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2005 GMC Sierra 2500HD Duramax Buildup - Overbuilt

A 1,000HP Duramax Built For Longevity

Jason Sands
May 1, 2009
Photographers: Jason Sands
Photo 2/14   |   McSwain's Casper currently holds the B/DT production diesel truck record at 166.850 mph over a measured mile, and has been GPS-verified with an exit speed of 181 mph.
Diesel engines lead a rough life They are expected to last forever and are built accordingly. So it should come as no surprise that diesel engine parts are surprisingly well adapted to racing. Diesel drag racing and sled pulling are hard on parts to be sure, but the engine only has to run for a few seconds. for an extreme test of diesel durability, we looked to another form of motorsports: land speed racing. In places such as the Bonneville Salt flats in utah, and the El Mirage dry lakebed in California, you'll find speed demons holding the throttle wide open for miles at a time, which is certainly a true durability test for any engine.
To get a good idea of what it takes to build a Duramax engine that can be held at peak power for minutes instead of seconds, we visited McRat Racing in Corona, California. Patrick "McRat" McSwain has been in the diesel performance industry for many years and is well-known for drag racing his '05 LLY Duramax, nicknamed Casper. If running 10-second quarter- miles is fun, running for five miles should be even more fun, right? The problem is, an engine that will survive at the dragstrip won't work in land speed racing.
1,000 Horsepower And 1,400 Degree EGTS
So how do you get an engine to make 1,000 horsepower at EGT levels slightly above towing temperatures? The answer is a lot of air, a lot of rpm, and some very precise fuel delivery. Believe it or not, the engine itself is surprisingly stock. The crankshaft, camshaft, and heads are all stock pieces, although Crower connecting rods were used since the stock rods tend to bend at high power levels. Also, SoCal Diesel modified a set of production pistons and supplied push rods and valvesprings for the engine. The engine's camshaft and timing gears were also keyed since the engine would be making big power at 4,500 rpm.
A tremendous amount of air is supplied courtesy of a prototype turbocharger kit from PPE, which features a Garrett GT42 turbo as the small, high-pressure turbo, and a mammoth Garrett GT55 as the large, low-pressure turbo. These two highly efficient, non-wastegated turbos combine to produce 60 psi of boost, while maintaining a boost-to-drive pressure ratio of about 1:1.
On the fuel side, a PPE lift pump keeps plenty of fuel coming to the set of Wicked Diesel stroker CP3 pumps, which keep rail pressure up, even at peak engine speed. Rounding out the fuel side of the equation are a set of custom injector nozzles from Dynomite Diesel Performance.
Keeping Down The Heat
Since durability is priority one for this engine, that meant keeping down the heat. To that end, the stock intercooler was replaced with one from Spearco, and a Snow Performance water-methanol injection system was used-although class rules prohibit methanol injection, so McSwain runs straight water. Tuning is also a big part of the equation. Injecting fuel too early on the power stroke can result in engine damage, while injecting fuel too late can cause EGTs to skyrocket. Since McSwain has been fiddling around with LLY Duramaxes for quite a few years, he's been able to make his own custom EfILive tunes that are a good balance of power and durability.
So What's It All Worth?
While McSwain has only done some preliminary dyno testing with this setup, it has still made more than 1,000 horsepower at the crankshaft. If you're used to rear-wheel horsepower numbers, this means 816 hp at 4,300 rpm, and 790 hp at 4,500 rpm on a chassis dyno. It should be noted that only diesel and water is allowed in the class that McSwain runs in, so all these runs were done without fuel additives or power adders such as nitrous oxide. Since Mc- Swain figures he needs about 900 rear-wheel horsepower at 4,500 rpm to run 200 mph, he has a little more engine tuning left to go to reach his mark. With a setup this wellengineered, we think he'll have no problem getting that extra 100 horsepower, and we wish him luck on his quest for 200 mph.
An Unbreakable Allison
Getting GM'S Allison transmission to live behind A 1,000-horsepower diesel street engine is no easy task, so McSwain left it up to one of the best Allison gurus around-Mike Lovrich of Inglewood Transmission. We were able to sneak a quick peak at the latest trick Lovrich has up his sleeve, a set of C3 clutch pack sprayers designed to keep from burning up the truck's clutches. The transmission also has the best parts money can buy from Sun Coast Converters to help it survive at this power level. DP


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