Dan's 3.5CSi project

[Clubsport_CSi]

Okay, to get it started, here is some first information on my own E9, which originally rolled off the line as a 3.0 CSi.

As already stated, two points up front that matter to me:
• From the start, I knew that after the overhaul I wouldn’t end up with a showroom-perfect car like the ones often presented here. That was fine by me, because I know the limitations of my own skills and I wanted an E9 to drive without constantly worrying about something going wrong and instantly racking up four-figure -or even higher- repair bills.
• In my view, the major tuning work by renowned “house tuners” in the late ’60s and ’70s, BMW’s own "accessories", and the E9-based racing cars justify extensive modifications to the base car and free you from any accusations of desecrating automotive heritage - as long as you stay period-correct (think even Schnitzer’s Green Monster)...

Two exterior photos to get an impression (they are a few years old, but I was short on time - both for wrenching and for shooting pictures). Still without major modifications as did not yet start project "weight loss" (my wife is fan of the chrome bumpers... but I got a nice black fiberglass rear bumper stored in my garage...).

 

[Clubsport_CSi]

To get it started somewhere, I wrote up some details on the heart of the car, the drivetrain:

Under the hood sits a 3.5 liter M30 from the B10 E34/B11 E32 — the final series M30 Alpina version with a catalytic converter (not here, obviously) and 254 hp. In my opinion, that swap brought huge benefits and was the best choice for day-to-day usability. For me, the original D-Jetronic was a nightmare to dial in and had a magical tendency to re-adjust itself after sitting for a while… With the Motronic, it’s simple: hop in, fire up, have fun. I am sure that there are others loving the D-Jet
or a nice set of carburetors - and they for sure have good reasons; but I am a huge fan of a bit more current fuel injection systems (there will be a change in the ECU used soon, to get rid of the AFM).

Of course, a bunch of additional mods were necessary to fit in the engine, including:
• Converting to an electric fan (Spal; removing the viscous clutch)
• Switching the throttle linkage from pushrod to cable
• Relocating the battery to the trunk
• Making room for the brake booster by modifying the brake booster’s mounting sleeve, shortening and retapping the master-cylinder pushrod, rewelding the flange, installing a small off-brand booster, etc.
I know that many people retrofit the 02 booster (did not know that an expert renewing the 02 booster is on this board when I did the swap) or the H31 hydro-booster, but the latter runs off the power-steering pump (I thought that's not the best choice if you consider pure mechanical steering somewhere in the future) and, in my experience, is hard to modulate by foot.
I initially tried fitting the oil-filter housing and cooler from one of my old 635 CSis, but they didn’t fit well - so I ended up using these parts from my old M5 3.6 E34. In hindsight, I probably didn’t need the oil cooler at all; I’ll keep an eye on temps and decide if it needs removing. Anyone made a similar experience?
For the gearbox, I went with a Getrag 265/5 dogleg with that first gear down to the left — a fantastic concentration exercise if you’re used to automatic shifts every day. I also installed a short shift kit using the Z3 shifter - mind you, I only used the one from the 3.0, not the M, yet the throws are almost too short. I’ll need to fine-tune that later...
The transmission bolts to a 3.0 CSi flywheel that Bamotec (located in Nuremberg) lightened and balanced (I recall it even being lighter than the S38B36 unit).
Of course, I had the driveshaft shortened by about 8 cm, rewelded, balanced, and fitted it with a new U-joint and center support bearing. Luckily, everything lined up perfectly during the build.

At the rear axle there’s a 40 percent limited-slip differential—probably the 3.45, though I might’ve used the 3.25; I’ll need to check my build journal. I once planned to add a B7 Turbo-style diff cooler, but it hasn’t been necessary so far.

A quick word on the exhaust: I didn’t fit the original Alpina header but a Hartge unit. At the point where the Hartge H5 3.5 adds an X-pipe, we merged the 50 mm primary tubes into a single 72 mm pipe in my setup. From there it runs in one pipe just like stock. My buddy and genius mechanic Klaus and I built the whole system ourselves — I ordered the parts and held the tubes while he shaped and welded them. The tailpipe is a shortened chrome S-pipe from a Diesel Sport ESD from the 530d E39 (some of you may know these). The flanges are positioned so you can easily disassemble each section. And the sound? well.. LOUD. And did not add too much sound insulation on the inside of the car. It aligns with the fact that the radio does not work well; you would not hear it anyways...

I have to admit that I got two left hands, so I have to shout out my Lower Bavarian crew, without whom I’d never have finished the motor swap!
So… I got carried away - sorry 'bout that.
I will try to post some more pics and information soon, but I am still a bit ashamed because I did not yet invest a lot of time to clean things up.
So please be gentle with your comments.

To be continued soon - warm regards,
Dan

 

[Clubsport_CSi]

Unfortunately, I lost some storage space, so I had to re-locate some parts...

 

[sfdon]

BIG exhaust…

 

[Clubsport_CSi]

BIG exhaust…

Well, we know, sometimes size does matter, right ?
Not sure if you indicate it might be too big?
The B10 and B11 do have 2x55mm tubes; same size from header collector to Y pipe on my car; afterwards I calculated that I need to have an approx. 78mm diameter single tube to obtain an area of the cross-section equal to the dual pipe setup. I think 78mm was not available as not a standard size so I went 76mm.
Did I calculate wrong?