Five Surefire Performance Boosts for Your Diesel

By Ben Wojdyla and Mike Levine

As much as we applaud and are amazed by the record levels of power available in the latest heavy-duty diesel pickup trucks, they carry price tags too steep for many buyers. But if you’re looking for more power from your current HD oil burner, here are five ways to boost horsepower and torque without breaking the bank.

Engine Programmers

Since the advent of electronically controlled engine management systems, power fiends have been hacking into black boxes to push engine powertrains beyond original factory specs (and emissions laws). The formula for grunt in any engine is properly combining air, fuel and the ignition point. Stand-alone engine tuners adjust all those variables. Not only can they change engine performance, but transmission shift points and diesel particulate filter regeneration cycles can be adjusted, too.

ECU tuning units, like those made by Hypertech, Bully Dog and Edge, can increase the fuel pulse duration, elevate the maximum rpm, change the way the engine responds to throttle input, modify shift points, adjust the speedometer to accommodate those huge new tires and lots of other goodies. The best part for most programmers — setting up the truck to run for unladen fuel efficiency or towing power — is as easy as selecting your presaved performance profiles. We're talking some serious power, too. Late model truck engines run well below their pain threshold to improve long-term durability, and improvements from a programmer of 150 horsepower and 300 pounds-feet of torque are not out of the question.

Installation is a snap, too, typically requiring nothing more than plugging the unit into your truck's OBD-II port (installed in most trucks since 1996) and mounting the programmer in a convenient place on the dash. All the brackets, wiring and hardware are included, and only simple hand tools are needed, making this the quickest and easiest proven power adder on the list.

Difficulty:

Cost: $300 to $600

Power gain: 100 to 150 hp, up to 300 pounds-feet of torque

Cold Air Intake

A cold air intake system replaces the factory airbox, filter and intake duct with custom hardware designed to improve power and fuel economy by increasing the amount of air flowing into the engine.

Installing an intake kit isn’t too difficult. The old intake has to be removed and replaced with the new kit. This can typically be done with common hand tools and about 30 to 60 minutes of effort.

Well-known manufacturers include Airaid, Banks and S&B.

Difficulty:

Cost: $150 to $550

Power gain: 10 to 20 hp, up to 30 pounds-feet of torque

Compressed Natural Gas Injection

Compressed natural gas injection adds more fuel to the fire, so to speak. CNG, which is mostly methane, acts in two ways in a diesel engine. On its own, it burns during combustion but also acts as a catalyst, improving the overall combustion efficiency of diesel to nearly 100 percent. It also lowers exhaust-gas temperatures, which can help prolong the life of engine components, such as the turbocharger. Refilling a cylinder is as easy as going to the CNG depot, and it can cost as low as $1.30 a gallon – about $2 less than diesel – though CNG price and availability varies greatly around the country.

CNG has been used as an industrial fuel for many years, owing to its low burning temperature, clean emissions and the ability to store large amounts of fuel in liquid form. Many home-brew CNG injection systems are available because all it takes to add is a tank, an expansion manifold and a nozzle in the intake manifold. Naturally, there are also sophisticated systems available, such as the regulator kit that DeLuca Fuel Products offers to meter CNG injections.

Installing a CNG kit can be a bit tricky. A storage tank has to be mounted somewhere on the truck made of steel, aluminum or fiberglass. A standard reinforced rubber line is run from the tank to the CNG regulator. The DeLuca system goes the extra step to guarantee proper conversion in cold climates by requiring that a spur line of warm engine coolant is run to and from the manifold. A newly drilled hole in the intake gets a manifold pressure switch, and a venturi nozzle is installed in the intake air stream.

Difficulty:

Cost: $1,500 to $2,000 (including tank) plus installation

Power Gain: up to 85 hp and 250 pounds-feet

Methanol/Water

Methanol and water have been used as reliable power boosts since World War II, when both Axis and Allied forces supplemented fighter plane engines with the potent mixture, sometimes doubling power output. A methanol-water mix is an excellent addition to a diesel engine already making lots of power by adding more fuel. The trouble with continually dumping more fuel into a diesel is the elevated exhaust temperatures are hard on the turbo, hard on the cooling system and generally bad for long-term durability. Methanol-water is a power-adder that significantly brings down exhaust temperatures while improving performance.

Like nitrous injection in hot rods, the methanol-water mix lowers intake air temperatures, creating a denser oxygen charge in-cylinder for more efficient combustion. Like CNG, methanol also acts as a catalyst, burning itself but also encouraging a more complete burn of the diesel fuel. Finally, the water vapor in the cylinder is superheated at the moment of combustion and creates steam. Like any steam locomotive enthusiast will tell you, steam can be a potent source of power. The best part? It actually returns improved fuel economy, with claimed 1-3 mpg increases.

Getting the system hooked up is a matter of how big and how sophisticated you want to go. One of the best methanol-water systems on the market comes from Snow Performance, which bases everything on a 51% water, 49% methanol mixture it calls “Boost Juice.” If you select the small-tank unit, a three-quarters-gallon reservoir can be fitted under the hood on the firewall; bigger reservoirs can be remotely installed. The fluid is driven to a manifold-mounted nozzle by a secondary firewall-mounted pump and all managed by a stand-alone controller that must be supplied with power.

Difficulty:

Price: $600 to $700 plus installation

Power Gain: 50 to 100 horsepower, 100 to 150 pounds-feet

Larger Injectors

Installing larger fuel injectors and a new fuel pump is the first sign that you've probably got a lust for serious power. The modern injection system of a diesel is as powerful as it is simple. Little more than an electric valve with a nozzle on the end, fuel injectors govern a lot of a diesel engine’s performance. Since throttling on a diesel comes from adding more fuel, having injectors capable of a bigger shot means more power can be made.

Consider the fuel injectors from Bully Dog. Installing six of its high-spec new injectors on a 24-valve 5.9-liter Cummins results in a staggering increase of 240 hp and up to 450 pounds-feet of torque, the company says. The price matches the performance, too, with that kit commanding a $1,500 price tag.

For such heavy performance, the installation is actually rather straightforward. Disconnect, one by one, the injector electric plugs and the high-pressure fuel line. Unbolt the injector from its base and gently pry it from the seat. Some injectors may require an injector puller. Replace the old injector with the new one and work in reverse, hooking everything back up. The biggest groaning point is that the high-pressure fuel lines after the diesel lift pump must be cracked. On old engines, this may mean the system will need to be primed, but most newer trucks will just require a bit of cranking to re-pressurize the lines. Two hours, and you'll be pull stumps again.

One cautionary note: More powerful injectors means more fuel will be burned, leading to higher exhaust-gas temperatures that can be tough on engine components not made to withstand the extra heat. You may wind up having to replace other parts in your oil burner if you follow this route.

Difficulty:

Cost: Depending on power increase and engine upgrades, up to $3,000 plus installation

Power Gain: 50 to 250 hp and up to 450 pounds-feet of torque

The Bottom Line

The beautiful part of diesel performance is that doing one thing usually does not preclude another. It's a mix-’n’-match situation. It may require a bit of tuning, but making your truck pull like a freight train might be much easier and more attainable than you think and less expensive the buying an all-new rig.