Ecodiesel power derating as temps rise?

[Gruffid]

Has anyone re-geared the diesel and still had the derating issue? Maybe I am wrong, but if the truck was lower geared it seems the engine wouldn’t struggle as much and hopefully not overheat as easy. I have towed with mine several times and seen the loss of power. Not had it go to limp mode yet. Towed my 2 horse trailer with 2 horses and my 5300 lbs travel trailer loaded for a trip. So far only in Texas so no major inclines yet. I have 4.88 gears on order and I am hoping this helps.

Casey250 (a YouTuber - stock gearing) has a VLOG where his JLURD and a friend’s JTD ( YouTube channel “EPIC Adventure Outfitters” - regeared) de-rated at the same time on the same stretch of road.

That leads me to believe it’s not gearing or tyre size dependent.

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[WXman]

I figured I'd just jump in here to talk a little about my experience. I just moved across the country CA to TN. I drove up into Utah through Colorado Kansas Missouri and down through Illinois and Kentucky. I had myself at 185lb my 120lb dog 10 full 20 gallon totes and some other gear for the trip. The outside temp going through Utah was topped at 105 and through Colorado at 98. I have been aware of the cooling issues with the diesels so was most nervous with Utah and Colorado because of the altitude and heat combo. But I am happy to report I had no issues what so ever and the trip mad me fall In love with the diesel gladiator even more. I watched my oil the whole time and the hottest I hit was 240. I stopped plenty of times to let the dog out and had no heat soak issues, and my mpg topped out at 32mpg. I know a lot have been having issues so I thought I would just give some good news ?

Matches the experience I saw from a guy in Arizona the other day. He said the weather has been torrid out there lately, and even driving up into higher elevations he has zero issues.

I'm starting to wonder why some of us never have issues and others claim they do. What's up with that? Heck I even have a 12k winch mounted right in front of my grille and I still never overheat even on the hottest days.

 

[foo.c]

We aren't talking acceleration, but work actually done. In first gear that work is done slowly. You are using the torque to accelerate it.

Torque multiplication still works at constant speed. It's just an example to show how it works.

Really what we are talking about is how much work the engine does to achieve a certain angular momentum of the wheels. The gear you are in plays a big role in that, certainly how much work the engine can actually do is also a factor in pulling a trailer at a desired speed or accelerating in a 1/4 mile.

 

[foo.c]

It's definitely more complex than that, which is why I said it "pretty much" sums it up.

I don't have the compressor map for this turbo, but I imagine the efficiency islands are only a few percent apart like most turbos, so there's probably not much effect from that. The efficiency is key in this situation, because it's going to take X amount of fuel to make the required power, along with a certain mass of air, whether that mass is delivered at a higher pressure and lower RPM, or a lower pressure and higher RPM. Remember that air gets compressed anyway for the combustion process, and a 20 degree rise in intake temp only means a 20 degree rise in exhaust temps. It just doesn't add that much heat to the system.

It's known that engines operate at slightly different efficiency levels based on RPM, gearboxes have different losses at different ratios, turbos have different efficiency islands, etc. You can tweak all these variables and come out with slightly different outcomes, but they all end up being very similar. The situation you are describing above is simply running in a different gear, which I think people would have figured out pretty quickly if it had much of an effect.

We're kind of ignoring things like overdrive divides the engine torque, and underdrive multiplies it. So, I don't know if they have tried it because they don't understand what that means. Could just be they don't want to slow down that much until forced to.

Could I be overstating my case, yeah. I haven't tried it in this vehicle. My experience is that boost produces heat. On the track it eventually overwhelms the cooling system in most street vehicles, and they de-rate as we're calling it here.

 

[just_another_guy]

We're kind of ignoring things like overdrive divides the engine torque, and underdrive multiplies it. So, I don't know if they have tried it because they don't understand what that means. Could just be they don't want to slow down that much until forced to.

Could I be overstating my case, yeah. I haven't tried it in this vehicle. My experience is that boost produces heat. On the track it eventually overwhelms the cooling system in most street vehicles, and they de-rate as we're calling it here.

We're not ignoring gear ratios, because they don't change the amount of work that needs to be done. Multiplying your torque doesn't change your power, because your higher torque is applied at lower RPM. There's no free lunch.

You're extrapolating way too much out of this "boost produces heat" statement as well. If you run high boost in a car it's pretty logical that you will make more horsepower, which will produce more waste heat from the higher energy output of the motor.

 

[foo.c]

We're not ignoring gear ratios, because they don't change the amount of work that needs to be done. Multiplying your torque doesn't change your power, because your higher torque is applied at lower RPM. There's no free lunch.

You're extrapolating way too much out of this "boost produces heat" statement as well. If you run high boost in a car it's pretty logical that you will make more horsepower, which will produce more waste heat from the higher energy output of the motor.

They do not change the amount of work, they change the engine load and boost in this case. You're saying it makes no difference. I disagree.

I have never seen a naturally aspirated car overheat on track (besides clunkers like at Lemons), and I have seen dozens of turbo and super charged vehicles of all makes overheat. That is my real world experience not an extrapolation. I'm not saying FI always overheats or NA can't overheat, but that's what I've seen.

 

[just_another_guy]

They do not change the amount of work, they change the engine load and boost in this case. You're saying it makes no difference. I disagree.

I have never seen a naturally aspirated car overheat on track, and I have seen dozens of turbo and super charged vehicles of all makes overheat. That is my real world experience not an extrapolation. I'm not saying FI always overheats or NA can't overheat, but that's what I've seen.

I'm not sure what you are defining "engine load" as if it's not the amount of work being done by the engine. And I'm not really interested in debating the track car anecdote because it's pretty pointless and this is getting off track from the original discussion

 

[foo.c]

I'm not sure what you are defining "engine load" as if it's not the amount of work being done by the engine. And I'm not really interested in debating the track car anecdote because it's pretty pointless and this is getting off track from the original discussion

An engine not connected to anything has no load regardless of the rpm (ignoring internal friction and what not). It's still spinning but you'll find it makes no boost once it reaches a constant rpm.

An engine pushing a vehicle has a load, now it can make boost even at constant rpm (if the load is high enough).

Can you see how gearing comes into play now?

 

[just_another_guy]

An engine not connected to anything has no load regardless of the rpm (ignoring internal friction and what not). It's still spinning but you'll find it makes no boost once it reaches a constant rpm.

An engine pushing a vehicle has a load, now it can make boost even at constant rpm (if the load is high enough).

Can you see how gearing comes into play now?

You seem to be hung up on the idea that boost = heat = bad. The turbo is adding some heat from the <100% efficiency level it operates at, that's a given. However, the majority of the heat is being released from the fuel. Charles's law is the entire principle that an engine operates on, without heat it cannot produce any power.

To produce power at low rpm, the motor needs to stuff air at a higher pressure to combust the fuel, since it is working with a lower volume. The cylinders are a fixed volume and will be filled fewer times per minute at the lower rpm, so they need a higher pressure to achieve the same mass of air. Think of it in terms of requiring x amount of fuel per minute to produce the required power - you can deliver the mass of air needed (in lb/min) for this process in different ways (high boost/low rpm, or low boost/high rpm).

Again, the gearing doesn't make much difference at all.

 

[foo.c]

You seem to be hung up on the idea that boost = heat = bad. The turbo is adding some heat from the <100% efficiency level it operates at, that's a given. However, the majority of the heat is being released from the fuel. Charles's law is the entire principle that an engine operates on, without heat it cannot produce any power.

To produce power at low rpm, the motor needs to stuff air at a higher pressure to combust the fuel, since it is working with a lower volume. The cylinders are a fixed volume and will be filled fewer times per minute at the lower rpm, so they need a higher pressure to achieve the same mass of air. Think of it in terms of requiring x amount of fuel per minute to produce the required power - you can deliver the mass of air needed (in lb/min) for this process in different ways (high boost/low rpm, or low boost/high rpm).

Again, the gearing doesn't make much difference at all.

boost = heat = potentially bad. Length of time is involved. Real world shows you can kaboom an engine at low engine speed and high boost if run long enough if you don't do something like derating. This is not a new phenomenon only limited to this platform.

I really can't disagree more about loads and gearing, but there's no point in me continuing I guess.

 

[just_another_guy]

boost = heat = potentially bad. Length of time is involved. Real world shows you can kaboom an engine at low engine speed and high boost if run long enough if you don't do something like derating. This is not a new phenomenon only limited to this platform.

I really can't disagree more about loads and gearing, but there's no point in me continuing I guess.

You can disagree, but if you aren't provided any evidence or logic to back up the claim I'm not sure what reaction you are expecting

 

[foo.c]

You can disagree, but if you aren't provided any evidence or logic to back up the claim I'm not sure what reaction you are expecting

What evidence are you expecting? I don't have an engine dyno, which incidentally works by putting a load on the engine and measuring the torque against it.

What do you think it would show if we put a transmission between the engine and the "brake". I bet it would show more torque in low gear, the exact amount of torque in the 1:1 gear and less torque in overdrive. Can we at least agree on that?

 

[just_another_guy]

What evidence are you expecting? I don't have an engine dyno, which incidentally works by putting a load on the engine and measuring the torque against it.

What do you think it would show if we put a transmission between the engine and the "brake". I bet it would show more torque in low gear, the exact amount of torque in the 1:1 gear and less torque in overdrive. Can we at least agree on that?

Torque is only the capacity to do work, you need to look at the rate at which it is being done (power). In the real world, you need to apply that torque over a distance to actually accomplish something.

Also, many dynos don't measure torque, they measure horsepower and then calculate the torque from the horsepower and rpm. You can do this because the relationship between the two never changes, regardless of what gearing your vehicle has.

 

[ShadowsPapa]

Torque is only the capacity to do work, you need to look at the rate at which it is being done (power). In the real world, you need to apply that torque over a distance to actually accomplish something.

Also, many dynos don't measure torque, they measure horsepower and then calculate the torque from the horsepower and rpm. You can do this because the relationship between the two never changes, regardless of what gearing your vehicle has.

When I was in college, now that I think of it, even highschool when I was the instructor's "aid" in a way, we discussed the workings of a simple dyno - at that time, they generated electricity through a load and the wattage was figured, and then HP derived from that.
Not sure I explained it right.............
There was also a simple small engine "dyno" that used a generator to apply a load and there was a lever on a spring scale to measure torque.
But the electrical explanation got me into remembering Watt's numbers for HP - what, about 746 watts?
What's the maximum watts generated on the dyno, divide that by ~746 for the result so it was a direct measurement of the HP.

Does that sound right?

 

[just_another_guy]

When I was in college, now that I think of it, even highschool when I was the instructor's "aid" in a way, we discussed the workings of a simple dyno - at that time, they generated electricity through a load and the wattage was figured, and then HP derived from that.
Not sure I explained it right.............
There was also a simple small engine "dyno" that used a generator to apply a load and there was a lever on a spring scale to measure torque.
But the electrical explanation got me into remembering Watt's numbers for HP - what, about 746 watts?
What's the maximum watts generated on the dyno, divide that by ~746 for the result so it was a direct measurement of the HP.

Does that sound right?

Yes, that's correct. I think this discussion has strayed a little too far from diesel overheating issues though, so I'm not going to pursue it any further

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