I'm in virgin territory,building a blow thru 406 cid sbc.large frame t76.
I have 2 questions.(for now)
1 well it seems like 1 question....if 1 5/8 tubes on the header will be more then enuff,would 2.5 inch cross over be enuff? it would be easier to work with over 3 inch and I would gain a little more room...I'm still gathering parts.thanks,
Scott

 

Im running 2.5 crossover. The biggest restriction is the turbine wheel. I think the most important is the down pipe.

 

2.5" here. Although I would consider stepping up the header size to 1-3/4.

 

I think the bigger header primaries will be better with 406ci, but I think anywhere from 2.5-3" will be fine for the crossover.

 

Use whatever primary is able to cover the exhaust port and 2-1/2" is more than enough.

 

well I have the headers already.1 5/8 I guess since it don't real matter I'll go 3 inch.on n/a or nos motors headers and exhaust counts..why not on turbos.I have seen some really bad jobs on some turbo cars,and they run great.as far as the down pipe I believe my turbo has a 5 inch flange.should I step it down to 4 inch?
is there a special flange to adapt the 3'' cross over pipe the rectanglar flange?or do you make it work with a hammer?
thanks
Scott
i will have a turbo camaro running soon.

 

You can make it fit with a hammer (rectangle it out). You can also buy flanges that have a 3" hole instead of the rectangular cutout.