V-Twin and V-4 motors 3

[kradicke]

With the current focus on economy cars, both hybrids and high efficiency IC motors... why is there such a lack of focus on V-twin and (especially) V-4 motors in the auto industry? Of course, these are two engine configurations also missing from the Bosch Auto Bible.

What I'm hoping will follow is a discussion about the pros and cons of such motors.

Thanks!

Kai

 

[AlexDring]

How are the motorcycle engines getting away with such balance issues? I mean you can pretty get any configuration of motor with minimal vibrations. Just curious.

 

[andyv8]

The other problem with V engines is that the valvetrain friction is substantially higher than an in-line engine. With fuel economy becoming even more critical, this is having almost as much effect as the increased parts cost of a V engine.
We're now even starting to look at going away from direct acting DOHC engines to roller rocker type camshaft actuation to reduce friction.

 

[dieselsmoke]

Alex Dring asks "how are the motorcycle engines getting away with such balance issues?" Motorcycle designers use a variety of approaches. 1)Rely on rider tolerance. Old Harley Davidsons had high engine vibration (the feel of power). 2) Smother it. When vibration became an issue Harley Davidson adopted rubber mounted handlebars and rubber covered foot rests. 3)Adopt a rotating counterbalancer. This is usually gear driven. This is currently a popular approach Many engines put the rotating weights in the gearbox. Aprilia uses two or more counterbalancers in a more complex scheme. 4)Use a 90-degree angle between cylinders. This eliminates the primary balance leaving a secondary imbalance that is often ignored. 5) Rubber mount the engine. 6) Mount the engine with cylinders in-line with the frame and the crankshaft transversely located. This is the 90-degree V-twin Ducati approach and is said by riders to be very effective. 7) I think, without any evidence, that modern motorcycles use tuning of the frame to avoid harmonic vibrations that remain after adopting various vibration reduction features in the engine.

 

[kawasakikev]

Think of motorbikes though! Although I'm a fan of the traditional across the frame 4, Honda and now Ducati have produced good engines in moto-gp and wsb. Suppose it just boils down to what you want the engine to do, compact, economical or powerfull.