Michael Galimi
December 1, 2007
Dez Racing's Brian Machie (right) and Mike Dezotell (left) handled the installation and dyno testing of the TFS Two-Valve intake manifold.

Choosing the right combination is critical in building an efficient engine combination. The old clich that bigger is better has been thrown around over and over, and by now, everyone knows that a big camshaft combined with the largest heads may produce the most horsepower on a track engine, but will it remain street-worthy?

Probably not, but finding the right combination of parts has become easier these days as the aftermarket offers various camshaft grinds to meet the needs of the engine as well as an assortment of intakes and cylinder heads. For the 5.0L crowd, there are dozens of intakes and cylinder heads from which to choose, giving that segment virtually limitless amounts of combinations. However, there isn't a one-part-fits-all application. The Two-Valve modular engine market isn't as fortunate to have as many choices as its pushrod brethren, but the mod-motor crowd does have options to help fit their goals.

TFS announced its development of a Two-Valve intake last year, and we saw a production piece at the '06 PRI show. After some delays, we finally got our hands on one and put it through its paces.

Over the past two years, the aftermarket has responded to the great need of induction solutions for the Two-Valve engines. We still rely on various stages of porting with the stock heads, but the choices of intake manifolds are greatly increasing. The stock heads seem to respond well to porting, but the stock intake manifold, often times slightly aided with a larger upper plenum and a bigger throttle body, has hampered its potential. A Bullitt intake manifold works OK, and porting it helps the situation, but there's still room for improvement.

Today, the market is far from its dismal status two years ago as we have counted seven intakes with more on the horizon. Each of these manifolds are designed for a different type of combination, so you can go from mild to wild. Some testing of milder intakes has proven to be not so effective in power production versus cost. Others served their purpose quite well, helping free up serious airflow to the hungry intake ports.

Stock Two-Valve intakes are made of plastic and feature long runners. They work fine with bolt-on items, but once you turn up the power, the manifold becomes very restrictive.

This month, we'll take a look at the new TFS Two-Valve intake manifold and unlock the mystery behind the aluminum. The Internet and various magazines have been buzzing with truths, half-truths, and flat-out incorrect info on this new intake manifold. We first saw the piece at the Performance Racing Industry show (commonly called PRI) in Orlando, Florida, where it was announced with great enthusiasm. After several delays in production, the intake manifold slowly hit the market this past summer. Still, with back-orders and long wait lists, there wasn't much data from other shops for us to study. However, thanks to Mike Dezotell of Dez Racing, we were able to test an intake without the required wait time. He had ordered an intake a while back to test in-house, and TFS delivered it just before we went to press with this issue. Finally, we were able to independently test this new intake manifold.

As we mentioned earlier, all of the parts have to work together in order for a combination to produce the power it was intended to. Generally, long-runner intakes work great in the low and midrange, and short-runner manifolds are better for producing power higher in the rpm range. Many of the Two-Valve intakes feature short runners, which moves the powerband up too high for most street engines. In short, the stock intake, with some minor enhancements, works pretty good up to about 400-450 hp.

Dezotell holds up the lower manifold, exposing the guts of the intake. The runners are much shorter than stock.

Due to the variety of rumors and assumptions about this manifold, we chose to go with a middle-of-the-road Two-Valve engine. The test subject, belonging to Keith Johnson, has a stock engine that breathes more air thanks to a ProCharger P1SC (12 psi of boost), Anderson Ford Motorsport cams, a TFS upper plenum (with stock intake), a BBK 70mm throttle body, Bassani shorty headers, an x pipe system, an axle-back exhaust, and a Tremec transmission with a Centerforce DFX clutch. In this trim, the car produced 441 rwhp and 413 rwtq.

Some of the rumors stated this intake was more suited for a car that has ported heads and makes far more power. Johnson's ride didn't have heads, but the airflow through his engine has been enhanced with the camshafts, exhaust, and blower. Logically, the next step is to add a set of ported heads to the fold, so upgrading the intake is easy to do and will suit him better in the future. We wanted to test the theory of this intake gaining power with ported heads only, and this car was perfect.

The Runners protrude into the valley, just like stock.

Installation was straightforward and rather easy despite the extra time required to remove the supercharger tubing and head unit. The first thing that popped into our heads while looking at the lower intake by itself was, This looks like an LS1 intake. While it's true with the runners being shaped similarly, the inlet is not front-mounted, and once the upper elbow is fastened to the lower, all similarities end. The aluminum body adds considerable weight in comparison to the stock plastic piece-but there are no more worries about blowing apart the stock one with a nitrous pop. A side-by-side comparison shows the TFS to have straighter runners near the ports in the heads. The stock ones have a sharp turn before the air exits into the heads. The stock runners are also long, whereas the TFS intake is much shorter.

Once installation was complete, we let the car idle for a bit to make sure nothing was leaking or loose. Then we strapped the car on the dyno and warmed up the trans and rear fluids. Once warm, Brian Machie of Dez Racing let it rip, and the white GT spun the drums to 454 rwhp and 415 rwtq. That's not bad for the first pull with the new intake-all variables remained the same as the baseline, like timing and fuel curve.

The stock water neck is reused and bolts to the intake.

"This is the first Two-Valve intake that we've tested that actually picked up power over stock with unported heads," Dezotell says. "At this point in time, the heads are the restriction, and this intake would have made even more power over stock if we had ported heads and/or a bigger blower on this car." A few more dyno pulls backed up our first run-within a couple of horsepower and lb-ft-and the first pull turned out to be the highest.

One observation we made after the first dyno run was the intake surface heat. A quick check with the heat gun showed the front runners at 115 degrees while the second set of runners was at 105 and the third showed 101 degrees. The front-runners were hotter because the coolant runs across them, and they're affected thanks to the aluminum construction. The upper elbow/ plenum showed a surface temperature of 82 degrees Fahrenheit.

Finished-except for the radiator hose.

According to Dezotell, these cars don't like hot intakes, so we threw two bags of ice on the intake manifold, not to bump up the numbers, but rather to bring the surface temps down to similar levels as the stock one. The extra run time upon initial startup added more heat to the engine when compared to the baseline runs. The ice dropped the runners down to the 90s, and the results were nearly identical-essentially the power curves shifted a bit and average power rose slightly but not significantly. We might have seen more power if we had iced the intake longer, but our goal wasn't to optimize the surface temps, only to bring them down a bit. In the end, we were too hung up on the intake manifold heat as the fuel probably cooled down the air temps considerably once inside the chamber. The air/fuel ratio was rich (read: safe), so the extra fuel was put to good use. As Dezotell said, the heads were the major restriction in this application, and we still picked up power, which made us happy.

There you have it. The TFS Two-Valve intake is ready for action in your warmed-over mod motor. Don't expect to pick up power on a virtually stock engine because this intake isn't meant for that application. It's geared towards the more serious engine with ported heads, a blower, nitrous and such. Bench racing sessions about this intake can now come to an end.