Fuel Economy M35A2 vs M35A3

[JasonS]

The LD, LDT and LDS engines are very efficient. QUOTE]

I have my doubts about this. The LDS engine has a rather high BSFC of 0.4 lb/bhp-hr at it's best. The ~same engine in White/Oliver tractors is renowned as a fuel hog. Also note that that tractor series is reported to have cooling problems.

Copied from: http://www.steelsoldiers.com/fmtv/20442-brand-new-fmtv-spotted-5.html

The Hercules engine (multifuel) never had to pass emissions either. FMTV was the first program that Congress had mandated had to meet emmissions standards for the year it was produced. The Israelis had to use and ambient temp of 140F plus 115F increase across the engine for heat rejection- giving a total engine out temp of 255F maximum. When White attempted to modify the multifuel to meet emissions, the engine failed miserably. I know this is going to anger a lot of people, but the multifuel engines, since inception, was a cluster@#$%. It was a poorly designed engine that had a BSFC of about 0.4lb/hp/hr fuel consumption, where even the noisy DDC 2 strokes were below that. It is also why the Herc could not cool itself-the radiator was designed to cool a much larger engine, due to the engine heat rejection. This is not to say that the Herc runs hot-it means that the Herc cannot stabilize it's temp at full loading without the oversized cooling system. And even this was not enough in the MidEast to do the job for the Israelis. I can explain in greater detail, but be aware-cooling is a VERY involved subject.

 

[combat32]

Last year at my club's annual 100 mile convoy part of it was through the Boston mountains here in Arkansas.Guy in front of me had an A3 and I was eatin his lunch on every hill in my bone stock A2, I too only run at about 2500 rpms and have never turned the fuel up on mine, I average 10 to 12 mpg on the highway with full canvas, not sure what he was gettin.

We were both pullin M105a2's

 

[glcaines]

Too slow for around here, I'd do that if I could but VASP would write me for obstructing traffic.

I don't think they can legally charge you for obstructing traffic. I believe federal regulations mandates a minimum of 45 mph on all interstates and this is doable in a stock A3 without overspeeding the engine in most situations. I have never heard of a minimum speed on state highways, but I could be wrong.

 

[dittle]

When I did get my A2 out on the interstate I got between 10 - 12 constantly running 9.00 x 20 NDTs (depening on route due to hills) without my cargo cover on. Have not checked with the cover on but I have heard it makes less MPG....not confirmed however.

 

[shovelheadmike]

That's interesting, I've been keeping to the slower roads instead of the interstate assuming that driving at redline burned a lot more fuel. Maybe I'll do all interstate next week (gonna piss some people off but F'em I'm bigger) to see what it does.

Not to nitpick words, but when you said "pedal to the metal" did you really mean that? I'm afraid of going too far over the redline and I try not to go over 2800. If I floor it on the highway the tach will bottom out. I've only done that once. Is there a limiter or will the 3116 just rev till it comes apart?

With the acelerator flat on the floor, it is about 2600 rpm and 50 mph. Pull out the hand throttle, and it is 2800 rpm and 52 mph. Best mileage has been on the highway at 50 mph--just under 12 mpg. Cargo cover not installed. Uphill, downhill, always 50 mph. However, put a M105 behind it, and that is not true--40-45 mph is it.

 

[mktopside]

I don't think they can legally charge you for obstructing traffic. I believe federal regulations mandates a minimum of 45 mph on all interstates and this is doable in a stock A3 without overspeeding the engine in most situations. I have never heard of a minimum speed on state highways, but I could be wrong.

Well, maybe not a ticket, but a "are you ok son?" stop would be a certainty.

 

[dittle]

I have heard of people getting pulled over in a car for driving under the speed limit. This was in town with a PD known for ticket giving for the most minor offense. Think they were going to see if they had a drunk driving since they were going slower than posted. Was not me, was a high school friend that this happened to.

 

[mktopside]

With the acelerator flat on the floor, it is about 2600 rpm and 50 mph. Pull out the hand throttle, and it is 2800 rpm and 52 mph. Best mileage has been on the highway at 50 mph--just under 12 mpg. Cargo cover not installed. Uphill, downhill, always 50 mph. However, put a M105 behind it, and that is not true--40-45 mph is it.

WTF...... Then what is up with mine? When accelerating onto the interstate I normally floor it until I get to 2750, then have to lift up on the throttle to keep it at 2750. If I keep it floored, I can hear the boost increase and I'll spin past 3k. My speedo starts bouncing over 53 as well.

 

[beachbummer]

on this subject

On this subject has anyone worked to get better fuel mileage out of either truck? I wonder what mods could be don't to increase fuel mileage on either truck? It there ANY conceivable way to hit 20 mpg? Would that not be sweet? Does running a mixture of waste motor oil/ diesel fuel get better or worse mileage? If running straight diesel are you guys putting in a gallon of 2 cycle oil?

 

[shovelheadmike]

On this subject has anyone worked to get better fuel mileage out of either truck? I wonder what mods could be don't to increase fuel mileage on either truck? It there ANY conceivable way to hit 20 mpg? Would that not be sweet? Does running a mixture of waste motor oil/ diesel fuel get better or worse mileage? If running straight diesel are you guys putting in a gallon of 2 cycle oil?

With either truck, if you put Lockouts on the front, and remove the drive shaft between the rear axles is supposed to really help. This also helps around town manners.

Have heard conflicting reports about larger tires giving both better and worse mileage.

 

[shovelheadmike]

WTF...... Then what is up with mine? When accelerating onto the interstate I normally floor it until I get to 2750, then have to lift up on the throttle to keep it at 2750. If I keep it floored, I can hear the boost increase and I'll spin past 3k. My speedo starts bouncing over 53 as well.

Sounds like someone has been turning things under the hood... Military wants these things dummy proof. Well, that is not possible. How about resistant. Should not be able to mash.down the fun pedal enough to damage the engine.

 

[mktopside]

Sounds like someone has been turning things under the hood... Military wants these things dummy proof. Well, that is not possible. How about resistant. Should not be able to mash.down the fun pedal enough to damage the engine.

It wasn't me, and I doubt it was who I bought it from (decodeme2) as he has more trucks than most motorpools and probably sells as many a month. .... and a helicopter gunship lol

Well, anyone know where the governer is on this motor? All I can do is find it and check to see if it's set right. F*** I have a pyro gauge around here somewhere, I better get that thing on and see where I'm at.

 

[flyxpl]

I had no idea the A3's had a gov. My A3 will go right up to the 3000 rpm mark if you let it , pushing close to 60 mph . At 52 mph it reads in the 2700 rpm range .

 

[shovelheadmike]

Throttle stop.screw perhaps?

 

[Squirt-Truck]

What is the final OD on the transmission in the A3.

FWIW, trucks are generally rated in Ton-MPG.

 

[shovelheadmike]

What is the final OD on the transmission in the A3.

FWIW, trucks are generally rated in Ton-MPG.

1:1 Final drive ratio. No overdrive.

 

[Floridianson]

Maybe I wrong and have not drive mine or even looked at it in months but I thought it was governed at 2600. I do know mine don't go much over 55mph. So maybe I'm gettin 2750rpm?
Maybe I need to turn the little bugger up some right.

 

[mktopside]

I took mine out on the road this afternoon, and I think my tach might be off a bit. On perfectly flat surfaces (not counting over revving from driving down hill) it does appear to stop accelerating at approximately 2900 rpm.

Then, my buddy wanted to go off roading so we did.....100 ft down the trail hit what I thought was a small puddle, which really turned out to be an ice covered 4ft deep mud hole.....set the CTIS to mud/snow/sand.....put it in low gear.....and promptly popped the drivers front tire.... had to call my buddy with the peterbilt wrecker to come winch me out.....only to be wenched clear to the cops showing up because what used to be park land 5 years ago is now owned by the toll road authority; but nothing was posted. Lots of jail time and fines threatened.

All's well that ends well. Convinced the cops not to arrest us, got the tire changed, and got home. I don't want to look at this truck for a week..... It'll take me that long to was the mud off lol.


I just wanted to check the tach and make a run down a trail real quick. What a night.

 

[flyxpl]

If it freezes it may take you weeks to get the mud off .

 

[Pooch1128]

2600?!?!? Lolol well, either my tach and my speedo are way off or my truck don't have that. My RPM displayed on the tach makes sense when I look at my speed, so I doubt it's off.

So your telling me that you guys just drive around at full throttle all the time and don't worry about over revving?


On mine I switch to DexIII right off the bat to get the crap out of the trans.....shifts better.

Since we use our A3 in the fire service, we are constantly running it "pedal to the medal" on the way to fire. It pegs out at 54 mph and 2800 rpm.