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Engine, Exhaust, Transmission Discuss the FR-S | 86 | BRZ engine, exhaust and drivetrain.


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Old 10-04-2016, 07:30 AM   #29
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Originally Posted by humfrz View Post
So, I wonder if anyone has actually measured the temperature of the transmission oil in a FR-S/BRZ, under or just after, an extended load (like a heavy track session) ...??

Anyone out there .. ??

humfrz
This doesn't exactly answer your question, but I thought you might be interested in seeing various temperature readings off GSpeed's car after a 30 min track session. Diff temps peaked at 290 F by the end, which is quite toasty. On my old STI, the rear diff temperature warning light went off at 302 F (at which point Subaru recommended changing out the fluid because it'd break down).

@GSpeed is going to measure transmission temps next, so they should have an answer to your q soon.

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Well, it's been almost a year since this car has been on track, but it's first track day was a success!



I didn't get any good video from the session; I need to relocate the camera. We also didn't get lap times, but that's my fault for not updating the new dash (long story) with the proper GPS files.

Here's a graph of temperatures throughout the session:



Oil and water look fine, and ambient temps were about 90°F. Check out that diff temp, though. Continuously climbing, and reached about 290°F by the end of the session. We're going to have to do something about that.

Here's something interesting, though. I've been doing a lot of research on oiling systems as we're starting to corner harder, and look at these pressure drops through hard corners:



That's Oil Pressure (light blue) and lateral acceleration (dark blue). You can see through the hard corners, there are times when oil pressure drops from around 45psi down to the 20s. That's not a good sign. Not that the motor's being damaged right NOW, but that behavior certainly isn't going to improve as cornering loads increase.

For comparison's sake, here's a shot of a car with a dry sump around the same track.



This car is cornering about 1.5G steady-state, and there's no pressure drops to be found. We're going to start looking into dry sump systems for this car. Subarus have a nasty tendency to spill oil into the outside head over about 1.3G or so, and we'll probably be in that range once we switch over to Hoosiers (which are sitting on the shelf).

We also suspect the transmission fluid is getting pretty toasty for a long session, too. We've got some new sensors on the way (for the trans, and to replace that erratic diff temp reading shown above) that should help figure out exactly what's going on. We know there are reports of people chewing up gears, but if that's because fluid temps are high, there are easier solutions than new gearstacks.

There's also still some weird behavior going on with the rear shocks. We found an issue with low gas pressure causing cavitation that KW supposedly fixed, but we may have to put them on the dyno again and see what's going on.

Over the next week or two we'll be addressing all those issues, as well as doing a new setup on the car (just because he went off hard last summer, and to re-balance the car with the cage). Once that's done, Dave will see how fast it'll go around the 1.7 CCW for comparison's sake, and then we'll start adding the really fun parts.

Jake
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Old 10-04-2016, 09:36 AM   #30
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Now I just wish that MT engineers were smart enough to design in a oil pump in the mechanicals.
For a stock setup it would do nothing but keep the oil circulating.
For an add on aftermarket cooler, you would just tap into the correct galleys and have a trans cooler that requires no pump.
Otherwise you need an external (usually) electric pump in addition to the cooler.
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Old 10-04-2016, 09:51 AM   #31
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The problem there is, if there is too much cooling, the trans would not get up to and maintain operating temp as a DD. A car has to be designed either as a track car or a DD in some respects. To be a DD, it requires certain upgrades to be a good track car- trans oil and motor oil coolers are a must. If they were included on the stock car, either it'd be expensive to include because of the additional equipment (some system to disable for DD and enable for the track) or run too cool which is also bad.
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Old 10-04-2016, 01:33 PM   #32
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Heat plus air plus mechanical pressure, doesn't physically break moecules, but it accelerates degradation through oxidation. It doesn't need to be all that hot for that.

Oxidation is what I'm referring to when I say breaking down.

This happens in many ways, with heat and mechanical work, and especially with air entrainment.

This slowly turns your nice oil into a mixture of aldehydes, ketones, peroxides and carboxylic acids that don't do a great job lubricating things.

Oxidation in oils accelerates quadratically at temperatures above approximately 75 C. The rate doubles every 10 degrees. In theory, it will oxidize with ambient air, but not fast. Fast oxidation comes from rapid adiabatic heating of entrained air bubbles. Like when they get crushed between gear teeth.
OMG, what do you do for a living specifically? I hope you are well compensated. I dearly miss my brief days of R&D.
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Old 10-04-2016, 01:34 PM   #33
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Now I just wish that MT engineers were smart enough to design in a oil pump in the mechanicals.
For a stock setup it would do nothing but keep the oil circulating.
For an add on aftermarket cooler, you would just tap into the correct galleys and have a trans cooler that requires no pump.
Otherwise you need an external (usually) electric pump in addition to the cooler.
$$$. Always $$$.
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Old 10-04-2016, 02:50 PM   #34
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Now I just wish that MT engineers were smart enough to design in a oil pump in the mechanicals.
For a stock setup it would do nothing but keep the oil circulating.
For an add on aftermarket cooler, you would just tap into the correct galleys and have a trans cooler that requires no pump.
Otherwise you need an external (usually) electric pump in addition to the cooler.
All that stuff can be found on Class 8 trucks--l drove a Kenworth years ago that had Eaton SQHP differentials--the P stands for pump. The trans was an RT-12513 and it may have had a pump, too. That extra stuff makes the driveline bigger, heavier and more expensive -- I don't think Subaru would go there.
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Old 10-04-2016, 03:05 PM   #35
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OMG, what do you do for a living specifically? I hope you are well compensated. I dearly miss my brief days of R&D.
I suspect ol @Spartarus is some sort of ...... scien-tiest ......


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Old 10-04-2016, 04:42 PM   #36
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I suspect ol @Spartarus is some sort of ...... scien-tiest ......
Ya think? Gotta be living that stuff to whip it out so quickly.
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Old 10-04-2016, 05:59 PM   #37
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Ya think? Gotta be living that stuff to whip it out so quickly.
Maybe he teaches a science course and he just cut and pasted that off his lesson plan ......


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Old 10-04-2016, 08:03 PM   #38
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Maybe he teaches a science course and he just cut and pasted that off his lesson plan ......


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Old 10-04-2016, 08:14 PM   #39
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Thanks, ....... I needed that!


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Old 10-04-2016, 08:36 PM   #40
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Originally Posted by Spartarus View Post
Heat plus air plus mechanical pressure, doesn't physically break moecules, but it accelerates degradation through oxidation. It doesn't need to be all that hot for that.

Oxidation is what I'm referring to when I say breaking down.

This happens in many ways, with heat and mechanical work, and especially with air entrainment.

This slowly turns your nice oil into a mixture of aldehydes, ketones, peroxides and carboxylic acids that don't do a great job lubricating things.

Oxidation in oils accelerates quadratically at temperatures above approximately 75 C. The rate doubles every 10 degrees. In theory, it will oxidize with ambient air, but not fast. Fast oxidation comes from rapid adiabatic heating of entrained air bubbles. Like when they get crushed between gear teeth.
YIKES! ....... this is getting more complex than I figured it would ......

Here is an interesting read:

http://www.machinerylubrication.com/...tion-lubricant

So, I reckon that the transmission oil in a FR-S/BRZ can be "broken down" by the process of oxidation.

So, if the temperature of the oil exceeds a threshold point, the oxidation process can take place.

As @Spartarus mentioned, "(I scraped it off the Internet) generally, oxidation will reduce the service life of a lubricant by half, for every 10 degrees C (18 degrees F) increase in fluid temperature above 60degrees C (140 degrees F)".

However, the manufacturers can add antioxidants and other compounds to slow down the process.

I want to thank @Spartarus for his insightful and thorough contribution to the discussion.

What is the conclusion .......hell, I'm not sure .....


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Old 10-04-2016, 09:03 PM   #41
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@JacksTrans is supposedly developing a transmission cooler
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Old 10-04-2016, 10:50 PM   #42
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@JacksTrans is supposedly developing a transmission cooler
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