June 1, 2006

Now that we've explored the majority of simple, bolt-on parts for the S197 Mustang, the next logical place to turn our collective attention is to the inner working of the engine. And, no matter how sophisticated or complicated an engine is, the true art of making power is getting more atmosphere stuffed into the combustion chamber. For decades, head porters have been enlarging the passageways and smoothing the aluminum of cylinder heads to hasten the trip from outside the air filter into the engine. Those artisans have always had the most influential role in helping hot-rod enthusiasts create more power.

It is no great surprise that Ron Robart, chief head porter and owner of Fox Lake Power Products, immediately went to work on the new Three-Valve heads. He had experimented extensively with the Three-Valve head in late 2003, when Ford launched the new F-150 powered by a modular engine carrying the same head design that would show up on the S197 Mustang in 2005. Those experimental attempts have paid off in spades, as Fox Lake has quickly jumped to the forefront of new Mustang-head modification.

We recently had a chance to follow along as our guys at MD Motorsports swapped out the stock heads of a customer's '05 Mustang with a set of Fox Lake CNC-ported Three-Valve heads. Reports of 20-35 rear-wheel-horsepower gains from test vehicles made us want to know firsthand what a head swap would do for the efficiency and power production of the newest small-block Ford.

Before we discuss flow numbers and what Fox Lake's mastery with porting tools will do for you, we need to examine the new head as it comes from Ford. Ron was enthusiastic about the basic design and engineering that went into the new Three-Valve head. Remember, when Ford went from the '04 Two-Valve to the '05 Three-Valve, it resulted in a 40hp jump in power. With all due respect to the variable cam timing and intake manifold, the new Three-Valve cylinder head is the primary reason.

"Ford drastically redesigned this cylinder head," Ron told us. "The Three-Valve head differs greatly from the Four-Valve head, and the most important part of that is the more vertical-straight up-angle of the intake port. It's going to make more power than the Four-Valve. Remember-when you bend air, it slows down. Ford straightened out that intake port, and it's a straight shot out the exhaust. You are going to make more power. It's not all in what you're going to see on the flow bench-that's just an indicator. This head flowing 270 cfm can make more power than a Four-Valve head flowing 300 cfm because the port is positioned better."