511 Rear-Wheel Horsepower for Only $25,000

4-inch Exhaust
A common misconception is that fat diesel exhaust systems make power. More accurately, they complement other components by reducing exhaust backpressure, which lowers EGT by 100 to 150 degrees F. Diesel Dynamics developed a 4-inch Therminator turbo-to-tailpipe system for the Cummins. It's made of 16-gauge aluminized steel with mandrel bends and a straight-through-style Walker industrial-application muffler.

The Therminator system bolts up to the turbo's 4-inch downpipe and is designed for better flow and faster turbo spool-up. Each kit includes enough tubing for Quad Cab and longbed applications, so the straight piece must be cut to length for shorter trucks. All necessary clamps and hangers are included, and Diesel Dynamics reinforces all joints with welds on its in-shop installations.

Bigger Fuel Line and Pusher Pump
Applications in excess of 350 hp need greater-than-stock fueling capabilities. Diesel Dynamics solves the problem with its Pusher fuel pump kit and Big Fuel Lines. The Pusher pump is a standard Carter unit, but testing several part numbers revealed the one that supplies enough juice to pump out up to 750 hp and 1,500 lb-ft at the rear wheels. The fuel-line kit eliminates OE restrictions caused by ID fluctuations and banjo fittings to increase fuel flow and keep the diesel cooler in the process.

Diesel Dynamics' performance bumpstick is ground from a new, marine-based cam and uses a keyed-and-bolted cam gear for high-rpm durability. Its profile improves turbo spool-up and fuel economy while reducing smoke and EGT.

Diesel Dynamics' performance bumpstick is ground from a new, marine-based cam and uses a k

To a Higher Power
If 500 hp isn't good enough, Diesel Dynamics offers packages that go to nearly 800 ponies and more than 1,600 lb-ft of torque. The company's proprietary 24v Performance Camshaft increases durability by improving cylinder fill at low and midrange rpm. Other characteristics include a 40 percent increase in airflow, turbo spool-up, and smoke abatement. Testing has also shown that this cam provides a 2 to 3 mpg increase in mileage and a 150 to 300 degree F drop in EGT. Diesel Dynamics' over-500-hp power packages can include a ported and polished head that has more than 28 percent better flow per cylinder, race-only Mega Mental fuel injectors, and even nitrous oxide.

Air Intake Box
This 500hp Cummins package includes an AFE "Funnel Ram" intake. The system supplies a 250 percent increase in airflow (820 cfm versus the stock 377 cfm), which helps lower EGT and decrease spool time. Another benefit is AFE's lifetime-warranted washable, reusable filter.

Clutch Upgrade
South Bend Ceramic-based clutches have been durability-tested in high-horsepower Cummins 4x4 drag trucks (see video clips on Diesel Dynamics' Web site). This clutch has also proven its worth in 25,000-pound towing tests; the increased holding power comes with a grabbier feel. For five-speed heavy-duty towing applications, Diesel Dynamics offers the South Bend clutch with an OE five-speed flywheel that has been redrilled to accept the six-speed 13-inch clutch and pressure plate. The six-speed NV5600 comes with the 13-inch clutch stock, and the South Bend offering for these have been tested to more than 700 hp. All of these clutches require surface-grinding the flywheel for proper holding power.

Possibly the most impressive part of this buildup is that it's based on glorified tractor parts. Diesel Dynamics can do all of these modifications in a day, and the competent home mechanic could conceivably button them up in a weekend. Compare the overall outcome to a new '04 1/2 Dodge with the Cummins 600 engine at 325 crankshaft hp, 600 lb-ft of torque, and a $36,000-plus MSRP.