Scotty

From the book entitled

Scientific Design of Exhaust and Intake Systems-Philip H.Smith and John C.Morrison

"It may be considered that the slightly increased area at this point is of benefit in reducing pressure,particularly as there is often a sharp bend in the cast manifold bolted thereto."

Its due to the bends encountered being so close to the flange.

I also remember reading something on exhaust by Bill Jenkens.

It stated that since there is a high pressure charge being released thru the opening of the exhaust valve that there was turbulance in the flow.This resulted in possible contamination of the incoming charge due to the camshaft overlap sucking the spent charge back into the cylinder.

Basically the spent charge would creep up the outer edges inside the pipe.By keeping the flange at a greater opening than the pipe diameter the spent charge has a more difficult time getting back thru the exhaust valve.The spent charge is blocked by the actual head material exposed by the flange opening.

Oldmics

I bought a new kit but we will be using the flanges and some of the tubes from those, nothing goes to waste.

I might add that they are a lot like Teds EMC headers so I would think performance would be close. The new ones will have some interesting bends to get around the steering box and even the pass. side will have to be close to the same to even things out.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

Tim, What about the set that was made for Charlie but didn't fit?


Lawrenceville, GA

Great stuff Ted!  I've been fallowing it from the start, I just wish I could send you the custom set that will be made for the "Uni" it would be interesting to see how they do.  Maybe in the winter next year if you have the "Mule" up and ready.

   God Bless.   Tim                           http://yblockguy.com/

350ci Y-Block FED "Elwood", 301ci Y-Block Unibody LSR "Jake", 312ci Y-Block '58 F-100, 338ci Y-Block powered Model A Tudor

tim@yblockguy.com  Visalia, California    Just west of the Sequoias

G'Day Ted,

           And guys, I follow this site a lot , even though i rarely respond, (guess that's obvious), As with everyone, a thank you for your time and efforts, and if i may, I have a question that i've not seen, heard of, read or been able to have answered. (that's not to say it isn't out there) But why are the header flanges shaped as per port design/shape, when round pipe is used? (obviously) That is to say, why not just round flanges for round pipe? When as often as not, the pipe is somewhat "re-shaped" to fit the flange anyway. This of course is irrespective of engine make. I can only assume that there is a very good reason for it, and although i do have a theory or two of my own, i'm unable to see it/them as viable all the same. My main reasoning is along the lines of the effect on the airflow, transitioning from port to pipe.

           Thanks for your thoughts and congrats on the EMC effort, "Outstanding"! I welcome any and all responses.

"MY TWO BOBS WORTH!" (Twenty Cents AUD)

Y-BLOCKS ROCK!!!!!

thanks ted. i love those graghs. what dia. is the outlet in each manifold. and what length pipes are you using. 56"?

 lincoln/merc. y-blocks &mel's                                                               bucyrus, ohio.

Another thing when I talked to Jay at Sanderson he said once they have a pattern they can do different sizing on the runners as going from 1 1/2" to 1 3/4" etc in some cases.

-Gary Burnette-

Wayne.  Took me a bit to figure out that you wanted to compare the ’57 exhaust manifolds to the Ram Horns?  If that’s the case, then here are the graphs for that comparison with and without mufflers.

 

 

Lorena, Texas (South of Waco)

...yeah, for the Uni', and what you said above is actually the path being taken, just not by me. I believe the cage guy is attacking that, but that's another thread

Todd in Central California...about half way between Fresno and Sacramento

1956 Thunderbird - 1960 F-100 - 1961 Starliner - 1961 Imperial

Oooooohhhhh, they're for the 'bird. I was thinking you were going to use them for the unibody. Nevermind.


Lawrenceville, GA