Muscle Mustangs & Fast FordsHow To Engine
Mustang GT Boss 5.0L Block And Stroker Upgrade
Building Big With A Ford Racing Boss Block And A RGR/JPC Stroker Combination.
The engine featured is slated for severe street duty, which includes massive boost from a ProCharger F1R supercharger. Burcham holds this combo in high regards, "this combo made over 800 rwhp, likes to rev to 7,000-rpm, and is more than capable of cruising the streets. This piece could have been turned higher [more rpm] but the stock intake manifold limited it. The 322 is very popular amongst our customers because the larger cubic inches makes great torque for around-town driving. The price tag is higher than a standard stroker mod motor because of the block, custom billet caps, and custom rotating assembly-but it does represent the ultimate Three-Valve combination. I run this same exact engine in my '05 Stang but with a JPC intake, larger cams and a shot of nitrous. That car ran 8.48 at 162 mph, made 1,050 rwhp, and runs in MM&FF True Street," adds Burcham.
"Overall, the block is very durable except for the main cap area. Ford Racing includes beefy main caps, but are not quite enough if you are looking to go over 1,000 hp. I have even seen the caps walk in the 800 hp range with a few supercharged combos," says Groh about Ford Racing's aftermarket engine block. So, his solution is a set of custom billet main caps that feature two additional holes and he modifies the block to accept the extra main cap bolts. These precision-cut pieces require a new line hone but add considerable strength over the production configuration. The caps have been battle proven in Burcham's mid-8-second ride and several 9-second players out of the JPC shop.
The bottom-end consists of a Paschal Performance crankshaft, Crower rods, and a set of CP pistons built to RGR's specs. Moving to the topside of the engine, RGR ported a set of Three-Valve heads and used Manley valves that are slightly larger than stock. Groh spends considerable time working on the ports of the factory castings. On the flow bench, the heads move 322 cfm on the intake side at 0.500-inch lift. Moving to the exhaust port, air rushes through at a volume of 215 cfm at 0.575-inch lift. The camshafts are custom sticks cut by Comp Cams and tailored for specific applications. The head flow numbers were quoted at those lifts because the cam boasts a measurement of 0.500/0.575, intake and exhaust respectively. The variable camshaft timing (VCT) has been eliminated using Paschal Performance's cam phase eliminators. "The factory cam phasers need to be eliminated at some point because of the aggressive camshafts and heavy valve springs. The factory phasers tend to fail when under serious loads," comments Groh.
This story showcases the engine being assembled with the new JPC Racing intake manifold, but when the shop installed it in the customer's car, a stock intake was bolted on. The throttle body was upgraded to a single bore unit. Moving on to the fuel system, the car runs a JPC return-style setup with MagnaFuel fuel pump and filter, larger feed and return lines, 96-pound injectors, and JPC fuel rails. A Versafueler drives the 96-pound injectors, despite them being low-impedance units. Stock ECU boxes can drive high-impedance fuel injectors but cannot operate the low-impedance ones. "We use the Versafueler to convert the signal so we can continue to run the factory ECU and still run large injectors," injects Burcham.