Das Beast: My E30 track / street build

[dvallis]

Haven't posted in a while so thought I'd share what we've been up to. Scale project is coming along well.

Load test. No deformation of platform


At the electronics lab. No load voltage output 0.6 mV


Output is 3.2 mV with me standing on it


Adding the circuitry. Scale measures the analog voltage locally with a 24 bit ADC, converts to digital data which is sent over an ethernet cable to the main box.


Here's the digital data. Each rising edge of clock samples a one or zero in the 24 bit word.


Putting it all together. You can see digital data for applied weight displayed on the LCD


Better load capacity and more accurate than your average bathroom scale :-)


Building the brain box


Adding keypad, power connector and scale connectors. Dust caps are a nice touch.


I'll use chopped and stripped ethernet cables to break out wires on the inside of the plugs


Adding the MCU board


LCD gets mounted on top with standoffs


So, there it is. Looking good. Lots of wiring to do now, and more code to write.

[Digitalwave]

That is awesome, but also seems like more work than it would be worth (time = money and all that).

[dvallis]

It's a hobby. Got anything better to do during COVID? :-)

[dvallis]

Scale is nearly done. Need to rinse & repeat three more weight platforms. Turned out good. We weight the Beast soon!

[dvallis]

Weight scale finished. Nothing ELSE to do during COVID. :-)



Drumroll .... Here's the weight with half tank of gas. So 2760 dry.



Here's the balance with 230 lbs of simulated me and gear in the driver's seat. Took some adjustment on each of the corner springs but we got a pretty good setup. 50/50 front/rear, left/right and 50/50 cross weight.



We're taking it to Harris Hill for a test & tune in the next couple of weeks.

[Digitalwave]

Very good balance numbers. Actually, some of the best numbers I've seen on an E30. Surprisingly heavy though! I just balanced my car again 2 weeks ago and it came in at 2,348 (wet, but without driver).

[dvallis]

That makes sense if you look at these numbers.

Here's my weight with cage, but without turbo etc. Pretty close to what you're at.



Then add other performance parts that weigh more than stock.



Then with me in the seat :-)



Looks like I'm ST3 in NASA, which is fine. Looking forward to running.

[Digitalwave]

That's interesting to see it broken down. I have about 40ft of tubing for my half cage, but otherwise have most of the other stuff save for the turbo kit and diffuser (both of which are heavier than I expected to be).

In Florida you'd probably need to be running 275 width Hoosier R7s and drive the absolute piss out of the car to hang in ST3, but no matter what, I am sure you are going to have a shit eating grin when you finally get to race this thing.

[dvallis]

That makes total sense. With a half cage and similar weight reduction you clock in right around 2,340 on my spreadsheet. Very cool for the numbers to line up.

Will be doing a lot of shakedown this weekend. Alignment tweaks mostly. Also adding hood vents next week. Gotta get the HOT out. :-)

[ForcedFirebird]

Fun note: 1.5" .120" DOM wall tubing weighs more than 1.75" .095, even though they both spec for the same vehicle weight. ;)

[dvallis]

This picture, just because finding oil leaks with UV fluorescent dye and "burn da eyes outta ya" UV lights is cool. Yes, we have safety goggles.

Minor seep from the top right front of the head. You can see it running down the side of the water pump etc. We replaced ALL those seals during the rebuild, so going to tighten the head studs and call it good.

[dvallis]

Some of you may remember this:



Which is actually this:



I finally got around to re-programming the whole AIM system today, and it ALL WORKS. I'm frigging overjoyed.

Here is the "warmup" screen. Oil pressure and fuel pressure are coming from sensors separate from the ECU. Good to seen them working. Rest of the data is via CANBUS from the ECU.



The "crew" screen shows things my crew chief might want to know before I go tearing off into the wild blue yonder.

VBAT : battery voltage
IBAT : current from the battery
IALT : current from the alternator
IBUS : current on the main bus.

And great for setting brake bias!

FBRK : front brake pressure
RBRK : rear brake pressure

Just noticed my brake pressure sensors need zeroing. Easy stuff with AIM. TPS gets calibrated through Megasquirt.



Diagram for clarity



Suspension travel sensors are also working. Need to zero them.



Took the car to an "undisclosed test location" (aka Mopac Expressway) and did laps of a to remain nameless service road loop. Here's a cut of the data log from Race Studio. Really interesting to see what the car is doing under load.



So, with that all working I've got 30 semi-private laps of Harris Hill scheduled for next month. There will be an obligatory track school, "Are you an idiot" checkout ride, then time to get some data.

[ForcedFirebird]

UV is fun. The stock ECU chip is a 255kb PROM, UV erase. Peel the sticker off, set it in the sun for a few days, and BOOM, blank slate. Amazing how photons can zap electrons out of memory. I have an old machine at the shop with 19kb of bubble memory...it holds about 350 lines of code.


EDIT: I LOVE the science, but WHEN CAN WE SEE RACE FOOTAGE?!?!?!

[dvallis]

A frigging PROM? No way? I used to code on those back in the stone age. Had a little UV shoebox for erasing them. How do you re-code an erased E30 prom?

Track footage next month. Actual race footage? Soon ..... I have a new Bell M8 SA2020 helmet coming next week. Getting the HANS re-certified. Need a new suit but the old one should be fine for DEs.

[dvallis]

Race Studio GPS data export into Google Earth. Pretty cool.