Long Tube Header Install

[NZGTRA17]

Originally Posted by PanozDuke

Kel,
Remind me again, what are the primary diameter on yours and the collector diameter and length before they merge.

Thanks,
Mike

Mike, 1 3/4" dia x 36" long primaries (measured to the merge section of the collector), 3" dia collectors, merge into single 4" dia pipe prior to 4" superflow muffler (3.5" modified to 4") and then 4" pipe to outlet in std location on RH side of the car.

The step on the GTS header will most likely help to broaden the torque range I suspect but still a short primary for a 5.0 working in the rpm range that most of us are using.

Kel.

[PanozDuke]

Kel,
Thanks. Tom and I are having a couple of sets fabed up using your example as inspiration. Hope to have some fixtures as a result so they could be more easily reproduced. We have your photos and wanted to be careful not to mess up the critical dimensions. How long are the three inch collectors? Does that matter? Suppose we went to a stepped design, how would that effect the primary length and where should the step from 1 5/8 to 1 3/4 be placed. Idea is same 6000 and below power band with 5.0 stroker and roughly the same heads, carb and cam as you are running. Thanks for the guidance.

Mike

[NZGTRA17]

Originally Posted by PanozDuke

Kel,
Thanks. Tom and I are having a couple of sets fabed up using your example as inspiration. Hope to have some fixtures as a result so they could be more easily reproduced. We have your photos and wanted to be careful not to mess up the critical dimensions. How long are the three inch collectors? Does that matter? Suppose we went to a stepped design, how would that effect the primary length and where should the step from 1 5/8 to 1 3/4 be placed. Idea is same 6000 and below power band with 5.0 stroker and roughly the same heads, carb and cam as you are running. Thanks for the guidance.

Mike

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.

[Cobrafang]

Me too me too.

[email protected]


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.

[NZGTRA17]

Originally Posted by Cobrafang

Me too me too.

[email protected]


Thanks

tom

Tom, sent this morn. Kel.

[PanozDuke]

Originally Posted by NZGTRA17

Tom, sent this morn. Kel.

Kel,
Thanks. If Tom's got it then I've got it (we're joined at the Panoz).

Mike