The 230 Headerfold project

[dave m]

Equal length header design

MM,

Just found this thread. I have a design for equal length headers for a long block 265" motor. This design is the classic 6 cylinder 6-2-1 split along 123/456 based on firing order. The promaries are 1.5" OD and have about a 40" primary length and equal length within about 3/8". All bends are standard mandrel bends. Here are some Visio drawings converted to *.gif.

//dave

[monkeymissile]

Dave,
this is fantastic info, I figured someone else had wandered down this road too. Have you made a pair yet?
Thanks very much for posting. Once I dig my truck out of the snow, I hope to get active on it again.

best,
Justin

[dave m]

Justin,

I have not built a set yet as I wanted to get some flowbench work completed... I was considering a reverse flow setup. Now I am 90% sure of not doing that.

If you are considering building a set send me a regular e-mail and I will get you all the dimensional details. some dimensions are visible on the drawing. Straight pipe has length while curves show radius and angle 3-90 is 90 degree bend on a 3" radius. I also have 2-3 sources of low cost mandrel bends and 3:1 collectors.

Do you by chance have a dimensioned drawing of the side of the 251 block? I saw one for a 230 on this site.

//dave

[monkeymissile]

Justin,

I have not built a set yet as I wanted to get some flowbench work completed... I was considering a reverse flow setup. Now I am 90% sure of not doing that.

If you are considering building a set send me a regular e-mail and I will get you all the dimensional details. some dimensions are visible on the drawing. Straight pipe has length while curves show radius and angle 3-90 is 90 degree bend on a 3" radius. I also have 2-3 sources of low cost mandrel bends and 3:1 collectors.

Do you by chance have a dimensioned drawing of the side of the 251 block? I saw one for a 230 on this site.

//dave

Dave,
I do plan to build a set, but not for a while yet. I'd be interested in the dimensions though so look for an email or PM from me. I did the dimensioned drawing for the 230 a while back, but I don't have one for a 251 because I don't own one! Sorry.

Justin

[pybyr]

split manifolds- another option

I've been following this "headerfold" thread on and off out of general curiousity-

for what it's worth, in Googling around for manifold options for my intake, which had some issues, I bumbled across this interesting site:

Kansas Kustoms now offers Split Manifolds (and he describes what's done and how)

http://www.inliners.org/Advertisers/kkk_ad1.html

and then also shows a Dodge 230 done up this way:
(scroll to bottom)
http://www.inliners.org/Advertisers/kkk_ad2.html

it's out of my budget given that I have an OK exhaust manifold and no need for a lot of HP or cost of two exhausts, but it's ingenious!

[monkeymissile]

split

Hi,
yeah, I'd seen these and there was discussion about the pros/cons of the design. What I concluded is that if I'm going to drop some cash into this project I might as well try to make it the best it can be. The main way to do that is to join pipes by their 180 degree firing order, 1+6, 2+5 and 3+4. A split manifold doesn't allow for this although it does allow for better exhaust evacuation and would therefore be better than stock.

[chriscase]

Making progress on my headerfold

It's coming right along.

Until just this minute, I was planning two headers, thinking that removing one at a time would facilitate valve adjusting. . But now I'm seeing that I have room to adjust the valves with the headers in place, so I may make them 6-2-1. Not a big difference from the two piecer, I would have made two sets of flanges, then wye-pipe, to a single 2 1/2" muffler. The 6-2-1 will make it easier to fabricate, only one set of flage/coupler needed. I built a jig, thinking you folks might become customers. A two piecer system would have a better chance of fitting other models.

You can see the mock-up of the intake. My plan there is to carve out an aluminum plenum, and press tubes into it. That way, I can drill for water heating, and make different plenums for different carb bases.

Nuther thought re: equal lengths systems. At 3,000 rpms, and 6 cylinders, each cylinder makes a pulse 25 times per second. At the speed of sound, the pulses are 533 inches apart. So a 3 into 1 system would have pulses 12 feet apart. So one pulse will be past the muffler before the next valve even opens. Not to mention the curves add resistance, so having one straight tube and one that has an extra 270 degrees of curves, means that they are not equal anyhow. So I don't think equal lengths would benefit us.

[chriscase]

6-2-1 Header pics

Here's the final. I went 6-2-1 for mine, it's easier to fab than two half-headers. And is still easy to get in and out. Plus, looks like more room to adjust valves than stock, though you'll still need asbestos gloves to do it hot.

Waiting for another 90 deg bend for the intake, I used up all the local guys had in stock. Meantime, I guess I can start milling the aluminum plenum-

Anybody got any input on plenum design? Should it have as big a cavern as possible? Small as possible? Or anydamthing?

[monkeymissile]

Chris,
bravo, nice work! I am very jealous. We just had our second child (a boy) and the weekend before I got my M43 running again with a used exhaust manifold. It looks like it will be a long time before I work on my own headerfold. Keep those pictures coming!

[MoparNorm]

Here's the final. I went 6-2-1 for mine, it's easier to fab than two half-headers. And is still easy to get in and out. Plus, looks like more room to adjust valves than stock, though you'll still need asbestos gloves to do it hot.

Waiting for another 90 deg bend for the intake, I used up all the local guys had in stock. Meantime, I guess I can start milling the aluminum plenum-

Anybody got any input on plenum design? Should it have as big a cavern as possible? Small as possible? Or anydamthing?

Nice job Chris! Looks like my Borla header on my Jeep 258....= )

[dave m]

Plenum size

Chris,

Concerning plenum volume, I have heard a rule of thumb as 75% of ine displacement. However Robby Gordons Hummer he ran in the Dakar 2007 rally had a 350" +/- motor with a plenum that was 100 to 110% motor displacement. Hope this gets you started.

Nice job on ther headers.

//dave

[MoparNorm]

Plenum/intake:
A large enough area to effectively allow the fuel and air to mix, such as the 75% ratio mentioned, more important is to emulate the Mopar Poly or Offy Dual Plane intake, which gives each cylinder an equal length runner, to provide uniform fuel/air mixture and velocity to each cylinder.

[maineSS]

Chris- Looks like another dyno run in your future. It would be interesting to compare the output of your header vs the cast iron freeflow manifolds offered by Stovebolt 6 and Pierce. Tom Langdon of Stovebolt 6 claims that a 10% gain is as much as you can hope for with the stock engine.
One problem with using tubing for your intake runners is the smooth interior surface- when fuel hits it, there's no chance of re-atomizing, and it will run into the cylinder as a liquid. If you can find a way to roughen it to at least an 80-grit finish, fuel droplets have a better chance of staying in suspension. Another thing to consider would be heat gain from the header into the manifold. Coating the header would help, as would elevating the manifold above the header tube plane.Do you happen to know what the cam specs are for the 230/251? If there's no overlap, (combined with the siamesed intake ports) then intake tuning is probably going to be a matter of restriction reduction and keeping airflow speed high.

[Jason Mills]

One problem with using tubing for your intake runners is the smooth interior surface- when fuel hits it, there's no chance of re-atomizing, and it will run into the cylinder as a liquid. If you can find a way to roughen it to at least an 80-grit finish, fuel droplets have a better chance of staying in suspension. .

I have been wondering just this same thing.. and if memory serves me, there is some kind of intake manifold gaskets... is it called "torque plus" manifold gaskets that have a very fine screen across the opening, that improves atomization of the fuel??? they are not supposed to be any good above 4000 RPM, but below it, they are said to improve power and fuel efficency..

[chriscase]

I'm working on the intake...

No big plenum, because I want to use the stock carb in the stock location.

I've hammered out a steel 'knuckle', four way tee, one for carb plus three intake runners. Now I'm waiting on some more, tight , u-bends- I'll make the center runner as long as the end ones. I'll probably polish off the welds and paint it- it will look 'organic', like it grew as a tree and roots. My design concept is "any****thingIdo will be better than the stock log".

I'm thinking that the steel tubes, in close proximity to the exhaust header, will stay warm enough to keep the fuel atomized. I've got a digital probe thermometer that might tell me some thing, I'll at least use it in the air filter to check intake temps, what with the radiator and headers. I haven't looked for a way to run a cool-air intake system, no obvious gap between the radiator and hood. Then maybe tape the temp probe to an intake runner?

Got lucky at the pull-your-part place the other day, bought a Flowmaster #50, with a 4' straight exhaust pipe, plus a tail pipe, all for $35. So I decided that 2 1/2" pipes and a Flowmaster #50 are puuurfect. The oval muffler will go in with the oval vertical, low inlet, and the outlet will just be under the frame. Muffler body just a scosh lower than the driveshaft, maybe a good thing that it is an all-welded 16 gauge can.

I'm having fun playing tinker toys with my spaghetti!

Back to the Dyno shop next week, hoping for 10%. But the cams on these flat heads have little overlap, probably even negative.

Ok, Here's some valve specs for Dodge car from Motors manual, 1935-'52, Intake opens at 0, pre '1940; 8-12 btdc, post war. Ex closes 6-9 atdc. So 1946-48 cam had 18 degrees overlap. No duration specs. Plymouth used that same high-overlap racing cam ;) , '46-52.