After being away from the forum for a few months, at last I've got some time to reply and share my experiences!
Rhynri wrote:old clunker wrote:
Unfortunately, it looks like only direct injection engines are suitable to run reliably on renewable vegetable oil based fuels, and engines with Lucas or CAV fuel pumps and injectors are unsuitable, and do not run reliably.
Some older Peugeot and Renault diesel engines have been modified to run on vegetable oil based fuels, but need more modification, and apparently are not as reliable.
At the moment, it appears all new indirect injection engines cannot run reliably on alternative fuels, so it is best to stick with old simple diesel engine technology!
I must admit, you have me confused, good sir. It's the new engines that have the direct injection. The old engines have prechambers, one of the reasons they are so loud and run at lower compression (also largely why glowplugs are required at lower temps).
I'd also have to vote that it's less of a conspiracy and more of the fact that vegetable oil isn't very homogenous, and when you are talking 18.5:1 compression and 30ft/lbs boost (even in a stock engine) having irregular fuel or fuel that doesn't burn cleanly can be devastating to your systems.
Many of these problems can be solved by "methanolizing" the fuel, basically converting it from SVO to bio-diesel (which you can do yourself, there are even machines you can build for about 300$ to automate the process for you). I apologize if I am repeating anything but I was having trouble with the page loading. There is a good guide here:
CLICKY!
Thanks for your thoughts and the interesting link about biofuel production, it's just that may not have seen the insides of small 'Yanclone' diesel engines, and they have been around for many years now. My
Suntom CH186F is direct injection into the swirl recess/combustion part of the piston, and no glowplug used, with the the injector directly located at an angle through the cylinder head, and over the piston area.
All small diesels I'm aware of used for motorbikes, appear to have similar construction with no pre-chambers or glowplugs, to keep it simple and cheaper to produce!
They use the effect of having very tight clearance between the top of the piston and the cylinder head to get the high compression pressure required for fuel ignition and combustion.
You'll be able to get an idea of this, when I post how I repaired/got the compression back in my Suntom (Yanclone) engine soon.
As for the running of Diesel engines with vegetable oils, that's what they were originally designed to do. Diesel fuel (heavy fuel oil as it is officially termed) also doesn't burn that cleanly and will slowly clog up engines in time, if routine maintenance is not carried out.
When I've had a close internal look at my Diesel engine, I can see obviously that it's been designed/optimised to run on diesel, with a less robust injector, fuel pump and piston head design than I would have liked, which could have been 'beefed' up by the manufacurers, with an addition of a glow plug in the cylinder head to improve complete combustion of vegetable oil mixes. The problem I have come across is incomplete combustion, due to the piston/combustion area not getting hot enough.
I hope this has answered your questions and made some things a bit clearer!
After being delayed by a major garage roof repair, boat work and repairs, at last I have some time to devote to motorbikes again!
'Clunkie' is just about up and running again, after a week's engine work and hassle bleeding air out of the fuel system. Hope to get a chance to test ride it soon, after a brief ride yesterday, with a frustrating time first getting some fuel to reliably flow to the injector.