MAW wrote:

DC wrote:

I used to spend a lot of time on the flow bench and discovered that if you keep the inside turn radius close to a quarter of the tube diameter you get respectable flow. If you go below a seventh of the diameter you loose big. FYI

DC I'm a little slow, could you put what you said into numbers?  I think you're saying if you have a 2" pipe the inside radius of the bend should be around 1/2"?  I think I'm misinterpreting something.

 You are correct. for a 2 inch pipe the inside radius is really good at 1/2 inch and bigger and still OK but not quite as good at  close to 1/4 inch. less than a 1/4 inch and the flow really suffers. It seems you get quite a lot more turbulence at the inside turn at lesser raduises.

Here is the finished product.  It is over 14' long when measuring from the header collector directly to the tail pipe tip, not taking in to account all the tubing it took to make all the bends.