RCJ wrote:I could change cam timing but, I'm really trying to think outside the box and get an edge on the competition.
Expanding the pipe at the head then reducing the size.Wouldn't that create a low pressure area when the gases speed up in the smaller pipe?
Making the pipe the same size as the exhaust port then a smooth transition to 1.625.This ideal is based off of D.Morgans pressure recovery post.
If the area is small, increases in size, then gets smaller again, there will be no pressure recovery at that point. There will just be a change in the form of energy from one form to another and then back. To recover pressure the area must continue increasing in size at a controlled rate.
Since you are building new headers I would suggest making them come off the heads straight as far as possible and at a slight up-ward angle and then nice sweeping bends. If you can make them exit up and a little away from the center of the bore also, that would be good too, but you can't do both pipes on the center 2 cylinders that way. This has always shown to flow the best on the flow bench on the 23* sbc ex ports and I see no reason to beleive it would like something different with faster moving ex gasses flowing through the ports/pipes, atleast as far flow goes.
I'd be suprised if collectors help power at and above 5900 rpm. From what I've seen collectors have more affect below peak tq than anywhere and I'm guessing your making peak tq at about 5000 rpm.
If you want to help power above peak tq. you need to help ve not fall off as fast, and I'm betting the stock vortec heads are the limit.
Can you redo the valve job?
A bigger valve?
I'd agree with the suggestion of backing the cam up some. I've seen that help power past peak tq several times.