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
 A shaft speed sensor from...  A shaft speed sensor from PPE is used to monitor the speed of the small turbocharger to make sure it doesn't overspeed and become damaged. |  A 4-inch-diameter hotpipe...  A 4-inch-diameter hotpipe is used to route exhaust gases to the large turbo, and V-band clamps are used on the high-pressure turbo, so something as simple as a blown boot doesn't ruin McRat Racing's attempt on another record. |  Not only does McSwain have...  Not only does McSwain have his rollcage certified to run 8.50-seconds in the quarter-mile, it is also SCTA-legal for land speed racing. Other interior features include twin fire systems that spray down both the driver and the engine. |
 McSwain's '05 GMC has also...  McSwain's '05 GMC has also run at the El Mirage dry lakebed. |  Depending on your tune, the...  Depending on your tune, the Duramax's stock rods will give up somewhere between 500 and 700 horsepower. In McSwain's setup, Crower connecting rods are used for maximum strength. |  In addition to land speed...  In addition to land speed racing, McSwain's truck has run a best of 10.59 seconds at 129 mph in the quarter-mile with his wife, Kat, behind the wheel. |