Originally Posted by stainlessguy

Ok, gotcha... you are precisely right and for you larger motor 1 7/8" would work best... ( also I didn't know that you had read the header design site).

If you are local to Cleveland we can build custom headers for you. Give us a call @ 800-878-3635.

I'm glad that you did because not many people know that headers can do THAT much. You are absolutely correct. These are all design aspects that we incorporate into our header but keep in mind that these processes that they are talking about are at an emperical level. As a general rule, because everyone's motor will be different from the factory and everyone will mod their engine different my statement was a just a generalization. As a rule more low end torque will be observed with a smaller primary tube (to a certain degree-- obviously) ... but the ultimate goal is to achieve all the things that you mentioned. These things as I'll explain are very seldom (if ever) tuned into perfect harmony on a street car.

In a factory motor the flow through each port and the AFR in each cylinder will be can vary significantly so that pulse wave in each primary tube will not be timed correctly to take full advantage of a properly designed header... especially at high RPM (not to mention from engine to engine). Stock car builders can have 500+ hours in cylinder head work (valve depth, porting, etc.) to get each cylinder to match the others PERFECTLY. For this reason it's mostly a myth that equal length headers on a street car will make you more power; because nothing else is equal.

We incorporate all that you read into each header but for a factory produced car used in non-competition driving we have to use the dyno and the track to tell us what works best for most cars. On 6.0L small blocks under 500hp the 1 3/4" seems to create the best performance.

Tell all you buddies to check out that site as well!!!

Thanks,
Rick Conway
Stainless Works
Sales and Tech.