Das Beast: My E30 track / street build

[dvallis]

Argh. I need a new fuel system.

Looked at my gas receipts for the last several fill-ups and the tank is only taking 8 gallons from empty to full. It's an 87 so I'm guessing the tank cross connection is plugged. Also the fuel pumps whine. May as well do it right and spend the money on new pumps and a new tank. (BM1A ~$200) Will probably replace the fuel lines with stainless as well. I looked at a fuel cell but I'm not crazy about the tire well location. Dangerous in a crash and not ideal for weight distribution. New stock tank is a better value.

Hmmmmm. A brand new tank, never been fueled. Safe to cut & weld. Sounds like time for a stock fuel tank with baffles!

[dvallis]

Saved ..... Maybe. Mechanic says my fuel gauge is likely gorked but can usually be saved by cleaning. Sounds like a weekend project.

[dvallis]

Some more lightweight racecar goodness today. Side skirts arrived. Part of the DTM Fiberwerkz stuff I found on Craigslist. Obviously no mounting hardware came with it, but I expected that. Aftermarket fiberglass usually requires a Body Work Artiste to install. Now all I'm missing is a fiberglass hood, trunk and sunroof plug.

Anyone out there know an honest, race car grade body shop in Austin? Just need to be reasonably competent.

[dvallis]

Test fitting the side skirts. Not bad. Will need to be blended into the wide body fenders.

[dvallis]

Today's project: Plastic front bumper upgrade with "IS" air dam install.

First, some background and terminology. The E30 "valance" is a metal structure that sits below and behind your bumper. In some cases it has plastic bits attached and acts as an air dam. There are also actual "air dams" that fit below the bumper, over the valance, such as one that came on the 325IS.

So, that's out of the way. I tried the pre-87 valance with plastic bumper but the fit was just not right. Too much gap on the sides and the bumper wasn't straight. The post-87 valance is indented on the sides, allowing it to fit right. Need to swap the post-87 valance back on.



Here's a look at the post-87 valance installed, and the IS air dam on the floor. Lights and inlets in the air dam don't line up with holes in the valance. Fabrication time.



Post-87 valance after some quality time with an angle grinder. Looks pretty good. Retained structural integrity and all the body mounting points.



IS air dam inlets are a bit too long. They touch the oil cooler. Angle grinder made quick work of that. I never realized how useful angle grinders are before this project. Now officially my favorite "go to" tool. And the Big Pocking Wrench. :devil:



Time to cut some mounting holes. Using 14x40 mm bolts in left, right and center.



Air dam attached to bumper. All bolts in.



Needed to cut holes in the air dam to access bumper mounting bolts.



Bolts attaching air dam sides to the valance. Will trim the plastic during final body work to match the wheel well arches.



And ....... here's the final product. I like it. Looks great. Once it's painted body color will look even better.





Declared victory, took a lap of the neighborhood and called it a day. Noticed the car feels more stable at high speed now. Will be interesting to eventually get a racing splitter on there and measure the actual down force. Fog lights will also get removed and turned into brake duct inlets.

It's definitely coming together.

[dvallis]

Next weekend project: Wiring cleanup and tar residue removal

Figured out how to remove the sunroof rear drains. They route to the trunk. Just un-attach from the inside plastic terminations and pull them out. 2 lbs gone.



Time to tackle the wiring harness some more. Did you know this mess is hiding under your dash? Also, here's some weirdness: This plastic box (65-81-1-373-726) is an "OBC RELAY". If it's not plugged in the car will crank but not start. Time to spend some quality time with the Electrical Tech Manual and figure that one out.



Looking better now. Pulled about 5 lbs of unnecessary wiring harness and cleaned everything up.



Relocated the ABS computer, OBC Relay and headlight switch to the dash center. This is only temporary since there will be a roll cage bar here. Ok for now.



I've been putting this off forever. Time to clean the darn tar residue off everywhere inside the car. Did my research and decided to use a heavy duty chemical called "Goof Off". Got out the safety goggles, respirator, elbow length chemical gloves and got to work.

Before ......



After ....... Good enough to be painted white after the cage goes in.



This Goof Off stuff works. It cleaned up the rear deck pretty good.



That's it for today.

[dvallis]

My gauge cluster backlights finally died today. For the last 3 months I had to give the cluster a good WHACK for them to come on. Loose solder joint or something. Time for aftermarket gauges.

After searching this forum and others I noticed there were no definitive technical write-ups on aftermarket gauges for E30s. Many "hook them to the cluster output" type of solutions. I am going to yank the whole cluster, throw it away and start from scratch with just signals from the wiring harness.

I'm a EE / Computer Engineer, so I can throw some light on the whole gauge mess. Let's start with the speedometer.

Our cars have a two lead hall effect sensor mounted in the differential. It's a magnetic switch that turns on/off in the presence of metal. A metal disk with 9 slots spins between two prongs of the hall effect sensor. This opens and closes the hall switch 9 times per rear wheel revolution.

The differential sensor does not create a signal by itself. It has to be fed a current, and this current turned into a voltage. In the schematic below, 12V is supplied to a current limiting resistor R1. The value does not really matter. I chose 10K to generate a 1.2 mA current into the hall effect sensor. Each time the hall effect switch closes, current flows from Pin 2 (12V) through the switch SW to ground. The voltage on Pin 8 (signal) is 0v. When the switch is open, pin 8 is pulled to 12V. This creates a square wave, 12V, 9 pulses per revolution. Speedometers such as a VDO 437 158 accept this signal and display it as an analog speed. The VDO gauge will auto calibrate, or you can manually input pulses per mile generated by your sensor. Doing the math for our cars:

1/tire diameter (1/in) x PI (rev) x (in/ft) x (ft/mi) x (pulses/rev) =pulses/mi
1/23.5 x 1/3.1415 x 12 x 5280 x 9 = 7,724 pulses/mi (i.e. the"Kalibrierung" value, also known as the "K" value. Means calibration in German)

Program this K value into the VDO and you will have a dead-on accurate speedo. Our stock units are programmed with K=7794. It's on the speedo face.



Here's a simulation of the above circuit at 60 mph. It the hall sensor generates a square wave at 129 Hz, period of 7.8 ms.



I'll be putting one of these in the car and posting photos.

[ncrmtrsprtsE30]

Nice build! I cant wait to see the wide body on!

My diffuser is Version 1.0, it does function, it was supposed to be temp until I build a nice one out of aluminum, but other things started happened. I am currently working on some other aero stuff.

[dvallis]

Good post on how diffusers work here.

[dvallis]

Planning the dash. View from the driver's seat. Gauges to scale.



Speedometer VDO 437-158 4" 140 mph $140
Tachometer VDO A2C59517117 5" 10 K rpm $119
Boost VDO 150-101 2-1/16" 15 psi $40
Clock VDO 370-155 2-1/16" 12 h $42
Oil pressure VDO 350-107 2-1/16" 100 psi $30
Oil temperature VDO 310-106 2-1/16" 300 F $29
Water temperature VDO 310-105 2-1/16" 250 F $29
Volts VDO 332-103 2-1/16" 12 V $29
Fuel VDO 301-020 2-1/16" 0-60 ohm $30
AFR AEM ATM-5790 2-1/16" 8-18 $212

[dvallis]

Today's project: Aftermarket Tachometer installation

Here's what showed up for Christmas. VDO gauges look good. They're a nice match for the BMW styling.


The only way to really figure out cluster wiring is take apart the connectors. There are wires with the same color on different pins. This is C2.


Decode everything using the Electrical Troubleshooting Manual


Here is an oscilloscope shot of the tach signal on C1.7 from the ECU. Looks nice and clean.


And .... it works. Going to bolt the tach here for now until a temporary dash is fabricated. The gauge backlight is a very crisp white. +1 for the VDO look.

[Northern]

If you're running MS for that turbo setup, you could just run shadowdash on a 7" tablet and skip the whole cluster thing. There's some circuit that needs to be completed for the alt to charge the battery in some models, but other than that, just keep the coolant and fuel gauges, rig up some dummy lights for oil pressure, and you should be good.

Not sure if you still plan to drop the CR to 7:1 with a .140" MLS, but I'm here to tell you to not do that. Kamotors makes 400ish with just ARP studs and maybe a regrind cam, the stock gasket is fine for that and more, as long as you don't get too crazy with the boost or timing.

[Mikerodrig27]

This is an awesome thread! Surprised you haven't put the fiberglass body parts on yet.

[dvallis]

Thanks Mike. Body work is going to be last. Still have to pull the engine, pull the wiring harness, rebuild engine, add the turbo, weld in the cage ..... you get the idea. ;-) I have a spreadsheet for it all.

Stay tuned for more of the dash build.

[dvallis]

Hey Northern ... It's going to be a Megasquirt build. Will use a tablet for tuning but manual gauges are a must for racing. No way I want to be in some 152 MPH sweeper and have my tablet reboot