Corvette Intake Shootout - Deep Breathing Exercises

Early in the development of the internal combustion engine, intake manifold design considered little more than the requirements of connecting the various cylinders to the carburetor. It didn't take long for hot-rodders and racing teams alike to realize the relevance of the intake manifold to engine output. High-performance aftermarket intake manifolds have become one of the most popular components in seeking to enhance engine output, with a broad range of choices, even from a single manufacturer. The difficulty can be narrowing down the selection to a specific style and type.

Running The Numbers
Talking theory makes for good conversation at the club, but analyzing hard numbers is the best way we know to get to the facts. To this end, we assembled a collection of Edelbrock's intake manifold offerings for the small-block Chevrolet, and took the trip out to Westech's dyno facility to run them for the numbers. Our test engine is a typical hot-street small-block, with a displacement of 355 cubic inches and a mild Comp street roller camshaft. Topping the mill is a set of Air Flow Research 190 cylinder heads, providing enough induction draw to produce serious power, while taxing the ability of an intake manifold to keep pace. Here is how they stacked up.

We used the Performer as our baseline intake, and were somewhat surprised to find that even on our stout 350, this intake offered credible output. The relatively low manifold height makes it an attractive alternative to stock in applications where hood clearance is an issue.

In output, the RPM closely followed the power curve developed by the standard Performer, but by 5,500 rpm the difference became apparent. Higher in the rev range, the RPM showed a clear advantage. The Performer RPM is about 0.7 inch taller than the standard Performer intake, and, like all the high-rise intakes tested, represents a hood clearance problem in most Corvette applications with stock flat hoods.

We never run out of good things to say about the AirGap intake. This manifold provides the torque advantage inherent in a dual-plane configuration, while consistently providing top-end power rivaling a single-plane right to the top of its rated rpm range. In an engine application running up to 6,500 rpm, there is little if anything that will touch the AirGap in output. The AirGap provided by far the strongest average output numbers in our tests.

We were curious to see how the larger-volume intake would affect the output of our 355-cube test engine. The consensus at the dyno facility was that the Victor Jr. was more appropriately sized, and the best choice in a single-plane intake. We were surprised to find a nearly identical power curve to the previously tested manifold.

Again, this manifold wouldn't represent an obvious choice for an engine configuration as tested, but we deemed it worthy of the experiment. The Super Victor provided an unexpected improvement in average torque as compared to the other single-plane intakes, and tied the Victor Jr. for top output honors, edging out the Victor E by a mere 1 hp.

True to form, the Victor Jr. made more outright horsepower than the dual-plane intakes; but as compared to the AirGap, not by a large margin on our test engine. Closer scrutiny, however, shows that the averages were down in comparison to the dual-plane intakes. In a racier engine combination at much higher rpm, the single-plane would likely be more in its element; but even in the range of our test, the enhanced power production up top was clearly shown.