Thread: From the mind

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Originally Posted by jerry clayton

so how many of you noticed that the two headers pictured probably aren't of the same set but of two different combos???????????????

Yeah, I counted the tubes and noticed the different pairing this morning when it was posted, and that the second one hadn't been fitted with the collector yet, but I didn't make anything of it since the second one wasn't mounted to the engine. I just figured that they built two different sets, and then did some dyno runs to see if one was better than the other. As I said above, it would be interesting to see some numbers on the mod motor running them, and comparisons between the two different configurations.

With standard Tri-Y headers as Doug Thorley used to build them, on one side of the engine the front and rear tubes come together in a Y and the two center ones do the same; on the other side, the front and third come together and the second and fourth. Those combos dump into the collector Y. That is for engines with a 1-8-4-3-6-5-7-2 firing order. That combo of pairing is what this looks like to me.

Originally Posted by Rrumbler

With standard Tri-Y headers as Doug Thorley used to build them, on one side of the engine the front and rear tubes come together in a Y and the two center ones do the same; on the other side, the front and third come together and the second and fourth. Those combos dump into the collector Y. That is for engines with a 1-8-4-3-6-5-7-2 firing order. That combo of pairing is what this looks like to me.

Rrumbler, I'd forgotten (CRS again) about the different pairings side to side to maximize scavenging. The SBF's 1-3-7-2-6-5-4-8 firing order would change the pairings, but I bet you're on target with the reason and I expect that's what Jerry was pointing out with his post.

Originally Posted by Dave Severson

Here's an excerpt from this year's Engine Master's competition, dang good numbers from a 4 valve mod motor with no supercharger, nitrous, or turbo!!!!! Read more: http://www.popularhotrodding.com/eng...#ixzz2hgptzTdG

Dave, thanks for the details, and for posting that link! Good stuff!