Eric English
April 9, 2014

Horse Sense

One of the most common themes in Mustangdom is not being able to leave well enough alone. It’s a condition that Marc Sorger surely has, evidenced by a full vinyl wrap that was going on the car as we went to press, along with new wheels. The evolution continues.

Go to the races, a car show, or your local cruise-in these days, and you seemingly can’t turn around without bumping into an engine swap that updates some of the classics of yesterday. We’re surely not complaining, for there are plenty of good reasons to put a LS in a ’66 Nova, a Gen III Hemi in a ’70 Cuda, or one our personal faves—a Coyote in a ’90 Mustang. Simply put, it’s tough to beat the combination of performance, reliability, and driveability you get with a late-model engine. Did we mention fuel economy?

Yet for all the good reasons to follow such trends, Marc Sorger found that repeatable big-time track power wasn’t really the forté of his GT’s stock Three-Valve mod motor. To be specific, it was the supercharged 4.6 in his ’08 GT that caused him woe, so Marc turned to a back-to-basics approach that many an enthusiast will applaud.

Incidentally, Marc bought his car new in 2008 with the intent of keeping it as a stock daily driver. That sounds familiar!

This ’08 GT is covered in a factory white wrapper, but it’s hardly subtle. Prior to installation of the full-race 358, owner Marc Sorger reports that local law enforcement pulled him over on the streets several times—but just out of curiosity and appreciation. Marc was impressed that one officer knew enough to think the car was one of the FR500 series builds, and thus checked for a legitimate VIN. He found it, of course!

“During the first few years I owned the Mustang, I used it as a street/strip car and eventually worked it into the high 9s on pump gas,” he said. “In late 2011, I decided I wanted to turn with it, and began building it for IRDC Conference racing and NASA American Iron Extreme.”

Work occurred after hours at Marc’s place of employment, TMS Performance in Auburn, Washington, where he’s general manager and jack of all trades. Initially the engine remained pretty well as it had been for straight-line duty. The 4.6 had been built by TMS a couple years earlier, and sported all forged internals, and an intercooled centrifugal blower pullied for as much as 20 pounds of boost.

“During the summer of 2012 I had a lot of fun running the car at track days, but found the supercharged 4.6 to not be the best arrangement for long periods of wide-open throttle. I had a lot of trouble keeping the coolant temp in check, partly because of the big intercooler physically mounting in front of a big radiator, partly because of the heat endemic to centrifugals.”

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Marc found that as coolant temps increased, the computer pulled timing, in turn raising cylinder temps and coolant temps—in other words, a viscious circle. “I could’ve prevented the computer from pulling timing, but that would’ve lead to detonation. I also could’ve helped matters a ton by backing off on the boost with a larger pulley, but I have a hard time taking horsepower off the table, even when it’s the right thing to do. I guess I’ve got a problem.”

At least there was a solution to Marc’s problem that amounted to little more than money and hard work. As you know by gazing at our pictures, Marc went with normally aspirated pushrod power—a devolution of sorts. Part of the financial sting was soothed by selling the supercharged Three-Valve, which was replaced by nothing less than a 2003 Nextel Cup NASCAR 358 from Roush Yates Engines.