Volvo reveals 450hp four-cylinder engine

[Porsche Guy]

Hmph, contentious discussion. The thing is, modern inline fours are more refined than ever thanks to increasing manufacturing accuracy and engine balancing progress. Be this as it may, whilst inline 4 smoothness and refinement is greatly improved over a broad-but-still-optimal RPM range, at the lower and higher ends of the operating rev range, the mechanical characteristics of the inherently unbalanced inline four comes to the - ahem - fore.

An inline six suffers no such perceptible loss of refinement regardless of the operating RPM. It's just that modern engine and transmission management systems are so good these days that engines are seldom found operating outside of their optimal RPM ranges.

I appreciate the info but my disagreement with Merc1 was based on the fact that he/she hasn't driven this Volvo's I4 and is already assigning it characteristic.

 

[Merc1]

Hmph, contentious discussion. The thing is, modern inline fours are more refined than ever thanks to increasing manufacturing accuracy and engine balancing progress. Be this as it may, whilst inline 4 smoothness and refinement is greatly improved over a broad-but-still-optimal RPM range, at the lower and higher ends of the operating rev range, the mechanical characteristics of the inherently unbalanced inline four comes to the - ahem - fore.

An inline six suffers no such perceptible loss of refinement regardless of the operating RPM. It's just that modern engine and transmission management systems are so good these days that engines are seldom found operating outside of their optimal RPM ranges.

Exactly. You don't have to drive it to know it won't match a 6 or 8 for refinement especially when you're really on it. It is still a 4-cylinder.

M

 

[Sunny]

Exactly. You don't have to drive it to know it won't match a 6 or 8 for refinement especially when you're really on it. It is still a 4-cylinder.

M

Marcus, Martin is strictly talking about I4 vs I6. Not all 6 and 8 cylinder engines are going to be inherently smoother than a I4. A V6 layout is way more unbalanced than a I4. And a V8 is not any more balanced than a I4. Only I6 and Boxer 6 engines will be inherently smoother than I4. Of course a V8, since it is usually found in more expensive/luxurious cars than a I4 will be smoother. But that has nothing to with the inherent balance of the engine layout.

Anyway details of the engine -

http://www.motorauthority.com/news/...cylinder-with-electrically-driven-turbo-video

 

[Merc1]

Marcus, Martin is strictly talking about I4 vs I6. Not all 6 and 8 cylinder engines are going to be inherently smoother than a I4. A V6 layout is way more unbalanced than a I4. And a V8 is not any more balanced than a I4. Only I6 and Boxer 6 engines will be inherently smoother than I4. Of course a V8, since it is usually found in more expensive/luxurious cars than a I4 will be smoother. But that has nothing to with the inherent balance of the engine layout.

Anyway details of the engine -

http://www.motorauthority.com/news/...cylinder-with-electrically-driven-turbo-video

I've said from the start an I6, not a V6. Most V6s are not all that refined either once you stand on it. A V8 isn't coarse and rough when really on it, at least in my experience. Every 4-cylinder has been, even in the 328i. I can't be caught out at times and it will tell you that it's a 4.

M

 

[Giannis]

Back in the day, Volvo used to have brilliant 5-cylinder engines and an inline 6. No matter the efficiency or power output, being able to choose a more-than-4-cylinder engine is important if you want to target the luxury market, in my opinion, of course.

Volvo's latest engines are surprisingly efficient, surprisingly refined, surprisingly torque-y at the lower end, and surprisingly boring.

 

[Wolfgang]

And a V8 is not any more balanced than a I4.

Hello Sunny, a crossplane V8 can be inherently balanced using counterweights. Attached please find a copy of the Bosch Handbook, found via google, albeit in Italian. Second order moments cancel. In order to cancel the first order moments, counterweights can be used as explained in the footnote. But true, still not as perfect as an I6 or boxer 6, as they are balanced even without counterweights.

 

[Sunny]

Hello Sunny, a crossplane V8 can be inherently balanced using counterweights.

Yes, but is a layout "inherently" balanced if you have to add counterweights? You could add balance shafts to a I4 to balance it too.

 

[Wolfgang]

Maybe Volvo plans to come back to the DTM? Towards the end the vid mentions Per Stureson won with a Volvo 240 Turbo almost 30 years ago...

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[Rolf]

Mercedes Benz are the masters of V8's amongst the German cars manufacturing them since the late 60's. Anyone who has been in a Mercedes V8 car will definitely say it is smoother than any 4 cylinder they have been in. This is experienced at low engine speeds as well as when banging against the rev limiter. This smooth as butter experience has been engineered in them since they first started building them and even in the 60's and till today the V8 is always considered smoother than a 4 cylinder engine even if it is not balanced. If you compare an E200 to an E500 in measured noise the V8 E500 will be noticeably quieter and smoother.

 

[Wolfgang]

Yes, that's true. Drive MB V8s daily. The new inline 4s are also pretty good though. Here's the funny (to me) looking balancer shaft of the new Mercedes-Benz four cylinder.

First use of Lanchester balancer shafts with antifriction bearings in a petrol engine

The secondary inertia forces inherently occurring in a four-cylinder in-line engine are compensated by two Lanchester balancer shafts in the bottom of the engine block. Mercedes-Benz is the first automobile manufacturer to use antifriction bearings to balance masses: imbalances are compensated by cylinder roller bearings, with axial forces from the gearing taken up by a ball bearing. This arrangement not only improves driving comfort, but also helps to lower fuel consumption thanks to considerably less friction. In view of the more favourable connecting rod configuration, the 1.6-litre version requires no Lanchester dynamic balancing.

http://mercedes-benz-blog.blogspot.com/2012/07/new-mercedes-benz-class-petrol-engines.html

 

[Mr Robert]

I've always been told that for refinement, you need an I6, a V12 or B:motor.