Intake Runner Length Calculator

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Grumpy Jenkins said 30 years ago (for V8) that developing a plenum volume on a dyno will trip 
you up every time. The best place to start is to get a good figure, then reduce the volume 
slowly until you get a slight power loss. The next-to-last (before the loss) volume -10% is 
what to run on the car.

• Larger the engine and higher operating range the larger the plenum and runner volume can be.
• In general if the runner area and length is good but the motor continues to pick up with larger plenum than used elsewhere you need more carburetor.
• If you have no or minimal power loss when the volume goes below 1 cylinder the carb is probably too big.

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