Phil and Bruce:
let me first say i am in reference to a small bore single cylinder diesel as a genset, running at constant speed and near constant loading.
i too have been a diesel tech for many years now, over 30, from everything to small diesels to 12v149 detroits (the monsters i love)
what i am in reference to is dual fuel operation, whereas the intake air is charged with natural gas, methane, propane and alcohol.
such an engine running in dual fuel mode, runs on both diesel and the other gas at the same time.
as the alternate gas enters the air stream the engine wants to raise in rpm, but the diesel govenor tapers back the diesel fuel to control the rpm, within limits of course.
most dual fuel engines in industry only get to around a 90/10 offset whereas there is still some diesel being injected as a pilot to initiate ignition. Without the pilot fuel (diesel) the high octane rating of the alternate fuel will not fire in a compression engine.
one of the biggest problems using this scheme on large multi cylinder engines are, timing control (need more advance running alternate fuel to gain lost power), the intake manifold not designed to be a wet manifold causing unequal distribution, and knock.
using a single cylinder engine, distibution problems are not of concern, or of small concern.
knock that plaques large bore engine's becomes less of a problem with smaller bores, the same as small high compression gas engines, big blocks engines are more finicky about high compression ratio's than their baby brothers.
a word on knock, basically what i am in reference to is, when the diesel is injected it fires, then it ignites the alternate fuel, if the engine has a large bore, you have colliding flame fronts causing a secondary knock. the smaller the bore the closer this occures. also this phenomena happens more readily at low or part loading.
the only remaining problem is one of advanceing the timing on a small fixed timeing single cylinder, this one is a difficult to alter problem. So i guess i will have to deal with some loss of power in dual fuel mode.
please see the following
http://www.saeindia.org/saeconference/ethanolreview.htm
http://www.vtt.fi/virtual/amf/annex-iii.html
http://www.ctts.nrel.gov/heavy_vehicle/ddc6v92ta.html
there is alot of testing and operation of diesel engines in dual fuel mode.
please see the following
http://www.energyconversions.com/products.htm
http://www.cleanairpower.com/technology/df_howitworks.html
http://pepei.pennnet.com/Articles/Article_Display.cfm?Section=ARTCL&ARTICLE_ID=235219&VERSIO
N_NUM=3&p=6
if you do a google search on dual fuel diesels and add alcohol there are alot of references to it being done.
don't get me wrong here, i don't think it is an easily done thing, but..
the small bore single cylinder engines can take alot more abuse than their big brothers, basically because of their simplicity.
not sure i am going to do it, but i am researching the idea.
bob g