FreightTrain
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In don't know about you guys but at 50MPH I have doing RAHHHHHHHHH RPMs but at 40MPH I am doing ruhhhhhhhhhh.....sorry,dont' know teh exact numbers as I ain't installed my new tach cable yet.
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ENGINE INFORMATION PLEASE
- Thread starter ironhorsethegeneral
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ironhorsethegeneral
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The truck has over drive transmission. At 2900 rpm it is running 53. My other truck at 2400 rpm it runs about 54. I am sure the engine in my 67 is a 2 1/2 ton not a 5 ton. Otherwise my bottom end would be
great with neck snapping acceleration. The transmission would have to have a lower overdrive in order to accomodate this engine at the current speed it is doing now with 1100 tires. If I put transmission from another truck that runs at 2600 rpm I would have increased speeds. This engine here has probably got a different stroke in order to make this engine do what it is doing. But my main question is Is this engine rare or can it later be placed with the same engine or would it have to be overhauled when the time ever comes? It seems that there is hardly any of these engines around except in 5 tons. But I am sure this is not a 5 ton. But seems to be rare in a 2 1/2 ton. Thanks for everyones input.
great with neck snapping acceleration. The transmission would have to have a lower overdrive in order to accomodate this engine at the current speed it is doing now with 1100 tires. If I put transmission from another truck that runs at 2600 rpm I would have increased speeds. This engine here has probably got a different stroke in order to make this engine do what it is doing. But my main question is Is this engine rare or can it later be placed with the same engine or would it have to be overhauled when the time ever comes? It seems that there is hardly any of these engines around except in 5 tons. But I am sure this is not a 5 ton. But seems to be rare in a 2 1/2 ton. Thanks for everyones input.
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All the Multifuels have the same 4.87 inch stroke.
- 1,046
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Engine components are designed with extra strength, also known as a 'safety factor'. I don't know what the LD/LDT/LDS rods can 'take' but I'm sure it's more than 100rpm over the no-load governed speed. I'll bet it is more like 1000rpm over.
Below is some info on Pontiac rods. There is a formula for determining rpm limits but unfortunately the definitions for 'rod strength' and 'inertial loading' are not provided. Instead the formula's results for various engines and rods is given. The bottom 3 lines are the production engines, (326/350/389/400), (421/42
and the (455 -bottom). All Pontiac rods have similar dimensions so can be swapped. The table shows just how far past the standard 5000rpm redline you can go while maintain a safety factor of 2 (like often or all the time). All figures have the same safety factor of 2.Amazingly, the 69' 303 racing engine superduty rod is just as safe at 9624rpm as the is 69' 400 cast iron rod at 6116rpm, or a 400 with superduty rods at 8103rpm.
And that's not what it takes to break the rod. The text also gives a formula for that (or how to get down to a safety factor of 1 w/higher RPM). To reach that the cast iron rod 400 would need to turn 8649rpm. (6116/x = .7071 or ~ 8649.4rpm). That's like 3650 rpm past redline, with the weakest rod in a fairly long stroke motor.
The LD/LDT/LDS can 'take' more than 3000rpm. JimK
p.s.(I won't go there)
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Wrong equation for last part. Edited [above]. Was 2250rpm, correct figure is ~3650 past redline. Sorry. JimK
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'millenium reo' had a cat 3208 and a spicer cm6000 series trans with .66 od. i had been relying on memory, but looked up the formula for rpm/mph and 56 mph is 2497 with 9.00x20. as everyone can agree the dataplate for trans on dash says maximum speed 56 mph, and the -10 manual says "recommended rpm range for cruising operation 1400 - 2200 and highest rpm to operate when pulling a very heavy load and when going up a very steep hill 2600". now you almost have to read between the lines here, but it seems clear to me that it was not intended to be run at 2600 for more than short bursts when you need max power.
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So Tom, if you are correct, what would have to be improved for the engine to "take" 2,600 rpm indefinetly?
Thanks Jim, for posting the info, which must have required some research.
Thanks Jim, for posting the info, which must have required some research.
bottleworks
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I don't think I want to jump into this thread too much, but...cranetruck said:
My deuce is my daily driver (unless it's going to rain). It's @2500-2600 RPM - 55ish MPH for the bulk of the trip each way. It seems to be holding up fine. I never go past 2600 RPM. I will report back here if I have any failures relating to engine speed (knock on wood!).
FSBruva
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I thought the issue with overspeeding was the danger of floating a valve?
Matt
Matt
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The -10 manual (TM 9-2320-361-10)
Operating speed(engine rpm) 1500-2600 (page 1-18 )
Maximum speed (w/Maximum Payload and Towed Load) - 45MPH (page 1-17)
Maximum speed (w/Maximum Payload only) - 56MPH (page 1-17)
The reduced speed when fully loaded w/trailer may have more than one reason. While the authority/ designers may be trying to protect the engine they may also factor in that fact that a fully loaded combined vehicle is much more difficult to control.
I think TM's need to keep text brief so as not to 'overcomplicate' the issue. They prob. also are assuming a worst case situation. The may also figure the drivers may, more often than not, be young and inexperienced.
As for running at 2600rpm all day:
These were built for hauling loads, relatively short distances, perhaps in combat, more often than not on poor roads, if any. When the army needs to send stuff cross country they use the commercial freight system w/trucks better suited to the purpose.
As a group we all seem to have a different agenda. Some might be found taking lawn chairs and a cooler down 8 lane I-95, in 80+mph traffic, on the way to Aberdeen... Can the Ld/LDT/LDS take it? Sure. Will it cut it's lifespan? Sure. But many can afford this as it still may take 2 lifetimes to wear it out. Those here that run cross country may wear theirs out a bit sooner but that may be OK as there will be some great stories for the grandkids...
Here is the truck I drove today, a non-typical commercial tractor trailer. I say non- typical because this spend half the day as a city pedal truck and the other half as a road unit. It is a no frills, no sleeper, small engine, work truck. The engine is the modern version of the ubiquitous Mack 673. It is a 05' Mack Vision - engine EM7-317(?) - engine is 728ci, turbo , intercooler, 278,000miles (currently), will run to ~1million miles. ~9mpg(?)loaded or empty.
Redline (dash) - 2200rpm
Visor info - Operating range 1100-1800rpm, do not exceed 2100rpm
No-load governed speed -2100rpm
Max rpm in gear:
1st-4th - 2000rpm
5th - 1925rpm
6th - 1725rpm
7th - 1425rpm (64mph max)
Looking at these numbers you can see on the big roads the engine runs at very low speed. This maximizes both fuel economy and engine life. The engine is geared to run just past torque peak so any additional load(grades) will cause it fall towards peak torque.
This is why commercial truck engines are different, and why they last longer.
Those here running multi-fuel at 2600rpm (or above) are probably doing so because it's inconvenient and expensive to have a custom made low ratio high gear set made (is there one?). Then, the task of installing it. New gearing, or perhaps a different tranny, may be what is really needed. JimK
p.s. additions:
Torque rating of a similar EM7-250 (an 02'' was last one I checked ) was 1040lb*ft at 1200rpm (though all these seem to be turned down from there).
Mack called these 'High Torque Rise". Torque builds fast at 1000 and is mostly in by 1100. It does rises a tad more, ~1200 is the peak. Above that torque fades slowly as rpms rise.
corrections:Correct the current miles 278K (not 250K) and Manufacturer's stated (visor) operating range 1100rpm - 1800 (not 1000-1800). 7th 1425rpm (not 1475)
Operating speed(engine rpm) 1500-2600 (page 1-18 )
Maximum speed (w/Maximum Payload and Towed Load) - 45MPH (page 1-17)
Maximum speed (w/Maximum Payload only) - 56MPH (page 1-17)
The reduced speed when fully loaded w/trailer may have more than one reason. While the authority/ designers may be trying to protect the engine they may also factor in that fact that a fully loaded combined vehicle is much more difficult to control.
I think TM's need to keep text brief so as not to 'overcomplicate' the issue. They prob. also are assuming a worst case situation. The may also figure the drivers may, more often than not, be young and inexperienced.
As for running at 2600rpm all day:
These were built for hauling loads, relatively short distances, perhaps in combat, more often than not on poor roads, if any. When the army needs to send stuff cross country they use the commercial freight system w/trucks better suited to the purpose.
As a group we all seem to have a different agenda. Some might be found taking lawn chairs and a cooler down 8 lane I-95, in 80+mph traffic, on the way to Aberdeen... Can the Ld/LDT/LDS take it? Sure. Will it cut it's lifespan? Sure. But many can afford this as it still may take 2 lifetimes to wear it out. Those here that run cross country may wear theirs out a bit sooner but that may be OK as there will be some great stories for the grandkids...
Here is the truck I drove today, a non-typical commercial tractor trailer. I say non- typical because this spend half the day as a city pedal truck and the other half as a road unit. It is a no frills, no sleeper, small engine, work truck. The engine is the modern version of the ubiquitous Mack 673. It is a 05' Mack Vision - engine EM7-317(?) - engine is 728ci, turbo , intercooler, 278,000miles (currently), will run to ~1million miles. ~9mpg(?)loaded or empty.
Redline (dash) - 2200rpm
Visor info - Operating range 1100-1800rpm, do not exceed 2100rpm
No-load governed speed -2100rpm
Max rpm in gear:
1st-4th - 2000rpm
5th - 1925rpm
6th - 1725rpm
7th - 1425rpm (64mph max)
Looking at these numbers you can see on the big roads the engine runs at very low speed. This maximizes both fuel economy and engine life. The engine is geared to run just past torque peak so any additional load(grades) will cause it fall towards peak torque.
This is why commercial truck engines are different, and why they last longer.
Those here running multi-fuel at 2600rpm (or above) are probably doing so because it's inconvenient and expensive to have a custom made low ratio high gear set made (is there one?). Then, the task of installing it. New gearing, or perhaps a different tranny, may be what is really needed. JimK
p.s. additions:
Torque rating of a similar EM7-250 (an 02'' was last one I checked ) was 1040lb*ft at 1200rpm (though all these seem to be turned down from there).
Mack called these 'High Torque Rise". Torque builds fast at 1000 and is mostly in by 1100. It does rises a tad more, ~1200 is the peak. Above that torque fades slowly as rpms rise.
corrections:Correct the current miles 278K (not 250K) and Manufacturer's stated (visor) operating range 1100rpm - 1800 (not 1000-1800). 7th 1425rpm (not 1475)
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- Location
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I wanted to add to my con rod ramblin'.
At very high rpm's the rod big end can go 'out of round'. Just .001-.002" will turn the bearing into a wiper. Without oil friction can spin the bearing which cuts off lube causing a rod knock. A rod knock imposes shock loads which can break the rod at lower rpm. This may(?) be the real problem with overspeeding the LD/LDT/LDS.
I have read (hot rod stuff) that rod bolts are often the weak link. And poor bolt management (under/over tightening, non-square bolt pads...) are one of the main reasons for rod failure.
Pontiac superduty rods address all of these issues. The big end is massive. It is a forged alloy of SAE 8640, factory heat treated and shot peened. The bolts are 7/16" Boron steel (larger dia.) and not torqued but tightened to .006" stretch with a rod bolt micrometer.
For those w/3500rpm LDT's, there are companies like Crower and Carrillo that may make custom rods that will get U to 4. JimK
At very high rpm's the rod big end can go 'out of round'. Just .001-.002" will turn the bearing into a wiper. Without oil friction can spin the bearing which cuts off lube causing a rod knock. A rod knock imposes shock loads which can break the rod at lower rpm. This may(?) be the real problem with overspeeding the LD/LDT/LDS.
I have read (hot rod stuff) that rod bolts are often the weak link. And poor bolt management (under/over tightening, non-square bolt pads...) are one of the main reasons for rod failure.
Pontiac superduty rods address all of these issues. The big end is massive. It is a forged alloy of SAE 8640, factory heat treated and shot peened. The bolts are 7/16" Boron steel (larger dia.) and not torqued but tightened to .006" stretch with a rod bolt micrometer.
For those w/3500rpm LDT's, there are companies like Crower and Carrillo that may make custom rods that will get U to 4. JimK