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Dez Racing Two-Valve Edelbrock Victor Jr. Test - Two-Valve Hustle
Dez Racing pushes a Two-Valve stroker modular engine to nearly 700 rwhp with an Edelbrock Victor Jr. 4.6L intake manifold
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.
Initial testing was conducted with the popular Trick Flow Track Heat intake manifold with a BBK 75mm throttle body. Boost is delivered by way of a ProCharger D1SC kit with an eight-rib conversion and a large air-to-air intercooler. The baseline runs showed manifold pressure at 18.8 psi at 6,600 rpm. Thanks to the street-driven nature of this beast, the car is run strictly on 93-octane pump gas, but the octane is spiked with a dose of methanol (50/50 mix of methanol and water) via a Snow Performance kit. The Two-Valve mill pushed the Dez Racing DynoJet chassis dyno to 677 rwhp and 564 lb-ft of torque with the long-runner manifold in place.
Swapping to the Edelbrock Victor Jr. 4.6L was fairly simple, but there are several noteworthy factors. The first, we relied on a set of Edelbrock fuel rails, which can cause an issue in some applications. The rails are fine in our application because the engine uses a Big Stuff 3 standalone EFI system. There could be a problem with cars that run a stock ECU and return-less fuel system. The stock fuel rails have a fuel pressure sensor mount, but aftermarket fuel rails don't have a provision for it. Aeromotive offers a sensor adapter that retails for under $50.
Another snag we ran into, thanks to yours truly, was in regards to the inlet elbow that mounts to the top of the Victor Jr. 4.6L intake. I had ordered the nice-looking box-style inlet elbow (PN 3850). The 3850 is a low-profile elbow, but the problem wasn't hood clearance. Actually, it put the throttle body too close to the shock tower, so there was no room for the supercharger tube to connect with the throttle body.
Our solution was to borrow (steal?) another Edelbrock elbow from a pushrod combination in the corner. It goes by PN 3849 but our test piece was 38493, which is coated black. The 3849 and 38493 require an '86-'93 5.0L throttle body and Dezotell grabbed a 80mm unit from inventory. Two other problems presented themselves with using the 38493 elbow. It definitely didn't clear the hood, and the stock throttle cable linkage wouldn't link up.
The first problem, hood clearance, was easily solved with another Edelbrock product, but we didn't get it in time for testing. The proper elbow for this application is PN 3847, which is Edelbrock's ultra-low profile elbow.
The other issue with the throttle cable linkage was easily solved, as Dezotell pulled a setup for an '86-'93 5.0L off the shelf.
No matter which elbow is used with this application, the supercharger inlet pipe will need to be modified or a new one made. Head wrench at Dez Racing, Brian Machie fired up the welder, plugged in a cutter, and grabbed some spare 3.5-inch pipe from the stockpile. An hour later the supercharger was connected to the throttle body via the newly made pipe and a rubber elbow. For those switching from a Trick Flow intake to the Edelbrock one, the alternator will need to be switched back around. Another option is to build two brackets to hold the alternator in place, which is what we did for the test due to time constraints.
For those keeping track, our parts list includes the Edelbrock Victor Jr. 4.6L SOHC EFI manifold (PN 28385), which retails for $289.99 from most mail-order companies. We also used an Edelbrock fuel-rail kit (PN 3639); that will set you back anywhere from $99.99 to $105.99 from most catalogs we referenced. The Edelbrock ultra-low profile elbow (PN 3847) goes for $111.49 for the as-cast version and $124.99 for the black piece. The 80mm throttle body for an '86-'93 5.0L High Output engine is on the list of parts as well. We've seen those throttle bodies go from $230 to $250 from most manufacturers. Dezotell added a few fittings to the new fuel rails, which brought the total cost for this conversion between $770 and $800. That doesn't include the labor, dyno time, or inlet tube fabrication. Also consider another $50 if you need the pressure transducer mount from Aeromotive.
The moment of truth came late in the evening when the '01 Mustang GT was strapped to the DynoJet chassis dyno. The testing procedure was simple-Dezotell would warm up the engine to be consistent with the baseline pulls and he would make three consecutive runs to ensure the numbers were accurate. A short break is taken between pulls to let the engine cool off, and we didn't ice the intake.
The car utilizes a Big Stuff 3 standalone EFI and it was kept in closed-loop mode so timing and air/fuel would remain identical in both tests. Closed loop is when the ECU operates in the user-defined values for fuel and timing-meaning the engine would use the same amount of fuel and the timing would be locked in. Dezotell had the timing set at 10 degrees total due to the pump gas and big boost. Open loop in a Big Stuff 3 system is when the ECU will alter the air/fuel ratio using the 02 sensors. A target value is inputted and the computer will constantly adjust to achieve the target value. The pulley on the ProCharger blower and crankshaft were left the same, changing them would negate our goal of an equal comparison.
Dezotell ran the car up to its redline of 6,600 rpm, and the final results was an impressive 695 rwhp and 566 lb-ft of torque. The calculator shows a gain of 18 rwhp and 2 lb-ft of torque-yes, the engine picked up torque despite the belief that short-runner intakes produce less torque than long-runner manifolds. Boost increased, despite the pulleys remaining the same, to 19.3 psi from the baseline of 18.8 psi. McCarthy attributed that to the Victor Jr. 4.6L being less restrictive.
Dezotell made a few back-up runs and tried turning the engine higher, but the peak power came at the same 6,600 rpm with both style manifolds. Both Dezotell and McCarthy feel there is another limitation, possibly cylinder head flow or the camshafts restricting the engine from going even higher. But the output increased in both horsepower and torque when we switched over to the Edelbrock Victor Jr. 4.6L intake.