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Vaporlock for Fuel Injected Engines

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panamared5(at)brier.net
Guest

Posted: Fri Apr 18, 2008 7:02 am Post subject: Vaporlock for Fuel Injected Engines

 	  Quote: 	
		    I don't have enough experience to understand why injected engines 

 have so much trouble when starting hot.


	


In my IO-360 there are stainless steel fuel lines running from the 

fuel distribution spider on top of the engine to each cylinder.  When 

the aircraft is on the ground the residual engine heat is absorbed by 

the fuel in the stainless steel lines and will vaporize.



There are varied and numerous solutions to this problem some that may 

work for you:

1.  Install a Purge Valve

2.  Use hot starting procedures as outlined in the Lycoming engine manual

3.  Reduce injector nozzle size to increase the fuel pressure in the lines

4.  Keep the high pressure boost pump on during while engine is 

running and you are still on the ground

5.  Take the top cowl off and let everything cool off

6.  Park aircraft into the wind, open oil dipstick door

7.  Install cooling louvers on the top cowl that only open when the 

aircraft is not moving

8.  Probably some others solutions as well



Bob

RV6 "Wicked Witch of the West"

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Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Fri Apr 18, 2008 6:56 pm Post subject: Vaporlock for Fuel Injected Engines

 	  Quote: 	
		  Park aircraft into the wind, open oil dipstick door 	


 >>>

  

 OK- my meager understanding of physics just screams at me to challenge this one, even though it's been pounded into our collective conscience ever since the invention of the cowling. Twenty+ Kt wind? Maybe.  But I am unconvinced that the airflow from above/below a just-shut-down engine would have any other natural tendancy but to RISE through the engine via normal convective action.  Assuming no "wind", air would be greatly encouraged to enter the outlet and exit the inlets.  Buttdraggers would have a rare advantage here. (save the venom, I gotcha on this one!) 

  

 I therefore theorize that positioning most conventionally-cooled flying machines (most RVs, for example) with their fannies pointed INTO the wind would benefit from some additonal airflow.  Conveniently owning one of these devices, I happened to be pondering this situation as I dismounted her one day after some particularly hot activity.  First I pointed her into a prevailing wind of approximately 10Kt velocity and unscientifically measured airflow by holding my hand just behind the cowl outlet.  Not much going on here.  I then danced a one-eighty with her and again unscientifically held my temp probe (upper 5-digit extremity) in proximity to her nostrils.  Whole lotta hot stuff coming out here.  Pretty much convinced me.

  

 I further postulate that opening mentioned oil door would short-circuit cooling air through the engine itself, actually reducing airflow to the engine/spider etc., but most likely helping cool fuel lines & pumps between firewall and baffling.

  

 Ye flying greybeards and physics profs, please explain the errors of my thinking & experimentation...

  

 From The PossumWorks in TN

 Mark Phillips, RV-6A "Mojo"

 http://websites.expercraft.com/n51pw/



Need a new ride? Check out the largest site for U.S. used car listings at AOL Autos.

  [quote][b]

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_________________
From The PossumWorks...

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Fri Apr 18, 2008 9:42 pm Post subject: Vaporlock for Fuel Injected Engines

After flying a 200hp Mooney(IO360-A1A) with a Skytec starter for 10 

years(~600 hours), whatever problems existed with the old Prestolite 

starters are virtually eliminated. The Skytec cranks engine plenty fast 

enough. The Mooney uses retard breaker mag with shower of sparks vibrator.

I just advance the throttle an 1/8th inch beyond where it was at 

shutdown(1000rpm), and leave the mixture at idle cutoff.

Crank, and if it hasn't started firing after 6 blades, slowly advance 

the mixture until it does fire.

Has worked very consistently for me, whether a 5 min shutdown or 2 hour 

shut down, or anything in-between. Very rare to need to make second 

attempt or go to flooded start routine.

Given that most of my flying is in Aridzona, ALL starts other than the 

first one of the day are hot starts.

=-O

Bob wrote:

 	  Quote: 	

>  I don't have enough experience to understand why injected engines 

> have so much trouble when starting hot.

 In my IO-360 there are stainless steel fuel lines running from the 

 fuel distribution spider on top of the engine to each cylinder.  When 

 the aircraft is on the ground the residual engine heat is absorbed by 

 the fuel in the stainless steel lines and will vaporize.

 There are varied and numerous solutions to this problem some that may 

 work for you:

 1.  Install a Purge Valve

 2.  Use hot starting procedures as outlined in the Lycoming engine manual

 3.  Reduce injector nozzle size to increase the fuel pressure in the 

 lines

 4.  Keep the high pressure boost pump on during while engine is 

 running and you are still on the ground

 5.  Take the top cowl off and let everything cool off

 6.  Park aircraft into the wind, open oil dipstick door

 7.  Install cooling louvers on the top cowl that only open when the 

 aircraft is not moving

 8.  Probably some others solutions as well

 Bob

 RV6 "Wicked Witch of the West"

- The Matronics RV-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RV-List

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

larrysallee(at)gmail.com
Guest

Posted: Fri Apr 18, 2008 11:34 pm Post subject: Vaporlock for Fuel Injected Engines

Hot start solution: Eggenfellner Subaru



On Fri, Apr 18, 2008 at 10:55 AM, Bob <panamared5(at)brier.net (panamared5(at)brier.net)> wrote:

[quote] --> RV-List message posted by: Bob <panamared5(at)brier.net (panamared5(at)brier.net)>

 

 

  	  Quote: 	
		    I don't have enough experience to understand why injected engines have so much trouble when starting hot.

 	
 

 In my IO-360 there are stainless steel fuel lines running from the fuel distribution spider on top of the engine to each cylinder.  When the aircraft is on the ground the residual engine heat is absorbed by the fuel in the stainless steel lines and will vaporize.

  

 There are varied and numerous solutions to this problem some that may work for you:

 1.  Install a Purge Valve

 2.  Use hot starting procedures as outlined in the Lycoming engine manual

 3.  Reduce injector nozzle size to increase the fuel pressure in the lines

 4.  Keep the high pressure boost pump on during while engine is running and you are still on the ground

 5.  Take the top cowl off and let everything cool off

 6.  Park aircraft into the wind, open oil dipstick door

 7.  Install cooling louvers on the top cowl that only open when the aircraft is not moving

 8.  Probably some others solutions as well

 

 Bob

 RV6 "Wicked Witch of the West"

 

 

 

 

 

 

 

 

 [b]

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chaskuss(at)yahoo.com
Guest

Posted: Sat Apr 19, 2008 3:50 am Post subject: Vaporlock for Fuel Injected Engines

Hi Mark,

 You can do a slightly more "scientific" test by simply watching the results on your CHT gauges at shutdown and then again, 10 minutes later with the nose into the wind and in the lee of the wind. Just an idea and worth what you paid for it.

Charlie Kuss

--- On Fri, 4/18/08, Fiveonepw(at)aol.com <Fiveonepw(at)aol.com> wrote:

 	  Quote: 	
		   From: Fiveonepw(at)aol.com <Fiveonepw(at)aol.com>

 Subject: Re: Vaporlock for Fuel Injected Engines

 To: rv-list(at)matronics.com

 Date: Friday, April 18, 2008, 10:53 PM

 Park aircraft into the wind, open oil dipstick door

 >>>

 OK- my meager understanding of physics just screams at me

 to challenge this 

 one, even though it's been pounded into our collective

 conscience ever since 

 the invention of the cowling. Twenty+ Kt wind? Maybe.  But

 I am unconvinced that 

 the airflow from above/below a just-shut-down engine would

 have any other 

 natural tendancy but to RISE through the engine via normal

 convective action.  

 Assuming no "wind", air would be greatly

 encouraged to enter the outlet and exit 

 the inlets.  Buttdraggers would have a rare advantage here.

 (save the venom, 

 I gotcha on this one!) 

 I therefore theorize that positioning most

 conventionally-cooled flying 

 machines (most RVs, for example) with their fannies pointed

 INTO the wind would 

 benefit from some additonal airflow.  Conveniently owning

 one of these devices, I 

 happened to be pondering this situation as I dismounted her

 one day after 

 some particularly hot activity.  First I pointed her into a

 prevailing wind of 

 approximately 10Kt velocity and unscientifically measured

 airflow by holding my 

 hand just behind the cowl outlet.  Not much going on here. 

 I then danced a 

 one-eighty with her and again unscientifically held my temp

 probe (upper 5-digit 

 extremity) in proximity to her nostrils.  Whole lotta hot

 stuff coming out 

 here.  Pretty much convinced me.

 I further postulate that opening mentioned oil door would

 short-circuit 

 cooling air through the engine itself, actually reducing

 airflow to the 

 engine/spider etc., but most likely helping cool fuel lines

 & pumps between firewall and 

 baffling.

 Ye flying greybeards and physics profs, please explain the

 errors of my 

 thinking & experimentation...

 >From The PossumWorks in TN

 Mark Phillips, RV-6A "Mojo"

 _http://websites.expercraft.com/n51pw/_ 

 (http://websites.expercraft.com/n51pw/) 

 **************Need a new ride? Check out the largest site

 for U.S. used car 

 listings at AOL Autos.      

 (http://autos.aol.com/used?NCID=aolcmp00300000002851)

Be a better friend, newshound, and 

know-it-all with Yahoo! Mobile.  Try it now.  http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ

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khorton01(at)rogers.com
Guest

Posted: Sat Apr 19, 2008 5:20 am Post subject: Vaporlock for Fuel Injected Engines

On 18 Apr 2008, at 22:53, Fiveonepw(at)aol.com (Fiveonepw(at)aol.com) wrote:

 	  Quote: 	
		     	  Quote: 	
		  Park aircraft into the wind, open oil dipstick door 	


 >>>

  

 OK- my meager understanding of physics just screams at me to challenge this one, even though it's been pounded into our collective conscience ever since the invention of the cowling. Twenty+ Kt wind? Maybe.  But I am unconvinced that the airflow from above/below a just-shut-down engine would have any other natural tendancy but to RISE through the engine via normal convective action.  Assuming no "wind", air would be greatly encouraged to enter the outlet and exit the inlets.  Buttdraggers would have a rare advantage here. (save the venom, I gotcha on this one!) 

  

 I therefore theorize that positioning most conventionally-cooled flying machines (most RVs, for example) with their fannies pointed INTO the wind would benefit from some additonal airflow.  Conveniently owning one of these devices, I happened to be pondering this situation as I dismounted her one day after some particularly hot activity.  First I pointed her into a prevailing wind of approximately 10Kt velocity and unscientifically measured airflow by holding my hand just behind the cowl outlet.  Not much going on here.  I then danced a one-eighty with her and again unscientifically held my temp probe (upper 5-digit extremity) in proximity to her nostrils.  Whole lotta hot stuff coming out here.  Pretty much convinced me.

  

 I further postulate that opening mentioned oil door would short-circuit cooling air through the engine itself, actually reducing airflow to the engine/spider etc., but most likely helping cool fuel lines & pumps between firewall and baffling.

  

 

	




This makes perfect sense to me.  Don't fight the laws of physics.



 --

Kevin Horton

RV-8 (FInal Assembly)

Ottawa, Canada

http://www.kilohotel.com/rv8

do not archive

 



 [quote][b]

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Charles Heathco

Joined: 10 Jan 2006
Posts: 201

Posted: Sun Apr 20, 2008 5:02 am Post subject: Vaporlock for Fuel Injected Engines

Hey Charles, you seem to be on to something. I will  try your wind theory next time. It makes sense. In no wind condition, I still  think opening the oil door helps. However, yesterday wind blew it closed while I  was at a group gathering, and I forgot about it, took off and it poped up. had  to go around slow reland and lock it.  I also experienced  minor vapor  lock after sitting hot for about 10 min, and was running 100ll. Cjharlie  heathco

   [quote][b]

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Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Mon Apr 21, 2008 9:52 pm Post subject: Vaporlock for Fuel Injected Engines

In a message dated 04/19/2008 6:52:30 AM Central Daylight Time, chaskuss(at)yahoo.com writes:

  	  Quote: 	
		  You can do a slightly more "scientific" test by simply watching the results on your CHT gauges at shutdown and then again, 10 minutes later with the nose into the wind and in the lee of the wind. 	


 >>>

  

 Hi Charlie!

  

 Excellent suggestion, and fer sure a good way to test & quantify.  As I currently have about 3-4 porcupines in the air, perhaps other RV-ers could take up the challenge and get some good, hard data and share their resuls here...

  

 Appreciate the interest,

  

 Mark Phillips



Need a new ride? Check out the largest site for U.S. used car listings at AOL Autos.

  [quote][b]

- The Matronics RV-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?RV-List

_________________
From The PossumWorks...

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