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Headers - Cylinder pairing
https://www.slantsix.org/forum/viewtopic.php?t=17483		 Page 1 of 1
Author:  Terencejiminy [ Tue May 09, 2006 5:34 am ]
Post subject:  Headers - Cylinder pairing
A looong time ago (Mid 60's) a gentleman in East Detroit Michigan created an experimental snake pit of pipes for the Ford Indy cars that actually was the mating of cylinders 180 degrees apart (into 2 seperate collectors)for smooth flow and scavenging coupled with equal length runners (measured by TOTAL VOLUME of the runner).
The pulse of exhaust from one cylinder exiting into the collector used the proceeding cylinder's pulse, the negative pressure behind it as it burst into the collector, to help draw it out behind it.
The problem with our 6 cylinders is that there isn't any 180 degree seperation between pulses. The closest we can get is the front 3 matched together and the rear 3 matched together. That is a seperation of 240 Degrees. This is of course in a 2 collector system.
By pairing the cylinders in a 3 collector system you can have 360 degrees of seperation with 1 & 6, 2 & 5, and 3 & 4 mated OR 120 degrees with 1 & 5, 2 & 4 and 3 & 6 mated. All of course with equal length runners.
Well there is the technology. Which one will work BEST?
I do not have a dyno, a tube bender and a Fab Shop to try them all.
I was wondering which, if any, of the 3 collector system had already been tried??
I saw (305 ci Chubby :oops: straight 6) the single (720 degree) collector header put on a dyno quite a few years ago and there was NO increase in HP or Torque. In fact there was a LOSS of 8% to 12 % over the 2 collector (240 degree) Clifford Header. They were testing Mega-Phones attached to the collector for Oval Track mid range torque.
I presented these questions to our Avionic and Power Plant Team here in Aircraft Maintenance. With some TOTAL ROCKET SCIENCE they tried to work it out on paper AND the Company 'Puter.
With a Slant/6 at 241ci, 10 -1 comp, and max rpms of 6700 (restricted by our wonderful economical head design) they BELIEVE the 120 degree pairings would work best because of the small 40 cubic inches per cylinder output pulse in 1 5/8" runners..
Just a side note they were very critical of the whole head design as the ports for intake & exhaust were next to each other transferring HEAT to the intake charge.... That was another 2 hour speel. :roll:
Note: My intention is for Drag Racing.
Any input is appreciated. :D
Thanks,
Terry
Author:  slantzilla [ Tue May 09, 2006 7:46 am ]
Post subject: 
IIRC, cylinder pairing has been tried and it did nothing. :shock:
Author:  SlantSixDan [ Tue May 09, 2006 8:03 am ]
Post subject: 
Port arrangement options on an inline engine:

All intakes on one side, all exhausts on the other (a "crossflow" head): This is the best for flow and heat management.

Intakes and exhausts on the same side, no two intakes or exhausts adjacent (this is what we have on the slant-6): This is second preference. There's more heat transferred to the intake ports, but it's even across all cylinders, and doing it this way facilitates efficient manifold design.

Intakes and exhausts on the same side, ports grouped: Not as good. Forces compromises in manifold design, and there can be uneven heat transfer to the intake ports.
Author:  emsvitil [ Tue May 09, 2006 2:16 pm ]
Post subject: 
120 degrees with 1 & 5, 2 & 4 and 3 & 6 mated is an odd-fire arrangement.

Only 1 of the pair would really benefit if there is a benefit...........


1 & 6, 2 & 5, and 3 & 4, 360 degrees of seperation.

Is equivalent to a tri-y setup on a 4-cylinder engine. You might notice something, but I think it would be a plumbing nightmare.......... I think tri-y's are supposed to be better for mid-range. The secondary pipe after each pair would also have to be equal length when they merge into 3-1 secondary collector.
You can probably use the length calculations for a 4-cyl tri-y with this setup.


I think the 6-1 systems have too much collector area. Any benefit of the equal-length pipes are probably lost at the collector.


And there may be some gain to the typical two 3-1 systems by playing with the length of the secondary pipe before they merge, or if the don't merge (dual-exhaust), by puttin a X crossover on the pipes (and playing with the length to the Xpipe)
Author:  AndyZ [ Tue May 09, 2006 4:38 pm ]
Post subject: 
[quote="SlantSixDan"]Port arrangement options on an inline engine:

All intakes on one side, all exhausts on the other (a "crossflow" head): This is the best for flow and heat management.

I remember hearing about someone who had a Frod 300 I6 that had a cut and welded head made from a 302. This gave a crossflow to that 6 and from what I understand, it ran quite well. That type of setup might be a bit tricky on the low side of a slant. Exhaust would be close to alot of things.
Author:  slantzilla [ Tue May 09, 2006 7:31 pm ]
Post subject: 
Quote:
I remember hearing about someone who had a Frod 300 I6 that had a cut and welded head made from a 302. This gave a crossflow to that 6 and from what I understand, it ran quite well.
Bruce Sizemore cut and welded 3 pairs of Boss 351 heads for a 300 six in a Pinto drag car in the late 70's. He ran very close to Pro Stock times with that car. :shock:
Author:  Terencejiminy [ Wed May 10, 2006 4:43 am ]
Post subject:  300 Ford 2 piece flow through racer head.
Jimmy Britt did this on a 312ci (6) oval track motor in the 70's here in southeast Michigan. Ran right up there with the SBC's. They only gave him a 100lb. weight break too. :?
Trick was that the head bolt pattern for the Ford V-8 and the inline 6 are identical per cylinder.
Developed by John Delorean's brother here in Detroit at Total Performance.
We (Mopars) do not have this shared bolt pattern AND cylinder spacing luxury. :(
Terry
Author:  75duster [ Sun May 14, 2006 10:07 pm ]
Post subject: 
theres a guy in california (i think) that takes 2 small block chevy heads and cuts one cylinder off f each one then welds them bace together for the chev 292 sixs

http://www.cdpautomachine.com/leo/cylinder_head.html
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