Blown Alcohol Header Selection

I'm either gonna build a 3.76" or 4.00" stroke BBC to run with my 12-71 Littlefield. Any suggestions on header/collector size? I just bought what I thought was a set of Dynatech 2 3/8" / 4.5". Turns out they are 2 1/4" / 4.0". Just wondering if they'll be ok or if I should look for another set.

 

size

bigger is better but I bet they will work

 

How hard are you going to spin the blower and is this a big bore engine?
If you are going to run in the range of a 4.0 stroke and 4.600 and really spin the blower, send that set back and hold out for the larger set. Standard bore and moderate blower overdrive, you should be fine.
But look at NHRA pro stock. After the merge those babies will get down to 3.5" collector point- (some even smaller) at the smallest point. With 500 ci and 10,400 rpm. And 900 ci IHRA stuff or 700+ with nitrous only run 5 or 5.5" collectors.

 

This will be a small-bore engine of 4.310, moderate boost of 20# and 8,000 RPM.

 

"COLLECTORS" what are collectors?????????????

 

You know, collectors. Those things right before the mufflers that the street car guys haveta run