Four-Valve Engine Build - Paid In Power, Part 3

As any project progresses, you hope there is a payoff. In the case of our 5.3L, big-bore Four-Valve for Superfly-DOHC, the payoff came with strong power numbers on the engine dyno.

Once our Livernois Motorsports-built, 5.3L was complete (Jan. '12 issue), it was bolted to Livernois' SuperFlow engine dyno and prepped to be run. On the dyno, the front engine dress is kept to a minimum, and it's run with an electric water pump. Kook's Custom Headers long-tube headers are used, and tuning is handled with a FAST XFI setup. We're not sure if we'll have a similar setup in the car, but we'll be sure to get you a rwhp number once it's in the Cobra.

Before making any pulls, there were a few small issues to iron out. The stock '03 Cobra heads don't have a coolant crossover in the rear, so coolant flow stops around the No. 8 cylinder. When this happens, temperatures rise and detonation (and other issues) can occur, resulting in engine damage. To remedy this, we contacted Lethal Performance for one of its Even Flow Cooling Mod kits. The kit comes with fittings, hoses, and all of the needed hardware to improve cooling of the Cobra heads.

When Livernois puts an engine on the dyno, it uses some modified pieces to make the dyno operator's life a little easier. One of these modified pieces is an intake manifold with modified fuel rails, which are altered for the dyno's coolant system. We supplied a ported intake manifold for the test, so Livernois wasn't able to use its dyno intake. This also meant stock rails wouldn't clear the coolant tubes, and the modified rails had nowhere to attach. A call to Aeromotive netted us a set of billet Four-Valve fuel rails, which Livernois had to modify slightly to fit.

With the engine finally alive on the dyno, Dan Millen made changes to the tune using the FAST XFI software before bringing up the revs. With the engine loaded, the first pull yielded 504 hp and 462 lb-ft of torque. We were ecstatic to hear such a high number on the first attempt. Then Millen worked his magic on the tune and power increased.

In the end, our Livernois/FRPP 5.3L cranked out 519 hp and 471 lb-ft of torque! We were excited to see that peak power was at 6,200 rpm and peak torque came in at 5,000 rpm. This will be a nice change for Superfly, as revs had to exceed 7,500 in the past to achieve peak performance. The outgoing engine made 360 hp on its best day, so this is a sweet improvement. It's also proof positive that you can indeed build a solid modular engine that will provide ample fun and quick acceleration without a blower, turbo, or nitrous--and all without the hassle of additional weight and complications from tubing, head units, intercoolers, and such.

In the following weeks, the engine will be shipped from Livernois' facility in Dearborn Heights, Michigan, to MM&FF Command Central in Tampa. As soon as we get our hands on Superfly's new heart and soul, we'll swap it and test it every way available. We're very excited to see the difference between the engine dyno and chassis dyno. The numbers are always different, and most people guess at the amount of driveline loss.

As soon as Superfly spins the rollers, we'll be sure to bring you all of the info, as well as quarter-mile numbers and some handling tests.