[Vwdiesel] 1980 Rabbit running the treadmill tonight!

Area31 Research Facility stephensrw at stn.net
Sun Apr 17 22:18:14 EDT 2005


The single cylinder, water cooled diesels I'm referring to make rated HP at
2200 RPM but pull like mules from 900 RPM.  Fuel economy will suffer sure at
the very low end but these engines still run on portions of a pint per hour

I did some 'speriments today with my VW 1.5D running at 1200 RPM.  I was
able to make 1.5 kW electrical load at this speed with winter diesel as fuel
using 0.9 litres/hour.  That means the engine will run doing this power
delivery for 4.2 hours on a US gallon.  There was not much heat generated
but the engine coolant did stabilize at about 185 F, the thermostat temp, so
there was enough heat to keep the engine happy.  The engine sounded very
quiet and relaxed like it could do this for years.  The efficiency was close
to the same as running at 1800 RPM and 3 kW load with a throttle governor.
I  measured  0.57 litres/kWh doing that and today at 1200 RPM slow speed and
1.5kW load got 0.60 litres/kWh.

I tried running the VW at 1200 RPM also on the waste oil and it was not
happy like it is on this sttuff at 1800 RPM and working hard.  The engine
got smoky and had to frequently be throttled up with a bigger load to 1800
RPM to clear.

Perhaps I need to re-think my Changfa purchase and buy a smaller one that
I'll be running considerably harder to make three kW.  That ought to get me
better economy, but at the expense of engine wear and shorter life.
Whatever I end up doing, it will be at 1800 RPM and slower.  I'd like my
small 24/7 plant to run 1200 RPM max.

I finally obtained my big 20 kW DC, 1800 RPM  generator (400 amps @ 50 VDC)
on Friday that I had arranged to buy from a local electric motor shop that
is closing down.  It weighs half a ton. I had to borrow a pickup truck to
move it.  It is now in my shop and I cleaned the commutator today and spun
it up to about 1/5 speed with a V-belt and 1/4 HP fan motor working really
hard..  Not enough RPM to wake it up yet even with flashing the field.  This
is a NICE generator. It is in beautiful shape.  The 24/7 putt-putt will spin
this to charge my forklift batteries.  I believe in over rated components to
prevent break downs but this margin is almost rediculous. ;)  The price was


----- Original Message -----
From: "Val Christian" <val at swamps.roc.ny.us>
To: "Area31 Research Facility" <stephensrw at stn.net>; <vwdiesel at vwfans.com>
Sent: Sunday, April 17, 2005 8:19 PM
Subject: Re: [Vwdiesel] 1980 Rabbit running the treadmill tonight!

> > I am looking at purchasing a large single cylinder Changfa diesel in the
> > 15-18 HP range to use to make domestic hot water for the house and to
> > a large DC generator that will charge forklift batteries as will my
> > wind turbine.  My plan is to run the Changfa near 24/7 at very light
> > and slow speed (maybe 900 RPM) hoping to get extremely miserly fuel
> > ion and very long engine life.  I posted a question earlier to find
> > out there with Changfa experience and you have fortuitously come
> > I'd like to discuss this with you off list or by telephone if you'd like
> > send me your phone number privately.
> Rob,
> The engines on the gensets I have are not Changfa.  Sorry.
> My take is that running any powerplant at a low fraction of it's design
> point will cost in some order of inefficiency.
> If you could sync your gensets, or dedicate loads to them, then you can
> stage the generators, based upon demand.
> Have you stumbled across a group covering the chinese aircooled diesels?
> I'd be skeptical about running a one banger at a reduced RPM.  My gensets
> run at 3600 rpm, and there's plenty of vibration, although, they do run
> quiet.
> Val

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