TINKRD

iTrader: (27)

Currently building an iron block 408 and have a set of OFI headers.

I was curious. Has anyone made a set of 1 7/8 headers? Due you think the 1 3/4 are too small for the amount of cubes???

qqwqeqwrqwqtq

1 5/8 would be more than adequate on that displacement. I would only consider 1 7/8 for something that was 2,000+hp.

engineermike

People have been over 1000 rwhp and 8's on a 1 5/8" header, so I don't think anything bigger is needed, regardless of cid. Just make sure they mate up to the exhaust port well.

Mike

TINKRD

iTrader: (27)

hmm..i wonder if i were to ship these headers back to joel if he could make me a set of 1 5/8??

qqwqeqwrqwqtq

To be more specific, your 1 3/4 headers will be just fine. My example of 1 5/8 headers being more than enough was just to further illustrate the fact that your headers are not possibly restrictive.

ChrisUlrich

So you couldn't have too big of a primary?

engineermike

I don't think anyone has spent the time or money on R&D to quantify exactly what's going on in the primaries of a turbo header to properly answer your question.

qqwqeqwrqwqtq

Generally, I believe using a primary that's excessively large will contribute to lag, or transient response, as velocity is reduced.

I also doubt that the increased lag would translate to any power gains considering the turbocharger is far more restrictive than any reasonable header primary. (In terms of most street/strip turbo systems with 7,500 or less rpm limit)

JZ 97 SS 1500

iTrader: (2)

1500rwhp has been done with 1 5/8's. I don't think you'll have a problem