Diagonally it is/was...... Glad that's over...... Now, Pete has made some cogent arguments as to why Honda did not pursue the longitudinal engine orientation beyond the aforementioned bikes. That being said, why then do you suppose Moto Guzzi adopted and stayed with the longitudinal engine orientation for lo these many years? Going further, ditto Ducati for staying with desmo valve actuation. I had the misfortune of working on one Duc/Desmo bike for a buddy years ago..... never again!
Mike
Good thought Mike - and I have always sort of wondered about that too.
It seems that some brands are wedded to a single architecture and that is a huge part of
who they are. For Harley, it is obviously 45 deg. V-twins, for Ducati, it is the 90 deg. L-twin, for BMW (in times past) it was the flat twin boxer engine (basically a 180 deg. Vee-twin) and as you say, for Moto Guzzi, it is the longitudinal 90 deg. V-twin. The Japanese manufacturers never seemed to get locked in like that did they? Among them, they have done singles, in-line twins, triples and fours (and even fives and sixes), V-twins (of many different included angles) and V-fours (in all orientations) and even flat fours and sixes - variety has been the spice of their lives!
Here in Windsor, we have a couple of Ford engine plants and the folks there have often remarked what a big deal it would be to shift from a 60 deg. V-6 engine block to a 90 deg. engine block configuration as would normally be used in a V-8. All of their big boring and honing machines are configured for the block angle layout and switching them around would cost BIG money (like hundreds of millions of dollars...). I suspect that is part of it with the motorcycle manufacturers above - back in the days of manually operated or even automatic (but not CNC) machine tools, changing the basic orientation of the engine block configuration would cost a ton-o'dough.
The other influencers are the marketing dept. (aka the
Beauty Police). The engine of a motorcycle plays a big role in the overall appearance and persona of the bike - and the marketers use it as a key selling tool. Heck - bike service shops even advertise that they
"work on V-twins" (i.e. Harleys & Indians) or they do not. The bike company
Beauty Police spin legends about the
reliability, maintainability, performance, torque, power and
speed as well as the distinctive exhaust note and vibration signature of
THEIR chosen engine configuration and they don't want to have to abandon all of that brand equity and figure out a new campaign for a new type of engine.
I watched an episode of Jay Leno's garage the other night and while I do like the show because you get to see some very pretty machines, the fact is that Leno should stick to the story about his specific car or bike and not try to talk about the engineering behind it - because often, much of what he says is only half-correct and sometimes it is absolute crap. In the last episode on YouTube he was talking about his 1953 Hudson Hornet and he was waxing eloquent about how the Hornet's straight-six inline engine had so much better torque than the V-8s of the day - and then he extended it to:
that is why the best diesels are also always straight-sixes - because they need the torque.....
blah blah blah.
What he was saying was absolute baloney. He really should leave the tech stuff to technical people and stick to his knitting as a humourist.
The things that determine the torque output of an internal combustion engine are:
- the number of cylinders;
- size of the air-fuel charge used in each cylinder (i.e. the displacement of the engine and whether or not it uses some sort of supercharger to increase the amount of air the engine processes);
- the process efficiency of the combustion chamber within each cylinder (which is affected by intake and exhaust system geometry, piston and valve motion imposed by the camshafts or in a two stroke, the cylinder ports & geometry);
- the throw (i.e. the half-length of the stroke) of the engine crankshaft.
The
geometric configuration of the cylinders (i.e. inline, Vee, radial or opposed, longitudinal or transverse - or even diagonal
) plays no direct role in determining torque or power output. The geometric configuration is all about ease and cost of manufacturing along with "packaging" the engine and intake/exhaust systems, the engine-transmission-driven wheel interface (i.e. chain or shaft drive) and it certainly affects the engine balance and vibration characteristics.
