Thread: hydrogen fuel

As far as fuel saving devices go, don't underestimate the value of water/vapour injection. I installed a system which was so simple onto a small 4 cylinder engined manual car and noticed a significant improvement in fuel economy. Using the same fuel type, running everything the same, no adjustments made or additional devices fitted. Now I did no actual technical testing of the mpg or anything like that, just a simple calculation of how many kms the car would run on a tank of fuel driving under the same conditions (aproximately 60% highway and 40% city traffic).

Before fitting the vapour device I was getting an average of 620 - 640 km from a full tank of fuel (45 litres) and this was consistent over 6 months. With a simple water vapour injection device fitted (not strictly injection as the engine vacum sucks the vapour in) and running under the same conditions, I managed to pull 750 - 780km to a tank. For a 16 year old barina that is pretty impressive. To me the proof of the pudding was that after removing the device, the fuel consumption went back to around the same as it originally was. I'm convinced and will be building a similar device when I get my series 3 registered. For $10 - $20 worth of materials and a couple of hours work it is certainly an improvement that pays for itself.

I've looked at a lot of these hydrogen and hydroxy gas systems and the theory is sound but the costs to put one together is a lot to risk on a whim. I think at the very least you would need a beefier alternator and possibly some better batteries to provide the sort of power to convert the water to a gas. They are normally a pulse type device so not a straight voltage in, this makes them slightly more efficient. I have seen a simple generator that runs from a 12v battery and fills a balloon which a small 4 stroke motor uses as a reserve tank to run totally on hydrogen, but when the battery runs low the system loses efficiency.

I'm sure its doable, but the fuel companies don't want you to know about it.

From my miniscule knowledge of water injection, I thought all that did was increase the compression ratio (as the injected water takes up volume in the combustion chamber and does not compress). You might as well shave your head(s) (to increase the compression ratio). Better still, you could fit a nitrous oxide system. Now that would be good. A Landy on nitrous. Go rev heads.

A little bit of trivia: If you look at the chemical reaction of the burn of a petrol internal combustion engine, a greater volume of water is produced than hydrocarbon fuel measured at standard temperature and pressure. I mention this so people will understand water vapour is part of the process anyway.

I thought that the water/alcohol injection didn't cause an increase in compression. Rather that it allowed higher compression to be run without the risk of detonation. There is some cooling of the air/ fuel mixture which allows for the possibility of more power.

I believe it was used on some WWII fighters to reduce detonation on take-off. The engines had fairly high compression to try to get useful power at altitude and this caused detonation problems at sea level.

So the water/alcohol allowed rather than created higher compression.

Originally Posted by vnx205

I thought that the water/alcohol injection didn't cause an increase in compression. Rather that it allowed higher compression to be run without the risk of detonation. There is some cooling of the air/ fuel mixture which allows for the possibility of more power.

I believe it was used on some WWII fighters to reduce detonation on take-off. The engines had fairly high compression to try to get useful power at altitude and this caused detonation problems at sea level.

So the water/alcohol allowed rather than created higher compression.

I have used water injection to prevent detonation on engines with too much compression. It allowed me to run a reasonable advance curve for cooler conditions without needing to retard the timing in hot weather. I did not get extra power or economy, the amount of water needed to stop detonation cooled the combustion enough to reduce power a little. I think these days a knock sensor and electronic timing is far better at managing detonation.

The last couple of posts relate to water injection not water/alcohol injection which is something different.

As you mentioned water/alcohol injection (and the two need to go together) is used in the aircraft. The power of a gas turbine (turbo prop) engine is very much related to the density of the fuel air mix going into engine. On hot days where density height is raised power in these engines power can be reduced on takeoff due lower density of the air fuel mix - water/alcohol injection on hot days at higher altitudes substantially increases power for takeoff.

I guess that in theory water injection in a car engine is trying increase the density of the fuel charge like a intercooler does on a turbo but I would have though that as the air molecules cuddle up to each other the extra space would have just been taken up by no combustible water - maybe this just damps the "detonation" allowing an engine to run at extreme timing configurations.

Garry

Could be unrelated but I have a cold air intake on the Commodore. I thought this increased the density of the air/fuel mixture. According to things I have read (No. Not Penthouse or Playboy.) this adds an extra three kilowatts.

My first car was a Morris 1300 auto and had a top speed (indicated) of 78mph on a dead flat road. On cold foggy nights it would get up to 83mph over the same roads - but only when the air was dense.

Originally Posted by garrycol

My first car was a Morris 1300 auto and had a top speed (indicated) of 78mph on a dead flat road. On cold foggy nights it would get up to 83mph over the same roads - but only when the air was dense.

Well known fact amongst the lads. Cars go faster at 3 am.