From basic bolt-ons to turbos,...
From basic bolt-ons to turbos, everything it takes to build serious 5.0L firepower is right here on the cart.
Modern modular motors have a lot going for them, especially with the recent introduction of the new 412hp 5.0L variant. Sharp-eyed readers will no doubt recognize that the Blue Oval marketing department took a retro step back because the original 5.0L had, and still has, such a strong following. In fact, 5.0L guys are diehard, often dismissing the modern mod motor for its lack of torque and the inherent limitations on displacement thanks to the diminutive bore centers.
Meanwhile, the trusty pushrod 5.0L has no such deficiencies, and can be taken to the high side of 370 ci with the proper combination of block, bore, and stroke. The limiting factor is actually the deck height. What the original 5.0L has over the modern machinery is also cost, as a 5.0L Mustang can be had for about the price of a decent value meal at your local fast food joint.
Knowing boost and juice were...
Knowing boost and juice were on the to-do list, we stepped up to a 4340 forged-steel crank from RPM. Working with the forged crank was a set of 4340 forged-steel rods (5.4 inches) supplied by ProComp.
To illustrate just how receptive the original 5.0L is to modifications, we put one through the ringer on the engine dyno, running it with a myriad of modifications. We did eliminate a few tried and true mods, however, like the air silencer removal, mass air meters (we ran with a FAST management system), and underdrive pulleys. But it did allow us to run the full gamut of performance upgrades starting with a simple throttle body and ending with a complete turbo kit. Along the way we tried a pair of intake manifolds, performance aluminum heads and even nitrous. In short, it was a full day of dyno testing and part swapping, but what better way to spend the afternoon than watching the power needle climb and climb and climb?
Not wanting to limit ourselves with a stock (junkyard) 5.0L, we built a 302 capable of withstanding our eventual boosted output. To that end, we assembled a 302 using a factory 5.0L roller block machined by L&R and assembled by Demon Engines. The short-block consisted of a forged-steel crank from RPM, combined with a set of forged rods from ProComp and matching pistons from Probe Racing. The flat-top pistons yielded a static compression ratio of 9.35:1 with the 61cc chambers in the stock heads.
Probe Racing supplied a set...
Probe Racing supplied a set of forged-aluminum flat-top pistons. The 0.040-over pistons, along with the remainder of the reciprocating assembly, were installed into a production 5.0L block. The pistons featured generous valve reliefs to allow for our high-lift Xtreme Energy cam.
In addition to the stock heads, cam, and intake, the build up also featured new hydraulic roller lifters, a double-roller timing chain, and hardened pushrods (6.25-inch), all from Comp Cams. The stock E7TE heads had been previously modified to accept screw-in rocker studs, which we used with self-aligning roller rockers.
We hoped to test stock rockers versus the roller rockers, but the modified heads would no longer accept bolt-down rockers. Other than the screw-in studs and a spring upgrade (to work with the Xtreme Energy cam installed later), the head ports, chambers, and valve job remained completely stock, meaning they performed just like a stock set would in terms of flow and power.
The short-block featured Fel...
The short-block featured Fel Pro PN 1011-2 head gaskets and ARP 7/16-inch-head studs. Note the use of a Meziere electric water pump, MSD distributor, and ProComp 28-ounce damper.
Stock 5.0L: 252 hp at 5,100...
Stock 5.0L: 252 hp at 5,100 rpm, 306 lb-ft at 3,300 rpm
First we established a baseline. We installed 36-pound injectors since we knew the power output would eventually exceed the flow of the stock 19-pounders. The motor was run with Lucas 30W (non-synthetic) oil, an MSD distributor, and a FAST XFI management system. Also present was a set of plug wires and fabricated valve covers from ProComp. Though we hoped to run the stock exhaust manifolds, a snafu resulted in us starting our baseline testing with shorty headers. The shorty headers make an interesting comparison to the long-tube Super Comp headers we eventually installed. Run with the air/fuel and timing dialed in for maximum power (13.0:1 and 36 degrees of total timing), the 5.0L produced 252 hp at 5,100 rpm and 306 lb-ft of torque at 3,300 rpm.
Hooker 13/4-inch Headers:...
Hooker 13/4-inch Headers: 261 hp at 5,100 rpm, 321 lb-ft at 3,400 rpm
We replaced the shorty headers with Hooker 13/4-inch Super Comps. Long-tube headers provide a tuning effect based on the primary length. Just like runner length in the intake manifold, the headers help scavenge the exhaust and therefore help draw in the induction charge. These pipes increased the power output throughout the rev range. The peak numbers jumped from 252 hp and 306 lb-ft to 262 hp and 321 lb-ft. The Hooker headers improved torque production by as much as 25 lb-ft at 3,000 rpm.
GT-40/AccuFab 65mm TB: 280...
GT-40/AccuFab 65mm TB: 280 hp at 5,300 rpm, 326 lb-ft at 3,400 rpm
The GT-40 intake offers a revised runner length and cross section. The tuning effect works on the induction side as the runner length and cross section combine to provide a minor supercharging effect. This ram effect greatly improves cylinder filling over the air drawn in by the simple downward stroke of the piston alone. Like the headers (only in reverse), this tuning effect is a function of the variables in the manifold, which must be optimized in the proper rpm range. On our mild 5.0L, the GT-40 intake increased output from 261 hp and 321 lb-ft of torque to 278 hp and 323 lb-ft of torque. These numbers were increased slightly to 280 hp and 326 ft-lb with the addition of a 65mm throttle body from AccuFab. The tuning effect is obvious in the power curves, as the stock (small and long-runner) H.O. intake produced more torque than the GT-40 up to 3,330 rpm...
Comp XE274HR Cam: 312 hp at...
Comp XE274HR Cam: 312 hp at 5,400 rpm, 349 lb-ft at 4,000 rpm
Next up was one of the author's all-time favorite 5.0L cam profiles, the XE274HR hydraulic roller cam offered by Comp Cams. The XE274HR cam (PN 35-518-8) featured a 0.555/0.565-lift split, a 224/232-duration split and an EFI-friendly (as well as blower and turbo) 112-degree lobe-separation angle. The author ran Crane's version of this cam in his personal 5.0L LX back in the day, and it works equally well in normally aspirated, turbo, and supercharged street combinations. The cam was chosen not for its maximum power potential, as the newer XFI cams certainly offer more power, but the XE274HR offers a near-ideal combination of drivability and power that is difficult to match. With sufficient valvespring pressure, head flow, and intake design, the XE274HR will rev cleanly past 6,500 but still provide sufficient idle vacuum, throttle response and even fuel mileage.
The 5.0L was first run with...
The 5.0L was first run with a stock five-speed H.O. cam. Hardly a performance piece, it was necessary to establish our bone-stock baseline. Comp Cams supplied a new set of hydraulic roller lifters, which we used with the production retainer assembly.