Car Care
Going with the Flow, Part 1
Upgrading a Wrangler's exhaust headers
Created by Steve TempleThe Jeep Wrangler has wonderful off-road capabilities, but it has at least one area in particular that could be improved: the exhaust system. Replacing the constrictive stock system with high-flow headers is done not merely to gain more power, though picking up some more ponies is a welcome benefit. The stock headers also tend to crack over time, despite the use of accordion-style expansion joints in the primary tubes.
Streamlined Flow
Aftermarket companies can often provide a solution to inherent design flaws. For instance, Gale Banks Engineering, a company well-known for its high-performance turbochargers and other performance upgrades, developed a TorqueTube exhaust manifold assembly that is streamlined to optimize flow and engine efficiency. The unit fits the 4.0L inline six found on several models and years of Jeeps (1991-2003 Wrangler, 1991-'01 Cherokee, '93-'01 Grand Cherokee, and 1991-'92 Commanche). The stock manifold's flange does not align squarely with the ports and restricts flow, but the TorqueTube corrects the problem with a half-inch flange that's machined dead flat and precisely fitted to the port pattern. When used in combination with the Banks Stinger cat-back system (see Part 2 of this article series), the power gain is as much as 25 horses. You can also hear the difference in the healthier exhaust note. An optional head pipe is available for the best flow.
Replacing the stock headers with the TorqueTube is somewhat involved since you have to remove several engine accessories and components. The toughest part is getting access to the bolts, since it can get pretty cramped in places. You'll need some socket extensions with swivels to get at some of them.
Unlike the cast-iron OEM intake manifold, the TorqueTube is built of heavy, 409 stainless steel designed to weather heat, stress and abuse. The flange is fully welded to the tube assembly on both sides, and Banks claims it will never crack or separate. The gasket is made of SMI 900, a material that stands up to super-hot temperatures—all of which should give Jeep Wrangler enthusiasts a whole lot more peace of mind the next time they head off-road for some four-wheelin' adventures.
Resource
Gale Banks Engineering, 546 Duggan Avenue, Azusa, CA 91702, 800-438-7693, www.bankspower.com
Step 1
Use a fuel-line quick-disconnect tool to clamp off the fuel line and prevent spillage.
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Step 2
Since the intake manifold provides a mount for the power steering pump, it has to be loosened to remove the stock headers.
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Step 3
After disconnecting the air inlet tube (not shown), remove the throttle cable, electrical connectors and vacuum lines.
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Step 4
Apply some lubricant to loosen the bolts for the lower end of the stock exhaust manifold. Disconnect and separate the oxygen sensor as well.
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Step 5
To keep the engine internals clean, use an air hose to clear away dust and debris before unbolting and removing the intake manifold.
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Step 6
First loosen but don't remove the bolts at the center and extreme ends of the exhaust manifold. These act as temporary supports while you remove the remaining bolts. Then remove the stock exhaust manifold.
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Step 7
Note the difference in the configuration of the stock versus the Gale Banks exhaust manifold.
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Step 8
Close-up of Banks headers shows the mandrel-bent primary tubes and seamless Y-connectors.
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Step 9
After cleaning off the old gasket material with a scouring pad and solvent (be careful that debris doesn't enter the ports), install the new high-temp, metal-reinforced gasket supplied with the Banks manifold.
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Step 10
Carefully fit on the new exhaust headers, and apply an anti-seize compound to the header bolts.
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Step 11
Be sure to torque down the bolts to 24 lb.-ft. and in the pattern shown in the manual. Attach the lower end of the manifold to the exhaust pipe. Now you can re-attach the stock intake, steering pump, fuel rail, vacuum lines, electrical connections and inlet tube.
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