LPG

[hondamake]

Running permanently on LPG is not a problem as long as the exhaust valves & seats are upto the higher combustion temperatures. In answer to the question already forming in your reasoning: Most modern engines that can run unleaded are good with LPG. The odd exceptions are well known within the LPG community, a small amount of research will show up the usual suspects. When you say methanol do you mean ethanol? Starting a cold internal combustion engine requires either excess fuel, some sort of fuel enrichment or air restriction, or an external heat source. If you have a very simple fuelling strategy, basic petrol carb or LPG mixer, then accelerator pedal to the floor and start cranking. Eventually there will be a high enough fuel/air ratio to fire up the engine, allow it to tick over for a few minutes and it should be driveable. The demands of our "instant results" culture means that this procedure is a not acceptable. Consequently if you have a modern petrol injected car fitted with a piggy-back LPG injection system you may have issues trying to make it start on LPG. If you or your fellow student would like chapter & verse on my experience then pm me for a contact number.

[mynameisowen]

Thanks for the reply; I do mean Methanol, though Ethanol aswell. My question stems from the fact that the reason Methanol and other biofuels are very hard to cold start is that they require a high amount of heat energy to vapourise, I was wondering if the same issue was present using LPG but I guess not!

For the good of understanding I'll explain my reasoning for others: To ensure good combustion the air and fuel must mix well, in order for this to happen the fuel (which is stored and injected as a liquid) must vaporise, often called atomization, in order to mix with the air properly. Injected fuel actually draws energy from the air it meets to vaporise itself, the amount of energy it draws is specific to the fuel used and is called the latent heat of vaporisation. Under normal running the inlet manifold and engine are hot enough to ensure good vaporisation, however when the engine is cold it can't vapourise the fuel and starting is poor or doesn't happen. In petrol engines most of the fuel injected during start-up just lines the walls of the combustion chamber/piston until its hot enough to start and lots is wasted. Cold starting is bad! It mostly comes down to good design, in our EJ9's the coolant pipe that runs into the throttle body is used to heat the air entering the engine to minimise fuel wastage and hydrocarbon emissions. Other engines use other ways, or don't bother...

This is a cool design which vapoursies the fuel before injection to allow starting with anything:

http://vfis.us/

Note the reason why its used:

"Ethanol and methanol have very high latent heat of vaporization at 0.913MJ/Kg and 1.154MJ/Kg respectively. Petroleum blended with ethanol/methanol can help recover more heat energy in addition to increasing vapor pressure."

Compare that to PURE Octane 298 kJ/kg. Irregardless of petrol composition it is much easier to start with that other fuels and is almost always mixed with the alcohol fuels, at least for starting.

In fact in Brazil (where they have large plantations of biofuels (poor rainforest, I know)), they have converted many cars to run on ethanol/petrol blends. However they often have rudimentary fuel heating systems to ensure the fuel can vapourise before injection.

[hondamake]

Your grasp of the physics and it's practical application can't be faulted. Some points I will make: 1. You've asked and answered your own question on propane, with every LPG strategy commonly employed the liquid is converted to a vapour before injection/induction. The vapouriser utilising the engine's cooling water to provide the heat. Experience has taught me that cold water, providing it contains sufficient anti-freeze, will provide just enough heat for just long enough for the engine to start and waste heat to become available. The diagram in the article you gave a link for, of an independant vapouriser, describes exactly the function of an LPG vapouriser. 2. Heating an inlet manifold to assist vapourisation is a common strategy with petrol, either injected or carburettor, with LPG it is common to disconnect/disable any heat source to avoid premature ignition of the gas in the manifold. 3. I still don't understand the role of methanol. I know it is used in some race applications but I can't see Joe, or Josephine, Public being able to refuel the family hatchback with it. It is so damn toxic! We use it occasionally in the gas biz but I won't allow the junior members of staff to use it unsupervised.

[mynameisowen]

I was not aware of its toxicity, the work my friend is doing is miles away from being implemented, just mindless research =P If you are interested it regards the development of "smart" ECU's which allow the user to fill up with any fuel ( however either SI or CI fuel, so you still cant put a diesel in a petrol). The ECU will then detect which fuel it is, indeed in which proportions it is, since its quite likely to be mixed with any other fuel the person has used recently, and then adjust ignition and fuelling to compensate. Its a pretty cool idea but still some way off.

Thanks for your insight, I'm jealous of the experience you have of modding your car(s) for so long, I need a decent job and some spare land and then I'll be following in your footsteps

[hondamake]

It's the age old paradox: When you're young and full of enthusiasm you have neither time or money, by the time you're my age you have time and money but can't remember what you needed them for. The research into multifuel engines sounds interesting but I can't see enough of a practical application to attract the research funding. In any society developed enough to provide something as sophistocated as refined fuel and the means of sale/distribution there must surely be a means of identifying what the product is. You do not go to the petrol station and pay anything that is asked for a lucky dip of something that may run your vehicle. QED if you know what you have bought you can tell the ECU what to expect i.e. Octane, calorific value, additives. Now an ECU you can self program is a sellable proposition, can't see any warranties being honoured though! Methanol is what bootleggers add to bathtub vodka to increase it's potency. They do this because they are too stupid to know the difference between it and ethanol, this is what causes spates of blindness, brain damage and death by poisoning in Glasgow.

[hondamake]

You've ignited my curiosity about using methanol as a vehicle fuel. You're right it is or has been widely used. Usually as a blend and it's popularity comes and goes with comparitive price fluctuation. If you do some research into it's toxicity I think you'll agree that it should be avoided in any quantity

[Dodo Bizar]

Well, over here it is hard to get one consistent blend of fuel. I always fill up with BP Ultimate. But I am lucky enough to have one BP station nearby and virtually everywhere on my routes. Some places sell E85, going to Germany you get E10 or something like that... which caused my father in law his Primera to throw error codes. Going back to old fashioned petrol 95 octane, his problems dissappeared.

So... the fuel overhere, it ain't refined or at least not consistent. My friend whoms D15B7 I mini-me'd blew his engine in 100 km after the built due to detonation, due too poor quality fuel (but he was cheap then ... I should have prohibited that fuel entering the car looking back).

Bottomline, I would be very interested in the technology which can adequately control ignition etc... which would also open up perspective to get 100% max power without tuning! As long as things are within certain constraints probably, but still.

[saxophonias]

What is the price of lpg per liter in your countries? Here it has climped to 0.9e while the petrol is at 1.83e

[mynameisowen]

I see what you are saying but the point wasn't to make sure the car can run on anything because people are dumb and might fill up with the wrong fuel (invisioning a time when you can fill up with whatever you want at the "petrol" station). Rather its to relieve societies dependance on one fuel source. If we all run E10 then thats 10% less petrol being used, thats a lot of barrels of oil that could be used to make more important things, plastics for example. However why not get rid of the complexities of tuning every car for E10; lets make cars run on whatever we throw in them. I doubt bio-fuels will ever overtake oil-based fuells but at least it could reduce dependance, and maybe make it cheaper for people as oil prices continue to rise.

PS. Joris, this technology would be for the "average guy", I reckon most performance cars would stay with petrol or a better fuel.

[hondamake]

I already know what the better fuel is, but you shouldn't trust my judgement when I get it for free. It must be said, however, that the quality of propane in the UK is strictly controlled. No matter whether you buy it for domestic heating, industrial processes, or auto use, it is one and the same fuel. Every parameter of it's quality is defined within fine tolerances. I assume it is the same within the EU? It is also worth noting that mixing propane with butane, which is common when either becomes scarce, will not detract from it's quality as a fuel.