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Fuel Flow variations
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jkreidler

Joined: 13 Feb 2008
Posts: 151
Location: Sheboygan Falls WI

Posted: Mon Aug 17, 2009 9:15 am Post subject: Re: Fuel Flow variations

We have the 'bulb' from Matt installed in the tunnel.  Unfortunately it has not eliminated variations with the boost pump turned on and off.  There is room for it, no pictures available though, sorry.



We are at the very same point you are Deems, in fact we are probably fighting the same battles.  I would give strong consideration before increasing the volume of fuel of air any more than absolutely needed in the tunnel.  Any increase might invite the fuel to get warmer, and increase the chance of vapor issues.  I say this because the tunnel is fairly warm, and with fuel boiling at ~125 degrees F, you can see the tunnel heat may be enough to create vapor already in the tunnel, long before it gets on top of the engine.  Juts my 2 cents....



What is your spread while trying to lean?  While performing the 'lean' test we nearly shut down the engine, not comfortable at all.  Next step is to swap out the high and low injectors to see if we can get closer, or at least consistent.  I do know the engine starts to run rough below 13.4 GPH at 65%, we need to do better than that!



Jason Kreidler

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Mon Aug 17, 2009 9:24 am Post subject: Fuel Flow variations

Linn As I understand the purpose of balancing injectors is to match fuel 

flow to EGTs. so that each cylinder is ba;anced at close to the same 

temps and fuel flows. Attached is the document I received from D. Rivera 

(at) airflow performance regarding his recommended process for balancing 

injectors. It required both EGT and GPH data.



Deems Davis N519PJ

http://deemsrv10.com/index.html



Linn Walters wrote:

 	  Quote: 	
		   



 I may be wrong here, but I don't think you get any valuable info from 

 fuel flow when trying to match injectors.  The data point is EGT 

 ...... which you work towards balancing the readings.

 What info do you get from fuel flow in this scenario?

 Linn

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rv10builder(at)verizon.ne
Guest

Posted: Mon Aug 17, 2009 9:37 am Post subject: Fuel Flow variations

The space issue is me Deems- getting the tube from the pump to the sensor is 

about 5-6 inches but the adaptors take a good 1 inch from that so if I 

needed to put a "t" in there for the bulb I would have no space for all the 

adaptors and such to work- it would be very difficult anyway. Certainly not 

worth that effort. If I needed to do it, which I wont, I would simply move 

the whole sensor to the front per the numerous feedback to that 

effectiveness.

Pascal



--------------------------------------------------

From: "Deems Davis" <deemsdavis(at)cox.net>

Sent: Monday, August 17, 2009 9:32 AM

To: <rv10-list(at)matronics.com>

Subject: Re: Fuel Flow variations



 	  Quote: 	
		   



 Thanks to all for their responses on this topic.



 What's driving me on this, is that I want to balance my injectors so I can 

 begin to play with LOP, and I'd like to have a more stable measurement 

 when collecting the data for the injectors. Thanks to the link on Matt's 

 bulb. I've got an email into him with some questions. Has anyone had any 

 experience with this? I'm just wondering if this is one of those thing 

 that should work i theory, but..... ? Also someone mentioned a lack of 

 space to install. I've asked Matt for dimensions. If it works this might 

 be the easiest 'fix'. We'll see,

 Deems Davis N519PJ

 http://deemsrv10.com/index.html



> *

> *

bcondrey

Joined: 03 Apr 2006
Posts: 580

Posted: Mon Aug 17, 2009 9:39 am Post subject: Fuel Flow variations

More info on the subject - here's the GAMI lean test.  

http://www.gami.com/gamijectors/leantest.php



Bob

N442PM



--

pitts_pilot(at)bellsouth.
Guest

Posted: Mon Aug 17, 2009 9:45 am Post subject: Fuel Flow variations

OK, I understand ..... the delta fuel flow rate gives Airflow 

Performance an idea of how much to change the injector size.  They can 

also do that with just the EGT spread, but I guess that would be the 

second best way. <GR>

When I get to that point, I'll be going down the same road ..... but I 

need to know where to move the sensor to while it's relatively accessible!

Linn

do not archive

Deems Davis wrote:

 	  Quote: 	
		   Linn As I understand the purpose of balancing injectors is to match fuel 

 flow to EGTs. so that each cylinder is ba;anced at close to the same 

 temps and fuel flows. Attached is the document I received from D. Rivera 

 (at) airflow performance regarding his recommended process for balancing 

 injectors. It required both EGT and GPH data.

 Deems Davis N519PJ

 http://deemsrv10.com/index.html

 Linn Walters wrote:

> 

>

> I may be wrong here, but I don't think you get any valuable info from 

> fuel flow when trying to match injectors.  The data point is EGT 

> ...... which you work towards balancing the readings.

> What info do you get from fuel flow in this scenario?

> Linn

Tim Olson

Joined: 25 Jan 2007
Posts: 2881

Posted: Mon Aug 17, 2009 10:14 am Post subject: Fuel Flow variations

You need to know how far apart in flow the injectors are when you peak  

each one.  I'M about ready to put out a blurb on that one after I'm  

back from vacation.

Tim



On Aug 17, 2009, at 9:55 AM, Linn Walters <pitts_pilot(at)bellsouth.net>  

wrote:



 	  Quote: 	
		   

 >



 I may be wrong here, but I don't think you get any valuable info  

 from fuel flow when trying to match injectors.  The data point is  

 EGT ...... which you work towards balancing the readings.

 What info do you get from fuel flow in this scenario?

 Linn

 do not archive



 Deems Davis wrote:

> 

> Thanks to all for their responses on this topic.

> What's driving me on this, is that I want to balance my injectors  

> so I can begin to play with LOP, and I'd like to have a more stable  

> measurement when collecting the data for the injectors. Thanks to  

> the link on Matt's bulb. I've got an email into him with some  

> questions. Has anyone had any experience with this? I'm just  

> wondering if this is one of those thing that should work i theory,  

> but..... ? Also someone mentioned a lack of space to install. I've  

> asked Matt for dimensions. If it works this might be the easiest  

> 'fix'. We'll see,

> Deems Davis N519PJ

> http://deemsrv10.com/index.html

>> *

>> *

Ron.McGann(at)thalesgroup
Guest

Posted: Mon Aug 17, 2009 2:42 pm Post subject: Fuel Flow variations

Watching this thread with GREAT interest.



I have consistently higher CHT on Cylinder #2 compared to the rest (when

running rich), with consequentially greater EGT.  I have trimmed the fwd

air dam, but it makes little difference.  Once running lean of peak, CHT

#2 is lower than the rest.  Suggests to me that I have a restriction in

either the line or nozzle to the #2 cylinder.  I am a philistine in all

things related to the engine.  How do you go about adjusting or changing

the nozzles?  Is this something an engine shop should be looking at??



Cheers

Ron

VH-XRM

--

speckter(at)comcast.net
Guest

Posted: Mon Aug 17, 2009 3:20 pm Post subject: Fuel Flow variations

It is very easy to get a little crud in the injector nozzles.  Disconnect

the fuel line from #2 injector and turn on the fuel pump with the throttle

partly in to flush out the line.  Remove the injector from the cylinder and

carefully disassemble the unit to clean it with and air line.  It is very

difficult to actually see the crud in an injector, but after cleaning they

work much better.



Gary Specketer



--

dlm46007(at)cox.net
Guest

Posted: Mon Aug 17, 2009 3:20 pm Post subject: Fuel Flow variations

I called Lycon to confirm my expectations of normal. I asked what should we

expect for EGT range and CHT range for any given power setting. Assuming

relatively new manufactured engine with new cylinders (not overhauled ,

welded, oversized, etc) one can expect the EGT range of 75 F and the CHT

range should be 50 F. Each change of MP will may cause a different cylinder

to have the peak temperature. Cylinders manufactured prior to say 2000 will

probably repaired and the repairs will change the temperature and pressure

characteristics. The implication of this is that if your EGTs or CHTs for a

given stabilzed power setting fall outside of these norms then , perhaps,

additional investigation is warranted, if not you may be chasing problems

that don't exist.



--

RobHickman(at)aol.com
Guest

Posted: Mon Aug 17, 2009 4:08 pm Post subject: Fuel Flow variations

In both my RV-4 and RV-10 I ended up moving the flow transducer to the line  between the Fuel Servo and distribution block on the top of the engine.   This location has completely eliminated any difference in displayed fuel  flow when the boost pump is on or off.  This is also the location that  most certified aircraft have you install the transducer.

  

 You want all the cylinders to peak at exactly the same fuel  flow.   

  

 Rob Hickman

 N402RH   RV-10

 

  [quote][b]

ricksked(at)embarqmail.co
Guest

Posted: Mon Aug 17, 2009 4:21 pm Post subject: Fuel Flow variations

Mine is in the stock location and for whatever reason it's constant and steady....Rob I meant to ask you, I love your paint scheme....Did you get that from the US postal service??    

  

Rick Sked 

N246RS 

do not archive

---

Bob Turner

Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA

Posted: Mon Aug 17, 2009 5:21 pm Post subject: Re: Fuel Flow variations

Ron, Have you tried the coke bottle test?

Pull the injectors off the cylinders, direct their output to individual bottles. Turn on the boost pump, fill the bottles half full or so. If #2's bottle is not up to the same level as the others, there's a restriction somewhere.

_________________
Bob Turner
RV-10 QB

Ron.McGann(at)thalesgroup
Guest

Posted: Mon Aug 17, 2009 5:52 pm Post subject: Fuel Flow variations

Awesome - thanks for the responses!



Thanks for this one Bob - I'll give it a try on the weekend!



Cheers,

Ron

VH-XRM in Oz



Do not archive



--

Kelly McMullen

Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ

Posted: Mon Aug 17, 2009 6:14 pm Post subject: Fuel Flow variations

I hear that some guy named Cox kind of messed with it. Lucky it doesn't have Horizon painted on the side.



On Mon, Aug 17, 2009 at 5:20 PM, Rick Sked <ricksked(at)embarqmail.com (ricksked(at)embarqmail.com)> wrote:

 [quote]

Mine is in the stock location and for whatever reason it's constant and steady....Rob I meant to ask you, I love your paint scheme....Did you get that from the US postal service??     

  

Rick Sked 

N246RS 

do not archive

---

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

robhickman(at)aol.com
Guest

Posted: Mon Aug 17, 2009 8:12 pm Post subject: Fuel Flow variations

We are still trying to figure out where the painter came up with the scheme, Â  he does drink a lot of Coors Light. Â We will have to see if the mountains show up when it gets cold. 

 

  Rob Hickman

  N402RH Â RV-10

 

 

 --

partner14

Joined: 12 Jan 2008
Posts: 540
Location: Granbury Texas

Posted: Mon Aug 17, 2009 10:22 pm Post subject: Fuel Flow variations

Apparently I missed this one,,,, where's a pic of Rob's 10..... Rob if you're tuned in,,,, are you going to be in Independence next week for the flyin?  We're going to try and make it.

 Don



--- On Mon, 8/17/09, robhickman(at)aol.com <robhickman(at)aol.com> wrote:



 [quote]

From: robhickman(at)aol.com <robhickman(at)aol.com>

Subject: Re: Fuel Flow variations

To: rv10-list(at)matronics.com

Date: Monday, August 17, 2009, 9:09 PM



 We are still trying to figure out where the painter came up with the scheme,   he does drink a lot of Coors Light.  We will have to see if the mountains show up when it gets cold.  



 Rob Hickman

 N402RH  RV-10

--

_________________
Don A. McDonald
40636

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