I know there is a loss in backpressure and so fourth, but how much loss in terms of torque, hp, or 14/ times.

Assuming I stepped up to 1 7/8" primary and 3 1/2" collector?
On a stock engine.

Yes it's overkill, but it's for future plans. Just an idea at the moment.

 

Ok for the last time backpressure is not good, less is more. The problem with big headers is that they lose exhaust velocity, and thus scavenging of the exhaust gases. This can lead to reversion of the exhaust gases which is even worse. I don't think you will lose much power at all going with 1 3/4 headers.

 

Well, maybe not backpressure, but there is something about having too big of headers. Exhaust Velocity then. But also, not using 1 3/4" header, 1 7/8" headers.

I know some bottom end will be lost, but just curious as to how much, just some idea.

 

In my opinion 1 7/8" headers are way too big for almost any street motor. I have 1 3/4" on my lt1 (dynoed at 400hp) I wish I would have went with 1 5/8" long tube headers. I am missing about 25-30 lbft of torque. Its your decision but I'd be willing to wager that you will be very disapointed if you go that big.
Hope this helps.
Kory

 

Well,

I see what your saying. And I know, every person comes on to this site, saying how they have plans to build some outrageous horsepower motor, and most never do.

But I'm sort of modeling my engine after a friends, he recently ran a 9.40 at 144.

But, an engine like that is not cheap, so I was curious of the side effects of running a header that size until an engine like that could be built.

I know running something like 400 horsepower a 1 3/4 header is more than adequate. I didn't really expect to get an answer as most people here haven't even thought about running a header that big, much less on a engine with minimum mods. Just figured I'd ask.

One other questions, anyone who has messed with a header of that size, I know hedman sometimes says modifications to the floorpans may be needed, anyone know if these hooker 1 7/8s would?

Thanks,
-Matt