75ZT Community

i am looking to maximise economy in my car, and im hopefully going to try a few unconventional methods. steady driving will only achieve so many mpg, so i want to try and get the most bang for my money.

after doing some research, based upon knowledge i already had, i want to expand the fuel with a little heat to increase volume, therefore decreasing consumption. i know exactly how i can do this, but i have a few questions that some may be able to answer.

with volume increasing, the burn will be leaner. this means the emissions wil b lower. this however is my concern. with the lower emissions, the car will try to compensate and add more fuel. what problems could arise from this? depending on the volume increase, could the emissions exceed the set parametres pre-installed in the ecu? what effect would this have? engine management light on etc?

i appreciate there will be a preformance drop, but im only interested in maximum economy. im not going down the road involving burning HHO gas, or anything drastic like stripping the interior, im only interested in cheap methods if you have any suggestions?

Coast in neutral when descending a hill, or two. (Probably dangerous to a certain degree). Useless around my neck of the woods, Fens.

i'll just pretend i hever read that piece of advice

by driving sensibly, ive already increaced my consumption from 37mpg to 45mpg, but i want to see an average of over 50, so im truing to achive it using a bit of science

Without giving it a lot of thought, I can't see how heating the fuel will help as the car electronics, as you say, will compensate for this. The system will always maintain stoichometric ratio in steady conditions. Don't forget that this is calculated by mass not volume.

At first glance the heated fuel may detract from the volumetric efficiency in theory, but I would have to give it some thought and not at this time of day!

Coasting is not that straightforward as the modern engines switch off fuel completely on the over run anway. At idle, which it would be if coasting, then it is using fuel again so it would need some calculating to see if it would save fuel or not.

after recently studying about engine efficiency, i know there are very few ways to increace the efficiency without altering size

-increasing the compression ratio
-increacing the temperature of the hot resiovoir (running temperatures)
-decreacing the temperature of the cold resiovoir (outside ambient temperature)

would i be correct in assuming this system would work on older engines which utilise carbs or even very early engine management sytems?

i am going to get hold of an early to mid 90's car in the near future and do some real life experiments, but i wont be able to compare findings with modern engines, due to the management systems, which is why im asking about other methods of increacing efficiency

RRobson wrote:would i be correct in assuming this system would work on older engines which utilise carbs or even very early engine management sytems?

Probably would as the metering systems were so crude anyway.
I can't see that it would gain much though, so I think that I'll stick with LPG (Liquified Petroleum Gas) where there is a big saving.

a little would be enough. a heat exchanger is very cheap to knock together...

LPG is a luxury i simply cannot afford to install. i did seriously consider one, and worked out how long it would take to repay ittself. cant remember exactly, but it was much longer than the length of time i kept the car, so im glad i didnt get it installed

if only pre-ignition wasnt such a big issue, there wouldnt be a problem with skimming 40 thou off the head

Hiya Reece, the only thing I can think of is on the gear changes. Don't go through all the gears, for example, start off in 2nd then change into top, and only use brakes for stopping..

Couple of extra pounds of air in the Tyre's will also helps slightly, as will keeping a big gap between you and the car in front to prevent having to brake so hard and often..

Heating the fuel sounds like fun, especially if its petrol! ..

Re skimming the head. As an apprentice I did that on an old Jag, the prob was that the pistons were cast iron the higher compression plus increase in revs resulted in a piston breaking right round a ring slot and the top coming completely off!

That totally wrecked the engine, even to the point of a conrod exiting through the side of the sump casting.. Experiments can prove costly innit.. lol..
...

RRobson wrote:if only pre-ignition wasnt such a big issue, there wouldnt be a problem with skimming 40 thou off the head

Propane has an octane rating over 105.
I keep meaning to fit an ignition timing advance processor to take advantage of it.
I suppose a re-map would probably achieve the same thing.

As your car is a V6, it's not going to help much.

The petrol engines run closed loop fuelling once the engine is warmed up. That is they monitor the mixture using the lambda probe in the exhaust pipe. They do this to compensate for changes in fuel density and air density depending if it's hot or cold, plus other things that can affect the burning process.

So if you do weaken off the mixture by making the fuel less dense, the ECU (Engine Control Unit) will simply open the injectors for longer to compensate. If you push it far enough that the ECU can't compensate, it will have a fault code for this and may put the light on (depends on the age of the car, I think).

You could, theoretically, intercept the signal from the lambda probe to convince the ECU it's running rich. You have to remember though, that this increases some emissions, while decreasing others. If I remember correctly, CO peaks at a stochiometric mix, NOx increases as you lean it off, unburnt hydrocarbons increase if you make it richer. I mention this because it might affect MOT test results, though I think at idle you wouldn't notice, and CO is lower in any case.

I'm not convinced in the economy improvement argument either. Decreasing the fuel used, will have an effect on the power, as you said. Less fuel for less power isn't increasing efficiency neccesarily, they go hand in hand anyway. You could get the same effect by pressing the go pedal less, because this also puts less fuel in, and decreases the air at the same time. So you need to be sure that the engine will actually be more efficient, that is the decrease in power from the fuel reduction is less than the decrease in fuel used.

Also, running lean = running hot, not a good idea with some engines.
It's a pity that catalytic converters were hoisted on the industry really, as they require more fuel to run them.
No good taking them off either, unless you remap the fuelling to compensate and then you have an engine running in conditions that it wasn't designed for.

Bernard wrote:Also, running lean = running hot

Yes, that's why the NoX increases, because the exhaust is hotter, and there's some unburnt oxygen. The extra heat allows the nitrogen to burn with the spare oxygen.

Cats themselves are sensitive to the heat. The worst is if you get unburnt fuel in the cat, as when it burns later it overheats the cat and destroys it. This most commonly happens when you get misfire as you run out of petrol.

Duncan wrote:

Bernard wrote:Also, running lean = running hot

Yes, that's why the NoX increases, because the exhaust is hotter, and there's some unburnt oxygen. The extra heat allows the nitrogen to burn with the spare oxygen.

Cats themselves are sensitive to the heat. The worst is if you get unburnt fuel in the cat, as when it burns later it overheats the cat and destroys it. This most commonly happens when you get misfire as you run out of petrol.

Sod the cat, I was thinking about valves.

How about something like this:

Hydrogen Generator Car Kit from Yorkshire Green Fuels Ltd

Generation of Hydrogen at Low Pressure as a Fuel for Car Engines: Zero Carbon Emission

Although it has been recognised for many years that hydrogen can provide an environmentally friendly fuel for car engines, there has always been concern about the danger of explosion from hydrogen stored in cylinders, to be released under pressure into the air intake system of the engine. The hydrogen generator kit for car engines sold by Yorkshire Green Fuels Ltd allays these fears because the hydrogen is generated as it is needed in a safe environment and introduced into the engine air/fuel intake without risk of explosion. The hydrogen gas is carried into the combustion cylinders mixed with air and fuel vapour and is ignited there, replacing as much as 25% of the fuel, with a corresponding increase in mileage per gallon. The combustion of hydrogen produces water vapour only, and therefore has no detrimental environmental effects - in fact it reduces the carbon emissions from your engine because it is cutting the proportion of carbon fuel used.

The kit only costs £125 which is not too bad.

More info here:

http://www.yorkshiregreenfuels.co.uk/hydrogen_kit.asp

An easy one to improve fuel consumption - throw out the petrol guzzling lump and throw in a diesel one.

carlpenn wrote:How about something like this:

Hydrogen Generator Car Kit from Yorkshire Green Fuels Ltd

Generation of Hydrogen at Low Pressure as a Fuel for Car Engines: Zero Carbon Emission

Although it has been recognised for many years that hydrogen can provide an environmentally friendly fuel for car engines, there has always been concern about the danger of explosion from hydrogen stored in cylinders, to be released under pressure into the air intake system of the engine. The hydrogen generator kit for car engines sold by Yorkshire Green Fuels Ltd allays these fears because the hydrogen is generated as it is needed in a safe environment and introduced into the engine air/fuel intake without risk of explosion. The hydrogen gas is carried into the combustion cylinders mixed with air and fuel vapour and is ignited there, replacing as much as 25% of the fuel, with a corresponding increase in mileage per gallon. The combustion of hydrogen produces water vapour only, and therefore has no detrimental environmental effects - in fact it reduces the carbon emissions from your engine because it is cutting the proportion of carbon fuel used.

The kit only costs £125 which is not too bad.

More info here:

http://www.yorkshiregreenfuels.co.uk/hydrogen_kit.asp

I do hope no one considers this seriously. I had to laugh very hard at their claims. However, as much as it would be funny to rip apart some of the statements on their website we best not detract from the original posters question.

There are a few (well OK a lot) of snake oil ways of increasing performance / decreasing consumption.

If they worked like they claim they do, then they would be fitted to cars already.

Take the hydrogen generator. The hydrogen is being created through electrolysis, using electricty from the alternator. The alternator takes power from the engine, and as more electricty is being used, the engine is working harder. None of the processes are 100% efficient, so the process of creating the hydrogen must take more energy, than is available from burning the hydrogen generated, itself. So it actually worsens consumption.

OK, I know you could start to look at improvements in efficiency when the engine is working harder, or using the alternator to produce hydrogen only when braking to reduce waste energy as heat, but the power generated by the hydrogen is still so minimal, dragging round the extra weight of the kit will still outweigh the benefit.

Other similar systems are the super capaicitor (no explanation how this is supposed to help) the airflow swirl inducer (which disturbs the precise flow of the intake systems designed by the manufacturers) the 'fuel magnets' and magic oil additives.

Today I went to see an acquaintance whose sanity until now I had no reason to doubt.
He was building a diesel engined agricultural pump in the workshop and is close to trialling a Brown's Gas device in it.
However, this seems even more unlikely as it comprises a vacuum pipe to draw moist air through a hot water tank and passing it through a smooth bored vertical tube in the exhaust downpipe. Also in the pipe is an iron rod which allegedly rotates at high speed due to a vortex effect. This, again he alleges, will break the superheated water vapour into its constituents of hydrogen and oxygen. The 'gas' then being drawn via the aforementioned vacuum pipe into the inlet manifold somewhat similarly to that of the early LPG systems.

I just don't believe it but this guy is normally no fool. I look forward to the trials.

SpongeBob wrote:

carlpenn wrote:How about something like this:

I do hope no one considers this seriously. I had to laugh very hard at their claims. However, as much as it would be funny to rip apart some of the statements on their website we best not detract from the original posters question.

So rather than belittle an honest (if not naive) attempt at helping a member, perhaps you would like to enlighten us with your considerable wisdom, failing that, move back to the other forum where your smugness will be more appreciated.

Thank you Duncan for a productive response, I had not given thought to the things you stated in your post.

I"m sorry if my response seemed terse, that was not my intention. At the time I was posting from my phone and had fairly limited time, but that does not excuse me.

I was merely trying to highlight the fact that the technology referenced which, although sound in principle, in practice does not work. Duncan's following post actually quite nicely embellished my post and as such I felt his post to be a sufficient follow-up to my own with his thoughts mirroring my own.


Indeed, I have seen the exact "hydrogen through electrolysis" process first hand and I can vouch that in the setup described, the amount of hydrogen produced would not be sufficient to run an engine on. Hydrogen is a viable fuel, but not by the methods in the website.