GSpeed's 2015 BRZ- SCCA Super Touring Build

[acpstunts]

Any update on how the new oil pan performed? Any correction to the oil pressure concern? Also how much oil exactly did it add to the capacity? Thanks!

[Jonsey]

Originally Posted by GSpeed

I can't find the numbers now, but I was happier with the brake bias numbers I was seeing with the Endurance kit when paired with slicks with a higher coefficient of friction. We also want the brake duct capabilities we'll get with the endurance kit since the car will be racing competitively with a supercharger.

Very interested to see what you come up with for brake ducting. I played with trying to duct my endurance kit a bit but couldn't come up with a path I liked with the large hose. Also interested to hear what you think of the pads.

[GSpeed]

Originally Posted by acpstunts

Any update on how the new oil pan performed? Any correction to the oil pressure concern? Also how much oil exactly did it add to the capacity? Thanks!

It didn't fit. It hit the OEM exhaust manifold in a few places, so we never ran it. Not happy about that, but looking at how the drains were identical to OEM, I doubt we'd see any improvements in oil pressure.

Originally Posted by Jonsey

Very interested to see what you come up with for brake ducting. I played with trying to duct my endurance kit a bit but couldn't come up with a path I liked with the large hose. Also interested to hear what you think of the pads.

I corrected my previous post, the pad information was wrong. We're running Ferodo DS1.11s in the front, and the same PFC 13s in the rear. Going to try and get PFC to make/sell us some pads for these calipers in 13s, I think. I'll let you know what we find for duct routing. May wind up making something off the fog light housings, since we don't need window washers anymore.

Jake

[GSpeed]

The driver is complaining that the car feels very "jittery" over disturbances in the track. Naturally, I'd guess that's due to the fact that the Tarmac 2s don't have a high-speed blow-off, or digressive valving, or however you want to phrase it. Basically, the damping curve is approximately linear. Higher-end shocks actually lower the rate at which damping force rises at higher speeds, which means the car is able to absorb high speed impacts (curbs, bumps, etc) without upsetting the chassis.

So, let's see how that looks in the data. Here's a plot from the MXL2 in the BRZ, showing left rear shock position (on top) and velocity (on bottom).



And, for comparison's sake, here's the left rear shock of a Viper GTS with Penske 8765s traversing the exact same disturbance on the track:



Both graphs are scaled the same in the Y axis, and the X axis lines are 0.5s on both graphs. So you can see the Viper shock gets the oscillation under control much faster and smoother.

Not trying to say the answer is a set of $15,000 shocks, but this is a great example of why digressive valving is so important on a track car.

[MaximeT]

Thank you, I want a shock sensor now :/

Great work.

[GSpeed]

Here's some temperature plots from our sessions last Friday. As you can see, differential temperature is rapidly approaching unsafe levels. Most evident in the longer, first session it ended the 20 minute session at 275°F, after starting at about 110°F.

Considering we're still at stock power levels, this is pretty concerning. We'll need to do something about that.

This is also great evidence of why data systems and good sensors are important. Considering this is a lightly modified car, on a cool day, and differential fluid is still reaching 275°F, I'd bet money most people without rear end coolers are toasting their fluid and not even realizing it. It's too soon to say, but it could have something to do with the axle failure issues if the diff is overheating on a regular basis.

[Takumi788]

Originally Posted by GSpeed

Considering we're still at stock power levels, this is pretty concerning. We'll need to do something about that.

Quite concerning. Do you think a high capacity dif cover could solve the issue or are we going to need to go all out with a cooler kit?

[ichitaka05]

Originally Posted by GSpeed

Here's some temperature plots from our sessions last Friday. As you can see, differential temperature is rapidly approaching unsafe levels. Most evident in the longer, first session it ended the 20 minute session at 275°F, after starting at about 110°F.

Considering we're still at stock power levels, this is pretty concerning. We'll need to do something about that.

This is also great evidence of why data systems and good sensors are important. Considering this is a lightly modified car, on a cool day, and differential fluid is still reaching 275°F, I'd bet money most people without rear end coolers are toasting their fluid and not even realizing it. It's too soon to say, but it could have something to do with the axle failure issues if the diff is overheating on a regular basis.

Thanks for the data. Now, I know why all Super Taikyu & other 86/BRZ race in Japan uses dif cooler in ALL of em.

[GSpeed]

Originally Posted by Takumi788

Quite concerning. Do you think a high capacity dif cover could solve the issue or are we going to need to go all out with a cooler kit?

A larger fluid capacity, for any system, just slows the temperature rise by increasing the thermal mass. As you increase the heat input (more power) or duration (longer sessions) the temps will climb faster. So, yes, higher capacity diff covers help, but they're not addressing the root cause of more heat being generated than the system can dissipate. With a proper cooler system, you can run indefinitely without overheating since all the heat generated can be rejected. I know that's a long answer to a short question, but hopefully it helps.

Originally Posted by ichitaka05

Thanks for the data. Now, I know why all Super Taikyu & other 86/BRZ race in Japan uses dif cooler in ALL of em.

Yep. We're going to try and find a way to do a mechanical pump. Electric pumps aren't all that reliable in comparison.

[ichitaka05]

Originally Posted by GSpeed

Yep. We're going to try and find a way to do a mechanical pump. Electric pumps aren't all that reliable in comparison.

CS-v3 have one too... but not sure it's mechanical or electric pump.

[Takumi788]

Sorry if I am taking away from your build thread but you seem like the people to ask. I have done some research on the diff matter and found myself with a few questions.

1) At what fluid temperature can damage to the diff occur?
2) What is the optimal operating temperature for 75w-90?

I was only able to find this data on Motul 300 75w-90 which leads me to believe any higher that 212 degrees Fahrenheit starts getting dangerous. Is that an accurate statement?

PROPERTIES
Viscosity grade SAE J306 75W-90
Density at 20°C (68°F) ASTM D1298 0.897
Viscosity at 40°C (104°F) ASTM D445 72.6 mm²/s
Viscosity at 100°C (212°F) ASTM D445 15.2 mm²/s
Viscosity index ASTM D2270 222
Flash point ASTM D92 200°C / 392°F
Pour point ASTM D97 -60°C / -76°F

[GSpeed]

Originally Posted by Takumi788

Sorry if I am taking away from your build thread but you seem like the people to ask. I have done some research on the diff matter and found myself with a few questions.

1) At what fluid temperature can damage to the diff occur?
2) What is the optimal operating temperature for 75w-90?

I was only able to find this data on Motul 300 75w-90 which leads me to believe any higher that 212 degrees Fahrenheit starts getting dangerous. Is that an accurate statement?

PROPERTIES
Viscosity grade SAE J306 75W-90
Density at 20°C (68°F) ASTM D1298 0.897
Viscosity at 40°C (104°F) ASTM D445 72.6 mm²/s
Viscosity at 100°C (212°F) ASTM D445 15.2 mm²/s
Viscosity index ASTM D2270 222
Flash point ASTM D92 200°C / 392°F
Pour point ASTM D97 -60°C / -76°F

No problem! I wouldn't say 212°F is a dangerous threshold, no. Generally you'd consider that an operational minimum, since at temperatures above that water that's collected in the oil (through condensation, for example) will boil off.

Generally the gear manufacturer will provide the operational limits if there are any specific ones. For example, Emco lists a maximum temperature of 330° for 15 minutes, or something close to that (going off memory). Anything above, or longer, than that will alter the case hardening of the gears and can cause permanent damage. Granted, that's an Emco and it's abnormally durable.

If our diff never got above 275°, I would be a happy camper. But from the data posted above, I don't think that's going to happen.

[Pat]

So basically if a normally aspirated BRZ never runs more than 20 minute sessions we shouldn't be too concerned, right? But if we go longer than that it we should consider a cooler?

[GSpeed]

Originally Posted by Pat

So basically if a normally aspirated BRZ never runs more than 20 minute sessions we shouldn't be too concerned, right? But if we go longer than that it we should consider a cooler?

Yes, that's the gist of it. There are lots of variables like tires, power, outside temp, etc. but generally yes.