LMTV or?...

[justin22885]

So then why does the M35A3 with a 3116 get double the fuel economy of an LMTV with the same engine? Is the deuce geared differently? Is it the transmission? Wind resistance sucks for both of them.

 

[Awesomeness]

So then why does the M35A3 with a 3116 get double the fuel economy of an LMTV with the same engine? Is the deuce geared differently? Is it the transmission? Wind resistance sucks for both of them.

I edited my previous post before you replied, but my guess is that it doesn't. Those people are mistaken / unrealistic. Physics just doesn't support that big a difference.

 

[aleigh]

I have a 3116 in my M1078 and if the engine fairy came along one night and swapped it out for a C7, adding the ECU and all, I wouldn't shed a single tear. I don't understand how in 2017 we can still be having the reliability debate about ECU, electronics, and engine advancements in general. Automatic trans ECU oh no... Like nobody has problems with manuals. I've been stranded due to a blown slave and unrelated my transmission in my JK needed rebuilding at 35k miles due to the famous manufacturing problem.

Remember when people thought ABS was going to be terrible? The brake fairy can come put ABS in my LMTV any time she wants.

 

[justin22885]

I have a 3116 in my M1078 and if the engine fairy came along one night and swapped it out for a C7, adding the ECU and all, I wouldn't shed a single tear. I don't understand how in 2017 we can still be having the reliability debate about ECU, electronics, and engine advancements in general. Automatic trans ECU oh no... Like nobody has problems with manuals. I've been stranded due to a blown slave and unrelated my transmission in my JK needed rebuilding at 35k miles due to the famous manufacturing problem.

Remember when people thought ABS was going to be terrible? The brake fairy can come put ABS in my LMTV any time she wants.

What do you really gain from all of that if not efficiency? Maintenance doesn't seem to be improved if not decreased because you are adding more components to the system. So what do you gain from the electronics assuming both engines in 100% working order?

 

[aleigh]

That's a great question. In the case of the transmission, IMO it makes the truck easier to drive which means I am more confident when I want some friend to pull a shift in the truck. And I prefer it a lot. I spent enough time driving Unimogs through I-90 memorial day traffic in Washington and up and down passes to know that shifting is frankly a pain in the ass. I am sure many will comment that it's no big deal but that's great, sure. I take long trips (10k a year so far in my LMTV). I've driven manual cars for years. My jeep is manual. But for something big and heavy the auto is the way to go.

In the case of the engine, setting aside fuel efficiency, easier cold starting, better power under high-altitude situations (pulling passes). I would disagree on the maintenance - I find it a lot easier to work on fuel injected computerized vehicles because the ECU is right there monitoring the engine all the time. While I am not trying to say it is some oracle of wisdom or whatever, it is pretty easy to hook up the diagnostics to it, watch all the engine parameters, and tune it. The same goes for the transmissions... You want to change shift points? Operating parameters? Can be done just in software.

 

[justin22885]

but then you have to rely on that software, and software glitches, wires go bad, and electronics fail more so than mechanical. I am not sure if it is different with diesels as i haven't done much work with them but my entry into mechanics began when EFI and electronic engine controls were the norm. I know more about electronically controlled engines and maintaining them (for gasoline engines at least). But then I see these older diesels like a Detroit 671 for example that have so little to them in order for them to function. They just work, no ignition system at all (but that's any diesel). But it was interesting to see an engine with no wires, no cables, bare minimum hoses and pipes just simply work.

 

[aleigh]

You could walk, you know. It's far more fuel efficient, you will get where you are going eventually, and you don't have to worry over the failure of anything electronic OR mechanical. Just heart disease and cancer.

"they just work" right until they don't. You've taken apart carbs right? Wait until you see the witchcraft that goes into mechanical rack injection on diesels if you have not already.

And you have to define unreliable. Does unreliable mean total maintenance cost (everything has a service life including electronic fuel injection components, like CPS sensors) or does unreliable mean surprising and mission-ending failures? Also when you replace 1 thing that was very unreliable (carbs) with 6 things that are orders of magnitude more reliable, your net reliability has actually improved even though you have "more things". "rely on software" when did yourself, someone you know, someone they know, or really anyone, experience a software fault in an ECU that left them with an inoperable engine? I am sure it happened somewhere sometime in some incredibly limited fashion, and if someone chimes in with that story, I feel like we've just found the exception that proves the rule.

And efficiency, which you are hand-waving away, is an excellent reason.

There are billions (millions?) of electronically managed engines in the world and billions (millions?) of automatic transmissions.

 

[simp5782]

I think someone is just looking to nit pick on something they know nothing about obviously.

I guess that 1 to 2 gallons you are going to burn on start up and shut down is really going to break the piggy bank.

Guess my 923A1 going 1500mi on 120 gal at 26,000lbs is gonna make you real sad and puzzle you.
Sent from my SM-G935P using Tapatalk

 

[Awesomeness]

What do you really gain from all of that if not efficiency? Maintenance doesn't seem to be improved if not decreased because you are adding more components to the system. So what do you gain from the electronics assuming both engines in 100% working order?

You gain ABS brakes (on A1 and up models). I don't really care about the electronic engine, it has pro's and con's (I'm not really worried about reliability but it is designed to be serviced with the diagnostic computer tools, so I would want to get those). But I would very much prefer to have ABS brakes!

 

[Awesomeness]

electronics fail more so than mechanical

This is the mistake in understanding. The electronics are significantly more reliable, however, they introduce more deadlining points of failure. So you can have a sensor/wire/computer go bad, and absolutely nothing works. In contrast, with a mechanical engine you will have more failures, but they will often fail more gracefully (e.g. you'll notice it getting worse and can still drive, or you can apply a physical remedy to limp home). This is why you get all the stories about "I had this sensor/wire/computer that broke and it left me totally stranded", probably also combined with the psychology that things you can't see or understand are mysterious and frustrating (rarely can you check an ECU and physically see that it's bad - if you don't have the right computer diagnostic tools you merely replace it and then poof, the engine works again!).

 

[NormB]

The lmtv Has an either injection system, I have yet to have to plug mine in to start it, at a buck a kwh I don't plug in unless I have to.

SERIOUSLY?

$1/kwh?

I'm paying 8.2 cents/kwh here in MD with BGE (yeah, I could change, but with bills under $200/month, not a lot of incentive to change for a couple bucks a month plus I get kickbacks for water heater and AC unit shutdown/control in peak hours).

I thought Alaska had endless oil? Or does that all go to balance of trade to China and elsewhere?

Man!

 

[big block 88]

Yes, this is the heart of the ridiculousness of the argument every time it comes up. Essentially yes, newer is better. Those opposed to change always point out some edge case where it isn't. I'm also a mechanical engineer, so I know better than anyone that not every new idea works out great the first time. But as I said, these trucks are decades old now, so we're beyond the growing pains.

I get it, you don't like them and had a bad experience. So I think to myself, "Do I trust this one anecdotal story (or even a hundred of them), or numbers like the 100,000 FMTVs the military owns, their reliability studies that show them to be the most reliable truck they've ever had, etc.?" There's really no comparison, and it just tells me you aren't interested in actually understanding. I have nothing against the old trucks. You're going to spend similar amounts of time/money/resources on old or new, so why not have the new?

If you wanted to make an actual logic-based argument why the newer trucks are worse, I think it would go something like this... The older trucks are being retired because they have been replaced, but are otherwise in well-kept condition. The newer trucks are largely getting auctioned because they are broken, or else they would keep them around longer. Both trucks are going to succumb to the age of rubber seals/o-rings/gaskets/etc. before they realistically reach the mechanical life of almost anything involved (e.g. transmission, engine, axles, etc.), and the older trucks have probably passed that life and had most everything replaced already, while the newer trucks are being got rid of exactly because those things are starting to fail (so they are going to need to be serviced by the new owner in the near future).

Spoken like a true engineer... (boy i sure hope you can list your credentials/degrees for me to drool over) my logic is these trucks couldnt be trusted to even leave base in a war zone.... reliability studies look great when all the trucks are sitting in motor pool and not being used or are just idled around base to be diagnosed.

i am biased to S&S building pure garbage and its no wonder the contract was redone to allow Oshkosh to step in and fix the pos'. But im not alone i have 3 associates that were state side and dealt with the trucks issues here stateside in just trying to get them shipped.

The technology is sound. The engine the trans are proven in other applications and even the trucks are proven in styer form. Its the workmanship and quality of s&s that i see as the blame.

But hey im no engineer.... just a guy that needed to depend on trucks to stay alive...

carry on im done. Best of luck to OP

 

[scottmandu]

So then why does the M35A3 with a 3116 get double the fuel economy of an LMTV with the same engine? Is the deuce geared differently? Is it the transmission? Wind resistance sucks for both of them.

The LMTV weighs almost 5000lbs more than the M35A3, and has a much larger frontal area (meaning more wind resistance).

HP on the M35A3 is 170, The LMTV is 50 hp more.

 

[scottmandu]

What do you really gain from all of that if not efficiency? Maintenance doesn't seem to be improved if not decreased because you are adding more components to the system. So what do you gain from the electronics assuming both engines in 100% working order?

More power, less noise, less vibration (which is why the cab airlift system was omitted for the C7 trucks) cleaner emissions, more torque. Diagnostics on an electronic truck is far faster, No injector rack to adjust controls are easier, plus there is a plethora of data stored in the ECM of a C7 or 3126 (time/mileage etc).

 

[justin22885]

I see the M1078s for $3-$5k but I have not seen the A1s anywhere. I am not opposed to an A1 with a different engine, ABS, and other features if I could find one.

What are the A1s going for? Another question is can either engine run on WVO, WMO, WATF, etc? I know most diesels can with some upgrades (like pre-heating the fuel). If so, I would in all likeliness put together something for properly filtering and cleaning that stuff and use it as a low cost fuel.

 

[scottmandu]

I see the M1078s for $3-$5k but I have not seen the A1s anywhere. I am not opposed to an A1 with a different engine, ABS, and other features if I could find one. How much are these generally costing now when they are available?

Over the past year running A1's have sold for $13k-$30K anything less than 10K is a gamble.

 

[justin22885]

Over the past year running A1's have sold for $13k-$30K anything less than 10K is a gamble.

Yeah, I was looking at something else. I am finding late 90s models for $15k which isn't bad either. But if an A1 is much more than that then I am not sure the upgrades it has are worth the initial costs and are probably upgrades I can add later.

Hmm, let me ask a different sort of question. Which vehicle is easier to work on between LMTVs and the 2.5 and 5 ton trucks? Which one is easier to get to the engine for tweaks or repairs?

 

[Coffey1]

Lmtv MTV once cab is lifted everything is right there.

 

[justin22885]

Yeah, that is what I was thinking as well. I am still considering the deuce and the 5 ton trucks as well though. If the 5-ton costs the same, gets the same fuel economy, has better brakes, better cab, and still gets the same fuel economy as the LMTV then it would probably be the better choice IF it could handle itself as well offroad. Alternatively the deuce might be more than enough for my needs. It is smaller and lighter than the other options, and has the most aftermarket and modifications and upgrades available to it. A bobbed deuce might be more than enough carry capacity for something that can still be driven and parked in town and in any parking lot.

 

[aleigh]

Reliable. Efficient. Cheap.

Pick 2.