Thread: What is the right intake runner for a street car?

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Originally Posted by James911

Hi,

for a street car you need high torque at low RPMs, for a race car you need high power at high RPMs.
For high torque you need heads with a smaller intake runner volume to get a higher port velocity and better mixture of the fuel and air, but you don't want runners too big, they will kill the low end torque because of the loss of the above mentioned port velocity. For racing use you need a high volume of mixture, which is only obtainable by having big runners.

So, if I want to set up a street car, what kind of intake runner volume should my head have? What is big, what is small?
E.g. I am interested in buying World Sportsman 2 Heads, which have a 200 cc intake runner. What do you think about them?
http://store.summitracing.com/partde...5&autoview=sku

If I want to run my car with LPG (propane butane), what do I have to consider when I choose heads? What is here the optimum of the intake runner for a street car?
What else is important? What kind of valves/valves seats do I need?

THX.

James

Here is one formula I use.
This is the amount of hp a given flow will support.
Flow at 28 inches of water X 2.06 = HP.
An example would be 270 X 2.06 =556 HP.
Most SBC 's seem to like around 180 cc port volume which would be enough to support 450+ hp.
At 400 HP and under I would try a 165 cc port volume.
Can you tell us more such as cam specs. and comp ratio etc.