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Small-Block Intake Manifold Survey

Comparing the performance intake manifolds for 289-302 engines.

Text and Photos by Tom Wilson - Originally ran in Super Ford Magazine July 1988

(Although this article is from 1988 and newer technology manifold have been released - such as the Weiand Stelth, Edelbrock Performer RPM and Victor Jr., many of the manifold designs are still valid for today. Where possible I have included crossover info to similar manifolds not tested. - Fletch)

To begin on the right foot, we’d like to point out the significance of the word ‘survey’ in the title. This is not an intake manifold shootout, nor is it a search for the ultimate horsepower, although these are performance manifolds. This is an overview of single-plane, single four-barrel intake manifolds for the small-block Ford, and where they make power in the rpm range. Thus, there are no winners or losers - selecting the best manifold from this listing depends on your application just as much as how each manifold makes power.

All work, and there was a bunch of it, was done at Cooks Auto Parts and Service, Inc. (24210 South Avalon Boulevard, Carson, California 90745, 213-830-6471), on Mike Cook’s SuperFlow flow bench and dyno. Besides a big thanks to Mike, we also wish to acknowledge our debt to Weiand Industries for the use of their small-block test engine. The ’85 ½ 5.0-liter HO crate motor was straight out of the Motorsports catalog except for the substitution of the M-6250-A311 Motorsport hydraulic camshaft (280°/290° @ 0.005", 204°/214° @ 0.050", 0.448/0.472 lift - Fletch) in place of the original. All other pieces were stock ’85 Mustang GT, including carburetion - Holley 600 cfm - and factory tube headers. No accessories were connected during testing, including the water pump, which was powered by an electric motor.

All manifolds were run out of the box with no modifications. Some of the intakes would obviously have made more power with minor casting clean up, but in the interest of comparing applies and apples, the grinder went unused. Other factors normally fiddled with during dyno tests were left alone for the same reason. Ignition timing was set once during the baseline run, then left untouched. Even the carburetor was left alone, except to install it on each manifold. In other words, this was a true ‘bolt-on’ exercise - the only differences we recorded should be the manifolds themselves.

Besides the dyno testing, we ran the manifolds across the flow bench, measuring a center and end port on each. An Alan Root/Motorsport aluminum cylinder head was used for this test, insuring there would be little or no restriction by the head. The port was run open, except for an intake valve inserted upside down in its guide to simulate an open valve.

Along the way, we acquired more dual-plane manifolds than we had originally planned for this all single-plane survey. We wanted to establish a reference point using a popular aftermarket dual-plane, so we ran the Edelbrock Performer. For baseline purposes, of course, there was the stock Ford dual-plane, and then there were the two Ford Power Parts dual-planes which showed up late in the series. They looked like they’d fit in, and they’re definitely not gas-mizer two planes, so we threw them in the pot, too. Plus, we’ll be seeing more of some of these manifolds in future surveys, as we sample the dual-planes and multi-carb manifolds in their own articles (never happened - Fletch).

There isn’t enough room here to make even a small dent in intake flow theory, so we are presenting more information without comment than usual this time. When drawing your conclusions, remember the operating range of your engine and the importance of low-end torque for street driving.

Report From the Flow Bench

Dyno Results

Note: Figures corrected to SAE standard: 29.92 in Hg barometric pressure, 60 degrees F dry air. Dyno acceleration: 600 rpm/sec. VE = Volumetric Efficiency; SCFM = Standard Cubic Feet per Minute.

 

Stock Ford (dual plane)

Edelbrock Performer (dual plane)

Edelbrock Torquer II (single plane)

Holley Street Dominator (single plane)

Offenhauser Port-O-Sonic (single plane)

Weiand 7515 (single plane)
(similar to Edelbrock Torquer 289 manifolds - Fletch)

Ford Power Parts "Cobra" (dual plane)
(similar to Edelbrock F4B and Shelby Cobra designs - Fletch)

Ford Power Parts "Tiger" (dual plane)
(similar to 1960s stock Ford cast iron manifolds - Fletch)

Offenhauser Tunnel Ram with Single Top*

Plotted Results

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