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Grant Eldridge · 01-06-2008, 02:34 AM

We were on the dyno today testing exactly this subject. We tried our regular stepped Hedman headers with two different merge collector sizes, also tried primary length short and long. We had an old set of Bill Thomas 2" race headers with long collectors we bolted on to see what would happen. To our surprise, the old 2" headers produced more hp and torque from 6500-7200, however overall from 5000-6500 there was a decrease that more than offset the top end improvement. Our feeling was that the step headers were better, but we never tested the 2" headers with longer primaries or with the merge collectors so I suppose more work would need to be done to try and really answer the question definitively. The sizes would not permit swapping primary extensions or collectors, that might have narrowed the gap, or even eliminated it. We were doing other work so went no further with the headers at this time, but thought it was interesting.
BTW, we run a 396 oval port in stock eliminator.....

01-06-2008, 02:34 AM	#8
Grant Eldridge Member Join Date: Jul 2007 Posts: 124 Likes: 0 Liked 0 Times in 0 Posts	Re: Stepped Headers We were on the dyno today testing exactly this subject. We tried our regular stepped Hedman headers with two different merge collector sizes, also tried primary length short and long. We had an old set of Bill Thomas 2" race headers with long collectors we bolted on to see what would happen. To our surprise, the old 2" headers produced more hp and torque from 6500-7200, however overall from 5000-6500 there was a decrease that more than offset the top end improvement. Our feeling was that the step headers were better, but we never tested the 2" headers with longer primaries or with the merge collectors so I suppose more work would need to be done to try and really answer the question definitively. The sizes would not permit swapping primary extensions or collectors, that might have narrowed the gap, or even eliminated it. We were doing other work so went no further with the headers at this time, but thought it was interesting. BTW, we run a 396 oval port in stock eliminator.....