Due to the number of threads that have been started regarding a specific header design, then hijacked by someone extolling the benefits of some other design, then had posts deleted, I thought I'd start a thread inviting the various header vendors, and any one else of course, to compare their headers!
I would ask in advance that, unless a post breaks the forum rules by being abusive etc., that no posts are deleted or modified. If you wish to modify your own post, please clearly marked the edit and if possible leave the original post visible. Please post all relevant modifications, cats, maps, etc. when quoting performance figures.
In an ideal world all the headers would be tested on the same car at the same time on the same dyno, in the real world this is impossible. Even testing the same car with different headers would not give a 100% accurate comparison due to changes in atmospheric conditions between tests as swapping headers over will take the best part of a day.
We're all grown up here, at least I'd like to think so, so please do not post inflammatory or derisory comments.
Generically and theoretically, 4-1 headers should perform better at high rpm, peak power being delivered at the maximum rpm even with a raised limiter. 4-2-1 headers should perform better at lower rpm, usually with a slight drop in performance at the very top end, peak power being delivered at slightly under maximum rpm. I believe the often quoted characteristic that 4-1 headers will have dip in power at lower rpms is relative to a 4-2-1 design and not the stock headers, at worst the 4-1 design should be similar to the stock headers.
The main discussions appear to revolve around the following headers, in alphabetical order :
Dinan
Equal length 4-2-1, firing sequence maintained.
Evolve
Equal length, 4-2-1, firing sequence not maintained.
OEM
Not equal length, sort of 4-2-1 but asymmetrical, firing sequence sort of maintained.
SuperSprint
Non Equal length 4-1.
Van Manen Original
Non Equal length 4-1.
Van Manen Varient II
Equal length? 4-1.
Of course there are others, discussions on those are also welcome.
I would ask in advance that, unless a post breaks the forum rules by being abusive etc., that no posts are deleted or modified. If you wish to modify your own post, please clearly marked the edit and if possible leave the original post visible. Please post all relevant modifications, cats, maps, etc. when quoting performance figures.
In an ideal world all the headers would be tested on the same car at the same time on the same dyno, in the real world this is impossible. Even testing the same car with different headers would not give a 100% accurate comparison due to changes in atmospheric conditions between tests as swapping headers over will take the best part of a day.
We're all grown up here, at least I'd like to think so, so please do not post inflammatory or derisory comments.
Generically and theoretically, 4-1 headers should perform better at high rpm, peak power being delivered at the maximum rpm even with a raised limiter. 4-2-1 headers should perform better at lower rpm, usually with a slight drop in performance at the very top end, peak power being delivered at slightly under maximum rpm. I believe the often quoted characteristic that 4-1 headers will have dip in power at lower rpms is relative to a 4-2-1 design and not the stock headers, at worst the 4-1 design should be similar to the stock headers.
The main discussions appear to revolve around the following headers, in alphabetical order :
Dinan
Equal length 4-2-1, firing sequence maintained.
Evolve
Equal length, 4-2-1, firing sequence not maintained.
OEM
Not equal length, sort of 4-2-1 but asymmetrical, firing sequence sort of maintained.
SuperSprint
Non Equal length 4-1.
Van Manen Original
Non Equal length 4-1.
Van Manen Varient II
Equal length? 4-1.
Of course there are others, discussions on those are also welcome.
