Diff Temp video
Posted: Sat Aug 18, 2018 2:34 pm
Nice video from Banks on diff temps. Thought of Twinstick when I saw it.
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https://forum.powerwagonregistry.org/viewtopic.php?f=39&t=5582
Haha, that tells me everything I need to know. Don’t need to watch it now.Reloaderguy wrote:This was posted on CF a few days ago. The diesel bros are all kinds of ass-hurt.
It's worth pointing out, however that FCA does make and include a finned aluminum diff cover on certain 3500 DRW trucks. I don't think there is a capacity difference though. Obviously Ram engineers think there is some benefit to cooling, the question is does the added capacity found in aftermarket covers do anything beneficial? I have no need for differential sight glasses, dipsticks, or drain holes.Bill2014 wrote: ↑Sun Aug 19, 2018 7:15 amLots of spent on mods and "improvements".
If you don't baseline and then quantify the impacts, you never know if the bang is worth the buck.
That's big value of the forum - not everyone has to experiment - we can learn from others that do it right and have the data from measured results to back it up.
The ring gear is throwing viscous oil that takes time to drain back to the bottom of the diff housing. Faster ring gear, throws more oil. I’d never really considered that, but it isn’t so crazy when you think about it.RustyPW wrote:What gets me is the level drops when up to speed.
I only see larger capacity being beneficial for really short duration events that generate a lot of heat. A larger volume of oil gives you a larger heat sink to accept short intervals of high heat rate that might cook a smaller volume of oil if the rate of heat rejection from the housing can’t keep up. For long term, steady state conditions, that bigger heat sink means nothing. It becomes a matter of heat transfer to the outside by (mostly) convection, driven by material, surface area, and air flow (including where/how that air is impinging the surfaces). As Banks suggested (I did watch it, couldn’t help myself), the ass end of a differential really isn’t getting the best cooling air flow. It really wouldn’t surprise me if more heat is getting pulled out of the front of the differential housing than the rear at highway speed. Larger surface area, directly impinged by the air flow.Reloaderguy wrote:It's worth pointing out, however that FCA does make and include a finned aluminum diff cover on certain 3500 DRW trucks. I don't think there is a capacity difference though. Obviously Ram engineers think there is some benefit to cooling, the question is does the added capacity found in aftermarket covers do anything beneficial? I have no need for differential sight glasses, dipsticks, or drain holes.Bill2014 wrote: ↑Sun Aug 19, 2018 7:15 amLots of spent on mods and "improvements".
If you don't baseline and then quantify the impacts, you never know if the bang is worth the buck.
That's big value of the forum - not everyone has to experiment - we can learn from others that do it right and have the data from measured results to back it up.
I really didn't even think about it.Low_Sky wrote: ↑Sun Aug 19, 2018 2:28 pmThe ring gear is throwing viscous oil that takes time to drain back to the bottom of the diff housing. Faster ring gear, throws more oil. I’d never really considered that, but it isn’t so crazy when you think about it.RustyPW wrote:What gets me is the level drops when up to speed.
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I installed a diff cooler on my Nismo. That diff is up out of the air flow. Plus it has 2, 3" exhaust pipes right next to it. It used to have a VLSD. When it got hot. It turned into a one wheel peeler. The VLSD just quit working the way it should. So I installed a OS Giken LSD. That LSD uses 75w-250 gear lube. With the diff cooler. On the track. It will get up to 270F. I can turn the diff cooler on, and it will drop the temps down to 145F after about 10 minutes. The most I've seen on the street is 255F after running 4 hrs at 80 mph.Low_Sky wrote: ↑Sun Aug 19, 2018 2:39 pmI only see larger capacity being beneficial for really short duration events that generate a lot of heat. A larger volume of oil gives you a larger heat sink to accept short intervals of high heat rate that might cook a smaller volume of oil if the rate of heat rejection from the housing can’t keep up. For long term, steady state conditions, that bigger heat sink means nothing. It becomes a matter of heat transfer to the outside by (mostly) convection, driven by material, surface area, and air flow (including where/how that air is impinging the surfaces). As Banks suggested (I did watch it, couldn’t help myself), the ass end of a differential really isn’t getting the best cooling air flow. It really wouldn’t surprise me if more heat is getting pulled out of the front of the differential housing than the rear at highway speed. Larger surface area, directly impinged by the air flow.Reloaderguy wrote:It's worth pointing out, however that FCA does make and include a finned aluminum diff cover on certain 3500 DRW trucks. I don't think there is a capacity difference though. Obviously Ram engineers think there is some benefit to cooling, the question is does the added capacity found in aftermarket covers do anything beneficial? I have no need for differential sight glasses, dipsticks, or drain holes.Bill2014 wrote: ↑Sun Aug 19, 2018 7:15 amLots of spent on mods and "improvements".
If you don't baseline and then quantify the impacts, you never know if the bang is worth the buck.
That's big value of the forum - not everyone has to experiment - we can learn from others that do it right and have the data from measured results to back it up.
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Isn't that what I said above? Aluminum conducts heat better than steel, Ram installs aluminum diff covers on 3500 duallies.13BlkPowerWagon wrote: ↑Wed Aug 22, 2018 4:29 pmAs an ex-test engineer for Dana corporation in Toledo, I am calling BS on this (and yet another reason I think Gale Banks is a better salesman than engineer...).
I've personally seen the difference on an M44 rear end, one with a cast aluminum finned cover, and the same axle with a stamped steel cover, towing the same load, under the same conditions, on the same track... The finned cover consistently saw 20-30*F cooler temps than the stamped steel cover at highway speeds (70mph), towing 7500lbs, with an 8'x8' wind sail. This was on a Titan test truck (not truly a standard M44, but that's irrelevant).
Now, did the axle live longer because of those lower temps? I have no idea... the truck caught on fire and burned to the ground before we finished the testing... but, the finned cover definitely lowered the temps of the gear oil.
Now, we never tested aftermarket pans, and I can tell you there is a scientific method to the design of the fins, so perhaps aFe's don't work as well as a factory designed pan.
Also, increased capacity has no effect on the steady state temperature of the oil (negating the minimal increase in effective transfer area of the oil to the case). Power through the R&P, along with the bearing losses, remains constant (increased capacity may actually increase these losses due to drag). Those losses create thermal energy, which can be measured (like in watts). The time it takes to heat the oil to steady state may change, but the thermal transfer coefficient doesn't with a capacity change alone (again, negating minor variances in material transfer areas). So, adding volume won't lower temperatures, by itself.
Changing the thermal transfer coefficient, and emissivity of the cover/housing, absolutely, without question (and according to the laws of physics), will effect the steady state oil temperature. Aluminum has a MUCH higher thermal transfer coefficient than steel. And while the machined fins look cool, black paint would improve it's radiant emissivity more-so than raw aluminum (though some paints are also good thermal insulators, so paint choice can have large effect).
Have I mentioned as an ex-Cummins fanatic, I don't like Gale Banks?
What's your beef with Banks? Never bought or used his products. Was thinking on getting a few things for my 6.7 motorhome.13BlkPowerWagon wrote: ↑Wed Aug 22, 2018 4:29 pmAs an ex-test engineer for Dana corporation in Toledo, I am calling BS on this (and yet another reason I think Gale Banks is a better salesman than engineer...).
I've personally seen the difference on an M44 rear end, one with a cast aluminum finned cover, and the same axle with a stamped steel cover, towing the same load, under the same conditions, on the same track... The finned cover consistently saw 20-30*F cooler temps than the stamped steel cover at highway speeds (70mph), towing 7500lbs, with an 8'x8' wind sail. This was on a Titan test truck (not truly a standard M44, but that's irrelevant).
Now, did the axle live longer because of those lower temps? I have no idea... the truck caught on fire and burned to the ground before we finished the testing... but, the finned cover definitely lowered the temps of the gear oil.
Now, we never tested aftermarket pans, and I can tell you there is a scientific method to the design of the fins, so perhaps aFe's don't work as well as a factory designed pan.
Also, increased capacity has no effect on the steady state temperature of the oil (negating the minimal increase in effective transfer area of the oil to the case). Power through the R&P, along with the bearing losses, remains constant (increased capacity may actually increase these losses due to drag). Those losses create thermal energy, which can be measured (like in watts). The time it takes to heat the oil to steady state may change, but the thermal transfer coefficient doesn't with a capacity change alone (again, negating minor variances in material transfer areas). So, adding volume won't lower temperatures, by itself.
Changing the thermal transfer coefficient, and emissivity of the cover/housing, absolutely, without question (and according to the laws of physics), will effect the steady state oil temperature. Aluminum has a MUCH higher thermal transfer coefficient than steel. And while the machined fins look cool, black paint would improve it's radiant emissivity more-so than raw aluminum (though some paints are also good thermal insulators, so paint choice can have large effect).
Have I mentioned as an ex-Cummins fanatic, I don't like Gale Banks?