GSpeed's 2015 BRZ- SCCA Super Touring Build

[GSpeed]

Originally Posted by redlined600

I think you guys would become quite popular if you could sort out a solid solution for E85 fuel starve.

I like the oil pressure sensor, definitely going to look into that.

Keep up the good work.

Thanks for the kind words. Fuel starvation is definitely on our radar. I don't want to start posting about it until I have something worth talking about, though.

[GSpeed]

We had another test day today. Since we cooked the NAPA pads last time, we installed some PFC Z-rated pads on the front. We were hoping to run some full race compounds, but they (PFC) are shut down doing annual inventory right now, so we couldn't get any in time. We had these on the shelves, though, so it was a great opportunity to test them out.

We got on track about 9:30 while it was still cool out, and snapped off a 1:32.4, our new fastest lap for the stock configuration. Predictive was showing a high 31 was possible, but we just couldn't get a clean lap in (lots of traffic). We ran 11 laps for the first session, then after looking at the tire temps, decided to add some camber bolts. We added about 0.8 degrees of negative camber, which really changed the balance of the car. It went from pushing through slow corners to rotating with a little throttle. It clearly could use some more camber in the rear to match what we've added to the front. We actually slowed down a bit, but that's likely due to the increased temperatures.

This was our first run with the engine sensors, wheel pots, and tire temps (rear only right now). It'll be a lot of fun to analyze all the data we collected this morning. I'm looking forward to getting some actual pitch and roll information before we start messing with springs and sways. I'll put up some stuff in the Aim system's thread about the installation.

We've logged 167 miles of track time in the past two weeks. Tomorrow morning, we're going to run a session or two while it's nice and cool on the RE71Rs and see how much time that gets us.

Summary
Configuration: Stock suspension and powertrain, PFC Z-rated front pads, OEM rear pads
Best Lap: 1:32.4

[philooo]

can't wait to see the temperature monitoring setup !

[JS + BRZ]

Subbed. Awesome!

[redlined600]

Since you have re71rs on stock wheels please run them back to back with 245s on 9" wheels (making the assumption that you're heading in that direction.) Except maybe on the longest tracks I'm convinced that 245s are net faster.

[GSpeed]

Originally Posted by redlined600

Since you have re71rs on stock wheels please run them back to back with 245s on 9" wheels (making the assumption that you're heading in that direction.) Except maybe on the longest tracks I'm convinced that 245s are net faster.

While that would be an interesting test, we don't have stock size RE71Rs. I'm sorry if the picture was misleading. The picture is of the stock tires, and the RE71Rs were installed (on RPF1s) after that picture was taken in preparation for tomorrow's test.

I would enjoy getting that information, but I don't think we could justify buying a set of tires for one or two tests. We bought 245s since we're planning on running them for a while as we test other components. Maybe once we're through the RE71Rs we'll test some other competitive tires like Rivals, but at that point, honestly, it'd probably be time for slicks.

[redlined600]

Originally Posted by PST

While that would be an interesting test, we don't have stock size RE71Rs. I'm sorry if the picture was misleading. The picture is of the stock tires, and the RE71Rs were installed (on RPF1s) after that picture was taken in preparation for tomorrow's test.

I would enjoy getting that information, but I don't think we could justify buying a set of tires for one or two tests. We bought 245s since we're planning on running them for a while as we test other components. Maybe once we're through the RE71Rs we'll test some other competitive tires like Rivals, but at that point, honestly, it'd probably be time for slicks.

Fair enough. Carry on!

[GSpeed]

Our test day today went really well. We bolted up a set of 245/40/17 RE71Rs on some 17x9+45 RPF1s, and immediately dropped 4.8 seconds! Quite a substantial improvement, which really shows how important tires are to a car.



Another member was out with his modified BRZ, so we had a great opportunity
to directly compare to another car.



With his massive Stoptech brakes, he was able to outbrake us pretty handily and passed us in short order.



We were clearly losing time to him in the twisty section as well. On the stock, soft suspension weight transfer just takes so long, so we've got some coilovers on order to get the car lower and speed things up a bit.

We ended the second session about 11:00. Track surface temps were nearing 100F, and we were roasting the RE71Rs. The car was being pushed hard, and the tire temps showed it. Taking measurements in the pits, we saw the shoulder of the right front was over 200F. The right front tire is always abused on counter clockwise tracks like this.

For our first session, we intentionally started the session with a slightly low tank of fuel (5/8ths full). We wanted to provoke some starvation and see how it looked on our fuel pressure sensor. The results were pretty interesting.

Here's a plot of about 15 minutes of track time. You can see pressure is sitting pretty right around 58psi or so, but when it starves, it dramatically plummets. There are six major events there, each one lasting for anywhere between 5 and 15 seconds. Every one of them occurred after an extended corner.



What's interesting is that the driver did not always notice, and the car certainly wasn't stumbling for the entire time pressure dropped. So this tells us the problem is much more prevalent and serious than it would initially appear. I would love to see similar plots from other users with modified cars. We're not really supposed to sell parts in these build threads, so I'll make a separate thread, but we just got our first batch of fuel pressure sensor adapters in. The more data we can get the better we'll be able to identify a solution.

Oil temperatures were also pretty high for the ambient temperature, so we'll start working on an oil cooler setup. Anyone have a wishlist, or anything specific they want in a cooler setup? Speak up now!

Summary
Configuration: Stock suspension, camber bolts, 245/40/17 RE71Rs
Best Lap: 1:27.6
Notes: Fuel pressure is ugly, oil temps are high. Stickier, wider rubber is good.

[philooo]

Originally Posted by PST

we just got our first batch of fuel pressure sensor adapters in. The more data we can get the better we'll be able to identify a solution.

PM me for the fuel pressure sensor I like what you are doing

[Toyarzee]

Awesome stuff. Much respect. Keep it up!

[Bramick]

Great to meet you today. Stop by tomorrow to check out the JRSC

[GSpeed]

As of today, I've finally got all the sensors working on the BRZ. The analog inputs on the Aim dash used Binder 719 series connectors, which are meant for 24ga wire. I didn't realize that at first, and ordered a spool of 20ga 3-conductor cable out of habit. I wish I'd paid closer attention, because that made soldering much more difficult than it had to be:



Little tiny solder cups, over and over and over. My eyes hurt at the end of each day. I did not want to cut the Aim harness, though, just to better future-proof the setup, so it was worth the hassle. The other end of the cables have 3-pin DTM connectors, which are fairly common. I didn't get any pictures of those.



The wheel pots were a challenge to figure out. Here's what I finally settled on for the fronts. I'm not a HUGE fan of the resolution on the front, but it should be sufficient. The MXL2's ADCs (analog to digital converter) are 12-bit, which means over the full range of the potentiometer, we've got 4096 (2^12) discrete values. For a 4" pot, that's near-as-makes-no-difference 0.001" resolution. I measured my install ratio as 3.822:1, so the front pot will be able to pick up a wheel displacement of 0.004". Good enough for a sports car.



Here's a close up of the lower mounts I machined for the fronts. I didn't want to drill into a control arm, so this guy just clamps on to the little hole in the control arm with a big turned "washer" on the bottom.

The AEM pressure transducers had crappy connections supplied. If you're going to use those, I'd highly recommend replacing the connectors with Delphi PN 13602480 (Mouser link here.) Much better quality, and it matches the connectors under the hood a bit better, too.



The rear shock pots were somewhat easier to install (since the wheels hopefully keep pointing the same direction the whole time). The right rear was mounted to the filler neck bracket that had a hole in the exact right location, with a little aluminum spacer to keep it at a good angle.



The left rear needed a little aluminum bracket added out of some scrap sheet and rivnuts, but it wasn't too much trouble either.



The lower ends of the shock pots were mounted to the lower shock bolt with an adapter turned out of some 3/4" hex stock. I like this method since it prevents anyone from accidentally using the pot as a droop limiter.

Front and center in that picture above are the rear tire temperature sensors. They're little 1/4" x 1" IR units that work with any thermocouple reader. Really neat little sensors. The lower half of that aluminum arm is held on with nylon bolts, so in the event of an impact, it'll tear away cleanly rather than get all caught up in the tire and cause problems. The wires lead up to some conventional thermocouple connectors that would be able to pull free as well.





The TC hub for the rear was mounted in the spare tire well with rivnuts, and some TC wire was used along with Binder 712 connectors to make some extensions to outside the trunk.



Since the TC hub was so far from the dash and CAN expander, I had to make an extension. Once again, 20ga was a mistake. 24ga would have been much easier to work with for this application.



Just like with the wheel pots, the front tire temp sensors were no fun. I finally settled on mounting them to the chassis rather than the upright. The data logs show no more than 90° of steering input at any point on a clean lap, so the sensors should have a good view of the tire at all times.



Here's a view from the top to give you a better feel for where they are. The fender liner was trimmed and replaced, but you can still see through to the tire from the engine bay. Once we're done testing tire temps, we'll probably replace the fender liner with an intact part.



The Aim thermocouple hub was mounted to the right side of the engine bay, so we didn't need to make an extension like in the rear. The fourth wire there is a reference IR sensor mounted in the belly pan by the right wheel to take track temperature measurements real time, so as to make it easier to compare tests from different days.




Thermocouple wire was run across the bay and along the strut brace. You can see the track reference sensor splitting off from the three tire temp sensors.



Here's how the engine bay looks currently. Thermocouple wire and instrument cable everywhere! We wouldn't have it any other way. It's hard to make informed decisions about performance modifications without the right data.

Once everything was hooked up and double checked, it was time to calibrate the wheel position sensors. Here's how we did it.

Tools required:

-Bore Gauges
-Calipers
-Floor Jack
-2/4/6 precision gauge block



A particular position was marked on the rocker as near to the wheel well as we could get. The distance from that point to the floor was measured and recorded, as was the shock pot position. The floor jack was used to very slightly raise the car, and a new set of values was recorded. This was repeated 20 times or so for the front and back of the car.



The values were put into Excel, where a near perfect linear fit was found (R² values of 0.9998 and 0.9997). For the front, the wheel moves 3.82" for every inch of shock pot movement, and the rear wheel moves 1.27" for every inch of shock pot movement. Given the rear installation location, this is probably very, very close to the rear shock motion ratio.



Now that we've got wheel pots on the car, we can do really fun stuff like calculate chassis roll and pitch. Here's a plot showing lateral acceleration (purple) vs. chassis roll (green). We've got a strong inverse relationship like you'd expect, and you can actually see the roll damping working. (Green downward slopes are smoother than purple upward slopes).

This information was also put into excel where we saw an average roll stiffness of 2.5°/G. I say "average" because the progressive spring rates are apparent in the data. Low lateral loads give a higher amount of roll per G. Once we get the new coilovers on the car, I'll put the springs on the spring tester and plot out the actual spring rate curves.

I hope everyone is enjoying this post as much as I'm enjoying doing the work!

[King Tut]

Originally Posted by PST

I hope everyone is enjoying this post as much as I'm enjoying doing the work!

I enjoyed it. The pics could be a little bit bigger though as they don't quite fill up two 24" monitors.

[Bramick]

21:9 monitors are out. Fill one of those!