trail rides.

  • A supplied breather hose secures to the aluminum air tube using the provided hose clamps. Note the clean TIG welds throughout the tube.

  • The Brute Force Intake System appropriately uses AEM's lightweight urethane, four-layer cotton-gauze filter designed for maximum horsepower increase.

  • As a final step, we installed the provided rubber gasket along the top of the aluminum heatshield.