water in fuel

Johnson .29??? Now there is a relevant engine.

A small amount of water may help with detonation on four strokes but having water mixed with fuel long term doesn't seem like a good idea. All of the oils and other additives surely must suffer under these conditions.

Spend a minute and do a google search on this group to get a pant load of stuff on this subject by many different experts...

Have fun with it!

FredD

Would that come from the increase in compression due to the water not being able to be compressed?

David - who has heard of the hassles that water > This has been discussed before, but I just read it in Joe Wagner's column in

With water in the fuel, as the fuel mixture vaporizes the water turns into water vapor and takes heat out of the mixture and thereby increases the density. In effect it acts as a mini supercharger. Some of the high performance piston engine aircraft, like the WWII Corsair, used water injection to boost power for short periods of time. I met some guys in Atlanta in the mid-1950s who used water in their fuel for competition UC team and rat racing. They claimed that about 10% water gave a noticeable performance improvement with acceptable fuel economy.

I doubt that any of the liquids in fuel can be compressed. The fuel that goes in the combustion chamber is in vapor form (including any water).

Though slightly OT, water injection is a trick sometimes used to suppress detonation in high compression engines or engines running high boost pressures (high effective compression ratio), though no mention of it increasing horsepower except by virtue of the fact that it allows the higher compression ratios. I remember an article quite some years back by, I think, Road and Track, where they built their idea of the ultimate "sleeper" car - a Trans Am looking quite stock on the outside with a Keith Black 427 on twin turbochargers and adjustable waste gate. They claimed 1350 HP on max boost. IIRC the waste gate could be set between 8 and 35 psi. The comment was made that if you sneezed with your foot on the gas pedal you'd be doing warp 9 when your eyes opened again. Anyhow, they used water injection for detonation control at the higher boost settings.

Mike D.

All the posts I've seen so far are for large, powerful, 4 stroke engines. Does it really do anything for a small 2 strokes? Personally, I'll stick with stock glow fuel. If I need more horses, I'll buy higher nitro content or install a larger engine. Dr.1 Driver "There's a Hun in the sun!"

That's my feeling as well.

BTW, ADI used in Reno racers is a mixture of alcohol and water.

There is one other consideration. When water is heated to above the boiling point (as it is in the cylinder) its gas expands to many times its liquid volume.

This characteristic has been used in some early jet airliners. (I think that some early Boeing 707 had water tank and injected water to increase thrust on take-off) Yes, this might work for a tirbine engine.

The offsetting factor is that when water evaporates, it absorbs, which could have a downside in an internal combustion engine.

Let's not confuses the issue here. The concept of water injection has been around since WWII or before. What we are talking about here is the addition of water (up to 20%) to glo fuel. Has anyone any experience with this other than the original author Bill Wagner in Model Aviation?

And the guys trying to beat them bought it and then couldn't figure out why their engines wouldn't start. :-) This gag has been played on a lot wannabe competitors in a lot of venues.

Red S.

Go back and read the article again. What he was saying in the article was not that you should add water in fuel. He was saying that the main cause of fuel degradation is not due to presence of water but from degradation of alcohol.

Alcohol has a definite degration path in order of increasing oxidation states( from methanol to formaldehyde to formic acid), and having oxidizer such as notromethane did not really help the matter. He proved his point by adding huge amount of water to his fuel. He pointed out the engine ran like crap on tat 20% water laced fuel,but it ran, and that was his point.

Yes, I did some tests a few years ago by adding measured amounts of water to fresh fuel then flying the model if the engine (an SC 1.08) seemed to run OK. Starting at 0.5% water and up to 3% there was absolutely no change in how it started and ran compared to the fresh fuel. At 4% the engine wouldn't even pop let alone start. What I found was that at 4% the water drove all the oil from solution and it settled at the bottom of the tank so the engine was drawing raw oil instead of fuel.

Back at home I found that the % of water needed to drive the oil out of solution was temperature dependent in that the cooler the fuel the less water could be tolerated. I had similar results with both all castor and all synthetics and got a virtually straight line graph of water%/temperature. Both fuels were zero nitro so I can't say what affect nitro might have on allowable water content.

Brian Hampton Adelaide, South Oz

OK, I read it again. Are you talking about the same article I am, on page 83 of the July 04 issue of Model Aviation? Quoting from Wagner's column, starting at the bottom of page 82. "Another topic I recently mentioned in this column was my successfully hand-starting and running a glow engine - with a small actual gain in performance - on fuel containing 20% water." Perhaps we are talking about different articles.

Red SO.

The guy doing the article got a slight RPM increase on a non-throttled control line engine. The test does not seem relevant to RC engines. He didn't have to idle, run at part throttle, or transition from one extreme to the other.

Seriously, did anyone read the article as a RECOMMENDATION to add water to your fuel?

I got the impression he was just trying to demonstrate that some of the myths about fuel going bad almost instantly when exposed to the atmosphere are overblown.

Maybe you just thought it was a gag and didn't bother trying it. Adding water will allow a higher percentage of nitro on the same compression ratio. If the engine is detonating just enough you can't hear it then adding water will indeed improve the power. Also it may cause the engine to peak with a leaner mixture without overheating, this may also increase power.

The problem with getting water in your fuel is that it usually doesn't happen instantly. It occurrs over an extended time during storage. This gives the water time to work its evil on the other additives to the fuel. If he REALLY wanted to do a test, he would let that same fuel sit for a month or two and try it again.

Then why don't any of the fuel makers or hot competitors do it? I have been at this a while and I know a few competitors. None of them have done it.

Exactly,look how much more profit they would make substituting 20% of the methenol with 20% water. DOUG

Even if everybody understood that you can add up to x% water with no problems and possibly even a power increase, would they pay the same price for fuel with water premixed in? I would guess not. If you read the article closely you will note that there was some issue with starting. Also there is the fact many do not believe the article, well that means that almost no one will buy fuel with water, even if discounted.