Following on from my forced induction questions, I was talking about how difficult it was to find a large petrol engine in the UK. I’ve been an engineer for over 10 years and have worked extensively on diesel engines which led me to thinking about a diesel to woodgas conversion.
After reading the discussions that you guys have had on here, i’ve found out from you guys that you need to use a small amount of diesel as an injection source.
Now, as I was working today, I was thinking to myself about how you would go about turning a Compression ignition engine to a Spark ignition engine. impossible right? No distributor for spark timing.
Well, i was wondering if there was a way to modify an injection pump to make a distributor and I think I have found a way to make it work. There’s a lot of very capable mechanics and engineers here so if you guys see any problems with this idea please speak up.
Using the injection pump (with an operating oil inside) Immense pressure is created when the Cams push against the plungers forcing fluid through the lines. If a peizoelectric hammer and crystal was placed at the end of a fuel line (i.e a barbecue style igniter) a high voltage will be created which could power a spark plug! peizo crystals create massive voltages capable of lighting gas as we know.
The job of machining a cylinder head to accept a spark plug instead of an injector is a fairly simple matter either shimming down or boring out and tapping to the correct size and thread.
Then adjusting the timing of the ignition is as simple as adjusting the fuel pump timing gear.
So basically, the idea in summary is to convert an injection pump into a hydraulic pump to actuate individual peizo ignitors and cause a spark.
Doing this would completely eliminate the engine’s ability to run on diesel but if woodgas is your only fuel source, i think it stands a chance of working.
I’ll draw diagrams as soon as i can get the time, just wanted to get this idea written down and into discussion
I didn’t take time to read all the way through the below thread but if you haven’t read it you may find some of your answers to the ignition question .
Hi wayne,
Thank you for the link. I hadn’t read that extract about the use of the venturi before. That will come in real handy I think as well as the extra valve for the additional air needed on startup. I don’t suppose anyone knows if there’s a diagram of this venturi they used in India?
When you have some time, I’d really appreciate your critique on my idea, I’ll draw up some diagrams to explain it better
You could put a target on the fly wheel and then space sensors for each cylinder around the fly wheel that would read the target? Then fire individual coil packs that are now common on most petrol engines. You will need to use 5 volt as the coil packs typically require a 5 volt signal.
If you are really savvy you could then place the sensors in a very advanced placement and use logic micro controller to control timing.
Another method would be to use a gear belt drive off of the crank and reduce it down to 2:1 and place a cam sensor on an idler pulley. Then you would have to feed this to a controller and then out to a set of coil packs.
I wonder how hard it would be to modify a existing distributor and put a gear belt pulley onto it and drive it off the crank with correct 2 to 1 ratio?
AlexH. I suspect that the piezo crystal triggers do not have the watts/joules to directly long enough duration truly fire a spark plug. Under compression conditions; and to establish an ionized pathway requires quite a bit of energy. Far more than open atmospheric pressure liteing off.
Could be used as trigger point. Then you’d have to boost it.
MattR. had a good idea with magnetic triggering systems. 5 volt referenced to be able to processor modify.
And I have twice in the past put up a link to using off-the-shelf 12vdc Hall effect triggers or proximity magnetic sensors amplified thru off the shelf auto ignition amplifiers. Using standard automotive ignition coils.
This info was based on US Chrysler, Ford and GM parts.
The exact same could be done with Robert Bosch, and French auto ignitions system parts.
Back about 12 years ago APL/Marcus Hartwick,Ken Boak,Mike Anthony, Andy Scofield and a host of others started a Lister project in converting a Lister 6hp CS engine to spark ignition and fueling it with a GEK. I came along about 9 months later. They started out with a simple magnet/hall effect switched ignition contorl. When I was brought over the first time there was a new ignition control with user adjustable timing. That was a sweet idea for finding the optimal timing for a specific rpm. Alas we had some difficulties with it.
Ken and I discussed that it may have been just as easy to use a magneto off a lawn mower or automotive distributor and associated controls to have a functional system. Some outboard boat motors used a cog belt to drive the ignition magneto. I had one such system but lost it in the fire.
The advantage of the automotive systems is spark advance. A magneto with an impulse coupling can be fitted to Fairbanks Morse or Bendix magnetos. These would then have the advantage of no electrical system needed and with the proper impulse coupling fitted to them, they will have retarded spark for easy and safe starting but with fixed advance amount for running.
There was a lot of information of the Lister project on the APL website but they removed it. Some was shared on Mike LaRossa’s yahoo woodgas and woodgas builders sites. All lost with the yahoo shut down.
The Lister CS engines were fitted with a cold start plug. This large threaded plug screwed into the pre-combustion chamber. It was easily machined to accept a small commonly available spark plug.
The nice part of the Lister system was the engine could be hand crank started on diesel and the engine then used to start the gasifier. We actually had a 9 year old boy start the engine.
One the engine is running a numberof methods can be used to get the gasifier operational. For larger engines I suggested using a venturi in the exhaust to create the gasifier starting vacuum. APL included that concept in the first powertainer and pursued patents.
Hi Matt,
I think this hall effect idea is a good one. This will result in a wasted spark on the exhaust stroke but that used to be the case on early hall effect systems anyway so it still works a treat.
After reading your respone, i looked into coil packs and found some components that I think would allow me to make this work by using the injector pump to time it and get a signal using that. Then its just a matter of using a 12v feed from the battery like standard coil pack systems. I’ll draw out some diagrams and annotate so you can all see what I’m thinking and critique it further and hopefully it may work
Thanks for the advice, I really feel this helped to point me in the right direction
Hi Steve,
I think you’re right, the Piezo system won’t produce enough voltage on its own after looking at sensors and transistors that are triggered by hydraulic and hammer effect pressure.
Matt agreed with you that a coil pack will be needed to boost the spark. I found a piezo, pressure sensor that can convert the pressure from the injector pump to a signal. wiring that to a CoP (Coil on plug) along with a 12v feed from the battery should allow the signal to actuate the firing of the spark.
I’ll have a look at your posts about using hall effect triggers as I think this is a great idea. I’d like to see if using the injector pump as an ignition timer would work but failing that, the Hall effect is reliable.
Yeah, i know what you mean, only problem would be making sure you get the correct firing order but providing you have a distributor with the same number of points as the cylinder numbers, that could work right? just a matter of matching the right port to the right cylinder. and with a 2:1 ratio, no wasted spark = more power
An entirely different approach might be to look for a purpose built natural gas engine. I know, MONEY. But you’re talking about at least some money anyway. Just something to consider.
Rindert
Hi Alex . my memory’s gone south for good these days , but i do remember a chap in your neck of the woods i think Devon/ Cornwall with a Lister spark conversion , i remember reading about it many years ago , i think Ron was on the right track with the APL labs thing as well , here is Ken Boak’s engine https://www.youtube.com/watch?v=kXX2GBHoeuo
Dave
That was the first major team work session which Ken Boak traveled from England to participate with. Mike Anthony came from Michigan and is seen standing next to the engine. I am forgetting the name of the gent who made the ignition package.
The first 10KW APL power pallet utilized a 3 cylinder 962cc Kubota natural gas engine with a direct coupled Meccalite AC alternator. It worked nice. There is still some mention of it on the APL web site. Alas - a photo link in the archive is a dead end. https://www.allpowerlabs.com/category/news/page/9
There is also some mention of the Lister project. http://wiki.gekgasifier.com/w/page/30448258/Spark%20conversion%20for%20Lister%20slow%20speed%20diesel%20engines
The Lister is a precombustion chamber diesel. The spark ignition taking place in the pre-chamber delays the ignition of the primary air/fuel charge. Hence the 45 degree ignition timing that is mentioned in the notes. During my last visit I made a number of spacers for the change over plug to test power output with lower compression ratio’s I don’t think Ken had a chance to experiment with it before he returned to England.
I’ve not navigated the APL site in over a year. I just found that Ken’s post from nearly a decade is still there.
I see Michael Shilo mentioned. His is one name I knew I couldn’t recall. I believe the ignition was assembled by Michael. Ken posted the circuit PDF http://wiki.gekgasifier.com/f/Lister_spark_IC.pdf
but providing you have a distributor with the same number of points as the cylinder numbers, that could work right? just a matter of matching the right port to the right cylinder. and with a 2:1 ratio, no wasted spark = more power