The Old Water Torture Trick.

[Peter Beeney]

This is really just a continuation of graeme jones’s thread, Contamination by water - is this why your engine won’t run? It seems I may have inadvertently hi-jacked that thread, I certainly didn’t mean to, so to avoid that here I’ve done a separate post anyway.

I have done some more experiments, the first was collecting the exhaust residue from a tankful of fuel, which amounted to some oil and about the same amount of clear liquid which I very much suspect was mostly water. However, this didn’t seem to tell me much more than I didn’t already know, so I thought a much better indicator as to how fuel actually behaves in an engine when it contains water was to try it.

So, using a new gallon of fuel as a base line I made 3 mixes, 2%, 4% and 6% water. The fuel is straight synthetic, 15% oil as apposed to the normal 17%. The engine used was the Irvine 53 in the trainer; 12 by 6 ACP prop. Standard ‘Quiet’ silencer. The first run was using the new fuel with no water, just to set the standard. Generally I started the engine, let it warm up at a fast tick-over for a couple of minutes with the glow clip on, then glow off and tune for max revs. In fact, the perfectly normal standard procedure. On the first run the rpm was 10, 200, clipping the glow back on increased this to a very steady 10,500. The plug I have in at the moment is an old short reach idle bar type, just one I put in when I gave the proper one to someone else to get him going, so there may be some scope to play with this. Throttling normal. Then I drained out the tank and put the 2% water in. To all intents and purposes the result was exactly the same, I really couldn’t see any difference. So then I tried the 4% water, and although the max revs were exactly the same the throttling appeared to be a bit fluffy, although how much of this I imagined it’s difficult to judge. However, changing to the 6% water did start to make a difference, I could not better 9,900 rpm, and the throttling was definitely a bit sticky, although it continued to run ok. When I put the glow on to try that I had 10,000 rpm. So after some more fiddling, with little improvement, I tried a quick flight with the Boomer, just to verify that it was flyable. Starting in every case had been the usual more or less straightaway occurrence. The weather condition were about right for Boxing Day, the humidity was 94%, the wing gusting toward 18 knots at times, the ambient 10 degrees C, but the vis. was good. When flying the model performed well, very much as it usually performs, again I was not really able to able to say there was much difference but it was only a short flight anyway because I didn’t particularly want to have to land in those conditions without the motor running. When I did land it was ticking over nicely, it continued to do so for a couple of minutes and then opened up, but not cleanly. There was about 30 cc’s of fuel left.

If anyone should want to duplicate these endeavours, I made the mixture by measuring 200cc’s of fuel in a graduated container, removed 4cc’s with a medical syphon, and replacing with 4cc’s of clean water; this for 2%. - 8 and 12cc’s for 4% and 6% respectively.

My comment would be, as always, that this is not a definitive test. There are many different combinations of fuels and engines, props and glow plugs, also 2 and 4 strokes. Plus weather conditions. But I consider it’s a starting point, and the one thing that struck me was that 12cc’s of water in 188cc’s of fuel seemed, at the time, a singularly large amount!! I don’t think water in this proportion could ever get into fuel accidentally. Even two percent would be really, really pushing it, in my opinion anyway. Had I not known about the water in the fuel I think I might have thought there was something slightly wrong, but I would have been quite happy to carry on. I was going to continue with an 8 and 10% water mix, although I think this would just simply deteriorate further, but I’m pretty sure it would run.

So, for me at least, the water in the fuel debate now has some perspective to it, I’ve never really considered this to be a problem, and this is certainly not going to change my view on that…….

Another point that struck me was that a small amount of water could be added per gallon of fuel and it might be extremely difficult to detect..

PB

[Engine Doctor]

Hello Peter. Very interesting testsand an interesting read. I have heard ,in the past of fuel being made with cheaper grade re-claimed industrial methanol that supposedly contains quite high ammounts of water . Actually addinig water to decent fuel would surely be suicide to any self respecting manufacturer,but as you say it is possible. In the past few years I can only recall a couple of incidents at our club when an engine wouldn't run without the glow attached or would suddenly cut and was found to be the fuel(old ,very old fuel) possibly contaminated with water through condensation. Recently the most common problem causing eratic running has been the use of cheap chinese glow plugs that dont react with the fuel .it appears that its not every plug but just an occsional dodgy plug in a batch.To eliminate that i always recomend proper OS or YS plugs .Thanks again for your time and effort .

 

E.D.

[kc]

Interesting test & results!

I seem to remember that water injection in car petrol engines has been done at various times for better performance. Even the Tyrell F1 racing cars were rumoured to have done this years ago. Somewhat similar situation?

[Spice Cat]

Erm.. Pete, how do you get the water out again?????

 

 

[Peter Beeney]

E.D. - Thanks for your reply. Yes, I too would very much think that anything less than first grade fuel would never be used by reputable suppliers, you’re only really likely perhaps to get a damp squib from a sale that seems too good to be true! I’m not sure that very cheap fuel is ever offered for sale, I don’t think I’ve ever seen any. I thought about the plug effect, it occurred to me that had I been able to experiment and find a plug that had given me a few more rpm and improved the throttling a touch then again were I not aware of the water content I would just blame the plug and not the fuel! It would appear that some form of cross-checking would be very much in order, as in running it through another engine, say, if you were suspicious about the fuel. Also I take your point about the Chinese plugs, I saw something like this, an engine that stopped instantly as soon as the glow clip was removed. This could well have been the problem. Certainly worth bearing in mind. Having said that, I wonder where the OS and YS plugs are now made……

Also that raises the very interesting question, if by just changing to another plug I could tacho 10,200 rpm, with reasonable throttling, on a 6% water content, at what point does this debate actually die? The fact that I could get an improvement just by replacing the glow clip back on certainly is a starting point. I think this may be worth a follow up, beginning with a handful of plugs, but it may have wait a while for some warmer weather, at least until the chill factor gets into positive territory. The cold tends to creep into the old bones a bit now, I’ve seen a few too many summers, as they say. I have to say, I think all the bets are on the event that I will not be able to improve the running, but, as always, I like to have a go at the homework first.
It doesn’t take long to assemble the bits to play with, probably longer to write up than actually do it!

The ‘high water content runs’ do not appear to have done any harm. I gave it a little playful exercise yesterday on the usual fuel and it was on fine form, a bit like a ‘rat up a drainpipe, but on steroids!’ to paraphrase a contemporary quote from the summer flightline commentary!

I think I may just be returning back here later!

Spice Cat - I think there are a couple of procedures that I might use to get the water out again. You will have noticed in my O/P that I said that I’d done a little experiment previously, this to collect the exhaust residue from a tank of fuel. Well, this was based on my very limited knowledge of the laws of thermodynamics. As I very casually see it, when the hot exhaust gas leaves the silencer, it expands out into the air; and as it expands, it cools; and when it when it cools it can no longer sustain the water content in the form of vapour, so that then condenses out. So with this in mind I stuck a twenty inch piece of copper tube over the exhaust outlet and collected all the liquid that ran out during a full tank run. This is about 20ml of oil and a clear liquid, could be mostly water, in about equal quantities. So if I do this same trick with the water-loaded fuel I have left, I should be able to collect most of this water; however, to further filter it out I probably need to pass it through a ‘still’, this gently heats the liquid until it evaporates, and then the different contents condense out at different levels. This is called ‘cracking’, I believe, perhaps a somewhat appropriate term just at the moment. So I could then recover my water in a fairly pure form! And that might be a first, I’m sure that the usual ‘still’ product is some illegal hooch!
Alternatively, I did relate in graeme jones’ original thread how I burnt the fuel off the water in a tin, but the water boiled when the tin got hot, this was due to the heat from the flames, and thus subsequently evaporated. So if I placed my tin in a tub of liquid nitrogen, which is very cold, and then burnt it off I’m sure it would stay cold long enough not to boil the water and so once the methanol had burnt away I would again be left with my original water!

And I’m now cooly thinking that all this only goes to show that if you ask a rather foolish question, you generally tend to get an equally rather foolish answer……

PB

Edited By Peter Beeney on 29/12/2011 13:44:42

[Engine Doctor]

Hello PB . Re the plug choice . Some years ago used a new ASP I found in the workshop bought a couple of years previously. It was fitted in a fun fly and run up at the field . I noticed that it had really Excellent idle (1200 rpm) but a rubbish top end (really rubbish ) of about 5000 rpm .performance was too low to fly the model. I looked at the fuel and plumbing , even stripped the exhaust to check for blockage . No problem found . I tried a different fuel with higher Nitro , no change . Finally I took out the glow plug and checked it and noticed the hole that the coil sits in was on the large side which would lower compression and retard the timing. Changed the plug for an OS and hey presto .Over 10,000 rpm and idle up to expected 2000 ish. The lesson learnt has helped with the odd problem engine ,especially FS engines that threw props . Of course most engines these day have far better manners and plugs (apart from the reaaly cheap chinese sort that includes spark plugs for petrol engines ) are generally better . Its worth remembering though as when things get financially tight these cheaper items re-apper in the market place and the associated problems follow ;that the younger flyers wont know about. Sorry have gone off thread will shut up now

[flytilbroke]

Thank you for this thread, the experiment and result. It does basically confirm the argument that some of us have stated against the old wives tale of the harm and indeed the lack of fact when claims are made of water in fuel. My experiment of leaving the cap off a container of fuel caused accusations of me not telling the truth... Vindication I think.

[Peter Beeney]

E.D. - Not at all, please don’t consider the thread, as far as I’m concerned you can write about anything you like, it’s all good and informative stuff. We’ll just assume it’s all about water, methanol and glow plugs for the time being, they are all closely associated in this these posts, but if anyone wants to chip in with anything else then that’s fine by me, I personally have no objections to that at all. My rather fatuous comments to Spice Cat, above, were simply as a consequence that for my sins we are acquainted, as may have been nearly obvious. He’s probably now skulking in the corner somewhere, trying to dream up a private type reply for when we next meet. Actually, he’s not a ‘alf bad lad, on the quiet. Don’t tell him that, though!

I rather tend to try changing plugs in the first instance, being naturally lazy and taking the line of least resistance, it’s the easiest thing to do, but of course they are frequently not the reason for erratic running. However, a small amount of tampering with a range of plugs, such as the Model Technics MaxFlash or FirePower types might be in order. Looks as though I’ll have to have to go a little bit of a shopping expedition. I might even be able to improve the ’53 in the trainer for a start.
I used the Fox variety for a long time, you could buy them from John D. Haytree back then. Certainly you’re right about plugs sometimes making all the difference, I remember once long ago, in the days when four stokes had not been around for too long, there was one, I think it may have been a Saito, which was playing up and couldn’t be easily fixed. One of the lads that sometimes worked in America said that he’d seen some good results over there using the Fox ‘Miracle’ plug and he just happened to have some; and it surely worked, too, an instant success! It caused a mild sensation at the time. I’ve always associated the detonation problem with a weak mixture, but I’m sure it’s possible the plug could make a difference here too. I’ve never had a case of detonation on any of my four strokes, but I’ve seen a few on others, including one on an early OS FS, where the prop stayed put on the crankshaft and so the cylinder was blown off the crankcase instead!

flytilbroke - Thanks for your reply. Yes, it certainly does put a reasonable perspective on it. I never took much notice of the stories anyway; and it will be even less now. But it won’t make any difference, ‘the water in fuel’ tales will still loom large occasionally. I’m sure it’s perhaps not the standard modeller in the field that worries about this, it usually seems to stem from one of the columnists in the mags. Perhaps they just want to stir the pot occasionally.

Because this is so easy to play with, it will be very interesting to see just how far I can take it…

PB 


Edited By Peter Beeney on 31/12/2011 22:41:54

[Shaunie]

"this gently heats the liquid until it evaporates, and then the different contents condense out at different levels. This is called ‘cracking’, I believe, perhaps a somewhat appropriate term just at the moment." Not wishing to be picky but this is "fractional distillation" or it is when applied to hydrocarbons certainly.

I am and always have been a lover of O.S engines but only ever use Enya No3 plugs, IMHO they turn any crabby engine into a pussycat, even use them in four strokes.

 

WOO proclaimed in RCM&E recently that fuel doesn't go off, I have half a gallon of "stuff" from about 1994. It was kept in the dark and firmly capped and gives about half the power of fresh fuel. If anyone wants a sample for water content testing let me know.

 

Shaunie.

[flytilbroke]

I will take Peter at face value,, Shaunie, my thought on your 1994 fuel. From the date it is likely to be Castor oil additive and Castor Oil being a plant extract it is quite liable to change even in the presence of Methanol which although another form of Biological product is less liable to change on it's own. Combined, there will be a slow change. That I think will be the main cause of the lower performance you report.

[Peter Beeney]

Actually chaps, just out of interest I’ve had a very quick read up on a couple of pages, and some of this may be much closer to the actual facts than I realised. ‘Cracking’ , and, more specifically, ‘Fluid Catalytic Cracking (FFC)’ are certainly the terms used when applied to separating out hydrocarbon fuels such as diesel and petrol anyway. In some quarters this is also referred to as distillation or sometimes fractional distillation, so it would appear to mean almost the same thing. My excuse is that I was trying not to to confuse Spice Cat too much, now the poor lad’s totally bewildered!

However, very interestingly, it seems there is a process, which has been used in the past at least, called ‘Azeotropic distillation’, whereby some liquid such as benzine is added to a mixture of ethanol and water to allow the water to be distilled off. In a cracking or distillation plant. I think this process captures all the different ingredients in their respective single forms, so we get the benzine, the whisky and the water back in separate jugs. Only to mix it back together again at the bar… If it works with ethanol it might well work with methanol, I think they are both very similar types of alcohol. So perhaps Spice Cat is right on the button, after all. Signs of a mis-spent youth, perhaps…

Thought I might just throw that in, for no good reason at all……

PB