Harness Your Diesel's Stopping Power
Ever had this happen? You're flat-towing your 4x4 through the mountains and there's a particularly long downgrade up ahead. Maybe your brakes are already a little hot, the pedal is a bit spongy, and you're worried about holding your speed down the hill. About now you're envious of the big-rig truckers and their jake brakes. Hey, what's that smell? Not the brakes, is it?
Getting to the trail head and home again should not be this nerve-wracking. If you tow with a diesel truck, you can eliminate a lot of this worry by installing a supplemental exhaust braking system. It's not a jake brake, but it does use engine power to supplement your wheel brakes. (See the accompanying What's a Jake Brake? story for how the big-rig setups work.)
One of the newest exhaust brake systems on the market is the Banks Brake from Banks Power. If you're a diesel fan, you're probably already aware of the wide range of performance products that come from Gale Banks' Southern California engineering facility. Banks Brakes currently are available for '94-'02 Ford Power Stroke diesels and the Cummins engines in '94-'02 Dodge trucks. GM Duramax applications will be available in the spring of 2002.
The main component of the Banks Brake system is an elbow-shaped housing that bolts between the turbocharger outlet and the downpipe to the exhaust system. Inside the housing is a vacuum-operated butterfly valve. When the system is switched on, a control valve senses when the driver lifts off the accelerator pedal and closes the butterfly valve. This causes exhaust backpressure to build behind the turbocharger. As the engine's exhaust valves open during their normal cycling, the waste gas trying to escape pushes on the air mass accumulating in the pipeline. This slows the engine's reciprocating assembly, which in turn slows the forward progress of the truck. As soon as the driver hits the accelerator pedal again, the butterfly valve opens and the exhaust is free to leave.
The Banks engineers designed the system so that it generates just enough pressure to impede exhaust flow without exerting so much force on the exhaust valves that they open. The butterfly valve doesn't completely close off the flow; in fact, the distinctive "whoosh" sound when the Banks Brake comes on is made by exhaust blowing around the valve. Plus, the vacuum actuator is spring-loaded to open the valve should it lose its vacuum supply, so there's no risk of the valve sticking closed.
The Banks Brake can actually improve engine performance as well as assist with braking. The brake unit's big bore and the new outlet pipe that's attached to it aid exhaust flow from the engine, even when coupled to the truck's stock exhaust system. If you're looking for even more power, you could add Banks' new Monster exhaust system to the brake, with its 3 1/2-inch outlet pipe and 4-inch tubing.
We visited Banks Power to watch a brake installation on one of the company's test mules, an '01 F-350 Super Duty dualie. Then we spent some time out in the real world to see if the brake worked as advertised. Dave Vermilion, the Banks technician who did the wrenching, rates the install as "medium" on the difficulty scale. As you can see from the photos, it's a bolt-on job for the most part. But you do have to disconnect a lot of hoses and wires to access the turbocharger, modify the truck's wiring system to connect the relays and switches, and cut away part of the truck's stock exhaust to mount the new outlet pipe. Vermilion estimates the do-it-yourselfer with the right tools and skills should be able to get it done in about five hours.
As for the testing, we rode with two of Banks' engineers, John Sinz and Troy Larson, as they made several runs up and down the Grapevine, that infamous stretch of Interstate 5 north of Los Angeles that challenges big and little rigs alike with a 6-percent grade. The Super Duty was hauling one of Banks' test trailers, loaded so that the combined weight of truck, trailer, and passengers was about 18,000 pounds.