Livernois Motorsports' main...
Livernois Motorsports' main man Dan Millen does some last-minute fussing over his 5.0 baby that will soon find a good home between the fenders of our 3g GT project. Stock of stroke but big of bore, our aluminum-alloy Modzilla short-block is topped by PI heads that were ported by Livernois headmaster Rick Swain and that rock to the tune of Livernois' Stage 1 cams.
Horse Sense:
When we slip our Livernois short-block, heads, and cams under the hood of the 3g GT, we'll do before-and-after chassis dyno testing to see how the combination responds to the boost of our ProCharger.
We showed you the buildup of our Livernois Motorsports 5.0 Modzilla short-block ("High Five," May '03, p. 134) and gave you what information we could about the company's PI head-porting methodology ("Head Games," June '03, p. 99). Now it's time to put all this muscle-building theory to the test on the Livernois engine dyno.
In case you missed our previous installments, the Modzilla starts off with a light but robust Cobra aluminum block with its bores enlarged from 3.552 to 3.70 inches. It's filled with JE custom-forged pistons atop Eagle H-beam rods. Tough stuff, especially when bolted to a Cobra steel crank using 31/48-inch ARP 2000 hardware. On the breathing side, Livernois' PI head porting is not radical, but rather it's intended to optimize flow while maintaining all-important velocity at midvalve lift, where an engine spends so much of its time.
Plumbing a computer-commanded...
Plumbing a computer-commanded modular on an engine dyno is an electrician's nightmare. To jolt the monster to life, Dan and his Livernois crew used ACCEL's Gen VII engine-management system and MSD's DIS-4 ignition and supporting hardware. For purposes of apples-to-apples comparison, 4.6 baseline testing-as well as our initial test with the 5.0 Modzilla-we used Ford Racing Performance Part's short-tube headers and a stock plastic intake manifold.
For our flagship project car, the idea of a 5.0 short-block made a lot of sense-after all, we don't call ourselves 4.6 Mustang & Super Fords. But even we're not quite loony enough to commission a short-block build just so its displacement would coincide with our magazine's title. Project cars take a fair share of abuse (just ask Associate Editor Johnson), so we sought the added durability of the Modzilla's proven components, along with Livernois' pain-staking balance and assembly technique. But, naturally, we also hoped for a bit of extra power from our additional 0.4 liters. Judging from the engine dyna-mometer results (next page), we won't be disappointed.
Modzilla Meets the Dyno
The first of the following charts compares the Modzilla, topped by Livernois' ported PI heads and Stage 1 cams, to a stock PI-headed 4.6 SOHC, similar to the one currently residing in our 3g GT. You'll notice some large gaps in data. While we normally chart dyno results in 100-rpm increments, the 4.6 baseline testing was done before our arrival. The dyno operator used 500-rpm reporting increments and quit the pull at 5,500 rpm since power was already falling off. For the balance of testing, 100-rpm increments were used, and we ran to 6,000 rpm. All figures were corrected for atmospheric conditions.
With a glance at the following spreadsheet, you can see that, at 3,000 rpm, the Modzilla combo was already up by more than 10 horses and 18 lb-ft of torque. By 5,500 rpm, where the 4.6 was heading into hibernation, we gained more than 52 hp and 47 lb-ft. So, aside from being stronger and lighter, the 5.0 combo is, as hoped, demonstrably more powerful. We can't wait to bolt this thing in the 3g GT and force-feed it with our ProCharger P-1SC.