Banks’ Duramax BIG HOSS INSTALL

Truckin' May 2005

by Tim Gavern

photography Tim Gavern

Instant Muscle-Truck In A Box

The latest generation of General Motors Duramax turbodiesels, designated LLY, are taking the truck world by storm. Even in stock form, they do everything right: They’re quiet and powerful, they have plenty of torque, and they’re fast.

The LLY Duramax diesel is so hot dealers can’t keep them in stock. This is amazing considering Duramax LLY turbodiesels cost nearly $6,000 more than their gasoline-powered siblings when equipped with the sweet-shifting Allison five-speed automatic transmission. But, even with the additional cost over the gas models, you get what you pay for–the Duramax LLY engine should last a few hundred thousand miles when properly maintained. Plus, the resale value will always be higher.

We’ve found what might be the best way to turn a Duramax LLY into a 9,000-pound musclecar. OK, muscle-truck. Most of you have already heard of Gale Banks, but did you know that his company, Gale Banks Engineering, has been building high-performance diesel products for more than 25 years? Its Big Hoss Bundle is a well-engineered and tested system that is able to generate 124 additional horsepower and more than 305 lb-ft more torque from a Duramax LLY-equipped truck. The difference in the truck is stunning, and the power is both useable and continuous.

The first thing turbodiesel consumers need to learn is that the big black trails of sooty smoke seen in every diesel tuner ad isn’t cool. In fact, it’s a joke. Black smoke is the telltale sign of a diesel engine being over-fueled. Adding fuel without adding proper amounts of air to go with it immediately raises exhaust gas temperature (EGT), which eventually leads to problems and shortens engine life. Gasoline engines throttle by air intake. Diesel engines, on the other hand, throttle by fuel intake. To put it simply, the more fuel a diesel engine takes in, the more power it makes. You can literally push enough fuel into a diesel engine that its physical strength cannot handle it, or there simply isn’t enough air to combust the fuel.

Because diesels make more power by pushing more fuel, many diesel tuners simply add a power programmer, diesel computer tuner, or whatever you want to call it, and call it a day. This is great if you only need extra power for 15 to 20 seconds at a time. Because soon after that, the EGT will skyrocket to the point where the safety temperature-limiting feature of the diesel tuner will shut off the additional fuel. No added fuel means no added power. 

Think of it this way: A diesel tuner working alone is like a nitrous oxide system–you can only use it for short power spurts. In the diesel’s case, the extra power stays turned off until the EGT cools down to acceptable levels. Only then will the horsepower be available again. And soon enough, it will be gone until the exhaust cools down again. And so goes the vicious cycle.

Let’s get back to the engine problems that can be traced to continually high EGT from over-fueling. The first is the uncombusted fuel, which you might recognize as the black soot that spews out of the tailpipe and contaminates the engine’s oil. This contamination rapidly breaks down oil, causing premature engine wear. The second is tales on the messageboards of pistons getting so hot they stick in the cylinder bores. That should be proof enough that it isn’t the right way to make power.

Banks’ Big Hoss Bundles are its top-of-the-line systems and include every power-making component in Banks’ power arsenal. First, a Banks Ram-Air lifetime high-flow air filter element supplies cooler, denser air to the engine. Next, a 4-inch stainless steel straight-through Monster Muffler and 4-inch stainless steel Monster Exhaust system with a 5-inch stainless steel double-walled tip cuts backpressure by an amazing 98.37 percent, according to the company. This allows the turbo to spool faster and run cooler. Less backpressure also reduces pumping losses, which is the amount of engine power required to pull air in and push exhaust out.

The turbocharger compresses the intake air, which also, unfortunately, heats it. Banks’ larger intercooler, called a Techni-Cooler, and its larger-diameter boost tubes cool the compressed air and increase its density as much as 10 percent in the Duramax LLY application. Banks is big on air density, and for good reason. To put it simply, for every percentage that the intake air can be made denser, an equal amount of horsepower can be made. In other words, 10 percent more density translates into 10 percent more horsepower. Cooler, denser, more-oxygenated air will allow more fuel to combust completely for more power without increasing EGT. In other words, the power you paid for is there–all of the time, not just when the EGT goes back down. Banks’ Six-Gun Diesel Computer tuner with Speed-Loader option is included to supply the necessary additional fuel for more power. Six-Guns have a six-position dash-mounted knob that increases power in 20 percent increments. Just turn up the knob for more power and suddenly you have a 9,000-pound race truck.

Banks' Duramax BIG HOSS INSTALL
1. The Banks Big Hoss Bundle kit as well as its Six-Gun Diesel Tuner Box. The kit includes a much larger intercooler, recontoured turbo down pipes, new 4-inch, straight-through muffler system, and all the necessary mounting hardware.
Banks' Duramax BIG HOSS INSTALL
2. The difference in the factory exhaust and Banks Monster Exhaust pipes (foreground) is clear. The stainless steel Banks Monster Muffler is designed specifically for diesel applications and features an exclusive expansion chamber that reduces the drone common to many performance mufflers when used in diesel applications.
Banks' Duramax BIG HOSS INSTALL
3. Banks master technician Dave Vermillion installed the Banks Monster exhaust pipes, as well as the Monster Muffler.
Banks' Duramax BIG HOSS INSTALL
4. In order to install the Banks Techni-Cooler, the grille, headlamp assemblies, and top radiator support required removal. Dave also removed the factory boost tubes for replacement with Banks’ large-diameter boost tubes.
Banks' Duramax BIG HOSS INSTALL
5. The difference between the Banks Techni-Cooler (top) and the factory intercooler is evident in the difference in thickness. The Banks Techni-Cooler is 2 inches wide, compared to the factory’s 1.5-inch-wide unit. Banks Techni-Coolers increase density by as much as 10 percent. This directly translates into an equal increase in power. It decreases loss in boost pressure and lowers EGT by lowering the intake air charge temperature.
Banks' Duramax BIG HOSS INSTALL
6. If the truck has air conditioning, the A/C condenser can usually be unbolted and pulled out of the way enough that it should not require complete removal.
Banks' Duramax BIG HOSS INSTALL
7. With the Techni-Cooler in place, Banks tech Dave Vermillion reinstalled the remaining factory components.
Banks' Duramax BIG HOSS INSTALL
8. Banks Monster Exhaust pipes are 4-inch-diameter stainless pipes that fit perfectly using factory-style hardware.
Banks' Duramax BIG HOSS INSTALL
9. The difference in the diameter of the Banks boost tube versus the factory boost tube is clearly evident. Its larger diameter helps decrease loss of boost pressure coming from the intercooler.
Banks' Duramax BIG HOSS INSTALL
10. Banks technicians removed the factory right-side exhaust manifold to install the pyrometer lead, which sends the EGT to the Banks Six-Gun Diesel Tuner. The exhaust manifold must be drilled and tapped to accept the pyrometer. Attempting to do this while the manifold is still on the truck could produce metal shavings that could end up in the turbocharger; the results of that could be devastating.
Banks' Duramax BIG HOSS INSTALL
11. Banks technician Chris Whitney replaced the factory boost tubes with Banks large-diameter boost tubes.
Banks' Duramax BIG HOSS INSTALL
12. A supplied pillar-mount instrument panel fit perfectly over the factory A-pillar cover. It was held in place with button-head retaining clips. Dave drilled a hole through the instrument console and the pillar cover for a retaining clip that will hold them together. There were many different options for the additional gauge placement, such as the one shown, as well as the top-of-dash, pod-mount instrument consoles, and traditional under-dash mounting panels.
Banks' Duramax BIG HOSS INSTALL
13. Dave installed the Banks Six-Gun Diesel Tuner knob into the dashboard.
Banks' Duramax BIG HOSS INSTALL
14. Here’s the Banks right-side boost tube after installation.
Banks' Duramax BIG HOSS INSTALL
15. The Banks Monster Exhaust features 4-inch stainless steel pipes with a 5-inch polished stainless steel tailpipe tip. The exhaust tip has double-walled construction to protect it from discoloring caused by exhaust heat.
Banks' Duramax BIG HOSS INSTALL
16. The Banks Six-Gun Diesel Tuner offers six levels of additional horsepower at the turn of a knob, along with the industry’s best safety features to help to protect your hard-earned investment from meltdown.
Banks' Duramax BIG HOSS INSTALL
17. Complete wiring instructions are included with the Banks Six-Gun Diesel Tuner. The Six-Gun is virtually plug and play with all major connections using factory-style harness connectors.
Banks' Duramax BIG HOSS INSTALL
18. After the Banks Six-Gun Diesel Tuner’s wires were routed and connected, the tuner was mounted to the side of the fuse box using the included strips of double-sided tape.
Banks' Duramax BIG HOSS INSTALL
19. The Six-Gun knob was positioned for easy access to the left of the steering column. Also evident is the Banks back-lit, pillar-mounted electronic analog-style pyrometer and boost gauges.
Banks' Duramax BIG HOSS INSTALL
20. With the Banks Big Hoss Bundle and Six-Gun Speed-Loader installed, the results speak for themselves. Gaining an additional 124 hp and 305 lb-ft of torque is amazing.

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