M54 is just a modern ETA

[Hermes]

The more I ponder this, the more I convince myself it's the case. Please convince me otherwise

BP, I better see you post quick since you love your old S50 swapped car

[zhpnsnv]

Well, not knowing anything about how they're built or the internals, I can comment on their driving characteristics: no. I'm assuming you mean the ETA from the 325e (and the other e-engined cars), the 2.7 (or so) liter 6 made to rev low, pack a punch, and get decent fuel mileage? If I remember correctly, the red line on my 325 was 4700 or something like that.

My M54-equipped ZHP wanted to rev. My ETA did not. Two totally different characteristics, one with more HP than torque (M54), the other with much more torque than HP (ETA). I don't see the similarity, but I'm excited to learn more.

[az3579]

I disagree with the M54 being the new ETA. The ETA was low revving, had torque through the rev range (except for after 4k rpm) and was decent on gas. It's more like a diesel than anything, only much smoother because it runs gas.

The M54 has torque mostly in the midrange and it revs up. It's not too bad on gas, but it is an amazingly refined engine. The M20 wasn't all that refined in my opinion; it was old school technology compared to what existed back in its time.

Oh, and let's not forget that the M54 is a lot more fragile with overheating.

Just out of curiosity, JP, what makes you think this?

Sent from my DROID RAZR HD using Tapatalk

[Hermes]

Ok, my thinking is that the regular 2.7 eta was a POS like both of you have stated. But if you build a stroker using 2.5i head, ported, hot cam, eta bottom, 2.5 ECU (to keep higher redline) you come up with an engine of similar power output as a 3.0l without the efficiency of VANOS. (My buddy has a stroker in his E30 and it reminds me so much of the M54)

The M54 is the last of the M20 line of small six engines, not at all related to the M88 or M30 line of big sixes. For all the years up to the point of M54 being introduced, a major issue automaker have had to deal with was fuel economy/emissions while having enough power. If the enthusiast community had figured out how to make decent power with an ETA based motor why couldn't the factory design one that way from the start? Yes I admit it is more fragile than with it's aluminum construction vs iron block but I still think it's just an evolution of that old slow 80s design.

BP, I drove my buddies car yesterday and it reminded me of my engine quite a bit. That is what prompted this

[brettbimmer]

Interesting comparison JP. I have to agree with those above that say that the M20 2.7 eta is more like a diesel with lower redline and higher torque then the normal 168hp. M20 2.5L.

I suspect that the M54 engine was engineered conservatively even in Alpina-cammed ZHP form, but I would suspect longevity would suffer if the factory turned up the wick with the M54. I personally would not put the M54 as a modern day eta, due to higher revs and moderate torque when compared with the eta.

Sent from my Droid using Tapatalk

[terraphantm]

I'd say it's a modern version of the m20b25, not the eta engine.

As for why we didn't have an M54 like engine back then... Developing double vanos along with an ECU fast enough to make good use of a continuously variable valve timing system took time. Sure they could have gotten the peak power back then, but it would have been peakier, and the engine would have in general run dirtier.

Alpina did essentially build the m20b28 that many enthusiasts do, so it's not like no one thought about it. It just didn't make sense on a large scale due to other industry factors.

[Junior2552]

The M54 is an updated version of the S50/52. As everybody else has stated, it's a higher-revving, livelier motor than the ETA. Having worked with both motors, I would compare them to one another, not the 20/ETA motors. The ETAs feel like dirt compared to the M54B30's higher compression and modern tech.

I did understand where your comparison came from, though. Pretty cool thought. Curious for other responses as well.