12/2-650 RPM or 12/1-1000 RPM

[Mikofox]

I know I need between 6.5 KW to 7.5 KW in an alternator, but I can't make up my mind if I should get a 12 HP Twin or Single.
I like the idea of the 650 RPM, but that would mean the Twin.

I take it that Twins are harder to work on, that more can go wrong, that they are louder.
Has there been a comparison in noise between the Twin @ 650 RPM compared to the Single @ 1000 RPM?

[JohnF13]

The answer is many questions......If you like the sound of a 650rpm engine (and they do sound much more pleasant that the 1000rpm units IMHO)
go for the twin.  They are no louder than the singles (you can muffle them down to virtually nothing) but it is a matter of personal preference.  I Don't think the twins are any harder to work on - with individual heads it is just twice the work!  The twins tend to produce a more even power wave, resulting in less light flickering (but this isn't a big deal anyway) 

Fuel consumption is probably a bit higher in the twin but again, nothing too significant.  Some people claim that there is more pressure on the gear train/cam assembly on the twins, but they all have centre bearings so I'm not convinced that is correct.

The singles are most likely marginally more reliable than the twins, but that depends on more on what brand you buy rather than the configuration.

Personally, I prefer the 650rpm engines, but I do have a 1000rpm twin for big power demands.

See - it's as clear as mud!  Your final arbiter may be price - the twins are quite a bit more expensive than a single.

[rpg52]

I would second JohnF13's comments, although I haven't worked on a twin, as he said, "that depends on more on what brand you buy rather than the configuration."  IMHO a good twin is much better than a less-than-good single.  The twin uses the more standard piston, sleeve and con rod of the extremely common 6/1, so parts are more available, and more likely to be so in the future.  Slow(er) speed is good.
Ray

[binnie]

I pondered over this question too. I saw & heard examples of them both running...I went with the twin due to the more subdued sound of a slow engine and the better balance that the two cylinders offers..The output is the same....just a matter of preference. They were rarer in the original Lister market..but that was probably due to the higer price than anything else. Let us know what you decide & the reasoning you base your choice on. I'm sure you will fall in love with whichever of the two you pick. If something goes wrong, it can be fixed.

[BobH]

Buy both, I did I.ll take the twin any day.

[diesel guy]

Mikofox,

How about a 14/1 at 850 RPM?

Diesel Guy

[Mikofox]

All good answers!
I'd sure like to get a second one, but our budget is extremely tight these days. If it were not for the money, I wouldn't even think of importing one myself. I'm just starting to get an idea on the whole procedure. I am looking forward to Steve's report on his import.

Since I had planned to order from Anand the 14/1 - 850 RPM is not on their list, but it would be a good alternative.

Regarding noise I'm confident that it will be easier to quiet them down compared to the 3600 RPM gas and diesel engines we were using in the past. I've tried a few mufflers on them, but depending on wind conditions, the noise of the engine turning, was heard farther than the sound of the muffler.

[rocket]

i add my vote to the twin