sheet metal intake

[Hudson Nut]

I'm going to make a new intake for my race car, so I can run a four barrel carb. I think i read somewhere that the plenum under the carb should be a percentage of the engine size... What is that percentage?

Thanks

 

[xctasy]

I'm going to make a new intake for my race car, so I can run a four barrel carb. I think i read somewhere that the plenum under the carb should be a percentage of the engine size... What is that percentage?

Thanks

1. If it isn't an isolated runner design, between 30 and 60%. Aim for 2.6 liters (45%) for a 354 cube engine.

2. If it is an isolated runner/ independent runner/ port on port item, where there is one venturi per intake valve, then you can get away with a 6 inch pipe the same internal diameter as the intake valve. For a nice big 1.875" valve, that works out to about 1.63 liters, or 28% of the engine capacity.

 

[Hudson Nut]

Thank you... I knew I could count on you

Dany

 

[6bangerbill]

My understanding is that an isolated runner set up did not have a plenum. If this is a dual 4 barrel manifold, What volume do you reccommend for each of the two separate plenums for max hp at 6500 rpm with a 300 bb ford six? Also a runner lengths and volume would be helpful.