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Old 10-04-2016, 08:30 AM   #29
DarkSunrise
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Quote:
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.

Quote:
Originally Posted by GSpeed View Post
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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GSpeed (10-04-2016), humfrz (10-04-2016)