T-Pain Is On A Boat: Re: [Electric Boats] Running an electric motor connected to the old Gasoline engine?

Tuesday, November 3, 2009

Re: [Electric Boats] Running an electric motor connected to the old Gasoline engine?

I can think of a lot of problems with a setup like that. The first is
that you'd want to pull the spark plug so that the compression stroke
isn't pushing back against your motor. Of course, with the spark plug
pulled, you'll want to shut off the gas line so that you don't go
blowing vapours all over your engine compartment with every stroke.
Another problem from pulling the spark plug is that you'll no longer be
blowing air out the exhaust system. Assuming that you have wet exhaust,
this means that the raw water cooling your engine will accumulate in
your muffler (nothing to force it out) until it backs up the exhaust
and into your cylinders, so you'd also want to shut off the cooling
system. Assuming that all the heat the cooling system had to remove was
produced by combustion, and not by friction, you still have the
parasitic load of the fuel pump and the water pump trying to pump their
fluids from a closed valve, so you should unhook those too (maybe even
just pull them right off the engine).

So after doing all that, you'll have a big useless metal contraption
between your motor and your prop shaft. It will continue to need to be
lubed, and you'd be well advised to consider how to keep the inside of
the cylinder from gunking up now that it's neither closed off by the
spark plug, nor is it burning off any contaminants a few times every
second when its contents explode. And in spite of all this, it's still
bound to introduce a fair bit of friction to the system, waste your
power, and require you to carry more battery. On top of that batteries
are heavy enough that you don't want to carry too much, even when you
aren't also loading your boat with a great big useless engine block.

So I'm not going to say that it's not possible (since I don't have data
handy on the power produced by the motor you want, or the amount of
resistance that the stripped-down engine would provide), but I am going
to fall back on that old aline about how just because something is
possible, doesn't make it a good idea.

If you want to use a full-on motor as a starter so that you can fall
back on it if your engine kacks out, then I can't see anything wrong
with that idea at first glance. But if you're looking to do this in
order to simplify installation of the new motor, the little bit of extra
effort to do a proper installaion now will save you a lot of grief in
the future.

HTH,
Kris

On Mon, Nov 02, 2009 at 09:24:07PM -0000, nd4speed_66 wrote:
> Greetings,
>
> Im new to this whole electric engine scene, but was curious if its possible to use an electrict engine to spin my old gas engine?
>
> I have a Vire 6 BVr, http://www.vire6.info/, which has a front mounted crank pully system with a combo start/alternator. The alternator died years ago, so its esentially just a starter. What I was interested in doing is replacing this starter with a Mars Brushless electric motor. This would allow me to use it to start the gas engine or leave the ingination off and drive the boat via DC power alone.
>
> Im assuming I would need to beef up the belt and pully as its currently a V groove. But would it be too inefficient to spin the single piston engine and transmission to drive the boat compared to having just the electric motor spinning the prop?
>
> Thanks for your response!
>
> Happy Motoring
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>

--
Kris Coward http://unripe.melon.org/
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