Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Ideal header tubing sizes......????

This really has nothing to do with our engines, but more so with engines in general.

Is there a formula you can use that will tell you the ideal inside diameter of the primary collectors, using say... cylinder volume, compression ratio, and max RPMs? I would also need to know the ideal exit opening of the collector that the primary tubes come into, like in a 4-1 header and so forth.

I am working on some other projects for other cars and I was just wondering if anyone knew of any formulas....

Nikolas

The process you are asking about is far more involved than that. There is not enough room on this board to post it all. Get the book Scientific Design of Exhaust and Intake Systems it is written by Philip H. Smith and John C. Morrison. The book contains what you are looking for. There are also a couple of websites that contain a wealth of info as well. Both use info. from the book, however just tidbits you realy need the book to get the whole picture. Try www.burnsstainless.com look in the tech articals there is some realy good info. there. You can also find alot of info at www.headersbyed.com Good luck and have FUN!

I went to Amazon.com and read the reviews on the book, 1 was good, the other 3 or so were bad, stating the book doesnt have enough up to date info, is basic, etc.

Amazon.com Book Info

Know of any other books that are up to date for more modern DOHC 4v engines? Or doest it really matter?

Nikolas

Did you check out the above websites? Did you look at there list of people that they serve? I assure you these 2 companies have there act together. They are the only 2 companies that havent been taken over by the marketing whores and only sell fad items! There stuff works! Yes the book is old however that means nothing. The engines today are still internal combustion engines and the laws of physics that applied then apply today, it does not matter how many valves or camshafts the engine has. By the way thats not new technology either it was pioneered many years ago, its just been the last 12-15 years that the automotive industry has started making it available to the consumer.

Rule of thumb for header tube size:- tube dia must be equal or 10% more in cross sectional internal area to the cross sectional area of the exhaust port (oval or round or square etc etc)......NEVER smaller in cross sectional area than the port.....

Your right Terry! and as you know there is much more to the design process than that.

The 'Smith & Morrison' text book should be 'standard' reading to all tuners, the physics do not go 'out of date'..this was a 'std' text book during my courses many years ago,it was first printed in 1962,my edition has,printed in the flyleaf 'This Edition not to be sold in the USA'...hummm....what have I got that the others dont!!!!!

Well my edition says that in 1972"Chapter 14 has been rewritten by a pollution research engineer to keep the reader up to date on the increasingly far-reaching requirements of fiscal policy in this respect {particularly in USA] and what is being done to meet them. That may be the difference Terry.

sweet.... I just spoke to a buddy of mine and he has this book...He is going to lend it to me so I can read up on this stuff.

Thanks guys....

Nikolas