Are all Deuces Multifuel?

[jime]

Okay, it's another dumb newbe question, BUT I DID A SEARCH!

Many of the auctions and ads say 'multifuel', but some don't. I know that there was a gasoline engine variant, but aside from this, are the vast majority multifuel?

Jim

 

[grounded]

Yes there is some that were gassers. But 95% of the auction ones now adays are "multi". Best to tell is to look at a pic of the engine, or also look to see where the exhaust comes out. if it dont come out the fender but out by the duals its a gasser. (dont know if any came out the fender)

 

[DanMartin]

Yes, there was a gasoline engine...the REO/Continental OA331 inline 6-cylinder engine was originally in the first runs of those trucks. The Military swapped out many for the LD-427 Multifuel engine, and then again for the LD-465 and later LDT-465 engines.

There are not as many "gasser" M-35s available due to the military refitting many of them during rebuilds throughout their lifetime, but they are out there. Usually early trucks that went to auction, civillian trucks, or fire-engines will still have the older gasser engine in them. I hear if you can get them running well, they are nice and will run circles around a multifuel. However, you will take a 50% or so drop in mileage.

Note that most gassers do not have the overdrive transmission unless it has been swapped out. limiting top speed somewhat.

 

[datsunaholic]

No, there were gasoline Deuces (the original M35 was a gasser, as well as ones built earlier) and there were later Deuces that were pure diesel (the M35A3, which was a near-total rebuild of an A2, used a Caterpillar diesel).

However, the auction description isn't the place to check that. The lack of "multifuel" in the description isn't a telltale, as a M35A2 was a Multi-equipped truck. It just means that the site didn't put that info in the description. I don't believe there have been any Gassers left in inventory for decades, at least not in any quantity. Occasionally they crop up on the GSA site though.

 

[maybefixit]

Other little tidbits:
The 5 ton trucks are not multifuel, and there are multifuel trucks without turbos. Wreckers and tractor(-trailer) type rigs, as I understand it. The M35A2C is dropside multifuel and M35A3 is Caterpillar rebuild with automatic transmission.

 

[Rolling_Eudaimonia]

Actually the LDT-465-1 C or D engine can be either in multifuel configuration or reverted back to the natural diesel standard it was originally designed for. This depends on whether the Fuel Density Compensator has been by-passed or not. Just look on the tank, it says "Diesel Only" the engine will run better on Diesel only. Now you can run in a standard diesel engine other fuels but without the FDC working properly the engine tends to get less power poor fuel mileage. They did make straight gas only trucks the M35A and M35A1 series trucks. The M35A3 has a Cat 3116 engine in it and that well you could run stuff like fuel oils, kerosene , Jet-A and so on in it. Again you want a fuel that has a high percentage of Oil in the content which is what allows the fuel to actually properly burn under compression.

Even when you buy a truck today and it says Multifuel on the ad it is a good bet around 1990-1992 it had the fuel density compensator bypassed in an attempt to make the engine more fuel efficient when running on diesel and meet EPA standards.

 

[Recovry4x4]

2 clarifications. There are multifuel, 5 tonners. M54A2 etc etc. The 809 series are diesel only. As far as the function of a multifuel, this is not determined by the FDC, it's determined by the combustion cycle process. Having a bypassed FDC only means that the IP cannot change fuel rates based on the viscosity of the fuel. The FDC actually works against Biodiesel.

 

[Rolling_Eudaimonia]

2 clarifications. There are multifuel, 5 tonners. M54A2 etc etc. The 809 series are diesel only. As far as the function of a multifuel, this is not determined by the FDC, it's determined by the combustion cycle process. Having a bypassed FDC only means that the IP cannot change fuel rates based on the viscosity of the fuel. The FDC actually works against Biodiesel.

I hate to break it to you but the LDS is just a Diesel Engine, just like any other Diesel engine it can run a greater variety of fuels than a gasoline engine. The real heart of the system to maintain power is the FDC... That is what makes it run other fuels efficiently.

I know you people think there is something mystical to the engine in the internal structure but it just a diesel engine. The Cummins C-Series engine when used by the military will run on Jet-A, Kerosene, Fuel Oil as well as Diesel and there are no differences between Military ISC engine and the civilian one(even the Military DT-466 is rated to use other fuels no changes however, from the civilian DT-466). The only feature that makes the LDT-465 a true multi-fuel engine is the FDC which allows the engine to run on fuels with a lower oil content than a normal diesel engine would run on effectively.

Even the name LD means Liquid Cooled Diesel Engine. I mean everything about this engine is a diesel engine. The only key to running stuff like Gasoline or a mix of Diesel and Gas is the FDC... Bypass that and the engine will run, but it will produce less power, get poor fuel mileage, smoke more possible under loads.

 

[maybefixit]

I stand corrected, thank you for the clarifications! Glad to have learned more about the hobby, and shaken the trees a bit.

 

[Recovry4x4]

I hate to break it to you but the LDS is just a Diesel Engine, just like any other Diesel engine it can run a greater variety of fuels than a gasoline engine. The real heart of the system to maintain power is the FDC... That is what makes it run other fuels efficiently.

I know you people think there is something mystical to the engine in the internal structure but it just a diesel engine. The Cummins C-Series engine when used by the military will run on Jet-A, Kerosene, Fuel Oil as well as Diesel and there are no differences between Military ISC engine and the civilian one(even the Military DT-466 is rated to use other fuels no changes however, from the civilian DT-466). The only feature that makes the LDT-465 a true multi-fuel engine is the FDC which allows the engine to run on fuels with a lower oil content than a normal diesel engine would run on effectively.

Even the name LD means Liquid Cooled Diesel Engine. I mean everything about this engine is a diesel engine. The only key to running stuff like Gasoline or a mix of Diesel and Gas is the FDC... Bypass that and the engine will run, but it will produce less power, get poor fuel mileage, smoke more possible under loads.

Hate to break it to you but you are completely wrong! Attached is a piece written by David Doyle that kinda sums up the operation and design of the "Multifuel" engine. I would suggest you invest a little research on the subject before stating incorrect information. Us people seem to be a little more informed on this stuff that you think. If you think I'm wrong, bring any other diesel out to any of the events we host and run it on pure gasoline. Oh wait, iit won't run on gas! My Multi's will run on straight gas and yes, the LDS motors are mutis and have an FDC.

"There are a lot of myths floating around regarding the Multifuel engine. I
will try to help you.
In the late 1950's the decision was made to adapt the G742 series vehicles
(as well as many other tactical vehicles) to run on diesel or gasoline or
various other fuels. Fitting the Continental LDS-427 turbosupercharged,
multifuel engine did this. This engine built under license from M.A.N.
(Maschinenfabrik Augsburg-Nurnberg) uses the Hypercycle combustion process.
Into the top of the piston of this engine is machined a spherical combustion
chamber. During operation the injector sprays 95% of its charge onto the wall
of this chamber in the form of a thin film. The remaining 5% is atomized.
(A conventional diesel injector atomizes much more of the fuel.)
The compression stroke, which generates temperatures in the 900-1000 degree
range, ignites this atomized charge, and the main portion of the charge is
gradually vaporized by an air swirl created during the intake and compression
strokes. Since the air swirl removes only the top surface of the fuel
sprayed on the walls of this combustion chamber during the power stroke
combustion is even and there is no detonation knock. "

 

[OD_Coyote]

opcorn: and beer.

 

[Rolling_Eudaimonia]

The Hypercycle is a diesel cycle and the concept is similar to a pre-combustion chamber that is all-- Or simmering chamber. basically all it does is pre-detonate a small amount of fuel to act as a catalyst for a more complete combustion of the fuel. All modern direct injection diesel engines do something very similar. Other wise the engine will knock... This is a diesel engine. This doesn't make it a multi-fuel engine. The Compensator is the heart of the multi-fuel engine.

You can take any direct-injection diesel engine and run it any number of high-oil content fuels without problems. But if you want to run it one mixes of say diesel-gas, diesel-oil, gas-oil, and so on produce the same power and fuel consumption you better be running a compensator of some type.

That big cup in the piston doesn't capture the fuel, it forces the compression ratio to drop so you squeeze more air and fuel into the chamber and thus use the heat from the from initial detonation to pre-heat the chamber. If you don't meter the fuel properly you won't have right amount of fuel for the heat produced in the engine.

This what the engine is and why they call it a diesel engine. That's why it's LDS and LD, or LDT and not LMT , LMS or LM because the engine is a diesel engine.

 

[Chevytruck]

I dont think you need the FDC at all with a multi...

there are people who bypassed it and have had no problems

 

[jime]

Hey guys, thanks for all the info. I thought it was just another dumb newbe question, but I guess I struck a nerve. You all answered the basic question and then some! Great! Thanks!

 

[Recovry4x4]

Direct injection engines generally do not use a precup, indirect injection engines do! Precups are in the heads and not the pistons. It's hard to inject partially atomized fuel into a precup in the head. You can run any multifuel on gasoline without the FDC in place. You can't run the other diesels on gas. You can argue all you want, but you can't dispute the facts. You seem to forget that the engineers designed it this way regardless of how you want on interpret it. As the enigneers have pointed out, straight gas is an emergency fuel but it will run on it. Try that with a 6.2 or a DT or a B series, it's not going to run. As far as the D on the names, it is a diesel, just capable of use on multi fuels.

 

[grounded]

opcorn: i stand behind Kenny.

hell mine is bypassed and i run Everything and anything threw my engine and it doesnt even hiccup.

 

[FMJ]

OMFG here we go again.....is that OTHER thread dead yet?

opcorn:opcorn:opcorn:opcorn:opcorn:

 

[Flea]

One search on the FDC will show the firestorms of the past concerning the perceived "need" to use the FDC to run multiple fuels. Under some circumstances, the FDC is warranted, and will keep power output linear (with biodiesel as the exception, IIRC; as Bjorn is quick to point out, it's technically a fuel viscosity compensator). But the overall design of the engine is to provide near-absolute multifuel capability. The FDC simply meters the flow for varying fuel types.

 

[m16ty]

One search on the FDC will show the firestorms of the past concerning the perceived "need" to use the FDC to run multiple fuels. Under some circumstances, the FDC is warranted, and will keep power output linear (with biodiesel as the exception, IIRC; as Bjorn is quick to point out, it's technically a fuel viscosity compensator). But the overall design of the engine is to provide near-absolute multifuel capability. The FDC simply meters the flow for varying fuel types.

When you do a search it will bring up a thread by Rolling_Eudaimonia. In the thread you will find that his theory of the FDC was shot down there by the people in the know here at SS.

Here we go again.

Better keep the popcorn comming! opcorn:

 

[ida34]

Kenny is right. All diesels will not run on gasoline. All the other fuels such a kerosene, JP8 and such are close enough to diesel to run in a regular diesel but gasoline will not.