swajames

In fairness, Acura's engine is a 3.5, not a 3.7, and the 3.5l VQ Infiniti makes up to 306 hp (from 290 to 206 dependent upon specific application, but it's essentially an identical engine). Both are are comparable (if not slightly better in one case) than the N52 on specific output. They were both on sale when BMW was still selling the 225 bhp I6 over here. The Acura meets ULEV-2 emissions standards (ultra low emission vehicle), mpg is a little worse than the 530i but then again it's larger in displacement and is more powerful. The Infiniti meets LEV-2 (low emission vehicle), and is again a little worse on mpg but again is up on bhp. The 530 emissions are also very good, at least on par (if not a little better) than these two, but you don't give up that much on mpg or emissions for up to 50 extra bhp with the Japanese V6's. As I said initially, the BMW I6 is a great engine but it does have V6 peers that are just about as good, and that was really the main point of my posts. A good engine is a good engine, doesn't really matter whether it's I6 or V6, it's not necessarily clear than one is inherently better than the other!

Ricracing

We are not talking about hp's, but of engine mechanical tech.

If you only look into given measurements, you could say the 70' BMW 1,5 litre F1 turbo engine was something:
More than 1000 hp's from a small row4...

In these days the small 2.0 R4 engines gives well more than 600 hp turbocharged and racetuned.

I'm still looking foreward to my first experience with a strong family car factory engine:
A sixinline full aluminum, direct injected and twin turbo charged 3.0 litre unit (handling all emission standards).

swajames

I agree, it's not just hp, but within their class the two V6's I mentioned (and arguably Honda's in particular) are amongst the most advanced on the market. I also agree that the twin turbo BMW engine is looking like a phenomenal engine!!

Ricracing

As V6 engines


PS. Just looked at a couple year old TV series where two Brittish guys drove with GS BMW 1150's
from Europe thru Eastern EU, Russia, Mongilia etc to Alaska and the US and met the Orange County
Chopper guys.

That's Boxer twin meets the V2 twins and nobody was talking about mechanical vibrations...

swajames

dlevi67

Well, I re-checked the Acura site, and you are right, it's a 3.5; don't know where the other sites got 3.7 from. But it pulls out 290 bhp, so specific power is 82.9, still below BMW's. And I found the 306 bhp in the AWD Infiniti, which does pull out 87 bhp/l, so better than BMW.

Even without this evidence, everybody would agree that a V6 can pull out the same relative performance as an inline 6 (or viceversa), given that even at 87 bhp/l we are still far away from top performance naturally aspirated engines (100+ bhp/l in road cars: BMW-M, Honda R; never mind motorcycles that pull out 120+ bhp/l with seeming ease).

However - and perhaps here we part company - an inline is inherently smoother, needs fewer components and is easier to manufacture - at the cost of greater size. None of which prevents either being the more powerful engine. There's nothing you or I can do to change the laws of physics. Which one is "better" will depend on many other factors, including application.

dlevi67

That's because their teeth had all fallen out because of the vibrations, but neither would want to be the first to admit it!

eegrad

I have learned a lot by reading this thread. I would imagine that over a long period of time, an I6 (if mounted perfectly vertical) will wear out less than a V6 or a boxer type engine. My theory is that when a cylinder is mounted horizontally (line in a boxer engine) or at an angle (like on a V6), the force of gravity will be constantly be pushing the piston against one side of the cylinder wall. I would imagine that this will cause it to wear sooner on that side, right?

Ricracing

You have not learned anything

A six cylinder engine, with the cylinders put in a row, is a mechanical stable engine!

The V6's need extra, non power producing contra weights, to get the engine stable!

dlevi67

Ric, with respect, but I think you are missing eegrad's point. Which BTW is correct.

Pistons in horizontal or angled engines will wear more rapidly on one side, though how much more rapidly is open to question. I have seen it "for real" in BMW boxer motorcycle engines; taking engines with a few tens of thousand kilometers apart, the pistons were considerably shinier on the "bottom" side, whereas the "top" side often still had the manufacturing tool marks (lathe rings) visible. I don't remember seeing this effect on "angled" engines, though I suppose it must be there, even if to a much lesser extent.

Nothing to do with balance or - as you put it - stability. If you fitted an I6 horizontally (I don't know of any, but the K series BMW motorbikes have I3 and I4 horizontal engines), it would have the same problem. It would however remain perfectly balanced.