i want a 4-1 with a nice 15 degree merge collector. primaries i am shooting for is a 30. i was going to run a 2.25 collector to a venturi with a 2.5 outlet. i wanted to run stepped primaries or reversion chambers. so should i run 1 5/8 out of head toa 1.75 runner? or a 1 5/8 runner from head to collector with a 1 3/4 chamber placed inline? or what about 1.75 runner from head to collector witha section of 2.0 as the chamber? will i see a differance in power in a stepped primary vs reversion chamber? this motor is mostly stock but may go with a set of skunk 2 stage 1 cams. and a phearable p28 program.

i knoiw most of you will probably tell me this is overkill. but thats fine.

 

All 16ga tubing. 1-3/4" off the head, up to 1-7/8", then up to 2" into a 2" inlet 4-1 collector with a 2-3/8" outlet that goes to a megaphone ending in 3" then tappering down to 2.5" to go out the rest of the exhaust. Primaries should be equal lenght ranging from 18"-24" long, so each section around 6"-8" long.

Talk to Burns about getting a collector. They make some good stuff.

 

to the anti reversion chambers.

 

primaries seen kinda short, have you proved that header design? i have seen your name around hear alot so i am figuring so.

 

Its similar to the one I'm building for my motor now. I also talked with Burns about it. I believe the sizes and lengths are also similar to some of RMF's H22 headers.

The 4-2-1 header I built made 14 hp over DC on a stock motor with 1-3/4" and 1-7/8" primaries to 2" secondaries.

 

want to sell that header?

 

I sold around 12 or 13 of them a few years back. Look for the Imagine Engineering H22 header. You should be able to find one for less than $500 shipped. I don't have any left and the one I'm building for my motor is a one time thing. Other than that I suggest a RMF, DTR, SMSP, or Hytech.

As far as the head work you could do something as simple as a pocket port, competition valve job, and mill it .030". That with the cams and Type-S pistons will get you where you want to be.