1 fast z Posted April 14, 2006 Share Posted April 14, 2006 Ok, so I have a 3.1 liter 12-1 TONS of head flow (225 cfm intakes, 145 ex) and .580 valve lift and 286 adv duration, ITB manifold, with MS, etc. I have been running a regular ole 1.5" primary heder with a straight 2.5" ex. I have planned to run the 1.75" nismo header. With probably a 3" exhaust, for simplicity reasons. Do you think the Nismo header will show any noticable gains? Quote Link to comment Share on other sites More sharing options...
johnc Posted April 14, 2006 Share Posted April 14, 2006 That header should work fine, although from what I've been told it would do better with more duration in the cam. If you're going with a 3" single exhaust, the "Y" pipe is important. Try to run a true merge to a 2 5/8" outlet that has a long taper (14 degree) transition to a 3" outlet. Something like this: http://www.burnsstainless.com/MergeCollectors/mergecollectors.html Quote Link to comment Share on other sites More sharing options...
katman Posted April 17, 2006 Share Posted April 17, 2006 If you're making 48+ hp per cyl (say 290+ hp overall) that's a good size primary. Go with the 2-1/2 collectors which is what I think comes on that header and merge it into the final 3" as John says. Quote Link to comment Share on other sites More sharing options...
Rebird Posted January 4, 2007 Share Posted January 4, 2007 this thread is old but here goes.... did the larger tube header pick up any power with your combo? Quote Link to comment Share on other sites More sharing options...
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