thinking of exploring another option

[Henry W]

Here is some intresting stuff.

http://www.dualfuelstrategies.com/

http://www.energyconversions.com/ECO.htm

http://www.energyconversions.com/Ecohardware.htm

http://www.cleanairpower.com/components.php

http://www.cleanairpower.com/duel-work.php


Henry

[mobile_bob]

thanks for the links Henry, the second of which provides support to what i stated in the thread relating to making a case for natural gas.
and follows very closely the results found in the pdf report from bangladesh as both relate to "knock" limit and the non linear natural gas
offset vs pilot diesel injection once you get over about 90% power level (in the bangladesh paper) and over about 75% in this second report
that shows up in the graphs on the catapillar engine's.

their use of computer control and fuel mapping for the offset of natural gas vs pilot injection is the epitome of dual fuel operation, however
it is doubtful the DIY community will ever adopt such strategies unless the technology is available for a very low price (which is also very doubtful)

the link you provided clearly illustrates some of the issues, showing clearly that dual fuel with nat gas is not just simply fogging the gas into the intake
in some crude manner without concern to outcomes, thinking that the engine will respond like a spark ignited engine that has much lower compression.

clearly two different animals all together, each having their respective pros/cons and set of compromises that must be made.

bob g

[Rob Windt]

"not just simply fogging the gas into the intake"
Too true, I convert vehicles to LPG and have done several diesels - post '01 diesels (in Aus') require a computer controlled management system and they are recommended for hard working vehicles, the exhaust temp' probe that shuts off the LPG over 600C is worth it's weight in gold, but we're not talking about road trains and those systems are pricey.

For pre '01 vehicles and gensets I'm happy to fog the gas in through a small orifice, about 3 to 5mm and have it powered via a throttle switch or turbo boost switch so that vapour only flows when the engine is starting to work, not at idle.
The orifice sounds tiny but it is easily checked by running the engine up to 2800-3,000 rpm and then switching the gas on, you are looking for the rev's to rise by 200-250 rpm

At this flow rate you will use one litre of LPG to every three of diesel and no modifications will be required, it will act as an accellerant and burn up the normally wasted diesel - no more black smoke, more power and, after two or three oil changes, no more black sump oil

Cheers
Rob
http://nakedmechanic.blogspot.com/

[BioHazard]

In the spirit of finding something cheap, and available, take a look in your local craigslist for old CNG vehicles. Alot of CNG fleet cars are around from ~10 years ago. This way the engine will already be setup for natural gas use, and you might get some extra stuff like tanks, plumbing, intakes, and ECMs all specialized for NG.

This would be a perfect example:
http://portland.craigslist.org/mlt/cto/2146254395.html
I think I might find out more about that engine...