LSX Dyno With Three Different Intakes - Eye Of The Tiger - Tech

Scoggin-Dickey Parts Center provided a factory LS7 intake, which came with injectors, fuel rails, and an electronic throttle body. The bare intake (PN 12569011) is currently available for $378.80; pricing for the assembled piece is on the way. Since the redline on an LS7-equipped C6 Z06 is 7,000 rpm; this manifold has proven to work well up to that rpm, and provide excellent torque on the low end while boasting a very reasonable price.

In order to make use of the Gen IV injectors, we sourced Caspers Electronics for Gen III to IV adapters (PN 109077). A shorter, 1.5-inch, version should be available by the time you read this, which have a tooled connecter and special tooled terminals that are "continuous" and manufactured in-house. Caspers is well known among GN owners, but is quickly gaining ground on the LS market with products such as this and many trick electronics designed with performance in mind.

With the factory LS7 intake manifold in place, the 451-cube LSX made 673.4 hp at 6,400 rpm and torque peaked at 601.2 lb-ft at 5,300 rpm on the School of Automotive Machinists' SuperFlow dyno (using Sunoco 100-octane). From 4,400 to 6,500 rpm torque was around 450 lb-ft or higher! This manifold seemed to like 26 degrees of timing on this combination, the AFR was kept at 12.8-13.3.

The Wilson Billet Bank intake manifold (PN 210002) came with fuel rails and was easily the best looking, a true piece of eye candy. As the designer of the original FAST LSX intake, you might say Wilson knows a thing or two about manifold design, the biggest difference is that this is a full-on race piece. The F1-style trumpets looked promising, and we couldn't wait to see how it did-seeming to be a great compromise between the factory intake and a carb-style. At $3,200 it wasn't exactly a steal, but when considering the man-hours that went into designing and building this billet 6061-T6 aluminum work of art, it's definitely not overpriced.

Wilson's 90mm cable throttle body (PN 474090, $459.67) also came with the intake, and is constructed of the same billet 6061-T6 aluminum and is CNC machined. These are easily some of the best throttle bodies in the business, designed with difficult to tune high-horse, boosted applications in mind. High quality brass throttle blades are used to control vibration and reduce thermal expansion. Drive-by-wire throttle bodies are also available.

The throttle body of choice for this intake was Wilson Manifolds' Dominator (PN 473200), which flows 1,484 cfm. LME and Performance Inductions recommended this over the 1,388 and 2,008 cfm models, given the combination. Tapered radius throttle bores and a 6061-T6 aluminum construction are just a few of its awesome features.

Not surprising, the PI intake was much better up top, requiring more fuel and two additional degrees of timing. Using this manifold, the LSX finally hit the magic number and then some: 720.0 hp at 6,800 rpm. Surprisingly though, this intake was also dominant at every rpm, including torque. Though the stock LS7 made more than the PI's 600.3 ft-lb at 5,300 rpm, it carried the torque much better and produced a flatter curve. Who would have thought? If only this thing would fit under an F-body cowl. Hmm ... who needs a cowl anyways?

Unfortunately the Wilson sheetmetal intake appeared all-wrong for our application. Torque hit only 594.5 lb-ft at 5,300 rpm and was not as effective as the stock LS7 in carrying it throughout the rpm range. Horsepower hit 673.2 at 6,600 rpm, indicating that this manifold is definitely more at home at higher rpm than stock. Wilson says a motor making peak hp at 6,800-7,000 rpm, and peak torque at 5,700-5,800 rpm, is much better suited to this manifold-as the test would indicate.

The final intake in our test is the Performance Induction Specialties manifold (PN LXR-4500EFI), which, as you can tell, has exceptionally long runners for low rpm power, but with more taper to work better at high rpm as well. It is a bolt-together design for ease of porting-first with the CNC, and then hand-finished, that owner Cary Chouinard says was originally designed for its race heads to replace a sheetmetal intake and then adapted to the LS7 once its potential was found. At $2,125 it's actually pretty reasonable, given its history of making over 950 hp on motor. This is the same intake Bischoff used to make over 700 hp on pump gas in the Engine Masters Challenge and we were hoping for the same.