what are the rules that need to be followed when determining how to make the bends ? .... is it just that each cylinder should be the same length. also how d you determine the size of the runners and how do you determine how long to make each one ?

 

bump

 

There are a lot of different factors that go into a header. Power-wise the first thing you have to ask is what type of motor it is (n/a or forced induction), where you potentially see the powerband at, what rpm's the motor is going to be mainly operating at (road race or drag?) and I'm sure I missed some other stuff off the top of my head.

The best way to figure out the above is through dyno-testing with adjustable length primaries. You usually want a 4-2-1 configuration for supercharged applications and motors that you're looking for more low-end torque while if you're looking for just peak horsepower gains you usually run a 4-1. Having slip-fit collectors you can say, cut 1" off of all 4 primaries and see if it hurts or helps and then adjust given the feedback from dyno-runs and/or quarter mile mph's. Equal length always helps.

Fitment and room to work with also makes a big difference in how you can run the tubes. There's a bunch more crap and just about noone will give you tried and true measurements to work off of.

 

good luck keep us posted

 

As stated above, there is a large number of inputs when determining header design. That is why caompanies like ours offer a design service you the fabricator to use. We design and suppl the proper parts you build a correct header and make money, win win if you ask me.

If you need a crash course in header design etc. please visit our website for some great info, see the tech article section http://www.burnsstainless.com