[Bimmer Pleaser]

I’ve noticed that my 2010 N52 idle (108k miles) is noticeably smoother than my 2015 N20 (CPO, still under factory warranty). I can feel very slight vibrations on the seat when I’m idling or stop the N20 but virtually no vibration or sound in the cabin when N52 is idling.
Is that normal? Does it have anything to do with N20 turbos?

[aaaaah]

An inline six such as the N52 (or V12) will generally idle much smoother than pretty much any other engine. Manufacturers work around the imbalance in other engines such as the N20 four.

[3rdcoast228i]

N20 is like a diesel for some reason. Mine does the same.

[MetalMK]

4 Cylinder Turbo VS 6 Cylinder, there will be more vibrations, it's even worse in 3 cylinder cars

[Questofthetune]

Originally Posted by MetalMK

4 Cylinder Turbo VS 6 Cylinder, there will be more vibrations, it's even worse in 3 cylinder cars

Yeah the mini with the 3cyl I got as a loaner idled like a harley.

[morphomeman]

Hence the auto shut-off. These cars are rarely sitting at idle.There is nothing like a straight six at idle, though, which is why I always defeat the auto shut-off on mine.
But the difference is just as pronounced under acceleration, where our X3 with the 4 stutters madly, vs. the smooth purr of the 6.

[Bimmer Pleaser]

So hypothetically if there was such thing as i8 engine it’d run smoother than an i6? The more cylinders in line the smoother?

It makes sense.

[aaaaah]

Originally Posted by Bimmer Pleaser

So hypothetically if there was such thing as i8 engine it’d run smoother than an i6? The more cylinders in line the smoother?

It makes sense.

Not quite, it has to do with multiples of inline six cylinders which is why a V12 is often better balanced than an I6 as it cancels out the secondary imbalance.

[3rdcoast228i]

Originally Posted by Bimmer Pleaser

So hypothetically if there was such thing as i8 engine it’d run smoother than an i6? The more cylinders in line the smoother?

It makes sense.

https://en.m.wikipedia.org/wiki/Straight-eight_engine

[RoundelM3]

Originally Posted by Bimmer Pleaser

So hypothetically if there was such thing as i8 engine it’d run smoother than an i6? The more cylinders in line the smoother?

It makes sense.

Straight-8 engines were quite popular from the early to mid-1900s and were inherently well-balanced and very smooth at idle and in their power delivery. My grandfather's 1953 Packard Patrician was so-equipped and had no discernible vibration when running. Today's inline-4 engines are a lot smoother than early designs due to the addition of contra-rotating balance shafts that damp out a lot of the inherent imbalance in these engines. Another interesting design was the inline-5 engine used by Audi in the late 1970s along with Volvo. While not quite as well-balanced as an inline-6, it was a big improvement over a 4-cylinder without being as long as the inline-6 for "packaging" considerations.