Gas engine running on Veggie oil - need help

**parkland** · Nov8-09, 09:17 PM

Before I get flamed for this, I am not running a gasoline engine directly with normal fuel oil or veg oil- I made a gasifier.

My gasifier is lame at the moment, but is just for testing purposes. It consists of a small fuel reservoir, suspended several feet up, then it flows down through about 50 ft of steel tubing which sits inside a stove that is red hot. The tubing itself also gets red hot. After the stove, the tubing comes out, and has a cooldown phase, with 5 feet coiled in a bucket of water.

After that, the tube goes into the air intake of my little 4 stroke gasoline engine.

I currently have no throttle, just as much oil drips down the tube.

My QUESTION is, how strong is gasified oil? I have talked to people who have built wood gasifiers, and say to use 50% wood gas and 50% fresh air for the stoic mixture, but my engine seems to run far, far leaner than 50% "oil gas".

PS If I get past this, I have a v8 chevy truck just begging for some nerdy modding.

**Danger** · Nov8-09, 11:04 PM

The main difference between a diesel engine, which readily runs upon recycled food oil, and a gasoline engine is that of ignition method. A gas engine has to have a high enough octane rating to eliminate pre-ignition. I don't know that such an engine can ignite and utilize any kind of oil, no matter how preheated it is. A diesel runs such high ratios that the heat of compression initiates ignition of the air/fuel mixture. The glowplug is just for starting.
I guess that the answer to your question depends upon the octane rating of your gassified fuel and the efficiency of the delivery system. Propane, for example, has a higher octane rating than any available pump gas, but you have to have a specialized carbeurator setup to use it. Aside from the mixture, the ignition timing has to be altered to make it efficient.

**parkland** · Nov9-09, 08:36 AM

OK, this oil is not "pre-heated", it is "pre-gasified". What is being sprayed down the engines air intake is a white gas that burns extremely well.
When I light the end of the tube with a lighter, the gas burns as if it was propane. The little engine seems to run extremely well, even with only primitive fuel metering.

I've already done the WVO in a diesel truck "thing", I think it's cooler to run a gas engine on WVO, even at a power reduction...

**xxChrisxx** · Nov9-09, 08:50 AM

What do you mean by how 'strong' is vegetable oil?

Also after extended running, take the engine apart and inspect it. The reason SI don't tend to run very well on ex food oil is a large build up of particulate matter. Diesels already dewl with this problem. It may or may not be a problem for practical application, and there has to be some way of solving it.

**parkland** · Nov9-09, 07:31 PM

What I meant is how potent the gas is, as in the gas from wood or garbage needs 50% stoic mixture, whereas my gasified oil seems to run well at a very lean mix.

I can not find any research on gasified oil.

**xxChrisxx** · Nov9-09, 08:08 PM

The stohiometric burn can be calculted from fuel composition, which needs the chemical formula for the fuel.

I suspect research on SI engines using vege oil is pretty rare. I've never heard of it being done before. They ussually use it in CI engines.

I think atm your best bet is a 'suck it and see' approach. Just record all the data you can yourself. Research has to be started somewhere.

**parkland** · Nov9-09, 08:39 PM

Originally Posted by xxChrisxx

I think atm your best bet is a 'suck it and see' approach.

Thats what She said

I guess I'll have to test myself, but I was hoping to start with better information, I work in an old garage, not a top of the line science lab.

**xxChrisxx** · Nov9-09, 08:55 PM

Some of the best things came from a man with a hammer in a shed.

Ok you wount be able to get lots of telemtary, but any data (even anecdotal) is a start.

If you manage to find a fuel flow rate that works 'best' that gives an idcication as to completeness of burn. The next step would be to try to measure exhaust temperatures.

**parkland** · Nov9-09, 09:07 PM

Actually I was planning on measuring exhaust temps from the beginning, as soot can easily be cleaned out by removing 6 bolts, melted piston or valves not so much.

This stuff burns a lot cleaner than you'd imagine. I have to say I'm very suprised that more people have not tried this. In a real life implementation, exhaust could be used to gasify the oil, maybe with a supplemental burner for starting and low load conditions.

**Ranger Mike** · Nov10-09, 05:58 AM

i been down this road before. i bought a diesel New VW beetle used...it now gets 44 MPG and i could add a chip to up it another 2 to 3 MPG...and I have all the stuff to convert it to veggie oil...i can tell you the following:
expect 10 percent less MPG with Waste Vegatable Oil (WVO)
winter is a real problem..the WVO must be heated to at least 140 degree befroe injecting into the combustion chamber. this requires a heat core ( electric or using radiator coolant, and heat coil mid chassia and one just before the injector pump
there must be a seperate fuel tank for WVO and the diesel starts up on diesel , GETS TO OPERATING TEMPERATURE, before the WVO is introduced via switching valve system.
finally the WVO must be purged before the diesel is shut down of risk lock up of injectors and pump (WVO whe nit cools is a wax like mess)
also the WVO must be dewatered and filtered to about 10 micron so as not to ruin the pump and clog the injectors. this requires a heating device and i use a centrifuge to further dewater the messy WVO. ther is also a large grey area regarding legality of operating a WVO om the public highway but this is for other discussions that i personally dismiss once we again hit $ 4.00 a gallon fuel...just listen to the news to find the sell price a barrel of oil is selling for and devide by 33 to get the cost of a gallon of gasoline...

**parkland** · Nov10-09, 07:23 PM

Originally Posted by Ranger Mike

i been down this road before. i bought a diesel New VW beetle used...it now gets 44 MPG and i could add a chip to up it another 2 to 3 MPG...and I have all the stuff to convert it to veggie oil...i can tell you the following:
expect 10 percent less MPG with Waste Vegatable Oil (WVO)
winter is a real problem..the WVO must be heated to at least 140 degree befroe injecting into the combustion chamber. this requires a heat core ( electric or using radiator coolant, and heat coil mid chassia and one just before the injector pump
there must be a seperate fuel tank for WVO and the diesel starts up on diesel , GETS TO OPERATING TEMPERATURE, before the WVO is introduced via switching valve system.
finally the WVO must be purged before the diesel is shut down of risk lock up of injectors and pump (WVO whe nit cools is a wax like mess)
also the WVO must be dewatered and filtered to about 10 micron so as not to ruin the pump and clog the injectors. this requires a heating device and i use a centrifuge to further dewater the messy WVO. ther is also a large grey area regarding legality of operating a WVO om the public highway but this is for other discussions that i personally dismiss once we again hit $ 4.00 a gallon fuel...just listen to the news to find the sell price a barrel of oil is selling for and devide by 33 to get the cost of a gallon of gasoline...

I've been down that road too. What I am talking about is not running WVO in a diesel, but turning diesel/ veg oil/ heavy oil into a flammable gas, and burning it in a gasoline engine.

**xxChrisxx** · Nov10-09, 07:34 PM

Tbh i'm very surprised it isn't detonating when the spark is introduced.

Try removing your spark plug and see if you still get a bang. (you may not due to relatively low compression)
The low compression ratio will be destroying themal efficiency.

**parkland** · Nov10-09, 11:22 PM

Originally Posted by xxChrisxx

Tbh i'm very surprised it isn't detonating when the spark is introduced.

What? I'm sure it is! or are we on different pages here...lol

Try removing your spark plug and see if you still get a bang. (you may not due to relatively low compression)

Tried before, hung spark plug on edge of hole, and pulled over the engine- some white gas came out and ignited, in a semi violent manner.(fast, but not loud)

The low compression ratio will be destroying themal efficiency. -Hey, maybe, but considering were talking about running a plane jane gas engine, from possible free fuel, I see grounds for development. :)

I realise that by reading this, immediately it sounds like I'm trying to make a diesel engine from a gasoline one- this is not the case. Once the oil is gasified, there is nothing "oil" about it.

The gas made from it, is best described as a "white fog", you can fill a bucket with it, but it is easily blown out by blowing on it. It acts and burns exactly like butane, only you can see it, and it stinks sorta bitter. (I tried to not inhale any, I was warned by someone smarter than myself that it is no good...)

When the engine is running, exhaust is always perfectly clear, leading me to believe that it is burning nice.

**chemisttree** · Nov11-09, 01:10 AM

You will need to condense the gas out of the generator and start from there. Do you think that you are running the engine on vaporized oil? Not likely. It is a decomposition product. You must isolate it and run that through an engine to determine the energy density.

I have heard of using Calcium hydroxide and high temperature to generate C8 compounds for gas engine use. Something you might try...

FYI
Calcium hydroxide = mason's lime

Expect a lot of ash...

**civ3** · Nov16-09, 04:20 PM

parkland,

I'm thinking about doing the same, but with waste oil instead as I have a lot of that. My primary concern is with the oven carbonizing the oil, eventually clogging the tube. Is there any evidence of carbonizing? Another concern would be the octane rating of the gasified product, whatever it is made of. You are not going to know if that's a problem until you put a load on the engine. You can try experimenting with the timing and see what you can get away with. Finally, I would be concerned of contaminates in the gasified product. If it was wood gas, obviously it would need a filter. For peanut oil, it might be clean. Try running the gas through a filter and see what gets trapped, if anything.

Have you tried not cooling the gas in the tube and cool it with the intake air?

When leaning the mixture out, I would check for knocking, engine responsiveness, and engine temperature.

**xxChrisxx** · Nov16-09, 04:32 PM

Originally Posted by parkland

I realise that by reading this, immediately it sounds like I'm trying to make a diesel engine from a gasoline one- this is not the case. Once the oil is gasified, there is nothing "oil" about it.

The gas made from it, is best described as a "white fog", you can fill a bucket with it, but it is easily blown out by blowing on it. It acts and burns exactly like butane, only you can see it, and it stinks sorta bitter. (I tried to not inhale any, I was warned by someone smarter than myself that it is no good...)

When the engine is running, exhaust is always perfectly clear, leading me to believe that it is burning nice.

Edited to remove rubbish information, see Brewnogs post instead ;)

Why do you want it to run as spark ignition instead of compression ignition anyway?