We can't even count the number of times MM&FF staffers and freelancers have poked and prodded at the venerable Two-Valve modular engine over the past 15 years. Take a casual cruise through the tech section on the magazine website (www.musclemustangfastfords.com) and you'll see that we covered nearly every conceivable part, from basic bolt-ons to all-out stroker engines. We've also lost track of the pounds of nitrous sprayed and boost that was crammed in by way of turbochargers and superchargersùsometimes by a combination of them all.
There is one component that we can't recall testing though--the Edelbrock Victor Jr. 4.6L intake manifold. It isn't a new manifold, as Edelbrock unveiled it a few years ago, but it somehow escaped a torture test on the pages of MM&FF.
The Victor Jr. 4.6L intake is a carburetor-style manifold, and by that we mean it looks like a spider with a center-mounted flange, normally designed to hold a carburetor. The 4150 moniker comes from the famous Holley 750-cfm carb and is the standard mounting for aftermarket carburetors. Edelbrock offers the intake manifold in both EFI and carburetor versions, making it a versatile manifold for swapping a Two-Valve modular engine into an older vehicle with either induction system. The intake is also considered to have a sizeable plenum and short runners, so it's suited for higher-rpm operation. We elected to test the intake on a supercharged Two-Valve engine and compare it to a long-runner intake that was already on the vehicle.
The general consensus on short-runner intakes is that they kill torque, but allow more power to be made higher in the rpm range compared to long-runner manifolds. In the Two-Valve world, the long-runner intakes are the '96-'98 (non-P.I.) intake, '99-'04 (P.I.) intake, Bullitt intake, and Trick Flow Track Heat. Generally speaking, high-rpm and big-cubic-inch engines benefit most with a short-runner intake manifold. This is due to the effect runner length has on cylinder filling at a given rpm.
Edelbrock engineer Brent McCarthy sat down with us to explain the effects of altering runner length. He began by explaining that the piston moving downward creates a lower-pressure area in the cylinder, which is then filled when the intake valves open and the higher pressure air residing in the intake manifold rushes in to equalize the pressure. The air/gas mix will continue to fill the cylinder until the intake valve closes and the column of air and gas bounces off the back of the valve, causing a negative pressure wave to head back into the intake. As the wave bounces off the plenum, it returns towards the valve as a positive pressure wave; if it gets there in time (when the intake valve is again open), the cylinder is filled with extra air.
By properly timing this wave, the engine can become more efficient. The one constant is distance traveled by this ram effect, but when the engine rpm increases, the induction cycle time decreases (the valve opens and closes quicker). McCarthy explains: "This requires a shorter runner, or the wave arrives after the party is over, when the valve is closed." A short-runner also has less distance for the wave to travel back down and go back into the cylinder at higher engine speeds.
For our test, Mike Dezotell of Dez Racing turned to an '01 Mustang GT belonging to Joe Picerello. The engine is a big-bore modular powerhouse using a Ford Racing Boss 5.0L block. It features 3.700-inch bores, and when combined with the 3.543-inch-stroke crankshaft, it works out to be a 305ci bullet. Moving topside, the shop bolted on a set of Trick Flow Twisted Wedge 185 cylinder heads (44cc combustion chamber). Dezotell also upgraded the heads with better valvesprings and a pair of custom Dez Racing camshafts. The specs on the cams weren't disclosed, but Dezotell said the shop came up with the design after years of testing and dozens of 600 to 700-rwhp Two-Valve engine combinations.
1 A ProCharger D1SC is responsible for the boost and it features an eight-rib drive syste
2a The baseline test was accomplished with a Trick Flow Track Heat intake manifold on top
2b ...The car produces 677 rwhp and 564 lb-ft of torque in that trim.