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Design for Alcohol Engine

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mountain4don

Joined: 18 Jan 2006
Posts: 29

Posted: Wed May 31, 2006 7:22 am Post subject: Design for Alcohol Engine

It seems that the drift is toward more alcohol based fuels in auto engines here in Iowa.  And more states are requiring alcohol in auto fuels to the point where it is difficult to find any straight gasoline anywhere anymore.  So the question comes up, should I be designing an engine system for my 601 XL that will take advantage of alcohol based fuels when I am installing the engine in a year or two?  Have there been any airplane engines set up for alcohol and flown with it successfully?  Any of the auto conversions?  I wonder about the altitude restrictions it would have due to its vapor pressure and the lower energy content requiring a higher fuel burn.



Don Mountain



 __________________________________________________

_________________
Zenith 601XL, tail done, working on wings

frank.hinde(at)hp.com
Guest

Posted: Wed May 31, 2006 8:06 am Post subject: Design for Alcohol Engine

Now there is a hornets nest if ever there was one...



I have run my stratus soob on 10% ethanol fuel for 400 hours witout any

issue. Do  search on the archives for a vapor lock free way to design a

fuel system, no matter what the fuel is...That is pumps in the wing

roots. And make sure you have high pressure air on the tank vents.



Data from a Hodges fuel vapour tester has shown E10 blended fuels to be

good to between 15 and 22,000 feet.



Note that these figures are at the temperature on the ground...Assuming

temp falls with altitude this gives a safety margin.



Note you can easily test each batch of fuel to give you the boil off

altitude. The issue is with the vapour boiling in the tanks, not vapour

locking the pumps ....As long as the pumps are not sucking on the fuel

of course.



The other argument against Ethanol blended fuels is they absorb

water...Should be a good thing except the solubility reduces with

altitude (or is that temperature?), so while you may have no water in

the sumps on the ground you could "make" water as you go higher. Is this

a real life issue? Personally I doubt it.



As to the reduction in range...Well there is not much one can do about

it...



I am planning to run my new Lycoming on autofuel and while the

manufacturers will tolerate that they go nuts about having any ethanol

in the fuel...Personally I am not convinced.



Frank

601 HDS Subaru 400 hours

RV7a FI Lycoming painting!



--

dredmoody(at)cox.net
Guest

Posted: Wed May 31, 2006 9:09 am Post subject: Design for Alcohol Engine

I believe that the issue is not about fuel boiling in the tanks. If the tanks are vented with the vent tube bevelled toward the oncoming air, the tanks should be pressurized slightly above the ambient pressure at which you are flying. Given our service ceiling limitation, if the fuel boils at that pressure there is little hope that any of us will make it back down alive.



The real life issue is in fact the fuel boiling (particularly if the fuel gets warmed by sunshine on the wings) when the pressure is significantly reduced by the pump having to suck it uphill in the fuel line. The bubble that forms in the line when fuel vaporizes tends to act as an obstruction in the line because when it reaches the pump, the efficiency of the pump on vapor is much less than on liquid. Also while the bubble is in the line and not going anywhere it requires the liguid fuel to pass around it. That results in a drastic reduction in the  effective diameter of the lumen of the fuel line. So until the pump finally moves the bubbles through to the output side, the fuel flow is cut severely. 



If the bubbles are not reabsorbed into the liquid fuel in the pressurized section of the line, they cause short periods of fuel starvation at the float bowl when they arrive.



Therefore, it's what happens between the tank and the carburetor that is of greatest concern to us inflight. Consider all the bubbles that are agitated into the fuel in the tank in turbulent conditions. They don't cause a problem unless the fuel level in the tank is low enough to suck some of them into the line. That's when the fun begins.



Locating a fuel pump in each wing near the tank is a good idea.



Ed Moody II

Rayne. LA

601XL / wings



 	  Quote: 	
		   

 

 Do  search on the archives for a vapor lock free way to design a
	


 	  Quote: 	
		   fuel system, no matter what the fuel is...That is pumps in the wing

 roots. And make sure you have high pressure air on the tank vents.

 

The issue is with the vapour boiling in the tanks, not vapour

 locking the pumps ....As long as the pumps are not sucking on the fuel

 of course.

p.mulwitz(at)worldnet.att
Guest

Posted: Wed May 31, 2006 9:55 am Post subject: Design for Alcohol Engine

There is another deadly issue with alcohol in aviation fuel.  With 

many states and the feds pushing use of alcohol we all face this 

issue if we use anything but 100LL in our planes.  This could be 

really fatal if the availability of 100LL ends -- a likely event 

since there is only one company in the world making the key 

ingredient for 100LL Tetra Ethyl Lead.



Alcohol is a strong solvent.  This means it will dissolve some of the 

materials used to seal up our power plants and fuel storage/transport 

systems.  When this happens there are two potential problems.  First, 

the fuel is seriously contaminated with the dissolved 

materials.  Second. the seals and other parts needed to keep the fuel 

flowing and contained disappear.



I have been trying to look into this whole problem since the warning 

email from EAA asked for political action in my state (WA) to prevent 

the existing bill requiring ethanol in all fuels from becoming 

law.  The law did not include avgas in its final version, but it 

requires ethanol in all motor fuels other than avgas.



I don't have all the answers yet, but one show stopper is the 

requirement in the Jabiru operating/maintenance  manual that requires 

use of alcohol free fuel.  I believe this is typical of all aircraft engines.



Paul

XL wings



 	  Quote: 	
		  The real life issue is in fact the fuel boiling (particularly if the 

fuel gets warmed by sunshine on the wings) when the pressure is 

significantly reduced by the pump having to suck it uphill in the fuel line.

frank.hinde(at)hp.com
Guest

Posted: Wed May 31, 2006 10:31 am Post subject: Design for Alcohol Engine

I don't have all the answers yet, but one show stopper is the

requirement in the Jabiru operating/maintenance  manual that requires

use of alcohol free fuel.  I believe this is typical of all aircraft

engines.



It is typical and the point you make about the seals is valid...BUT....



Alcohol proof seals are available. Indeed Airflow Perfromance uses seals

that are alcohol compatible in their aircraft engine FI systems. The

real problem posed by the makers of Lycoming clones is the

susceptability to vapour lock and thus "forbid" the use of Alcohol.



When I started digging on this issue I found what they were really

talking about was fuel boiling in the fuel injection lines...This is NOT

vapour lock...This is a "hot start" issue and taxiing issue.



Secondly all "proper" aircraft engines come with mechanical fuel pumps.

The undercolw temps on aircooled engines on the ground are usually WAAY

higher compared to a water cooled engine.



So now think about it...Mechaical fuel pump in a VERY hot cowl...What do

mechanical pumps do in a low wing airplane?...They suck...(in more ways

than one) on what is now WARM fuel. Yes I know they all have blast tubes

to cool them but they barely work to avoid VL on take off after a hot

taxi. This is a potentially deadly setup as warm fuel will boil with

almost no provacation from sucking.



It is hardly any wonder then that they are nervous of using an even

higher vapour pressure fuel than 92 Octane mogas, especially when the

thing coughs and splutters during taxi due to the injection lie boiling

issue. Of course there is normally an electric boost pump to augment the

mechanical pump but they cannot guarantee a prospective builder won't

try to avoid the complexity of the electric pump.



So I think the seal issue is resolvable (whether Jabauru will provide

such seals is another matter of course) and if electric fuel pumps are

used in the "hydraulically correct" place then alcohol might be much

less of a demon than the airplane engine makers proclaim it is.



Frank 



--

cgalley(at)qcbc.org
Guest

Posted: Wed May 31, 2006 11:13 am Post subject: Design for Alcohol Engine

The fact that Alcohol is a solvent is NOT the problem.  Alcohol with 

moisture is a weak organic acid; corrosive.



If solvents were a problem, then there would not be any toluene in 100 low 

lead as an octane enhancer.  Toluene can and has taken the paint off 

airplanes.



Cy Galley

EAA Safety Programs Editor

Always looking for ideas and articles for EAA Sport Pilot



---

noelloveys(at)yahoo.ca
Guest

Posted: Wed May 31, 2006 11:50 am Post subject: Design for Alcohol Engine

Paul:



I see you missed two points.  I mention them only to reinforce your stand on

ethanol.  



First alcohol has a natural affinity to water.  This will allow water to

pass through your gascolator and enter the venturi of your carburettor where

it can freeze into ice.  So the possibility of carb ice increases with

ethanol.



The second point is for those poor folks among which I'm one who presently

fly a two stroke engine.  The lead in 100 LL ( that should be 100 Loaded

with Lead) will come out of suspension with the gas and deposit itself in

the roller bearings of our engines.  This is a lot more dangerous than just

fouling the plugs!!



I noticed the group representing the people who build the ethanol plants

were saying that the cost of production of ethanol is less than gasoline.

I'll put it straight .... They are lying !!  Unless the farms where the

sugar cane or corn is grown are growing the plants without the use of Diesel

tractors or harvesters and don't have to pump their water, the cost of

making ethanol will always be higher than fossil fuel and the green house

gasses given off by the production will be higher than if the ethanol

weren't made in the first place.



Noel



[quote] --

noelloveys(at)yahoo.ca
Guest

Posted: Wed May 31, 2006 12:00 pm Post subject: Design for Alcohol Engine

 	  Quote: 	
		    I don't have all the answers yet, but one show stopper is the

 requirement in the Jabiru operating/maintenance  manual that requires

 use of alcohol free fuel.  I believe this is typical of all aircraft

 engines.


	




I'm willing to bet that the seals are not the only reason that Jabiru

requires the use of alcohol free fuel.  

Another reason could be the amount of water vapour, or lack of it given off

when alcohol burns.  Also any blow by could cause some interesting things in

the crank case.  Oh yes alcohol has an affinity for water... How do you feel

about water condensing inside your crank case?



If ethanol was economically feasible for all, not just the people who erect

the ethanol plants I'd say we have to work around it.  But ....  The

production of ethanol causes elevated emissions of green house gasses and at

best it's a stop gap.  Something worse than putting Chicory in coffee to

stretch out the coffee. 



Noel

noelloveys(at)yahoo.ca
Guest

Posted: Wed May 31, 2006 12:11 pm Post subject: Design for Alcohol Engine

Eight hours bottle to throttle should be for planes as well as pilots.  For

any one who has composite fuel tanks believe me the solvent action of

ethanol is paramount.  There is two ways of protecting your engines form the

effects of ethanol.  Mix a bit of "Top Lube" in with the gas... Ethanol has

an affinity for water but it has a greater affinity for oil.



The other way is to remove the ethanol from the gas.  Wash it out with water

which is easy to separate from the gas.



Noel



 	  Quote: 	
		   

 

 

 

 The fact that Alcohol is a solvent is NOT the problem.  Alcohol with 

 moisture is a weak organic acid; corrosive.

 

 If solvents were a problem, then there would not be any 

 toluene in 100 low 

 lead as an octane enhancer.  Toluene can and has taken the paint off 

 airplanes.

 

 Cy Galley

 EAA Safety Programs Editor

 Always looking for ideas and articles for EAA Sport Pilot

frank.hinde(at)hp.com
Guest

Posted: Wed May 31, 2006 12:24 pm Post subject: Design for Alcohol Engine

Actually the major cause of camshaft failure in Lycomings is corrosion

from water that already collects in crankcase even using 100LL...At

least that is the theory...



It's a shame the political weight that has been thrown behind this

ethanol production nonsense. Probably too late to stop it now unless

something unpleasant happens...Like Chernobyl for instance.



I even heard sombody saying...WOW E85 is 15C a gallon cheaper!...yes and

it will get less miles for every one of those gallons too! 



Frank



--

Gig Giacona

Joined: 10 Jan 2006
Posts: 1416
Location: El Dorado Arkansas USA

Posted: Wed May 31, 2006 1:23 pm Post subject: Re: Design for Alcohol Engine

The problem with that is there will be a major change in the octane of the final fuel. If it was 87 octane with the Ethanol it isn't going to be 87 without the Ethanol.



 	  noelloveys(at)yahoo.ca wrote: 	
		  

The other way is to remove the ethanol from the gas.  Wash it out with water

which is easy to separate from the gas.

_________________
W.R. "Gig" Giacona
601XL Under Construction
See my progress at www.peoamerica.net/N601WR

noelloveys(at)yahoo.ca
Guest

Posted: Wed May 31, 2006 2:11 pm Post subject: Design for Alcohol Engine

What you say is true.   



What other octane boosters are available???



Noel



[quote] --

Bill(at)flyinmiata.com
Guest

Posted: Wed May 31, 2006 3:06 pm Post subject: Design for Alcohol Engine

toluene 

Bill Cardell (TurboDog's Dad)

www.flyinmiata.com

1-800-FLY-MX5S

tech 970-242-3800



--

noelloveys(at)yahoo.ca
Guest

Posted: Wed May 31, 2006 3:57 pm Post subject: Design for Alcohol Engine

Is Toluene available?   I've only seen it discussed as a refinery additive.



Noel



[quote] --

naumuk(at)alltel.net
Guest

Posted: Wed May 31, 2006 4:27 pm Post subject: Design for Alcohol Engine

You can buy it in lab quantities from Fisher Scientific, if nowhere else.



                                                    Bill

---

Bill(at)flyinmiata.com
Guest

Posted: Wed May 31, 2006 5:41 pm Post subject: Design for Alcohol Engine

Most hardware and paint stores carry it. Works wonders in forced

induction applications to kill knock. 

TurboDog's Dad

Bill Cardell

www.flyinmiata.com 

1-800-FLY-MX5S

970-242-3800



--

randy(at)shadycreekoutlaw
Guest

Posted: Wed May 31, 2006 5:45 pm Post subject: Design for Alcohol Engine

It can be had at your local Sherwin-Williams paint store...  I used to buy 

it and use it as an additive in kart racing engines...



Randy

http://www.n344rb.com

601XL - Plans Building

Working on Wings



Do Not Archive



---

noelloveys(at)yahoo.ca
Guest

Posted: Wed May 31, 2006 5:55 pm Post subject: Design for Alcohol Engine

I guess the last question is how much would you add to a gallon of gas to

increase the octane rating the 5 or so points lost by the removal of

ethanol??  



I read somewhere that mixing kero 1:100 with gasoline will also increase the

octane rating about 5 points.



Noel



[quote] --

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