[RABAUKE]

Interesting article

http://driving.ca/auto-news/news/motor-mouth-4

[mkoesel]

I didn’t know about the Jaguar rumor. That’s pretty intriguing. I strongly doubt they will be able to abandon V8s altogether - at least not for another generation or two - but the move back to an inline six would be pretty major news for them.

The Mercedes M256 is a brilliant engine. I was surprised and somewhat disappointed that they held it back from US release with the recent S Class LCI. In any case, though, it’s coming to the US soon - reportedly in the the new CLS as the first car to wear a new ’53’ AMG nameplate. BMW needs an engine like like this in their lineup. The 48V electrical system with integrated mild hybrid is a great package.

[c1pher]

I think the only real drawback to inline six is the length of the motor and how it is placed in the car. They are simpler, have much less NVH (which contributes to reliability and longevity) and are fairly powerful and efficient. Obviously BMW has figured it out and most of its I6 motor cars are close to 50/50 weight distribution. I think car manufacturers would use the I6 more but probably figure they can put a 4cyl engine in for an economy car (cheaper) and a v8 can take up less space longitudinally if they want a more performance oriented car. I think the way BMW has incorporated the I6 by continually improving it is probably the only way they could get to where they are. I mean the S55 has as much power as a small block v8.

I learned about I6 through owning a Jeep Cherokee which had a 4.0L I6. We put 350,000 miles on it. And for being 15 years old was able to get 19 mpg on the highway and made 190 HP when new back in 2001. I regrettably gave it to my son and within a year it got stolen. I wish I kept it. I know it would still be running. Anyway my experience with the Jeep made me like BMWs more than I already did. I always wanted one but as I discovered most of the cars were I6, I knew I had to get one.

[Efthreeoh]

That article makes it sound like BMW invented the I6. The inline 6 has been well known for its natural primary balance and low secondary harmonic balance. The rotating 3-piston setup almost eliminates the rocking couple effect. A flat 6 does the same thing as does a 60 deg. V6 block. No wonder that 2 of my BMWs are N52's and my scooter is a Honda F6.

Industrial diesel engines are primarily large inline 6 engines, so the attributes are far from forgotten in the engineering sector. Cummings warrants some of their big rig engines to 500,000 miles.

The half-liter cylinder size has recently been determined by engine engineers to be the most powerful/combustion-efficient size (and also suitable for forced induction), which is why most modern automotive gasoline engines are separated by 1L increments regardless of block configuration. A secondary benefit is in the manufacturing process where production tooling needs to be sized only for one cylinder bore size.

Which brings the discussion to the move to V-configuration engine blocks. When V-8s became prevalent in automotive use, production tooling could be better suited to produce both 90 deg. V-8s and 90 deg. V-6 blocks. Mercedes abandoned its inline 6 in favor of V-6 production on the same engine lines as their V-8's and as a secondary benefit engine compartment packaging.

I think where BMW really gets credit historically is keeping adherence to the engineering principles of 50/50 weight balance and keeping all the heavy parts between the axles. The inline six helps in this design regard. Yet recently, upon the advent of computer-controlled stability systems, I think BMW is getting away from some of those principles in recent designs. For example the 1-series is now FWD. I thought I'd never see a front-wheel-drive BMW. Blasphemy IMO. I'm afraid blue gauge back-lighting is next.