Dual Exhaust on M

linemanfarmer · Oct 9, 2009

I am wanting to take my Pulling M, and make it a little more showy, sound different, fullfill my personality of hotrods and, just see if it can be done. I am wanting to put dual exhaust on it. My true dream of this, is to have it true duals. In other words, leaveing cylinders #2 and 3 where they are and somehow getting 1 and 4 together, and go over the top of the valve cover to the other side, so that the stacks are across from eachother. I thought of cutting the manifold at #1 and 4, welding those shut and makeing a set of headers to do that. Also thought about cutting a hole in each of those outside manifold and doing nearly the same. Or last, not wana do it much (because I think the exsisting stack will see more flow) is to T into the exhaust pipe and go straight across. I just am wanting to see it when idleing, each exhaust pipe is getting everyother fire! I don't know if this will ever work. but let me know what ya'll think.

Thanks, Derek

Redwolf · Oct 9, 2009

Yes, it could be done. Problem you must overcome is keepeing enough backpressure in each exhaust tube and keeping tube equal length. the equal pressure and lenght will allow the engine to run the most effiencient. A extreme difference in backpressure will cause the motor to run lean in one cylinder and not another. This would be a tuning nightmare as you would have a tough time controlling the fuel mixture.
So in short, neat in theory, almost impossible in reality.
Good luck!

rustyfarmall · Oct 9, 2009

I've kind of been dreaming similar dreams myself, only I've been thinking more along the lines of 4 pipes coming up through the hood, all in a row. I don't know if such a thing will ever happen, but it is an interesting dream. I think the only way it can be accomplished is to discard the cast iron manifold and start from scratch with some tubing.

For what it's worth, I do not expect a modification of that nature would improve the performance or power one little bit. A heavily modified engine turning ridiculous RPMs MIGHT benefit.

ryanwheelock · Oct 9, 2009

I own an exhaust shop and have done lots of custom bending with my pipe bender. What you want can be done, running the # 2 and 3 together and then 1 and 4. I would do it for you but live in northern michigan. Try to find a good exhaust shop that does custom pipe bending in your area.
Ryan

JMOR · Oct 9, 2009

(quoted from post at 08:24:25 10/09/09) Yes, it could be done. Problem you must overcome is keepeing enough backpressure in each exhaust tube and keeping tube equal length. the equal pressure and lenght will allow the engine to run the most effiencient. A extreme difference in backpressure will cause the motor to run lean in one cylinder and not another. This would be a tuning nightmare as you would have a tough time controlling the fuel mixture.
So in short, neat in theory, almost impossible in reality.
Good luck!

Ideals.! However, all cylinders are not equal length now, as from factory. Clearly the two center cylinders are closer to the end of exhaust pipe than the two outer cylinders by roughly half the manifold length. Furthermore, any single exhaust "V" engine (V6, V8, etc.) has 2 or 3 feet of cross-over from one bank to the other, with the exhaust pipe exiting to muffler from only one bank. A 2 or 3 foot difference & they have been running like that successfully since 1932 on Fords and even longer in a few others.

scot in pa · Oct 9, 2009

Actually, if a set of headers and an exhaust is built right, the outgoing gasses will start to draw the intake charge into the cylinder before the exhaust valve even closes. Back pressure is a bad thing, and can burn valves.

S.Crum · Oct 9, 2009

I've done many builds similar to this in my shop. I've utilized various sizes of tube in the same header to even out the flows and combined tubes in line with the firing orders to maximize the scavenge effect in the exhaust. This maximizes the volumetric efficency of the engine.
The big thing in doing things like this is how pressure resistant is your checkbook?
Money is never an object until the payment is due.

Theman · Oct 9, 2009

Derek,
If you decide on putting 1&4 across from 2&3 (cool thought), I suggest you run 2&3 over the valve cover and exit the hood on the right side. Then join 1&4 over the centerline of the manifold and exit the hood in the original hole. This will make your tube lengths nearly identical. The trick may be threading the piping around the steering shaft and radiator brace.

NDS · Oct 9, 2009

A good starting point would be a LP manifold. The intake on the LPs is a seperate casting and has no connection to exhaust manifold and is said by some to give a little more power.

Janicholson · Oct 9, 2009

I agree there are no advantages to back pressure. A 2 stroke on an expansion chamber at the right RPM is a tuned system to do just that. It is more like a pipe organ than a pipe. But realistically on a Farmall engine that is near stock it is just cosmetic. I like the idea though. I have CNC machined a 1/2" plate to match a gasket (Toyota 3TC)then used that as a start for the header. JimN

linemanfarmer · Oct 9, 2009

Guys, thank you much for replys. I have been pondering on it all day on how i'd go about it. Since its gonna be crappy weather all weekend...im gonna try and get a start on it. It may not look the best. I am worried about welding on the old castiron. I've got nickel rod, but not sure yet. Also to make to pretty sharp 180 degree bends from the exhaust port going back over the top of the valve cover is gonna be tough. I've some elbows and old headers to try to use. I'll keep ya'll posted!!

Thanks, Derek

scot in pa · Oct 10, 2009

One of the MOPAR mags did an article on headers and exhaust a few years back. They somehow measured the gas flow through the cylinder once they got headers and and X pipe in the exhaust, and the intake was moving into the cylinder at something like 55 MPH before the piston even reached TDC. But that was probably turning 4 or 5000 RPM. I don't know if an old 4 cyl IH would survive a jaunt into that RPM range, let alone sustaining it.

Dual Exhaust on M

linemanfarmer

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Redwolf

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rustyfarmall

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ryanwheelock

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JMOR

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scot in pa

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S.Crum

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Theman

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NDS

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Janicholson

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