Header primary tube size: big or small?

What are the pros and cons to large primary tubes vs. smaller tubes? Torque, Hp, sound etc... Have a set of very large primary Hooker fenderwells and a set of smaller tube Stahl fenderwells for the '55 and dont know which to go with. Haven't run the Stahl's yet so no opinion on my part. Thanks again,
-Dean

 

If you dont see over six grand very often stay with the small diameter header.
It will have better low end torque.
Big tube headers are great if you are running mostly high(4500 to 8500)rpm but are generally a waste on the street.
been there,done that,got the t shirt.

 

I totally agree.

I built a set of fenderwell headers for my desert race truck out of 1-5/8 id and they work very well up to about 5800 to 6000.

My truck is a very mild 350 about 350 hp. The cam is good for 1500 to 6500.

Being 1-5/8 their smaller than most headers.

Bill

 

I'd generally agree too. 1 5/8" is fine for most mild small block applications. Check out www.headerdesign.com for some pretty cool science on tube sizes.

Hank

 

Most people oversize their headers because they believe bigger is better. While your peak HP number may be down with the smaller headers, you'll actually make more usable power.

 

if you're building a badass big cam high revving motor, go with big tubes....and if you have the big headers already, that's a perfect excuse to build that kind of motor for it

 

yes..all of the above

 

I like the way you think

 

I have Hooker adjustable junior stock fenderwell headers on my 331 injected small block
they are 1 5/8" primaries into the collectors with 2 1/2" turn outlets hope they work well up to 7000 to 7500. My car is all steel with old school parts from 60's 9" with 4.86 ratio and a 4 speed 2.64 1st gear
when I was a teen this same engine was carb single plane and 4 speed with cyclone headers lol.
ran good on street tires and 4.88's low 8. in the 1/8 driven to the track.

I had another set of hookers sold to a friend for his 55 they were not fenderwells they had 1 3/4" primaries and 3" collectors off my other engine that was blown injected alky which I removed to put back the same motor I had as a teen. a bit more practical for this car

 

I made my own years ago for our race car turned 7200 ton off the corners with 1 5/8 on 3/8 high bank.on a longer track I would have tried 1 1/2 or bigger probably but probably would have lost off corner

 

I’ve got some huge 2” fenderwell headers on my 10.5:1 , 327 Model A , they look bad ass and sound great , if it has a loss of low end torque I can’t tell

 

I usually go by what exhaust valve diameter I have in the heads..... 1.600" diameter valves.. 1.625" primary tube size = perfict!....