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Lower Your Trans Temps! Mishimoto R&D: 2018+ Wrangler JL Transmission Cooler

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rubileon

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For practicality sake, I'm not sure how much room there is for another fan in that stack of cooler stuff that's already in there.
The some of the aftermarket forced induction makers add a very thick air-air intercooler in front. A modern low profile fan shouldn't be a problem compared to how much space those fat air-air intercoolers and their hoses need.

https://www.procharger.com/truck-superchargers/dodge/jeep/2018-jeep-wrangler-jl-36
r_supercharger_system_procharger_intercooler_right.jpg


https://www.rippmods.com/collections/jeep-jl-wrangler/products/2018-jl-wrangler-supercharger-system
VJA55cHDd.jpg



And remember, we're not trying to replace the existing system... we're just adding an extra pusher fan to turn on/off as we wish (or have it turn on when a sensor detects a certain temperature in the transmission cooler or where ever.
 
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Mishimoto

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The 83% increase in fluid capacity amounts to an extra 0.23 quarts.

The other two big numbers;
  • 93% increase in external tube area over stock transmission cooler
  • 195% increase in internal fin surface area for comprehensive cooling in even the harshest conditions
seem impressive too, but what about the actual performance?

How much cooler does the transmission run with the Mishimoto aftermarket Wrangler JL transmission cooler installed?

Thank you.
Also I'd like to know if it's better than putting a smaller pusher fan, considering the work and potential warranty issues involved in replacing. The temps are fine when moving so the cooling is needed when stationary which I don't think is best solved by a bigger heat exchanger?
Hey both,

If you read through this post, you'll find our testing results: https://www.mishimoto.com/engineering/2020/08/jeep-wrangler-transmission-cooler-2018-rd-pt3/

To summarize, we bench test our coolers vs. the stock unit so that we can have a direct comparison between the two, without having to worry about outside factors like ambient air temp, airflow, or varying load due to road conditions or traffic. In our bench testing, we found that our cooler reduced inlet and outlet temps by about 10 degrees over the stock cooler. Our cooler also flows better than the stock unit, which means it can cool the fluid faster.

@rubileon a bigger cooler will have an effect on temperature during low speed/stopped conditions because of two things: greater thermal mass and greater surface area.

The Mishimoto cooler overall has more mass than the stock unit, which can absorb more heat from the fluid without any airflow. Think of it like a heat sink on a diff cover or a computer CPU. Adding those fins adds mass to the diff cover and also adds surface area.

The extra surface area also means that there's more material in contact with the air, which transfers heat better. It also means that there's more surface area in contact with the air that the fans move, so it's essentially like increasing the flow of the fan.

Hope that helps answer your questions!

The pre-sale for this trans cooler has ended, but if anybody would still like to order, please shoot me a PM and I'll see what I can do for pricing.

Thanks!
-Steve
 

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rubileon

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Hey both,

If you read through this post, you'll find our testing results: https://www.mishimoto.com/engineering/2020/08/jeep-wrangler-transmission-cooler-2018-rd-pt3/

To summarize, we bench test our coolers vs. the stock unit so that we can have a direct comparison between the two, without having to worry about outside factors like ambient air temp, airflow, or varying load due to road conditions or traffic. In our bench testing, we found that our cooler reduced inlet and outlet temps by about 10 degrees over the stock cooler. Our cooler also flows better than the stock unit, which means it can cool the fluid faster.

@rubileon a bigger cooler will have an effect on temperature during low speed/stopped conditions because of two things: greater thermal mass and greater surface area.

The Mishimoto cooler overall has more mass than the stock unit, which can absorb more heat from the fluid without any airflow. Think of it like a heat sink on a diff cover or a computer CPU. Adding those fins adds mass to the diff cover and also adds surface area.

The extra surface area also means that there's more material in contact with the air, which transfers heat better. It also means that there's more surface area in contact with the air that the fans move, so it's essentially like increasing the flow of the fan.

Hope that helps answer your questions!

The pre-sale for this trans cooler has ended, but if anybody would still like to order, please shoot me a PM and I'll see what I can do for pricing.

Thanks!
-Steve
Thanks for the reply Steve. I'm still not sure if a similar effect can be achieved by adding an extra pusher fan to the factory cooler.

While the outlet pressure benefits are clear, the cooling function and the delta seems identical. I was hoping to see a bigger gap between the inlet and outlet temps in the newer cooler.
Jeep Wrangler JL Lower Your Trans Temps! Mishimoto R&D: 2018+ Wrangler JL Transmission Cooler MMTC-JL-TempGraph


Also...
"the dyno fan pushed air through the cooler at a steady 20mph (the average speed of air behind the grille at highway speed)."
Because of the choice of x axis here, what we can see in this graph is the benefit of a steady flow of air. Which is why I'm wondering if the airflow is increased by adding a even a little fan, how much more can we get out of the stock oil cooler.

Also I think people would be more interested when air speed is equivalent to crawling speeds vs. highway speeds. The demographic that has oil temps too high at highway speeds would be smaller I imagine.
 
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Yellow Cake Kid

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It looks like a best case 4% improvement.

I think I would be more interested in observing how the performance of the two devices compared with a fluid source that was continuously supplied at the 200*F rather than considering the effect of repeatedly cooling the cooled fluid in a resonant cycle of declining temperature.

The rapid decline in inlet temp, as shown at either cooler, doesn't seem to exemplify what I experience with my Jeep, unless I have just finished some slow poke off road climbing and then begun driving at highway speeds down a long hill.

I am concerned about increasing effective cooling while driving continually at very low air speed and producing heat with the transmission.

At 100 seconds the inlet temp is still fairly similar, and the outlet temps are also fairly similar. If the coolers were continually supplied 200 degree Fahrenheit fluid would the difference stay the same or would the Mishimoto cooler begin to appreciably outperform the stock cooler as the duration increased?

Thank you.
 
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The only thing that is missing from this equation is the ambient temperature. If it was 30Ā° outside, then these results aren't as impressive than if it was 120Ā°.

Also doesn't the transmission have a thermostat anyway, and would never cool to the levels seen in this graph? I know that it is designed to operate within a specific temperature range, and apparently it even has a warmer (@25:37):

 

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This is for the ZF 8HP, but I can assume the Torqueflight 850RE is similar. From: https://www.import-car.com/zf-8hp-transmission-replacement/

This thermostatic bypass valveā€™s function is to let the oil circulate through the cooler only when the oil has achieved a certain temperature. In most cases, it starts to slowly open at 75 degrees C (167 degrees F) and open completely at 90 degrees C (194 degrees F). This process helps the transmission get to operating temperature faster than if the oil ran through the cooler when cold.
So everything beyond 200 seconds on that graph doesn't mean much, but the Mishimoto cooler appears to hit the 167Ā° thermostat minimum about a minute earlier than the OEM cooler. It would be far more interesting to see how the cooler performed at 250Ā°, and with a set amount of BTUs being added to better simulate driving conditions.
 

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While I will typically be the first to challenge company claims, their sample testing was just a simple comparison of how their cooler cooled vs the stock cooler. Sure, there are lots of holes in the testing when compared with real world testing (like how did the input temperature cool down, and how is that relevant to demonstrating the cooler offers improved performance?). It's not uncommon for me to see 250+ trans temps, so I'll take a 4% reduction in trans temps. We'll see. I wished I better documented how and what situations I've seen high temps to see if there is really much of an improvement afterward.
 
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JimLee

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Maybe the Tazer guys can solve that?
I keep hoping one of the aftermarket guys (Tazer, Superchips, etc) come out with a way to override the automatic fan programming, i live where it's insanely hot, If I could flip a switch and have it run at 100% it'd probably stay that way all spring, summer, and fall.
 

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I just received the transmission cooler today. Of course, no instructions are included, but there was a piece of paper that said to go to the website. Once you get there, good luck finding the instructions. They really need to fix that - well...the website is pretty horrible. Good luck even finding the cooler in the first place (you can't find it searching by vehicle).

I finally aligned the stars and finally found the instructions. I started to think that the instructions were fairly well written. I spent many years writing instructions for a living, including automotive parts and accessories, so I can appreciate effective instructional materials. However, they completely missed the procedures for setting proper fluid level. That's a huge omission.

And there was this other part of the instructions that left me wondering what I was doing (see red box below). :)

It'll probably take a while until I actually install the cooler, as I'd also like to source the larger Gladiator grille openings and, of course, I need some trans fluid.

Jeep Wrangler JL Lower Your Trans Temps! Mishimoto R&D: 2018+ Wrangler JL Transmission Cooler Mishimoto Cooler Oops
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