Electric Chicken
Well-Known Member
Mine is geared so tall and for whatever reason; I'm assuming programming, it sucks on hills.
The Madness Is Finally Being Stopped
- Thread starter freedhardwoods
- Start date
Great advice back in the day. Now you just let the truck do it's thing. If things begin to heat up, the ECM will make adjustments. If your maintenance is current, there will be no failures such as blown coolant hoses and you will make it to the top just fine, and efficiently as possible.
It will even shift the gears for you so you Instagram scrolling isn't interrupted!
Electric Chicken
Well-Known Member
Yeah I called the dealer about something. I think I thought I had a bad head gasket or something and they said these trucks are designed not to let you hurt them. And they've never had to do a head gasket job on this model.
So basically you can't kill it even if you try. Unless you literally neglect the maintenance.
They also recommended running the piss out of it every so often. Their words.
Electric Chicken
Well-Known Member
Is the pyrometer the exhaust temperature gauge? I do have one of those. If not, I'm clueless.
I think my torque flatlines somewhere around 1700 RPM but haven't found a chart saying so. Definitely feels like it though.
Redline is about 2200RPM, which is kind of crazy when the LTL with a big cam Cummins turns 2100 @ 65mph.
freedhardwoods
freedhardwoods
If everyone would drive the truck I started in, they would really be glad to get back in whatever they are driving now.
1966 cabover IH with a 238 Detroit. 4" of solid rubber between the frame and walking beam was the suspension.
About 10 years ago I was on I-70w coming out of Baltimore grossing 75,000 with a 500 series 60 and passed a truck with a 238 and an empty flatbed going uphill.
1966 cabover IH with a 238 Detroit. 4" of solid rubber between the frame and walking beam was the suspension.
About 10 years ago I was on I-70w coming out of Baltimore grossing 75,000 with a 500 series 60 and passed a truck with a 238 and an empty flatbed going uphill.
389 Hood
Well-Known Member
Yes, pyrometer is exhaust temperature gauge. Manifold pressure starts to drop when torque rise is reached, meaning the engine has reached it's rated power. After that, you're just burning fuel.
Torque rise usually peaks at about 1100-1300 RPM, depending on the engine and transmission.
Two totally different engines and geared totally different. Your Mack shouldn't exceed 1900. If it does, the shift points may have been adjusted. But if you just put your foot to the floor, 1900 should be about the max it will turn.
389 Hood
Well-Known Member
Very first truck was a B model Mack with a 220 and a 5X4 twin stick. Then I graduated to 1962 GMC 9500 with a 238 and 5 speed with 2 speed rear. Then I bought my first truck in 1978. A 1970 COE KW 125, with a 318 and a 13 speed RoadRanger. I thought I was king of the hill. I had a truck that went over 55 mph, used a gallon of oil a day and got about 5 mpg. It had 6" straight pipes coming off the manifolds and up the back of the cab. I'm to this day, deaf from that truck.
Duck
Sarcastic remark goes here
I was talking about fleets turning down the HP/torque too. That's what I meant by they're designed to be flat-footed.
If you're focusing on fuel economy on rolling hills, you'd actually step on it (not all the way) on the downhill and let gravity help you build up momentum that will help you up the next hill so you don't have to use as much fuel on the climb.
On mild hills like I-80 in western Iowa, that would be how you'd save fuel.
Doesn't help as much when the grades & curves or traffic prevents you from being able to store up as much kinetic energy as you can safely, though. Gotta use common sense, and don't let your speed get out of control on a downhill, of course.
But that works for any vehicle, even cars or motorcycles.
And there's a point where wind resistance eats up more energy than gravity and a light throttle setting can gain you.
It would take me more than the 48% remaining on my phone battery to explain this stuff fully, but it's pretty basic physics.
I'm always aware of how much energy I'm using, wasting, conserving or storing as I drive any vehicle. Sometimes I even do math in my head: Approximate vehicle weight, current speed, instant MPG gauge, lateral acceleration vs center of gravity height vs axle width, etc..
I don't do it for fuel economy though. I used to do it to baby the vehicle to make it last longer, but now I do it simply because I've developed a loathing for wasted energy.
Why stay on the gas at 55 mph all the way up until it's time to hit the turn signal for a right turn, then brake off all the energy you invested getting accelerated a few miles back?
I let off the gas early and am usually down to 30-40 mph before I even think about the brakes.
Brakes waste energy. I use them as little as possible.
Basically just to prevent crashes.
Top priority = safety
2nd priority = watch for cops if I'm going downhill or if there's no cross traffic & I want to blow through a stop sign in the middle of nowhere at 3AM
3rd priority = use as little energy as possible.
Duck
Sarcastic remark goes here
Another thing to think about is how much fuel does your (truck) engine use at full throttle, RPMs in the sweet spot?
If you've got the pedal to the metal, it's going to burn that much fuel per minute regardless of whether you're doing 70 mph or 35. Except if you're doing 35 you're only traveling half as far on that fuel.
So you're better off flooring it before you get to the hill then you would be if you maintained your speed until the incline slows you down & you spend more time per mile, running the engine at max power.
Only until wind drag becomes an energy conservation problem.
If you've got the pedal to the metal, it's going to burn that much fuel per minute regardless of whether you're doing 70 mph or 35. Except if you're doing 35 you're only traveling half as far on that fuel.
So you're better off flooring it before you get to the hill then you would be if you maintained your speed until the incline slows you down & you spend more time per mile, running the engine at max power.
Only until wind drag becomes an energy conservation problem.
Electric Chicken
Well-Known Member
2200 Redline isnt what it actually shifts to, that's just where they painted the tach.
I don't remember what it actually lets itself go to during an acceleration but it's nowhere near that.
Electric Chicken
Well-Known Member
I'm still on the same brakes as it had when I bought it. I too try to use them as little as possible. I'd rather put the Jakes on low than touch that pedal.I was talking about fleets turning down the HP/torque too. That's what I meant by they're designed to be flat-footed.
If you're focusing on fuel economy on rolling hills, you'd actually step on it (not all the way) on the downhill and let gravity help you build up momentum that will help you up the next hill so you don't have to use as much fuel on the climb.
On mild hills like I-80 in western Iowa, that would be how you'd save fuel.
Doesn't help as much when the grades & curves or traffic prevents you from being able to store up as much kinetic energy as you can safely, though. Gotta use common sense, and don't let your speed get out of control on a downhill, of course.
But that works for any vehicle, even cars or motorcycles.
And there's a point where wind resistance eats up more energy than gravity and a light throttle setting can gain you.
It would take me more than the 48% remaining on my phone battery to explain this stuff fully, but it's pretty basic physics.
I'm always aware of how much energy I'm using, wasting, conserving or storing as I drive any vehicle. Sometimes I even do math in my head: Approximate vehicle weight, current speed, instant MPG gauge, lateral acceleration vs center of gravity height vs axle width, etc..
I don't do it for fuel economy though. I used to do it to baby the vehicle to make it last longer, but now I do it simply because I've developed a loathing for wasted energy.
Why stay on the gas at 55 mph all the way up until it's time to hit the turn signal for a right turn, then brake off all the energy you invested getting accelerated a few miles back?
I let off the gas early and am usually down to 30-40 mph before I even think about the brakes.
Brakes waste energy. I use them as little as possible.
Basically just to prevent crashes.
Top priority = safety
2nd priority = watch for cops if I'm going downhill or if there's no cross traffic & I want to blow through a stop sign in the middle of nowhere at 3AM
3rd priority = use as little energy as possible.
Don't see that as an issue anymore. The fleet trucks climb the hills just fine. I can climb a little faster with 500hp than 455hp, but the difference would be minimal as the torque is the same. That said, I don't climb the hill as fast as it can be climbed, I'm more concerned with fuel economy than being first to the top of the hill.
Electric Chicken
Well-Known Member
I either have a worn out truck, a detuned truck, or way too much drag because I don't have any pedal left when I'm climbing any sort of hill, and I lose speed.
389 Hood
Well-Known Member
Not necessarily. I think you said it was set at 450HP in some other post. What is your torque rating set at? Also, what is your transmission torque rating? You don't want to set the torque at 2050 or whatever the software allows and have a 1600 pd ft rated transmission main shaft.
That's another problem with a rheostat pedal, you don't get to feel the engine through the pedal. You're still going to lose speed going up a hill, or even an overpass. If you were to compare what you think is a drop in speed with a diesel, do the same load with a gas engine and see where you sit.
My 600's wouldn't maintain speed up inclines, but at the same time, they wouldn't be sitting in the right lane with the flashers on. Empty, grossing 60k it maintained, but with 150k on the deck, you knew it was there. Torque moves the load, not horsepower.
Electric Chicken
Well-Known Member
Yeah I'm not pulling anywhere near 150k.
It's a 445hp engine. I don't know the torque. But that doesn't mean it's actually set at 445. It could have been detuned by the fleet that owned it. They pulled tubes full of bulk with it.
Duck
Sarcastic remark goes here
Is there anything in your computerized dash that shows fuel flow, as opposed to MPG?
It'd be cool if there was.
No
Duck
Sarcastic remark goes here
We know the truck has a fuel flow meter somewhere because it's required for the MPG display.
Van Wyk's Volvos would show fuel flow instead of MPGs when you're parked & you set the fast idle. It showed it in gallons per hour.
One time when I had a faulty speed sensor I had to limp it about 150 miles to a shop. It would not give me much boost at all, and it was topping out around 55 mph.
The MPG display was showing gallons per hour.
I had to set the "fast idle" to 1200 RPM. The pedal only gave me about 900. Shifting was a bitch
But who knows? We know the parameter is monitored by the computer. Maybe with a laptop it can be programmed into the display.
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