Right, really stupid question here, but is a 60 degree v twin engine with one crank throw odd fire?

I assume so but in email conversation with Bill Shurvington he asked whether it was odd fire or even fire and I had to be honest and say I am not sure.

Having thought about it, unless I am missing something really obvious, it must be odd fire, but is that right?

Being it a high rpm engine build for fast acceleration etc. i´m sure its odd fireing..
(not fireing at the same time)
i mean that when piston 1 is in in the fireing stroke (downwards) piston 2 is in the compression stroke..(upwards)

i guess its the most easy way of balancing
the thing a bit out..

Tks

If that's a stupid question then I must be stupid too - I've never heard of that

That's what I mean!! I have heard of it, but never paid any attention as all the 4 cyl engines I am used to are even fire.

TKS - even fire doesn't mean firing at the same time, it means even phasing of firing points of each cycle, which is why I assume it must be odd-fire.

The cylinders are 60 degrees apart, its a 4 stroke engine and there are two cylinders. Each cylinder fires every 720 crank degrees, and the crank has only one throw.......oh i'm confused!!

http://en.wikipedia.org/wiki/V6

look at that..

Tks

Right, think me and my boss have just worked it out!

See what you get but we make it 420deg and 300deg between ignition trigger points, so definitely odd-fire

[Edited on 16/11/06 by NS Dev]

Not quite as simple as that - you basically need to know specifically for the engine in question whether it's odd or even fire - just its geometry isn't a dead give away. For example my Honda V6 is a 90 degree V6 which in theory has to be odd-fire. However, instead of pairs of pistons sharing journals on the crank shaft, the journals are appropriately offset round the crank to allow the engine to be even-fire despite its geometry.

Sounds like a 60 degree V-twin should be odd-fire if it has a simple crank with the pistons sharing a single journal, but it may infact have offset crank journals and be even-fire. I'd say the latter is most likely in a decently engineered modern engine.

Liam

edit: oh just noticed you said the crank has one throw. If you're totally sure about that and the pistons definately share the same journal then it has to be odd fire. A pain for megasquirting if i'm not mistaken, assuming that's why you were talking to Bill

[Edited on 16/11/06 by Liam]

Yep indeedy!!!

Certainly is odd-fire, common crankpin, and I've been searching on all the flipping mega-billy sites and not one useful bit of info so far found!!!