Mailing List flyrotary@lancaironline.net Message #32152
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] Re: Water in Gasoline
Date: Wed, 7 Jun 2006 23:49:58 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi Barry,
 
Thanks for the succinct summary of the article.  Engines stop if they try to run on a mixture too rich in water and may seize if a 2 stroke.  Glider time is glider time {:>).
 
Ed
----- Original Message -----
Sent: Wednesday, June 07, 2006 10:33 PM
Subject: [FlyRotary] Re: Water in Gasoline

Ed,
 
I read the article but it didn't give me much pause.
 
They start with the fact that gasoline with water is a problem to engines because they stop when they try to burn water. Okay, so far, so good. Then they point out that MBTE oxygenated gas doesn't absorb very much water. In case of water contamination, see problem one.
 
Ethanol and water absorb 3.8 teaspoons per gallon without a problem. So they point out that ethanol-oxygenated gasoline is actually more tolerant of water and, therefore, less likely to cause problems for minor contamination.
 
The glitch comes if one has more water than that. Then phase separation occurs and the excess water starts to absorb ethanol out of the gasoline. Then four-stroke motors have problem number one (i.e. not running).
 
But for two-stroke engines, the water-ethanol mix can displace the gas-oil mixture THAT LUBES THE ENGINE. That's why they remark that the effects on two-strokes can be bad--inadequate lube.
 
My take is:
a) this effect is only present for gasoline that's so contaminated that the ethanol can't absorb all the water,
b) the difference between four-strokes and two-strokes is that four-strokes quit running whereas two-strokes quit running and can seize, and
c) if you left your OEM apex seal lube in place instead of going to just oil-fuel mix in your gas tank, you still might be okay. More reason to install Richard Sohn's little lube pump reservoir and just replace those goofy oil injection nylon lines with stainless ones.
 
In note b above, if both four-strokes and two-strokes both quit in the case of gross water contamination, it probably feels the same to you experienced glider pilots. But if you have really displaced all your lube through water contamination, then two-strokers get to rebuild the engine too. That's bad but not unexpected when one runs out of lube, no matter how it's delivered to the engine.
 
Barry Gardner
Wheaton, IL
----- Original Message -----
Sent: Wednesday, June 07, 2006 7:37 PM
Subject: [FlyRotary] Water in Gasoline

I ran across this interesting article on the effects of water in gasoline and in combination with alcohol could have on engines.  Possibly indicates that MoGas with Alcohol might be a potentially very bad combination for 2 stroke engines in particular.  But, read for yourself if interested.
 
Ed
 
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com


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