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Hey everyone! Has any one ever done or heard of a turbo e12 and if so, would be able to point me towards that info? I would hope to keep the same engine so it still fits without much hassle. I want to be able to add more power without doing a complete engine swap. I appreciate any feedback you may have.

Thanks and stay safe.

alpina B7
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zanes turbo
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car of the month Jan 2000

adika wrote: ↑Wed Dec 16, 2020 9:01 pm Hey everyone! Has any one ever done or heard of a turbo e12 and if so, would be able to point me towards that info? I would hope to keep the same engine so it still fits without much hassle. I want to be able to add more power without doing a complete engine swap. I appreciate any feedback you may have.

Thanks and stay safe.

Back in the '70s to early '80s there were bolt on turbo kits for the M30 six with high mount turbos, from H&B, Callaway/Miller & Norburn, Kormann, BAE. BAE you can see here on a 1976 530i Turbo:

530i Turbo BAE

Hard to find one of those kits now, closest would be to get a turbo system off an e23 745i Turbo. Those have the benefit of an intercooler too.

Vintage turbo kits for e12s occasionally pop up but they're generally either incomplete and/or need rebuilding. I know the appeal of a turbo kit is bolt on performance but it's more than just adding the plumbing if you want a motor that stays together. Compression ratio (different pistons), methanol injection, stronger head gaskets all need to be addressed if you expect to boost an m30 beyond a few pounds of pressure. You can also improve the performance without going the turbo or swap route. There's lots of information here on Motronic conversions and cam choices. Header and exhaust options are still available too.

Really intended more for E28s, but TCD is still making them I believe. Not cheap, but HP for BMWs doesn't come cheap unfortunately.

http://turbochargingdynamics.com/?wpsc_ ... tegory=m30

HP doesn't come cheap for any make. There is no such thing as a cheap Craig's list LS motor or swap. I believe the bolt on kits back in the day were running around 5-6 psi, working with stock compression 8.1:1. And that was enough to get 0-60 mph in 7 to 7.5 seconds on a 530i or 630i, which was flying in the late '70s. But, if you want 300-400 hp from a M30, you are going to need an intercooler, special head gasket and many other things, including careful boost enrichment provisions.

Depends on what you want, or how much you want? If you go beyond 300 hp, you are going to have to start thinking about gearbox, halfshafts, diff etc standing up to the torque and heat generated. Going from a stock 530i to a M90 motor with no pollution controls would be very noticeable.

Those high mount turbo kits put the turbo awfully close to the aluminum head, which was why on the 2002 Turbo and e23 745i BMW put it low.

This is Bill Gau's Bavaria with a 3.5L, injection and a Callaway turbo kit. Would be enough for most.

Blown Bavaria

The late 80s 3.5 is probably the best candidate for a stock turbo, the heads rarely crack and the head gasket design makes it slightly less likely to blow a HG. They used to be everywhere and dirt cheap but as E28s have become rare and collectable, not to much.

But even a stock low compression 3.5 is a huge difference. More torque than HP, but some of that too. To me it feels like a small block V8 from the 60s. Put your foot down at seemingly any RPM and it just starts pulling. Want to accelerate from 75 to 100? Just put your foot down, no downshifting, it just pulls.

But a 10:1, 3.5 is another huge step up. Still more a torque meister than top end, but a definite wow factor. When I finally got mine running right, admittedly with very, very old and hard tires, 225/50-16, I could step on the pedal in first and break the tires loose. Rolling at 10 or 20 MPH, not dropping the clutch or anything, just step on it.

Mike W. wrote: ↑Sun Feb 28, 2021 1:56 pm The late 80s 3.5 is probably the best candidate for a stock turbo, the heads rarely crack and the head gasket design makes it slightly less likely to blow a HG. They used to be everywhere and dirt cheap but as E28s have become rare and collectable, not to much.

But even a stock low compression 3.5 is a huge difference. More torque than HP, but some of that too. To me it feels like a small block V8 from the 60s. Put your foot down at seemingly any RPM and it just starts pulling. Want to accelerate from 75 to 100? Just put your foot down, no downshifting, it just pulls.

But a 10:1, 3.5 is another huge step up. Still more a torque meister than top end, but a definite wow factor. When I finally got mine running right, admittedly with very, very old and hard tires, 225/50-16, I could step on the pedal in first and break the tires loose. Rolling at 10 or 20 MPH, not dropping the clutch or anything, just step on it.

The turbo kit Miller & Norburn sold in the old days was engineered by Reeves Callaway. He must have been a very smart fellow because it truly was a bolt on, and when you consider that limitation it was effective. Enough to give a 320i the acceleration of a 528i. There was a vapor separator cannister for the turbo's oil supply related to the oil pan, and a screw in pressure switch going into the intake manifold linked to an electric solenoid for boost enrichment. The kit got rid of the EGR and smog pump, and could still pass, at 49 state level reading between the lines.

All 1978-87 Euro 3.5s were rated at 160 kw (218 hp DIN) and 310 Nm (228 or 229 lb/ft) at the respective speeds of 5,200 rpm and 4,000 rpm. They were supposed to use 98 RON leaded fuel, which is about the same as today's 93 unleaded (average of RON & MON).

The world 3.5 (e32, e34 motor) in SAE was 208 hp at 5,400 rpm and 225 lb/ft at 4,300 rpm. By comparison a 1985 Mustang GT 5.0 had 210 hp at 4,600 rpm and 265 lb/ft at 3,400 rpm, but, the Ford 302 V8 weighs 200 lb more than the BMW M30 six. Even a modern LS motor weighs 100 lbs more.

The 3.5 six is a very efficient motor because you are getting almost all the displacement you can get from a given block weight. Even the BMW M60 3 liter V8 from an e34 530i weighed 60 lbs more according to BMW.

I think Alpina's e34 Alpina 3.5 B10 motor made 260 hp DIN without a cat. According to Autocar magazine 50-70 mph using the lowest gear you can, took exactly the same time in the e12 M535i, e28 M5 and e34 M5 3.6