please dont laugh. Is there a certain header size max or min for turbos. Looking to build something in 82-91mm size. Curently have no2 setup with 2" headers. thanks john

 

how big is the motor? probably one of the most common size primaries are 1 3/4. Im probably gonna build mine 1 7/8 for a 393ci

 

not sure of motor size yet probably 370-400 inch area. The current heads I have now a 1-3/4 header would not cover exhaust port. 1-7/8 would be smallest I could possibly go. Also this is a sbf.

 

I see the majority of the header sizes as
1 3/4 but I see no problem with 1 7/8. Especially with bigger cubic inches. When I talked to Pro Turbo kits they said that 1 3/4 was big enough for alot of power but there was nothing wrong with 1 7/8. Like I said.... since Im building mine from scratch anyway I figure why not go a bit bigger.

 

It has been said that when two sizes of primarie tubing are being considered, err on the side of small.

Reason for this is higher velocity through the small tubing, less surface area for the header to act as a heat sink and pull heat out of the exhaust gasses.

Since you're limited to 1 7/8" as a minmium, that would be what I would go with. Just make sure that there is a little lip from the exhaust port to the header, to act as an anti-reversion device.

Great explainations in Turbochargers and Maximum boost.

 

thanks for the help, john