Photos and Words by Zach Taiji
Many of you probably know by now that my buddy Diego has been accumulating parts for his E30 Turbo Build. He started buying bits and pieces last summer with an increased workload and time off from school. At least six months later, and the build has begun. Long nights were ensued in his secluded garage within the neighborhoods of rural Sequim, WA. All we needed were tools, an old BMW, a snail (namely a Holset H1C), and some other goodies.
We started with this well taken-care-for gem of a BMW E30. It’s a 1987 325is with the reliable and fairly fuel efficient Inline-6 M20B25 engine. Definitely not the ideal candidate for most E30 turbo applications, as most people usually swap in the S50 from the E36 M3, but Diego wanted to do something different that would prove a very fun daily driver and nothing too flashy.
First off, he swapped in a modified stock differential that went from 3.73 to 2.79 to accompany the Turbo boost, a remanufactured driveshaft with new joints, and also gave the transmission a couple goodies so that it could hold up from the extra power. A Gripforce F1 stage 3 ceramic clutch and heavy duty pressure plate would be enough for now. It wasn’t easy working on the transmission and differential, as the bolts holding them up were tucked away into the frame tunnels and a full removal of the exhaust was necessary. The flywheel was also resurfaced while work was done on the transmission, and a new slave cylinder installed.
Once that was finished, we moved onto the next step, which was preparing the motor for a little extra induction, and getting most of the maintenance out of the way so that the car would be in good health. The first thing we did was replace the Timing Belt, Waterpump, Pulleys, and drain the BMW of its fluids. The timing belt was a bit time consuming as we had to get all other belts and pulleys out of the way, and slipping it on was a bit tough. We also had a bit of trouble trying to find the timing mark at first, but thank god for Bentley Manuals!
Soon after was preparing the motor with a Valve Lash Adjustment and giving it stronger head studs (12.9 grade metric blue-coated steel) as well as replacing all gaskets and cleaning it up a bit. Also pictured below are the Bosch 30lb/hr “red top” injectors installed. I should also mention that Diego is going through school to become an Auto Tech, so he doesn’t just look like he knows what he’s doing!
Now most of the hard stuff was out of the way, and up next was the fun. Let me introduce you to Snail and its companion. It’s a Holset H1C Turbo out of a Cumminis Diesel Truck mated to a 321 SS OBX manifold adapter (T3) with 44mm WG provision. Boost is expected to kick in at right around 3k with this setup.
But first we had to do a little more preparation. An oil return line bung was welded onto the oil pan and the intake manifold was drilled for vacuum lines . We didn’t have a welder handy so we had the pan taken to a local machine shop, who did it no problem.
Then a couple other things such as super stiff UHMW motor and tranny mounts were put onto the car as well as a poly diff mount. These really help the drivetrain put power down with minimal deflection and movement. They’re extremely stiff but worth the extra cabin vibrations.
Now was the fun part. The turbo was bolted on, along with the manifold, 44mm Wastegate, and type-RS Blow Off Valve. A custom 3″ Downpipe was also created with various flex pipes and couplers. To make sure that the on board computer and electronics would be able to handle such foreign objects, an AFM tweaked for 30lb injectors, M20 A/F Management, Turbo Charged Dynamics Tune, and Motronic 1.3 524 ECU were installed.
Turbo Charged Dynamics Tune which is good for 12 PSI:
Just a few more things needed to be done, and she would be up and running. First thing was a 29x11x3″ FMIC. The intercooler was so big that the bumper wouldn’t fit, so Diego decided to run the E30 without a bumper cover for a little while until he could trim it.
Lastly, Gauges were hooked up into the car. Starting with boost, oil pressure, then AFR’s.
This little E30 would then come alive. We took it for a test drive and I got a chance to get a little video, the car really opens up once it hits boost. Diego didn’t push the car 100% because boost was spiking a little higher than he was expecting (around 20psi). He seems to have sorted out the issue since then, which is believed to be too big of a Wastegate spring and loose Diaphragm. The only other thing needed to be done to the car is getting a full exhaust welded together, which should be happening pretty soon. Estimated power to the wheels and a butt dyno say anything near 300WHP, which is quite a lot for a 2600 lb car! Once everything is all dialed in, the E30 will be getting a proper dyno. Until then, I’ll leave you with this teaser; stay tuned for a better video and more photos of the car soon!
E30 Turbo Teaser from azntaiji on Vimeo.
