![]() This product is said to work wonderfully with the use of square-bore carburetors. This Edelbrock 2701 Performer Intake Manifold is considered the best intake manifold for various reasons. Most of us wouldn't stress over four-hundredths and a half mph.1. These numbers underscore just how competitive the market is for single-plane, small-block Chevy intake manifolds. If you test at the track, air quality can affect performance more than that during one day of testing. ![]() It spit out a difference of 0.06 second and 1 mph. We did a quick comparison of the two manifolds at the opposite ends of that spread (Holley Strip Dominator and the Professional Products Hurricane), and using our Orange Peel Chevelle as the simulated vehicle, we entered the power into the Quarter, Pro dragstrip simulation program. While we're on the subject of close numbers, the average-torque results reveal there are 11 manifolds in the middle of the field that are separated by a mere 8 lb-ft of torque that's less than a 2 percent difference in average torque. We averaged two pulls to create one curve for each manifold. When our retest resulted in numbers within 2 lb-ft and 2 hp, we decided nothing had changed since those numbers are within a half-percentage point. Toward the end of the test, we also re-baselined the engine to ensure that power had not dropped off due to abuse. We also ran several tests (at least three but up to five runs) on each manifold until the power stabilized and we had two similar pulls. To eliminate variables, we tried to maintain a consistent air/fuel-ratio curve for each manifold. We have strived to make this test as accurate as possible, but it's likely that each manifold's performance could be easily influenced by our engine's specific combination of displacement, compression, cam timing, and port flow. Only a few intake manifolds required mixture adjustments, and using an MSD crank trigger unit and distributor, we kept the timing rock-solid at 36 degrees so we wouldn't have to worry about resetting ignition timing each time we removed the distributor to swap an intake. We also wanted a big enough carburetor that it would not be a restriction, so we selected one of Holley's new Ultra HP 850-cfm carburetors that offered reliable fuel mixing and excellent consistency throughout the test. Compression ended up at 10.1:1, which allowed us to run this engine on pump gas, though we ran Rockett Racing fuel to ensure consistent performance. The point was to make the engine dead-reliable. We also added a set of Crane Gold 1.5:1 roller rockers and proper-length Crane pushrods to ensure a stable valvetrain. The cam we chose is a Crane with sufficient specs to push the peak-rpm point up to 6,500 rpm but is still suitable for the street. The heads feature a 215cc intake port with 2.08/1.60-inch stainless-steel valves and roller springs capable of controlling the mechanical roller cam. We upgraded the heads to a pair of TFS Super 23 aluminum castings to ensure we got the most out of each intake. You may recall that Rodney spins an internally balanced 4340 Scat steel crank, Scat I-beam rods, and a set of Icon forged pistons. So if you only take one thing away from this story, burn average torque into your memory bank. ![]() The only instance where peak horsepower is really critical is if you have a close-ratio, eight-speed trans that can keep the engine within 1,000 rpm of its peak-horsepower rpm, but since we're not talking about Formula 1 here, that isn't really relevant to the average car crafter's car. You might have a manifold that makes good peak horsepower, but if it loses torque in the middle rpm band, the peak-horsepower number is not nearly as important as the average power. Apply a higher average torque, and it will accelerate any vehicle quicker. You will get tired of hearing that in this story because that's the hammer we're bringing. We think average torque is the most important factor that we measured in this test. We've also calculated average torque between 3,500 and 6,500 because that is the rpm band where these engines will spend the majority of their time during a quarter-mile run. ![]() We measured plenum depth because that's important for making good power. We measured carb pad height because the manifold has to be able to fit under your hood. For this latest adventure, we assembled 19 small block Chevy single-plane intake manifolds and ran them all across a 550hp, 406ci small block Chevy. ![]()
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