Carb spacers that actually work.
Plenty of folks have penned articles on carburetor spacers. Some work; some don't. So when we came across a series of spacers from HVH (High Velocity Heads), we were, to say the least, a wee bit skeptical. When it comes to conventional carb spacers for your Corvette, you might find a horsepower or two in some cases, move the power band around a bit and help distribution in other cases, but for the most part, there isn't much extra grunt available from a spacer. At least that's what we thought.
The truth is, the HVH spacer just might be set to revolutionize the carburetor spacer business. But let's back up for a minute. Who or what is HVH? Joe Petelle and his son, Keith, are HVH or High Velocity Heads. HVH may not be well known in the world of Corvettes, but it's another story in Winston Cup Racing, where they designed and ported heads, as well as intake manifolds from 1980 to 1992. Petelle and company designed a series of intake manifolds for Brodix and also created the layout for the Canfield big-block Chevrolet head. Currently, they primarily build carb spacers, but they also do limited amounts of custom cylinder head (yes, they do work on iron as well as aluminum heads and basically port anything that flows air).
The carb spacer designed and built by HVH is called the "Super Sucker." At first inspection it looks like a conventional four-hole spacer, but a closer investigation reveals it is a long distance from what one might term "normal." For example, the material is a plastic composite, and the spacer isn't simply cast. Instead it's actually CNC-machined. The area between the respective holes is carefully profiled. The top side (carburetor mount side) looks like any other four-hole spacer for a standard Holley flange, but the bottom (intake manifold side) is far different than anything you've probably seen before (see the accompanying photos). But how things look quite often don't equate to horsepower. The big question is - does it work?
We decided to test the Super Sucker on a SF901 dyno, using a very typical (for a street-driven Corvette) small-block Chevy. The engine in question was a relatively mild 355ci small-block Chevy with a set of mildly reworked small valve heads. If you check the volumetric efficiency of the engine, coupled with the brake specific, you'll find the engine is a reasonably efficient piece, considering it's docile inventory of components. Data was corrected for 29.92 inches Hg., 60-degree F dry air. The tests were done in a conventional A-B-A format (for the sake of simplicity, we haven't included the final back-up test; it pretty much matches the first test exactly). The baseline test results are as follows:
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Chart 1 RPM
Torque
HP
Volumetric Efficiency
Brake Specific Fuel Consumption
Carb spacers that actually work.
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