Superformance Exhaust

greg schroeder · #1 (**permalink**) 07-07-2009, 10:42 AM

the headers I put on my 427R were not like the new 402 type. They were larger than the exhaust port by height and just really close on width and had 2 inch primaries to match the 2 inch primary side pipes. I can't say for certain, but I think they are big block headers reflanged, not positive. The other 402 type header looks really similar to the AFR 205 exhaust port shape. You'd have to measure the header width internally to tell if they're perfect. From the looks of them the bolt holes look like they might be a bit tight. The design of the new type looks nice compared to the old for sure. I had mentioned before the headers I had were good for about 10 wheel HP. Side pipes were about 25 wheel HP, Pro-Systems carb about 30 at the wheels and all the fuel delivery and intake changes were about 10 wheel HP.

These are my headers, old and new.

This is an AFR 205 head exhaust port according to an ebay ad were I got the image. Accordding to the tech line at AFR the 205 exhaust port is 1.342" wide and 1.375" high. The heads have both 2 inch wide bolt holes and 3 inch wide bolt holes. According to the tech line at AFR the 185 head is 1.335 wide and 1.4 high and have only a 2" wide bolt pattern.

wanab5150 · #2 (**permalink**) 07-07-2009, 05:22 PM

Well, with the 205cc port being 1.342 x 1.375 the 1.650 O.D. "402" headers I have should be more than big enough to eliminate any restriction. As I mentioned...they expand to 1.75 about 6 inches from the flange and remain that size all the way to the collector.

I always matched gaskets and cleaned up welds on the flange in the past, but with the clearance I think I will just leave them alone. In the beginning of this thread I was afraid even the "402's" were to small, but I am relieved I won't have to spring for new headers.

I'm glad to see the port size numbers...thanks, Greg. I'll have the new 3 inch mufflers in 3 weeks. tom

Bxx1 · #3 (**permalink**) 07-08-2009, 01:46 PM

"I'm glad to see the port size numbers...thanks, Greg. I'll have the new 3 inch mufflers in 3 weeks. tom"

Tom, I would like to hear the exhaust, before/after setup.

Ron