[Cobrafang]

Me too me too.

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Thanks

tom

Originally Posted by NZGTRA17

Mike, the collectors are 6" long with the tapered section being 4". The collectors are Hedman items. I have an excel spreadsheet which has all the fomulas in it that I used to calculate critical diameters and lengths of the system. Happy to share this with you. All of the formulas are straight out of the A Graham Bell book that I mentioned.

Note that I built my system to work with a 347 so the 1 3/4" primaries and 36" length are tuned for an engine of this capacity and 5600rpm to suit endurance racing. By using the formulas you can play with critical dimensiosn to suit your application.

Regards using a step in the primary pipe, I have not experimented with this. I have done some reading on the theory of stepped pipes and there is a lot of evidence to support using this approach (they use multiple steps in F1 headers). I expect that using say 1 5/8" stepping up to 1 3/4" will provide a slightly lower peak torque rpm and a broader torque curve. Having said that the 5.0 and more particularly the 347 have a very flat torque curve in the configuration that we use them so hard to say what gains you will achieve. I suspect that the stepped configuration would have more effect when longer duration camshafts were used and low speed torque was affected.

Drop me your E address by PM and I will send you the spreadsheet Mike.

Kel.