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LOP (Lean of Peak) Injector Tuning

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Tim Olson

Joined: 25 Jan 2007
Posts: 2872

Posted: Sat Aug 22, 2009 7:18 pm Post subject: LOP (Lean of Peak) Injector Tuning

For those who are interested in running LOP and who want to

get better injector tuning to make their engine run smooth

when Lean of Peak, I wrote up my recent experience in tuning

the injectors. It was cheap, and very very easy.



http://www.myrv10.com/N104CD/upgrades/20090822/index.html



There will be a future update to the write-up, as I'm working

on a project on another engine, but the info here should give

you what you need to get started tweaking your own system.

It's so simple that there's no reason not to get your engine

set up for great operation.



-- 

Tim Olson - RV-10 N104CD

540 hours and climbing

Tim Olson

Joined: 25 Jan 2007
Posts: 2872

Posted: Sat Aug 22, 2009 7:18 pm Post subject: LOP (Lean of Peak) Injector Tuning

For those who are interested in running LOP and who want to

get better injector tuning to make their engine run smooth

when Lean of Peak, I wrote up my recent experience in tuning

the injectors. It was cheap, and very very easy.



http://www.myrv10.com/N104CD/upgrades/20090822/index.html



There will be a future update to the write-up, as I'm working

on a project on another engine, but the info here should give

you what you need to get started tweaking your own system.

It's so simple that there's no reason not to get your engine

set up for great operation.



-- 

Tim Olson - RV-10 N104CD

540 hours and climbing

Dick Sipp

Joined: 11 Jan 2006
Posts: 215
Location: Hope, MI

Posted: Sat Aug 22, 2009 8:58 pm Post subject: LOP (Lean of Peak) Injector Tuning

Tim:



Great post as usual on your injector balancing experience.  I had very 

nearly the same experience and results with two minor variations; a complete 

Airflow Performance system vs. your Silver Hawk and we started by installing 

.026's in all cylinders and then balancing.  I ran most of the tests at 

10-11 MSL and verified at the results at 7.5.  Don R. felt that at the lower 

power settings of around 50-60% the flow divider begins to be the 

determining factor and by going to the smaller .026s the flow divider is 

taken out of the equation.



There was an interesting series of pictures and notes regarding burned 

pistons (don't remember where I saw them) where the author thought the cause 

was "rapid" mixture leaning used by LOP operators.  He felt the rapid rise 

in EGT was the cause.  I disagree.  GAMI recommends the "big pull" from rich 

to LOP and then a finer adujustment to prevent spending more time in the 

danger zone of peak to 100 rich of peak.  Also with a rapid initial mixture 

leaning I doubt the cylinder or piston temp will increase before it cools 

from steady LOP operation.  Further at <65% I do not think you can do 

anything to the mixture that would harm or overstress the engine.



Regarding long range cruise I was happy to find that my engine seems equally 

smooth at 2250 as at higher RPM.  I see about a 1GPH reduction in fuel flow 

with each 100 RPM reduction at full throttle settings and there is very 

little airspeed loss as the prop is taking bigger bits (sorta like 

overdrive). Charles Lindberg showed the P-38 pilots in the South Pacific how 

to double their range by running "over square and lean".  Finally, to 

prevent the prop driving the engine during higher speed descents I keep the 

RPM at least "2" oversquare below manifold pressure.  This is common 

practice with the big radials and it would seem equally applicable to our 

engines.



Dick Sipp

N110DV 175 hours

speckter(at)comcast.net
Guest

Posted: Sun Aug 23, 2009 4:10 am Post subject: LOP (Lean of Peak) Injector Tuning

Is there a danger with running too much over square?  Dick mentions 2" but I

have been running more than that (2200 and 26")LOP. I have not seen much

info on running over square.



Gary Specketer



--

N777TY

Joined: 09 Apr 2006
Posts: 69
Location: Charlotte, NC

Posted: Sun Aug 23, 2009 6:33 am Post subject: Re: LOP (Lean of Peak) Injector Tuning

Dick,



I think you're referring to this document:



  http://www.eci.aero/pdf/93-6-7.pdf



(though, no photos in it..)

_________________
RV-7A
N777TY

AV8ORJWC

Joined: 13 Jul 2006
Posts: 1149
Location: Aurora, Oregon "Home of VANS"

Posted: Sun Aug 23, 2009 6:44 am Post subject: LOP (Lean of Peak) Injector Tuning

The challenge is to avoid Detonation and the earlier than planned

destruction of the engine.  That can be a factor of compression ratio of

the cylinder, quality and octane of the AVGAS, carbon and garbage

deposits inside the combustion chamber and the ignition event.  The

lower the RPM, the higher the throttle the greater the risk.



Several pilots are running upward of 10.0:1 pistons, choose their avgas

supplier wisely, run a well timed ignition system and gently increase

the throttle.  GAMI has made a business of educating pilots. Others try

marginal gas quality, ragged ignitions and throw caution to the wind.



Choose wisely. Fly Safe.  Check your % of power tables for LOP

operations.



John



--

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Sun Aug 23, 2009 7:24 am Post subject: LOP (Lean of Peak) Injector Tuning

All of the LOP information is GREAT. Keep it coming !!!!!!! I have a 

question:



When leaning the engine, the 'old traditional / prior to gages' way was 

to lean it until it begins to 'stumble' and then richen it up a bit. 

When I lean using the EGT gages I notice the 'stumble' when the 1st 

cylinder goes lean. If you continue to lean until all of the remaining 

cylinders peak (LOP), What happens to the 'stumble' ??? Does it even out 

/ go way with the engine running smooth? Does it persist? Since any 

changes in the engines smooth running are a concern in flight, I'd 

appreciate learning what those of you that are routinely running LOP are 

experiencing.



Deems Davis N519PJ

http://deemsrv10.com/index.html



gary wrote:

[quote] 



 Is there a danger with running too much over square?  Dick mentions 2" but I

 have been running more than that (2200 and 26")LOP. I have not seen much

 info on running over square.



 Gary Specketer



 --

billderou(at)yahoo.com
Guest

Posted: Sun Aug 23, 2009 8:46 am Post subject: LOP (Lean of Peak) Injector Tuning

I believe tuning the injector nozzles will create a smoother running engine and that in itself has value. However, I have been mystified during these conversations as to the value of running LOP vs fuel economy. There was never enough data in the emails to get the whole picture. The question I always had was how much speed are you willing to loose to gain how much fuel efficiency?

  

 Thanks to Dave's pic of his panel and my own experience I was able to put a picture together.

  

 The following numbers are in statute miles and the Density Altitude is similar. If we assume that the top speed of our RV-10's is 205mph then Dave is flying 20% (164.5smph) under max and achieving 18.6smpg while leaned to approx 25deg LOP. An averaged flight in my plane is 6% under max speed (193smph) achieving 19.1smpg while leaned to peak. My definition of peak is when 3 cylinders drop.

  

 Typical panel setup for me is: WOT, 10-13K feet, 2380-2420rpm, 10.1-10.3gph, lean to peak.

  

 These are only two datapoints. What are others achieving? And please provide the whole picture - what is the percent under max speed you are willing to fly and the miles per gallon you are achieving as a benefit. I assume the whole LOP (other than a smooth engine) is to achieve fuel efficiency.

  

 What am I missing?

  

 Bill DeRouchey

 N939SB

  

  

  

  



--- On Sun, 8/23/09, Deems Davis <deemsdavis(at)cox.net> wrote:



 [quote]

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

Subject: Re: LOP (Lean of Peak) Injector Tuning

To: rv10-list(at)matronics.com

Date: Sunday, August 23, 2009, 8:22 AM



 --> RV10-List message posted by: Deems Davis <deemsdavis(at)cox.net>



All of the LOP information is GREAT. Keep it coming !!!!!!! I have a question:



When leaning the engine, the 'old traditional / prior to gages' way was to lean it until it begins to 'stumble' and then richen it up a bit. When I lean using the EGT gages I notice the 'stumble' when the 1st cylinder goes lean. If you continue to lean until all of the remaining cylinders peak (LOP), What happens to the 'stumble' ??? Does it even out / go way with the engine running smooth? Does it persist? Since any changes in the engines smooth running are a concern in flight, I'd appreciate learning what those of you that are routinely running LOP are experiencing.



Deems Davis N519PJ

http://deemsrv10.com/index.html



gary wrote:

[quote] --> RV10-List message posted by: "gary" <speckter(at)comcast.net>

 

 Is there a danger with running too much over square?  Dick mentions 2" but I

 have been running more than that (2200 and 26")LOP. I have not seen much

 info on running over square.

 

 Gary Specketer

 

 --

Tim Olson

Joined: 25 Jan 2007
Posts: 2872

Posted: Sun Aug 23, 2009 9:16 am Post subject: LOP (Lean of Peak) Injector Tuning

This is just a guess, for me, to answer your question, but first

I'll pass on what my experience has been...

When I lean up to and past peak, there is never a period where

it stumbles.  It keeps running smoothly and as you get further

and further LOP, you can hear the engine start to lose power...

it gets quieter. If you run that way for a couple minutes and

adapt to the sound, you will easily hear and feel the extra

power come back as you richen it up towards that -25 to -50F

LOP again...and feel even more power as you richen it back to

ROP operation.  The old "lean to stumble" works well with the

carbureted planes I guess. (In my opinion though if it's

really that non-precise, carbureted engines in general are

kind of "sloppy", and not really going to be nearly as

good for LOP) Probably everyone should be using a 6 probe

monitor for their operations.

So my opinion on the answer to the question would be...since

you're running a fuel injected engine, if it's stumbling

when it gets to peak on one cylinder, I would guess (just

a guess) that it won't go away as you keep leaning further.

It would probably be the case that something is preventing

you from getting it smooth...be it timing, compression, or

something else. The hope is that you can determine what

exactly that is, and then make it work so it is smooth.

This is the big headache for me in the later part of that

writeup.  My pal with the 10:1 pistons, we really have to

apply ourselves to figure that one out.  He ordered the .026

injectors, so we'll see soon how that plays out. Maybe that

would be all it would take for you too. I'm hoping that we

can make it perfect and then provide more info to all others

who face the same hurdle.

I am just finally able to get to replying today, and I've

gotten a couple of great offline emails.  One of them

brought up something that I should mention that is

important and I'll add this warning into the write-up soon.

I wrote there that you should use a timing light to time

both systems. This is something basically being said by

Klaus at Lightspeed. Of course, it's in his interest to

urge you to be very precise in determining timing. It would

be ideal if you knew it exactly. But, timing a system with

a timing light, being up by the prop when it's moving,

is a very dangerous thing. The writer, and A&P himself, said

that static timing of a mag can be very good. I agree.

I felt like a slacker that I've never used a timing light

on my plane, but I feel my mag was timed pretty well by

standard simple static timing. But, in this extreme case

of this 10:1 engine, I'm not sure what to do. Klaus

says use a timing light and get it exact...then tweak

the systems or maybe just the mag, and do some testing...try

advancing a little.  I don't know what to say but...BE

CAREFUL if you're working near a moving prop....take it from

Stein. 

Also, I assumed that with higher compression you would need

to slightly retard the timing. That may not be the case.

Klaus said LOP sometimes works better with advanced timing.

Anyway, he said not to use the adjustable timing knob addition

on the lightspeed..it's too dangerous to mess with. But,

the one big thing he did say that makes perfect sense is

to READ THE INSTALLATION MANUAL AND FOLLOW THE DIRECTIONS.

So, we're also going back into the Lightspeed install and

going to make sure the engine is set up properly per that

manual.

Wish it was simple answers for everyone, but there are going

to be some unique cases, with the various engine setups.

Tim Olson - RV-10 N104CD

Deems Davis wrote:

[quote] 

 All of the LOP information is GREAT. Keep it coming !!!!!!! I have a 

 question:

 When leaning the engine, the 'old traditional / prior to gages' way was 

 to lean it until it begins to 'stumble' and then richen it up a bit. 

 When I lean using the EGT gages I notice the 'stumble' when the 1st 

 cylinder goes lean. If you continue to lean until all of the remaining 

 cylinders peak (LOP), What happens to the 'stumble' ??? Does it even out 

 / go way with the engine running smooth? Does it persist? Since any 

 changes in the engines smooth running are a concern in flight, I'd 

 appreciate learning what those of you that are routinely running LOP are 

 experiencing.

 Deems Davis N519PJ

 http://deemsrv10.com/index.html

 gary wrote:

> 

>

> Is there a danger with running too much over square?  Dick mentions 2" 

> but I

> have been running more than that (2200 and 26")LOP. I have not seen much

> info on running over square.

>

> Gary Specketer

>

> --

coop85(at)verizon.net
Guest

Posted: Sun Aug 23, 2009 10:54 am Post subject: LOP (Lean of Peak) Injector Tuning

Bill,  

   You address an interesting question.  The primary debate has been on whether to choose the old school Rich of Peak (ROP) or Lean of Peak (LOP) which is why the big fuel savings over slight airspeed drop numbers.  Seems that most of us were taught to either richen slightly after the engine stumbles in the absence of good gauges, or run around 50 to 100 ROP depending on cruise or power requirements.  Your choice to go at peak certainly accomplishes most of the LOP intent of saving gas without the speed drop.    

I have read on the forum somewhere that some companies actually recommend running at peak, whereas I’ve also read some concerns over that setting so I’m hopefully there are some educated answers out there.  My overall understanding is the key is to keep the CHTs under control and otherwise where you set the mixture shouldn’t do any damage provided you are under 65% power.  Amazing how what should be a fairly straightforward topic has so many perceptions.    

I for one have been very please with LOP and really appreciate Tim’s write-up as I would like to make it even better.  I have the same setup and stayed clear of tweaking because I didn’t know we had the same injector options as the Airflow Performance setup, so THANKS.  

Marcus  

Do not archive  

From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Bill DeRouchey

 Sent: Sunday, August 23, 2009 12:38 PM

 To: rv10-list(at)matronics.com

 Subject: Re: LOP (Lean of Peak) Injector Tuning  

I believe tuning the injector nozzles will create a   smoother running engine and that in itself has value. However, I have been   mystified during these conversations as to the value of running LOP vs fuel   economy. There was never enough data in the emails to get the whole picture.   The question I always had was how much speed are you willing to   loose to gain how much fuel efficiency?   

Thanks to Dave's pic of his panel and my own experience I   was able to put a picture together.   

The following numbers are in statute miles and the Density   Altitude is similar. If we assume that the top speed of our RV-10's is 205mph   then Dave is flying 20% (164.5smph) under max and achieving 18.6smpg while   leaned to approx 25deg LOP. An averaged flight in my plane is 6% under max   speed (193smph) achieving 19.1smpg while leaned to peak. My definition of   peak is when 3 cylinders drop.   

Typical panel setup for me is: WOT, 10-13K feet,   2380-2420rpm, 10.1-10.3gph, lean to peak.   

These are only two datapoints. What are others   achieving? And please provide the whole picture - what is the percent   under max speed you are willing to fly and the miles per gallon you are   achieving as a benefit. I assume the whole LOP (other than a smooth engine)   is to achieve fuel efficiency.   

What am I missing?   

Bill DeRouchey   

N939SB   

   --- On Sun, 8/23/09, Deems Davis <deemsdavis(at)cox.net>   wrote:   

   [quote]   

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

   Subject: Re: LOP (Lean of Peak) Injector Tuning

   To: rv10-list(at)matronics.com

   Date: Sunday, August 23, 2009, 8:22 AM      

--> RV10-List message posted by: Deems Davis <deemsdavis(at)cox.net>

   All of the LOP information is GREAT. Keep it coming !!!!!!! I have a   question:

   When leaning the engine, the 'old traditional / prior to gages' way was to   lean it until it begins to 'stumble' and then richen it up a bit. When I lean   using the EGT gages I notice the 'stumble' when the 1st cylinder goes lean.   If you continue to lean until all of the remaining cylinders peak (LOP), What   happens to the 'stumble' ??? Does it even out / go way with the engine   running smooth? Does it persist? Since any changes in the engines smooth   running are a concern in flight, I'd appreciate learning what those of you   that are routinely running LOP are experiencing.

   Deems Davis N519PJ

   http://deemsrv10.com/index.html

   gary wrote:

   > --> RV10-List message posted by: "gary" <speckter(at)comcast.net>

   > 

   > Is there a danger with running too much over square?  Dick mentions   2" but I

   > have been running more than that (2200 and 26")LOP. I have not seen   much

   > info on running over square.

   > 

   > Gary Specketer

   > 

   > --

taildragon(at)msn.com
Guest

Posted: Sun Aug 23, 2009 1:21 pm Post subject: LOP (Lean of Peak) Injector Tuning

<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]-->  Yes, I find this subject interesting, too. 

  

 I have a question: What are you seeing for peak EGT at various power  settings, say at 75%, 65% and 55% power settings?

  

 Roger

 [quote]   ---

Kelly McMullen

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

Posted: Sun Aug 23, 2009 2:50 pm Post subject: LOP (Lean of Peak) Injector Tuning

Peak depends on a lot of factors besides power setting...OAT,

altitude, exact probe placement, type of instrument, etc.   I've seen

anywhere from 1400 to 1500 peak on the IO-360 in my Mooney. I have

UBG16 with fast acting probes mounted 1.5" below exhaust port flange.

I try to climb at 1200-1250F EGT, but don't obsess on it.



On Sun, Aug 23, 2009 at 2:19 PM, Roger Standley<taildragon(at)msn.com> wrote:

[quote] Yes, I find this subject interesting, too.



 I have a question: What are you seeing for peak EGT at various power

 settings, say at 75%, 65% and 55% power settings?



 Roger



 ---

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

Kellym

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

Posted: Sun Aug 23, 2009 3:13 pm Post subject: LOP (Lean of Peak) Injector Tuning

Deems, if you get a stumble when first cylinder reaches peak you may 

need some injector matching. While I may sense a hint of roughness as I 

get near the last cylinder to peak, there is no stumble and continue to 

run fine until it wants to quit near 70 LOP.



Deems Davis wrote:

 	  Quote: 	
		   

 

 All of the LOP information is GREAT. Keep it coming !!!!!!! I have a 

 question:

 

 When leaning the engine, the 'old traditional / prior to gages' way was 

 to lean it until it begins to 'stumble' and then richen it up a bit. 

 When I lean using the EGT gages I notice the 'stumble' when the 1st 

 cylinder goes lean. If you continue to lean until all of the remaining 

 cylinders peak (LOP), What happens to the 'stumble' ??? Does it even out 

 / go way with the engine running smooth? Does it persist? Since any 

 changes in the engines smooth running are a concern in flight, I'd 

 appreciate learning what those of you that are routinely running LOP are 

 experiencing.

 

 Deems Davis N519PJ

 http://deemsrv10.com/index.html

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

Kellym

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

Posted: Sun Aug 23, 2009 3:21 pm Post subject: LOP (Lean of Peak) Injector Tuning

Hi Bill,

LOP fuel economy is only one part of the picture, and is NOT the main 

reason to do it. Your engine will run cleaner, use less oil and last 

longer running LOP. It causes the flame to burn slower(like higher 

octane) giving a flatter pressure pulse to the piston, so that the peak 

pressure is less, but the average work is close to same. If you are 

below 7500(approx) you can add throttle to make up for lost power. As 

long as you are LOP, power =14.9 * gal/hr. So 10gph=149hp. (57%)

75% then = 13.1 gph, if, and only if, you are running LOP. So if you can 

find an altitude where you can go LOP and then adjust throttle for 13.1 

gph, you should see somewhere around 190mph. Of course once you are high 

enough that you are at WOT and less than 13.1 your power is less and 

speed will be less.  I typically give up 5-7kts to fly LOP, which is 

okay as long as I am not fighting a headwind.



Bill DeRouchey wrote:



[quote] These are only two datapoints. What are others achieving? And please 

 provide the whole picture - what is the percent under max speed you are 

 willing to fly and the miles per gallon you are achieving as a benefit. 

 I assume the whole LOP (other than a smooth engine) is to achieve fuel 

 efficiency.

  

 What am I missing?

  

 Bill DeRouchey

 N939SB

  

  

  

  

 

 --- On *Sun, 8/23/09, Deems Davis /<deemsdavis(at)cox.net>/* wrote:

 

 

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

     Subject: Re: LOP (Lean of Peak) Injector Tuning

     To: rv10-list(at)matronics.com

     Date: Sunday, August 23, 2009, 8:22 AM

 

     

     <http://us.mc344.mail.yahoo.com/mc/compose?to=deemsdavis(at)cox.net>>

 

     All of the LOP information is GREAT. Keep it coming !!!!!!! I have a

     question:

 

     When leaning the engine, the 'old traditional / prior to gages' way

     was to lean it until it begins to 'stumble' and then richen it up a

     bit. When I lean using the EGT gages I notice the 'stumble' when the

     1st cylinder goes lean. If you continue to lean until all of the

     remaining cylinders peak (LOP), What happens to the 'stumble' ???

     Does it even out / go way with the engine running smooth? Does it

     persist? Since any changes in the engines smooth running are a

     concern in flight, I'd appreciate learning what those of you that

     are routinely running LOP are experiencing.

 

     Deems Davis N519PJ

     http://deemsrv10.com/index.html

 

     gary wrote:

      > 

     <http://us.mc344.mail.yahoo.com/mc/compose?to=speckter(at)comcast.net>>

      >

      > Is there a danger with running too much over square?  Dick

     mentions 2" but I

      > have been running more than that (2200 and 26")LOP. I have not

     seen much

      > info on running over square.

      >

      > Gary Specketer

      >

      > --

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

Dick Sipp

Joined: 11 Jan 2006
Posts: 215
Location: Hope, MI

Posted: Sun Aug 23, 2009 5:51 pm Post subject: LOP (Lean of Peak) Injector Tuning

There are limits to "oversquare" operation on the power charts in the 

Lycoming operators manual.  They vary with all the other engine parameters 

but

the limits are higher than one would probably guess, several inches MP over 

RPM in hundreds in most cases.  These are the hard to read two page charts 

and the limit is just a line and is easy to miss.



My normal cruise is 55-65% power, 10.5-11.5 GPH and 160-165 KTAS.



Dick Sipp



---

Tim Olson

Joined: 25 Jan 2007
Posts: 2872

Posted: Sun Aug 23, 2009 5:55 pm Post subject: LOP (Lean of Peak) Injector Tuning

Bill,

Regarding the speeds, I don't know why Dave was only getting 164.5

statute mph, but my LOP cruise is typically way better than that,

which is about 143kts, right?  If I am way lean of peak, and/or

very heavy loaded, I MAY get slowed down to 155-156kts TAS, but

on plenty of trips I'm seeing speeds of 164-166kts at LOP cruise.

If I fly ROP, I'd say most commonly I'll see 173-175kts, sometimes

slower. I've found that between leaning variations, turbulence,

altitudes flown, and loadings, that the speed can be all over the

map, but I don't know that I've ever really seen constant enroute

cruise figures of less than 152kts on my trips.  So if I am

getting, say 189-190 statue mph on many flights, and I'm generally

burning 9.5-10.5 gph at my most commonly flown altitudes,

I'm probably pushing right up near that same 19.1 statue mpg

on many flights.  There are times I'm a bit less, but loadings

and the other factors don't always duplicate themselves.  I'll

tell you what though, there's no way that I'm not getting

better efficiency than someone flying ROP.  As Kelly pointed

out, it's the temps, the cleanness, and all sorts of other

things that are benefits too.  I'd say that you will usually

lose 6-10kts depending on many factors, such as how far you

lean past peak.  I usually just go for 25 LOP on the last

cyl. to peak.

Regarding flying ROP or at peak, like you are talking about,

I tend to agree that if you're way down in power like at

65%, you're probably not going to hurt anything too bad.

But, for those who are running 50-100 ROP, you probably

want to do a bit of studying up.  I don't have the numbers

committed to memory, but there is a window at higher power

settings where you really don't want to stay, and I

think in order to stay out of it you really have to

either fly WAY ROP, or go LOP.  Again, don't quote me,

but if you venture over 75% power, I'd avoid that range

from maybe 125 to 0 ROP. (Can someone verify that? I've got

docs but I'm not going to dig them up right this minute)

So I'm not saying you're doing anything wrong, at the

lower power levels you can get away with anything. But,

I think you picked a pretty lowball datapoint from David

if you're going to use his 164.5smph.  Scott Schmidt

and I both just flew together for 3.75 hours running

LOP and we blew that speed away by at least 10kts

for the whole trip, on something like 9.5 gph.  He was

lighter loaded than me and burned about 2 gallons less

over the entire leg.

So the point is, I don't think most people will give up enough

speed to worry about it a whole lot.

Tim Olson - RV-10 N104CD

Bill DeRouchey wrote:

[quote] I believe tuning the injector nozzles will create a smoother running 

 engine and that in itself has value. However, I have been mystified 

 during these conversations as to the value of running LOP vs fuel 

 economy. There was never enough data in the emails to get the whole 

 picture. The question I always had was how much speed are you willing to 

 loose to gain how much fuel efficiency?

 Thanks to Dave's pic of his panel and my own experience I was able to 

 put a picture together.

 The following numbers are in statute miles and the Density Altitude is 

 similar. If we assume that the top speed of our RV-10's is 205mph then 

 Dave is flying 20% (164.5smph) under max and achieving 18.6smpg while 

 leaned to approx 25deg LOP. An averaged flight in my plane is 6% under 

 max speed (193smph) achieving 19.1smpg while leaned to peak. My 

 definition of peak is when 3 cylinders drop.

 Typical panel setup for me is: WOT, 10-13K feet, 2380-2420rpm, 

 10.1-10.3gph, lean to peak.

 These are only two datapoints. What are others achieving? And please 

 provide the whole picture - what is the percent under max speed you are 

 willing to fly and the miles per gallon you are achieving as a benefit. 

 I assume the whole LOP (other than a smooth engine) is to achieve fuel 

 efficiency.

 What am I missing?

 Bill DeRouchey

 N939SB

 --- On *Sun, 8/23/09, Deems Davis /<deemsdavis(at)cox.net>/* wrote:

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

     Subject: Re: LOP (Lean of Peak) Injector Tuning

     To: rv10-list(at)matronics.com

     Date: Sunday, August 23, 2009, 8:22 AM

     <http://us.mc344.mail.yahoo.com/mc/compose?to=deemsdavis(at)cox.net>>

     All of the LOP information is GREAT. Keep it coming !!!!!!! I have a

     question:

     When leaning the engine, the 'old traditional / prior to gages' way

     was to lean it until it begins to 'stumble' and then richen it up a

     bit. When I lean using the EGT gages I notice the 'stumble' when the

     1st cylinder goes lean. If you continue to lean until all of the

     remaining cylinders peak (LOP), What happens to the 'stumble' ???

     Does it even out / go way with the engine running smooth? Does it

     persist? Since any changes in the engines smooth running are a

     concern in flight, I'd appreciate learning what those of you that

     are routinely running LOP are experiencing.

     Deems Davis N519PJ

     http://deemsrv10.com/index.html

     gary wrote:

      > 

     <http://us.mc344.mail.yahoo.com/mc/compose?to=speckter(at)comcast.net>>

      >

      > Is there a danger with running too much over square?  Dick

     mentions 2" but I

      > have been running more than that (2200 and 26")LOP. I have not

     seen much

      > info on running over square.

      >

      > Gary Specketer

      >

      > --

dlm46007(at)cox.net
Guest

Posted: Sun Aug 23, 2009 6:19 pm Post subject: LOP (Lean of Peak) Injector Tuning

I was not using WOT at 10000 MSL. DA was 14000+. I don't know the weight but

we had OSH baggage and camping gear. I typically get about 150KTAS at about

8.5-9 gph. IIRC TAS is affected about 2 mph per 100 pounds gross weight

change. My numbers were from pictures just after departing OSH which would

mean higher gross weight rather than later in the flight. 36 gals burned in

the four hour flight to Tulsa after an OSH taxi and number 6 IFR departure

off of R09. After having flown for so many years at slower ground speeds

150KTAS GS or better seems enough. Of course if headwinds are involved I may

push the power lever forward but avoiding a fuel stop also figures into the

calculation.



--

billderou(at)yahoo.com
Guest

Posted: Tue Aug 25, 2009 1:12 pm Post subject: LOP (Lean of Peak) Injector Tuning

Hi Tim-

 If I dissect the trip with you and Scott Schmidt you were flying at 14% under max (176.5/205smph) at 9.5gph which yields 18.5smpg. This is the same efficiency as David flying 20% under with reduced power. Not much different than the 19.1smph that I reported. The difference could easily be explained by atmospherics or loading.

 My interest is cross country efficiency and I thought there was a significant miles per gallon increase with slowing the plane down and running LOP. My original thought was to collect data points from everyone and plot airspeed percent reduction vs the miles per gallon at LOP. We know when running ROP the speed increases little and the consumption lots. I made a somewhat speed run recently at 8000ft/DA 10425, WOT, 2400rpm, lean 25degF ROP, 200mph TAS, 13.6gph. A 3% drop in speed yielded 14.7smpg.

 With still just a small amount of data it would seem that right at peak EGT is the maximum fuel efficiency/airspeed optimum and the fuel efficiency remains (or drops slightly) as you lean into LOP territory.

 I ran into Scott on a grass strip in the middle of Idaho. He has a beautiful aircraft.

 This is getting too far from the theme of injector tuning so I'll drop off but may bring up efficiency and prop settings at a later date.

 Bill DeRouchey

 N939SB

--- On Sun, 8/23/09, Tim Olson <Tim(at)myrv10.com> wrote:

 [quote]

From: Tim Olson <Tim(at)myrv10.com>

Subject: Re: LOP (Lean of Peak) Injector Tuning

To: rv10-list(at)matronics.com

Date: Sunday, August 23, 2009, 6:53 PM

 --> RV10-List message posted by: Tim Olson <Tim(at)myrv10.com>

Bill,

Regarding the speeds, I don't know why Dave was only getting 164.5

statute mph, but my LOP cruise is typically way better than that,

which is about 143kts, right?  If I am way lean of peak, and/or

very heavy loaded, I MAY get slowed down to 155-156kts TAS, but

on plenty of trips I'm seeing speeds of 164-166kts at LOP cruise.

If I fly ROP, I'd say most commonly I'll see 173-175kts, sometimes

slower. I've found that between leaning variations, turbulence,

altitudes flown, and loadings, that the speed can be all over the

map, but I don't know that I've ever really seen constant enroute

cruise figures of less than 152kts on my trips.  So if I am

getting, say 189-190 statue mph on many flights, and I'm  generally

burning 9.5-10.5 gph at my most commonly flown altitudes,

I'm probably pushing right up near that same 19.1 statue mpg

on many flights.  There are times I'm a bit less, but loadings

and the other factors don't always duplicate themselves.  I'll

tell you what though, there's no way that I'm not getting

better efficiency than someone flying ROP.  As Kelly pointed

out, it's the temps, the cleanness, and all sorts of other

things that are benefits too.  I'd say that you will usually

lose 6-10kts depending on many factors, such as how far you

lean past peak.  I usually just go for 25 LOP on the last

cyl. to peak.

Regarding flying ROP or at peak, like you are talking about,

I tend to agree that if you're way down in power like at

65%, you're probably not going to hurt anything too bad.

But, for those who are running 50-100 ROP, you probably

want to do a bit of studying  up.  I don't have the numbers

committed to memory, but there is a window at higher power

settings where you really don't want to stay, and I

think in order to stay out of it you really have to

either fly WAY ROP, or go LOP.  Again, don't quote me,

but if you venture over 75% power, I'd avoid that range

from maybe 125 to 0 ROP. (Can someone verify that? I've got

docs but I'm not going to dig them up right this minute)

So I'm not saying you're doing anything wrong, at the

lower power levels you can get away with anything. But,

I think you picked a pretty lowball datapoint from David

if you're going to use his 164.5smph.  Scott Schmidt

and I both just flew together for 3.75 hours running

LOP and we blew that speed away by at least 10kts

for the whole trip, on something like 9.5 gph.  He was

lighter loaded than me and burned about 2 gallons less

over the entire leg.

So the point  is, I don't think most people will give up enough

speed to worry about it a whole lot.

Tim Olson - RV-10 N104CD

Bill DeRouchey wrote:

[quote] I believe tuning the injector nozzles will create a smoother running engine and that in itself has value. However, I have been mystified during these conversations as to the value of running LOP vs fuel economy. There was never enough data in the emails to get the whole picture. The question I always had was how much speed are you willing to loose to gain how much fuel efficiency?

  Thanks to Dave's pic of his panel and my own experience I was able to put a picture together.

  The following numbers are in statute miles and the Density Altitude is similar. If we assume that the top speed of our RV-10's is 205mph then Dave is flying 20% (164.5smph) under max and achieving 18.6smpg while leaned to approx 25deg LOP. An averaged flight in my plane is 6% under max speed  (193smph) achieving 19.1smpg while leaned to peak. My definition of peak is when 3 cylinders drop.

  Typical panel setup for me is: WOT, 10-13K feet, 2380-2420rpm, 10.1-10.3gph, lean to peak.

  These are only two datapoints. What are others achieving? And please provide the whole picture - what is the percent under max speed you are willing to fly and the miles per gallon you are achieving as a benefit. I assume the whole LOP (other than a smooth engine) is to achieve fuel efficiency.

  What am I missing?

  Bill DeRouchey

 N939SB

 --- On *Sun, 8/23/09, Deems Davis /<deemsdavis(at)cox.net>/* wrote:

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

     Subject: Re: LOP (Lean of Peak) Injector Tuning

     To: rv10-list(at)matronics.com

     Date: Sunday, August 23, 2009, 8:22 AM

     --> RV10-List message posted by: Deems Davis <deemsdavis(at)cox.net

     <http://us.mc344.mail.yahoo.com/mc/compose?to=deemsdavis(at)cox.net>>

     All of the LOP information is GREAT. Keep it coming !!!!!!! I have a

     question:

     When leaning the engine, the 'old traditional / prior to gages' way

     was to lean it until it begins to 'stumble' and then richen it up a

     bit. When I lean using the EGT gages I notice the 'stumble' when the

     1st cylinder goes lean. If you continue to lean until all of the

     remaining cylinders peak (LOP), What happens to the 'stumble' ???

     Does it even out / go way with the engine running smooth? Does it

     persist? Since any changes in the engines smooth running are a

     concern in flight, I'd appreciate learning what those of you that

     are routinely running LOP are experiencing.

     Deems Davis N519PJ

     http://deemsrv10.com/index.html

     gary wrote:

      > --> RV10-List message posted by: "gary" <speckter(at)comcast.net

     <http://us.mc344.mail.yahoo.com/mc/compose?to=speckter(at)comcast.net>>

      >

      > Is there a danger with running too much over square?  Dick

     mentions 2" but I

      > have been running more than that (2200 and 26")LOP. I have not

     seen much

      > info on running over  square.

      >

      > Gary Specketer

      >

      > --

pitts_pilot(at)bellsouth.
Guest

Posted: Tue Aug 25, 2009 2:12 pm Post subject: LOP (Lean of Peak) Injector Tuning

Bill, please continue to gather data ..... for those of us that still 

dream of a flying airplane.  It's my understanding that LOP has 

significant savings.  IMHO, the data points should contain your numbers 

below plus MP.  I'd also be curious what your CHTs and EGTs are.  I 

think the -10 can do better with some attention to cooling drag.

Linn

do not archive.



Bill DeRouchey wrote:

 	  Quote: 	
		   Hi Tim-

 If I dissect the trip with you and Scott Schmidt you were flying at 14% 

 under max (176.5/205smph) at 9.5gph which yields 18.5smpg. This is the 

 same efficiency as David flying 20% under with reduced power. Not much 

 different than the 19.1smph that I reported. The difference could easily 

 be explained by atmospherics or loading.

  

 My interest is cross country efficiency and I thought there was a 

 significant miles per gallon increase with slowing the plane down and 

 running LOP. My original thought was to collect data points from 

 everyone and plot airspeed percent reduction vs the miles per gallon at 

 LOP. We know when running ROP the speed increases little and the 

 consumption lots. I made a somewhat speed run recently at 8000ft/DA 

 10425, WOT, 2400rpm, lean 25degF ROP, 200mph TAS, 13.6gph. A 3% drop in 

 speed yielded 14.7smpg.

  

 With still just a small amount of data it would seem that right at peak 

 EGT is the maximum fuel efficiency/airspeed optimum and the fuel 

 efficiency remains (or drops slightly) as you lean into LOP territory.

  

 I ran into Scott on a grass strip in the middle of Idaho. He has a 

 beautiful aircraft.

  

 This is getting too far from the theme of injector tuning so I'll drop 

 off but may bring up efficiency and prop settings at a later date.

  

 Bill DeRouchey

 N939SB

coop85(at)verizon.net
Guest

Posted: Tue Aug 25, 2009 4:40 pm Post subject: LOP (Lean of Peak) Injector Tuning

Great explanation Kelly, THANKS.



Marcus

--

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