It took the Canadian armed forces to get that bunk...

[Dirtymilkman]

People tend to forget, horsepower is bragging rights. It's torque that moves you. And on semi's you want that torque to start on the very low end of the RPM range. My 16 liter peaks at around 1100 rpm but it's a relatively flat torque curve. That's what a truck needs. 

[6368]

18 minutes ago, Dirtymilkman said:

People tend to forget, horsepower is bragging rights. It's torque that moves you. And on semi's you want that torque to start on the very low end of the RPM range. My 16 liter peaks at around 1100 rpm but it's a relatively flat torque curve. That's what a truck needs. 

I hear people often say this but it doesn't seem logical to me.  Torque is simply a measure of force.  i could generate 3000ftlbs by hanging a 300lb pound guy on the end of a ten foot pipe but i won't get that much work done.  Horsepower is a way to measure the ability to get work done.    

[Underdog]

Torque gets the load moving, horsepower maintains. 600 hp doesn't do anything to get you moving in direct drive. You need torque multiplying GEARING to get going. That's why your 180 hp B-75 has 20 forward gears. It's amazing the work that got done back in the day with less than 200 hp. And today's spoiled "drivers" won't even consider driving a truck with less than 500. Been there, done that, looking to simplify my life. Looking forward to getting my E6 350 on the road.

[Oso2]

4 hours ago, chu613 said:

We used to pull 63.5 tons with 12L 460hp Macks up here in Alberta. Right now I do the same thing with MP8.
From 63.5 to 75 tons you are looking at just over 10 tons difference. 600 hp isn't necessary let alone 700.
There's a difference between need and want
 

Well said. There are plenty of fuel trucks going up and down the road at 63 tons with their 13L Volvo, Mack and Paccar engines - those all top out at 500/1850.  A company that I know of had 450/1650 ISX's. It did the job - and the company probably saved $10 grand in extended warranty costs. I could see how you might want a 15L for 75 tons.

I wonder if a lot of this has to do with American truckers and their high speed limits of 75mph in places, vs. the slower Canadian limit of 65mph.  Many guys will slow down to 55 or 60 just to save fuel. And at 75 tons, I'd be more worried about stopping power.

 

 

[TS7]

You do not need 600 hp to pull a gravel train in Michigan. Waste of fuel.

[Dirtymilkman]

1 hour ago, 6368 said:

I hear people often say this but it doesn't seem logical to me.  Torque is simply a measure of force.  i could generate 3000ftlbs by hanging a 300lb pound guy on the end of a ten foot pipe but i won't get that much work done.  Horsepower is a way to measure the ability to get work done.    

Leverage is not torque. Torque is actual twist. Horsepower is a number made up by using torque in a calculation. A dyno will measure torque and using a calculation,m gives you a HP number. HP will not help you from a dead stop or pulling a long hill. 

[mrsmackpaul]

3 hours ago, Dirtymilkman said:

So my pickup with 420 HP and weighs 2.5 tons is overkill?  Haha

NO NO thats different that sounds like a whole heap of fun to me 

 

Paul

[6368]

I think i understand what you are saying. but torque has no time/ distance (rpm)  component  and that is why we need horsepower.  Yes, the dyno measures torque and rpm and computes horsepower from those two figures.  An engine making 2000ft/lb  at 500rpm  will still do less work  than another engine making 1000ft/lbs at 1500 rpm.   I know i'am not explaining myself well but i still believe it.

[mrsmackpaul]

Swishy described this torque HP issue once best it went something like this 

"HP is how fast and hard you hit the wall and torque is how far thru the wall you go" 

please forgive me Swish man if I have that all wrong 

 

 

Paul

[41180]

To me it's a matter of choice. If you want to haul big loads with a 300 go ahead if you a 450 go ahead if you want a 600 fine. Everyone gets work done their own way !! The trouble is mack is low on choices . 

[HeavyGunner]

17 hours ago, mrsmackpaul said:

 

But I do wonder in today's high HP world with M drive, are we breeding less competent drivers ???

Paul

Yes. They're putting autos so you can throw a newbie with little to no experience behind the wheel of a truck. I understand wholly all of you who learned how to drive and are now enjoying your autos in stop and go delivery and vocational work. But as far as I'm concerned you can have be auto I'll keep the stick, I'm far more comfortable with it. 

[Oso2]

29 minutes ago, logtruckman said:

To me it's a matter of choice. If you want to haul big loads with a 300 go ahead if you a 450 go ahead if you want a 600 fine. 

Choice? I think the word you're looking for is "affordability." We all want 700 ponies and an unlimited account at the Flying J.

[Timmyb]

You know what, in the world of increasing emissions controls I would think the opposite would be the norm. 

For example, in an egr engine, the egr valve is closed under full load. And an scr equipped vehicle uses less ad blue when it works. So the harder the engine is working the cleaner it is. 

And I believe 8hp/t is a bit rich. So to pull 100t you'd need 800hp? 

[kscarbel2]

Saying out loud what most of us know, a 1970's air-to-air 285 horsepower 300-Series Maxidyne, with the hood-located reverse air scoop, will walk away from today's alleged 400-425 horsepower tractors. It's massive "whistling" power is at your command.

[TeamsterGrrrl]

On the flatlands of the midwest the 285 and 300 Maxidynes would run with the Cummins and Cat 350s and even 400s at times. The secret... Mack quoted net power at the wheels, and the powerband was an incredible 1200 to 2100 RPM. While everybody else was shifting gears, you just kept your foot in it and went over the hill!

Back when I was tabulating the results of the Truck magazine road tests I noted one anomaly- Engines with broad powerbands like the Maxidyne did better than their HP ratings suggested, and engines with narrow powerbands like the Volvo F7's did worse than expected. And again, Mack's honest ratings helped too- For example, the last six cylinder Mack Maxidyne was rated for 370 HP, but that rating was at 2100 RPM governed speed, at peak power at around 1700 RPM it actually put out 405 HP. Volvo's replacement, the MP7, has a 405 HP rating, but actually puts out no more power than that 370 HP Mack engine it replaced. And while the highest Mack HP rating we saw in North America was only 500 HP from the E9 V-8, given Mack's more honest rating I suspect that engine would give Volvo's MP10 a run for it's money, and the higher HP E9s offered in Australia and in the Renault Premier would probably embarrass the 605 HP MP10. 

[41chevy]

4 hours ago, Timmyb said:

You know what, in the world of increasing emissions controls I would think the opposite would be the norm. 

For example, in an egr engine, the egr valve is closed under full load. And an scr equipped vehicle uses less ad blue when it works. So the harder the engine is working the cleaner it is. 

And I believe 8hp/t is a bit rich. So to pull 100t you'd need 800hp? 

How about 43 metric tons plus trailer with 70 h.p.? Pull any weight with gears.

Edited March 11, 2017 by 41chevy

[TeamsterGrrrl]

Yup, seen a 100+ ton loaded railcar moved with a 40 HP tractor...

[41180]

6 hours ago, TeamsterGrrrl said:

Yup, seen a 100+ ton loaded railcar moved with a 40 HP tractor...

So that 40 hp tractor could pull 50 ton  at highway speeds lol.. 

[dexter860]

Yeah , no doubt drivers aren't as competent, I'm only 34 but growing up around trucking with dad and the old trucks they used to drive compared to now, no AC, no power steering,  it's pretty disgusting when drivers aren't even expected to know how to shift gears anymore, but I guess that's the way it is , autonomous trucks are just over the horizon.

[41180]

I like to drive our old superliner with no a/c a crappie stereo a dynatsrd that barely works . Then I drive my Titan and enjoy the quiet cab,nice stereo, modern engine brake. I embrace the new stuff I'm noTV to proud to admit it.  

[BillyT]

In the late sixties, Overdrive did a road test out of the Allentown Pa Mack plant pitting a237 maxidyne equipped R model against a 250 Cummins equipped R model with a 10 speed RR!  Equal loads and trailers using two equally skilled Mack test drivers! They ran on the hills around Allentown and some fairly level sections of the Pennsylvania turnpike. The Maxidyne 5 speed outperformed the Cummins 10 speed on the hills and they were pretty close on the level! I believe Mack defined usable horsepower with the Maxidyne series of matched engines and transmissions! In the early years of the Maxidyne the old drivers berated those who drove the Macks as a bunch of rookies etc Lol I remember making a fool of myself the first time I drove a Maxidyne!, being used to shifting at 16 to 18 hundred rpm and the thing wouldn't go in! However like all equally spec'd trucks they don't all drive the same! I had a couple R and U models that would downshift smoothly at 1400 on a hard pull!

How long do the Canadian armed forces keep those tractors? I'm sure they're well maintained,a heavy hauler might do well to buy one or more when they auction them off! Eh?

[mrsmackpaul]

Some interesting thoughts there. I didn't mean to open a can of worms.

A thought that was put to me a while ago was they don't so much teach kids today to spell at school as much as we once did and they don't teach maths anymore to the same degree no more long division and things like that.

Anyway a friend who is a school teacher was at a wedding and a person at the table was getting all very opinionated about this and how the teachers should all be made to start teaching kids these things these day and if they don't they should all be sacked and on and on it went.

Anyway this school teacher friend of mine told this bloke she was a school teacher and while she under stood what he was saying a lot of schooling from 30 years ago isnt worth teaching as the relevance has left the world and spelling is fast becoming one of those things as has long division short hand driving a type writer  and the list goes on and on.

My point is maybe learning to shift gears is going to become a thing of the past and maybe thats not a bad thing either maybe learning to drive with out only 300 HP isn't a bad thing either I don't know though.

I do believe learning to operate anything were you can feel whats going on gives future operators a much better understanding of the limitations surrounding what they are trying to do and in return make them a much more efficient operator. 

I also noticed a film clip the other day that Macks biggest selling transmission is the M drive today so that has got to say something on its own.

Paul

[HeavyGunner]

21 hours ago, TeamsterGrrrl said:

On the flatlands of the midwest the 285 and 300 Maxidynes would run with the Cummins and Cat 350s and even 400s at times. The secret... Mack quoted net power at the wheels, and the powerband was an incredible 1200 to 2100 RPM. While everybody else was shifting gears, you just kept your foot in it and went over the hill!

Back when I was tabulating the results of the Truck magazine road tests I noted one anomaly- Engines with broad powerbands like the Maxidyne did better than their HP ratings suggested, and engines with narrow powerbands like the Volvo F7's did worse than expected. And again, Mack's honest ratings helped too- For example, the last six cylinder Mack Maxidyne was rated for 370 HP, but that rating was at 2100 RPM governed speed, at peak power at around 1700 RPM it actually put out 405 HP. Volvo's replacement, the MP7, has a 405 HP rating, but actually puts out no more power than that 370 HP Mack engine it replaced. And while the highest Mack HP rating we saw in North America was only 500 HP from the E9 V-8, given Mack's more honest rating I suspect that engine would give Volvo's MP10 a run for it's money, and the higher HP E9s offered in Australia and in the Renault Premier would probably embarrass the 605 HP MP10. 

So why would mack not capitalize on an engine that makes more horsepower then claim less? Doesn't make sense to me. Where do you come up with idea that Mack has always sand bagged its hp ratings? Is it based in actual fact or just "it feels like it pulled better"?

[TeamsterGrrrl]

Because Mack used to be a pretty honest company.

[theakerstwo]

Back when the NH335 was running in many trucks, I know of 237 engines that would leave here with the Cummins and be on location next day same time. From the amount of trucking I have done, I found that in a six hour run, 50 more HP doesn't get you there any sooner if you're running the speed limit. Many guys that try to run a Maxidyne think they have to shift at 1700 when not knowing that is were the Maxidyne is pulling good.