Mom's Spaghetti: Boosted 1991 325i Coupe

[Evan_VRM]

I got my first E30 when my senior year of high school - a red over tan 1990 325i coupe with 280,000+ miles. It served me well throughout college and well into 300k mile territory, including frequent (snow-tire equipped) trips to Mt. Baker in the winter- sometimes with 5 people and their ski gear! A couple years after I got my car, my mom was tired of daily driving the family Porsche 944 Turbo, and really liked my car, so she decided she wanted a black-on-black coupe with an automatic transmission. My dad and I found a clean car that meet the description down in Oregon, so we went and bought it the next morning. I became slightly bitter because my mom now had a cleaner E30 than I did. By the time I was a senior I started work on turboing my car, and while in the process it got totalled by an oncoming driver coming into my lane. I ended up replacing the core support and front sheetmetal but the car was never the same and I sold it. A year or so later I found a white on tan 1989 sedan with a snapped timing belt for cheap. I bought it, fixed it, and drove it to work every day. Not too long after I got the white car dialed in my mom was in the market for an E90 sedan (to match my E92 M3) but they were too attached to her E30 to sell it. We decided I would sell my sedan, give them the money, then take her car. I liked the family connection and wanted a coupe for my long-term E30 anyway, but by this point the car was a bit worse for wear. In early 2019 I finally got serious and tore the car apart to make it how I wanted - a turbo 5-speed car. This started with the 5 speed swap, 3.73 LSD and a rebuilt M20, and light turbo prep: Oil drain, ARP's and a Clutchmasters FX400. And a set of Style 5's. I drove it like this for a year or so, including a road trip to LA and back. Finally in late March of this year I found myself with quite a lot of newfound free time so I started the turbo portion of the project. I decided to go with a RSI manifold, Comp 6262 turbo, and MSPNP. Install was pretty straight forward. The hardest part was trying to fit the intercooler while keeping my ice cold AC. After I got it running I had some hiccups- a tuner from hell, shitty knock off injectors, a blown headgasket, garbage intercooler etc. But I worked through them over the next few weeks and finally at the beginning of August had all the bugs fixed and got a proper tune. The car made 416.8whp (uncorrected) and 410lb ft. at 17psi. And I love it. I've been driving it at every opportunity and don't plan to stop. I am a bit hungry for more power though.. I would run higher boost but I am unsure about how much the rods will tolerate. I also installed some GC coils. So that's how the car sits today. I still have a never ending to-do list but I'm loving just being able to drive it.

[varg]

Nice car. Keeping AC with a turbo setup is something a lot of people don't bother to do, personally I can't do without it. What's with that condenser? Is it an E30 parallel flow condenser turned vertical or is it off of a different car? Also where do you see full boost on a typical pull, looks like a little after 5,000rpm by the look of the torque plot, assuming you have a stock cam where the NA torque peak is before 4,500rpm.

[Evan_VRM]

It's a universal condenser mounted vertically with some lines I made up. Full boost depends on gear, but I definitely hit it lower than 5,000rpm. Probably closer to 3,500. This is with a stock cam.

[varg]

That's really good for such a large turbo. At second look power does fall off early for anything but a stock cam, I was seeing what I expected to see with that 6262. Fun powerband.