Jay Comment & "Book" questions

[Qikbbstang]

   Have to say your book has already burned up serious hours as I flipped around comparing data and enjoying the numerous tech treats you included in it.
         I got a big kick out of the Header Section especially studying the FPA vs JBA Tri-Ys.  One thing you failed to note but obviously included in the specs was JBAs using larger secondary tubing then FPA. The effect of the numerous variations of primary tube order, collector size etc that you'd mentioned are only further scrambled by JBAs using larger secondary tubing, oddly longer primary tubes (they're both tri-y's for same car) and with respect to your great running truck-headers... perhaps JBAs larger ports@flanges could help flow get  out of the heads and or produce an anti-reversion step.. BTW the JBAs you tested were Stainless w/ Ceramic Coating.
   I still say the dam header Mfgs screw up by going cheap and hard angle cutting the tubing out of the port at the flanges rather then using a proper tight ($) mandrel bend. The result of the angle cut tubing is the exhaust pulses richochet off tubing walls rather then curve around bends - no doubt the hitting the wall could cause unwanted reversion back right into the exhaust valve pocket.
1)What intake(s) were used during the header testing on each engine?.....
  2)Can you please offer up comments on EGT variations from intake manifolds to headers and vice versa?................   





 What

[rcodecj]

  Have to say your book has already burned up serious hours as I flipped around comparing data and enjoying the numerous tech treats you included in it.
         I got a big kick out of the Header Section especially studying the FPA vs JBA Tri-Ys.  One thing you failed to note but obviously included in the specs was JBAs using larger secondary tubing then FPA. The effect of the numerous variations of primary tube order, collector size etc that you'd mentioned are only further scrambled by JBAs using larger secondary tubing, oddly longer primary tubes (they're both tri-y's for same car) and with respect to your great running truck-headers... perhaps JBAs larger ports@flanges could help flow get  out of the heads and or produce an anti-reversion step.. BTW the JBAs you tested were Stainless w/ Ceramic Coating.
   I still say the dam header Mfgs screw up by going cheap and hard angle cutting the tubing out of the port at the flanges rather then using a proper tight ($) mandrel bend. The result of the angle cut tubing is the exhaust pulses richochet off tubing walls rather then curve around bends - no doubt the hitting the wall could cause unwanted reversion back right into the exhaust valve pocket.
1)What intake(s) were used during the header testing on each engine?.....
  2)Can you please offer up comments on EGT variations from intake manifolds to headers and vice versa?................  
You are absolutely right about the effects of a hard turn immediately out of the head and into the header primary tube. Flow is disrupted and cost hp.
 What

You are absolutely right about the effects of a hard turn immediately out of the head and into the header primary tube. Flow is disrupted and cost hp.

[jayb]

Glad the book is keeping you out of the bars, BB    For the 428CJ header tests, I used the Blue Thunder intake, and for the 390 Stroker engine tests I used the Performer RPM intake.  I think this is stated somewhere in the introduction to the exhaust testing chapter; if not, it's a glaring omission.

Regarding EGT, there is really no way for me to measure the EGT with any of the exhaust manifolds, and even with some of the headers, without drilling holes in them for the thermocouples.  I did have holes drilled in some of the headers already, but not all the headers I tested belonged to me, so obviously those that belonged to others (like you, for instance) didn't get drilled.  Also, I was reluctant to drill any holes in the exhaust manifolds, because repairing four 1/4" holes in cast iron per manifold is a bigger challenge than just welding the holes shut in a pair of steel tube headers.  Besides, I just plain didn't want to drill holes in the rarer factory exhaust manifolds.  So I don't have a lot of exhaust manifold to exhaust manifold or header EGT data.

For the intakes I did collect exhaust temperature data on every test.  There is a LOT of data there, of course, and I haven't gone through and analyzed it all that extensively.  However, I would say that generally speaking, the more horsepower the engine made, the higher the average exhaust temperatures were.  So, the higher horsepower dyno mules showed higher exhaust temps than the lower horsepower versions, and the higher horsepower manifolds on a given dyno mule showed higher temps than the lower horsepower manifolds.  As far as exhaust temperature variations from cylinder to cylinder, there was a lot of this, and the better manifolds generally had tighter EGT distributions.  The single plane intakes did not always follow this rule though; as I recall the Performer RPM had better EGT distribution than the Victor intake, but the Victor made more power on the higher HP engines. 

Hope that helps - Jay