Speedmaster 1-147-074 MidRise Air Intake Manifold Machine Polished

Pontiac 326 350 389 400 421 428 455 MidRise Air Intake Manifold Machine Polished

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The Speedmaster MidRise Air design features the identical plenum and runner design as the normal MidRise. The main difference is that there is an open area under the plenum chamber. This feature is sometimes called an air gap design. The air flowing under the plenum provides a cooler charge for the incoming air with less heat transfer from the engine. This cooler air charge provides additional power and torque.