I need some recommendations for a header. I'm currently running a cheap tri-y that starts to loose power at 6800. My cams should still be building to 7200, But I need to not loose too much up to 7900. Currently I drop 8hp between 6800 and 7900. Obviously I need a 4-1 style. Do I want 1.5" primaries, stepped primaries? bigger? I'm at a loss other than off the shelf stuff.
Miata 1.6 headers
- Thread starter PMcCartin
- Start date
Lots of variables. I run FP4 Integral cams and with a Boig header Power increases to 7600rpm and flattens out. No drop to 8200 rpm rev limit. Did you properly port match both intake and exhaust. Ect, ect.... I believe the header is a 1 5/8" tube. Valve springs are important also. Used to fall flat at 7500 rpm. I believe J Prather sells these headers.
Chris
Chris
It is port matched, fresh springs and valve job. The cams are Integrals .375" street cams. So they're a good bit less than the FP cams. I'm convinced it's a header problem based on some dyno time with the stock engine. I went from a 4-1 to the 4-2-1 gained in the middle and lost up top. Now with the "big" motor the loss is accentuated more.
This is an autocross car, but I figured you guy's would have more data on this. Thanks for the help.
I've talked with JP a bit on his (Boig?) header. And Stahl on theirs. I'm still confused.
This is an autocross car, but I figured you guy's would have more data on this. Thanks for the help.
I've talked with JP a bit on his (Boig?) header. And Stahl on theirs. I'm still confused.
jstinehelfer
Well-known member
I have used the Bob Boig headers (1.75 inch pipes ) on engines up to 200hp at the crank and up to 8400 rpm and they work well. I have a spare set that are older (7 or 8 years) but still in very good shape that I would sell for $200. I do not have the needed 4 into 1 collector.
Jim
Jim