Stock M35A2 being run on the chassis dyno at SECO

[AMGeneral]

I found this video while surfing on Youtube, stock M35A2 being run on a chassis dyno at SECO in GA. It doesn't give any hp or tq numbers unfortunately.

http://www.youtube.com/watch?v=_37MhtDQL-w

 

[91W350]

Not the most exciting run to watch! I was surprised how much the rear axles and truck hopped around.

 

[jrobinson5093]

i would like to know the numbers

 

[mlap1088]

so how bout them numbers?

 

[Jake0147]

Since it's a stock truck at a stock truck repair/refurbish center, I'm guessing the numbers you want to see are in the TMs, and the dyno is to verify repairs and/or run in new parts in the prescribed manner without having to foot a full registration for test drive purposes.

 

[WillWagner]

Most likely 75 to 80% of flywheel rated HP. So if the engine is rated at 139 HP, you will see around 104 to 111 or so to the ground. Maybe a but less since it is also going through a transfer case as well as a transmission.

 

[bearboley]

Would that be the wrong time to flip the front axle engagement?

 

[Dirtygrunt]

that looks faster then 55!!!!

 

[militarysteel]

i'd like to see how much you get from disconnecting the rear axle,

 

[patracy]

Most likely 75 to 80% of flywheel rated HP. So if the engine is rated at 139 HP, you will see around 104 to 111 or so to the ground. Maybe a but less since it is also going through a transfer case as well as a transmission.

Better lower that percentage even more. That's for a common rear wheel drive vehicle. In addition to the RWD setup, you've got two extra driveshafts spinning. (Intermediate and jack shaft) The t-case is going to slosh around oil and probably pull down 2-5% there as well. But then there's the extra ring and pinion. Plus the two bull and spur gears found in the axles. Also there's the tremendous rotating mass our trucks have as well that they have to speed up. There's simply no way a 139 crank HP would ever measure out to anything above 100whp.

 

[brianp454]

Exactly correct! I saw this on YouTube long ago and asked if they would post the info, but no response. Too bad... Would have been a nice thing to share.

Better lower that percentage even more. That's for a common rear wheel drive vehicle. In addition to the RWD setup, you've got two extra driveshafts spinning. (Intermediate and jack shaft) The t-case is going to slosh around oil and probably pull down 2-5% there as well. But then there's the extra ring and pinion. Plus the two bull and spur gears found in the axles. Also there's the tremendous rotating mass our trucks have as well that they have to speed up. There's simply no way a 139 crank HP would ever measure out to anything above 100whp.

 

[ATPTac]

The poster of the video put this comment up further down:

the Stock Multifuel engine was rated at 140 hp, what we got was about 90 to 100 hp at the rear wheels, the M800 series with the 855 was about 250 hp, we tested those and the m939 which was an 855 cummins, we got about 210 to 220 hp at the rear wheels

 

[patracy]

That's a very very generous dyno. I'd question their calibration of it. Those numbers (even though their vague) are still very high.

 

[brianp454]

Thanks for the info! I recall looking into this, er, maybe four years ago and don't recall ever seeing that. These numbers suggest the stock LDT-465 in the truck is getting about 68% of the power to the wheels while loosing about 32% to parasitic losses. That's inline with what I would expect. For the 800 and 900 series trucks with the NHC-250 they are getting 88% to the wheels while suffering 12% in losses. These losses are less than I would expect as I would expect them to be similar to both trucks due to similar apparatus in the drivelines. Maybe someone can speak to the diferences in detail that might affect losses? This leads me to think the NHC-250 is actually more powerfuel than rated and the multifuel is perhaps a bit less powerful then rated. I know that my M35A2C when completely stock often struggled to get up to speed when in 4H or 5H, even on flat ground. It got much better after bypassing the FDC without any tweaks to the IP. I've observed that the truck barely maintains speed when taking the it out of gear on a downgrade, suggesting the losses in turning the runnign gear are significant. My car or light truck will gain speed under the same circumstances (same downgrade). I've also noticed that the LDT-465 often runs best when it's been ran earlier in the day or just after taking on fuel. I've speculated that this is due to warming things up, but it may just be an anecdote.

The poster of the video put this comment up further down:

 

[3dAngus]

All my deuces have required about ten miles driving time on them to optimize performance on the road.

None of them have been really good about starting, warming and then driving where optimum performance was achieved. It helps to warm up the differentials and tranny to get full performance, and the only way to do that, that I know of, is to get it running.

He did go through several runs, so no telling where the numbers come from, but you would normally think the last run would produce any published numbers.

Chaining the rear end to the building upright like that sure is interesting.

 

[EMD567]

I think they were doing a speed test. The rear set of axles look like they have 1100's on the ground. Fronts are 1100's also.

 

[ATPTac]

I agree Patracy, I would have preferred to see an actual dyno chart and not "90-100hp". And my Deuce also really seems to open up, for lack of better terms, after driving for a while and getting everything nice and warmed up.

 

[aheilmann68]

Also something to consider is how the injection pump was set up. My M925a1 had no power on a hill. I ordered a fuel button figuring it was 27 and drop 5 safely to a 22 and to my surprise I had a 32 in the IP. I am interested at how the 800 series and the 900 series had a difference for the same setup unless the automatic transmission is that much of a loss.

 

[Merc1973]

As posted in the comments by the Uploader:

MrNeibarger

1 year agoin reply to kblackav8or

the Stock Multifuel engine was rated at 140 hp, what we got was about 90 to 100 hp at the rear wheels, the M800 series with the 855 was about 250 hp, we tested those and the m939 which was an 855 cummins, we got about 210 to 220 hp at the rear wheels

Edit: ATPTac beat me to it...