Brutus Rocks - Tech - 1965 Chevy Chevelle
Details, DetailsLately we've been interested in how much power the engine makes in the car. Often the engine is equipped differently in the car from the way it was tested on the dyno. Prior experience has shown that little details, especially at over 550 hp, can have a big effect on power. One thing we tried was to bolt on a 4-inch-tall, 14-inch-diameter air cleaner to see if it would cost power. Our first hurdle was that most of our carbureted air cleaner bases hit the ACCEL fuel rails. We found a relatively flat 14-inch-diameter base that cleared the rails, but it interfered with the throttle linkage. To make it clear, we added a 1-inch-tall spacer between the throttle-body and the air cleaner base, which immediately cost us 10 hp. We discovered that by maintaining the radius from the air cleaner base into throttle-body (or carburetor), the power came right back.
If you look closely at the two photos, there is a gentle radius in the air cleaner base that matches nicely with the beginning radius of the throttle-body. When the spacer is added underneath the air cleaner base, this disrupts this radius, leading to turbulence entering the throttle-body and lost power. We're not sure how this would relate to a carburetor at the same power level, although its possible the same thing could occur. Remember that this is strictly an airflow issue, since fuel is introduced farther downstream. It's also possible that there could be power losses associated with an adapter like this, even at 400hp levels. Just like everything else in life, it's the details that make the difference.
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