thedudeZ

iTrader: (14)

Putting this in the n20 section because its an n20 specific question.

I've been running the ebay stainless 1 3/4 headers but with the new motor wanted to be sure I had enough flow and edelbrock was closing out on their larger primary headers. They claim 1 3/4 stepped 1 7/8 but the pictures speak for themselves. I figure maybe the stepped down portion is 1 7/8's at least but for sure the collector is 3.5in.

The exhaust port on the head is closer to the size of the edelbrocks but is it better to dump into a more open space or what?

Also I don't understand why the edelbrocks header flanges were welding on the head side and not on the outside?

Which ones do I use for the most power with a nitrous 383? Camera phone is taking a crap so please excuse some of the poor quality pics but they give you the idea.

https://ls1tech.com/forums/album.php?albumid=23283 Link to photo album.

soundengineer

iTrader: (16)

for the most part, a stepped header will be better than a straight header, but of course, bigger would be better... go from a 1-7/8" stepped to a 2"

but its going to be dependent on how much power you are making...
if you are around 500, you need a 1-7/8 and a dual 3" exhaust out or a 4" single out
above that, you can utilize bigger and bigger(within reason)

the welds are supposed to be on the head side, seals better,
you want it as a build up so you can plane it flat to get the seal you need...
it also wards off warping an entire flange which would cause leaks
the exhaust pipe is pushed through the Flange, and then welded on the outside of the pipe on the head side of the flange
then you mill the pipe that is sticking out until you have a flat even level surface across all exhaust pipes

thedudeZ

iTrader: (14)

Thanks for the reply. Biggest issue I had was the uneven/unfinished ports measuring 1 5/8 I.D.

I am still working on smoothing those ports out.

thedudeZ

iTrader: (14)

Any other thoughts from the big boys on if the actual smaller beginning stepped primary edelbrocks would be better than the true 1 3/4 with 3in collectors?