MyE28.com

Caught this on my CCA chapter's Facebook page yesterday.

Thinking of selling my ready to boost e34 5 speed comes with a extra engine that has a blown hg and 5 speed tranny looking for trades of something must be manual don't want ur shit box projects please prefer it to be lowered can add up too a grand cash if I like it needs a little message me for more info

I asked him what made it "boost ready" and what engine it was, he says m50b25 non-VANOS and it has a Cometic headgasket. Dude sounds like a bit of a young punk, honestly. I think he's selling an e34 525i automatic with an extra engine and 5-speed transmission along with it. If anyone is interested, I can point you in his direction.

I'm curious about how "boost ready" a setup like that really would be though. The m50 non-vanos is a 10:1 motor. I don't know if he put a thicker head gasket on it or not, but the static CR would still be pretty high. How much boost would that be able to run safely on pump 93 and a chip? Or would you need to go to standalone to pull it off?

All just curiosity, I have no interest in this project at the moment, but I'd appreciate any info you guys might toss out because it intrigues me. I like the m5x series of motors, and I think a mildly boosted one in an e28 would be a great car.

Jeremy, I also like the M50XX engines. Let me play devils advocate here: what makes this engine more interesting to turbocharge than the M30B35 in an E34? Seems to me the M30 would be safer, and probably stronger. Certainly the CR in the M30 would be more attractive to me as a boost-ready engine. So, is an M50B25 a better way to go than an M30B35 for such an E34 project, with boost? An interesting question.

Well, you get the 4-valve head and much better top end pull. You'd lose some midrange torque most likely compared to an m30 and have a lower threshold for boost on pump gas on a stock motor due to the compression ratio. The m50 is a much more "refined" motor than the m30, too. The m5x is also more compact (around m20 size) leaving more room to work for piping, and the smaller displacement would probably yield better cruise fuel economy as well.

People get insane boosted power from the m5x and s5x motors, but those are highly modified examples. I'm curious about what stock could get you.

I think there's even a twin-screw kit that fits on the m50. Expensive, but damn would that be nice.

Jeremy wrote:I think there's even a twin-screw kit that fits on the m50. Expensive, but damn would that be nice.

This is actually a great supercharger kit, almost identical to the S50 kit for the M3. I can tell you from personal experience that the M3 Vortech supercharger, even the early version, is superb in the M3 (and the M50/S50 engines are very similar). I saw the entire build, even participated a bit, and the end result was very satisfying. I think I'd go this route over a t'charger. In the end, the Vortech supercharger in the M3 gave a new 1 series, with its twin turbo setup, a real run. 1/4 mile time was 13.8@102 mph (at mile high altitude). So if you could replicate this in an M50 in an E34, it would be something.

Still on the fence about whether a turbo'd M50 would be better than a boosted M30, though. I mean, with all of the development that's been done to boost an M30, and the fact that it has a safer CR, I'd be inclined to give it the benefit of the doubt from a 'bulletproof' standpoint. Then again, that M50, with it's 4V/cyl and newer architecture, especially given the fact that the E34 is heavier, might be worth the trouble. An interesting comparison. You gotta love the sound of a supercharged engine though!

As much as I love my M30, those m50's are great engines to boost, honestly even better. You cant swing a dead cat without hitting a stock bottom end m50 with over 400 reliable HP in some corners of the country. The only real things that require scrutiny are tuning and an anal level of head/deck prep to keep the HG in place. ARP's and a good gasket are pretty much a requirement.