REFLECTOR: More leaning learning.
Scott Derrick
scott at tnstaafl.net
Tue Sep 1 08:24:15 CDT 2009
Oh,
Sorry Terry. Didn't realize you already were running an EI. That
explains why you can almost run LOP. Most IO540's have horrible peak
egt spreads.
I think Ken's recommendation of using Airflow's injector
restrictor's would be the ticket. Though a quick injector swap may be
very enlightening. Just note down who you swap so you can undo it later
if needed.
Scott
Terry Miles wrote:
> What about shutting off the mag and running only on my Jeff Rose? I just
> didn't want to do that, but it might be a step in the direction of a more
> even across-the-cyl combustion picture.
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Scott Derrick
> Sent: Monday, August 31, 2009 21:05
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: More leaning learning.
>
> Terry,
>
> Glad to hear you are cognizant of the issues. Sounds like you are tuned in
> to LOP.
>
> as long as you lean as you described below, above 8,000 ft, that should be
> perfectly acceptable. Because the engine is making less than 75% power at
> full throttle, and leaned to your described settings probably closer to 50%
> power.
>
> But that is not leaning to LOP, that is leaning to best run. I did that all
> the time in my Bonanza above 8,000 ft because my engine like yours couldn't
> run LOP, the mixture spread was to poor. It was carburated.
>
> I believe you have three alternatives to being able to truly run LOP. At low
> altitude, even in a cruise climb.
>
> 1.) Expensive but guaranteed to work is to order GAMIjectors from GAMI
> http://www.gami.com/ Looks like it would be $800
>
> 2.) Play swap the injectors. Swap the leanest cylinder(first to peak) with
> the richest cylinder(last to peak). See if it improves.
> Re-evaluate. Sometimes you have to do a few swaps with different cyls.
> It all trial and error. Cheap, relatively easy and perfectly legal in
> an experimental. Sometimes it works sometimes not. It didn't for my IO360.
>
> 3.) My Io360 would not run LOP, even after playing swap the injectors. I
> then installed a Lightspeed Ignition system. It improved the fuel burn
> so much I could then just barely lean to 50-60 LOP. I couldn't get
> below 10-20 LOP before the Lightspeed.
>
> Maybe somebody else knows of another method to improve your fuel spread.
>
> Scott
>
>
> Terry Miles wrote:
>
>> Bernard,
>>
>> Thanks for the thoughts. I was indeed sweet spot oriented.
>>
>> Someone posted that power point that was provided at OSH. Slide six
>> of that presentation might be one to consider so we are all on the
>> same page with the same data.
>>
>> In my Ly IO-540, there is a 60 degree spread from the coolest to the
>> hotest cylinder, and about a 60 to 80 degree spread in peaks temps when
>>
> leaning.
>
>> Here is a question for the group. You look at your engine analizer and
>>
> see
>
>> this: -61, -91, -36, -71, -31, -61. I didn't make this up. It is out
>>
> of
>
>> my engine log. Taking cylinder #5 another 19 degrees cooler and will
>> have the power stroke on cylinder #2 signifcantly out of the balance.
>> Look at that PP presentation and look how power drops off when a given
>> cyl is past 100 LOP.
>>
>> I understand what Scott is saying. Believe me. I would never ignore
>> you, man. Every fool and his dog is making presentations on this LOP
>> issue like it is some new discovery, with the usual crap about OWT
>> that were sound advice for carburated engines. Several of write
>> ups--due maybe to editoral demands for not too much detail--do not
>> provide "big picture" explanations, let alone adress EGT spreads
>> within a single power plant and how they should be addressed in
>> practice. As Scott has mentioned when you are at altitude, when full
>> throttle is below 65% the concern with "over pressure" within the given
>>
> cylinders is greatly reduced.
>
>> When it sounds and feels the best to me in this airplane with this
>> engine,
>> #2 is about -60 LOP and #3 and #5 are right near peak. If I pull #3
>> and #5 to -50 LOP and let it sit and then enrich again it is clear the
>> mixture was too lean. This is sitting in a cruise situation on a 3
>> hour cross country at a constant speed making small adjustments and
>> waiting for things to stabilize.
>>
>> Terry
>>
>>
>>
>> -----Original Message-----
>> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
>> On Behalf Of Scott Derrick
>> Sent: Sunday, August 30, 2009 21:58
>> To: Velocity Aircraft Owners and Builders list
>> Subject: Re: REFLECTOR: Fuel Consumption Performance
>>
>> But Bernard, to have all the cylinders Lean of 50 LOP, you have to
>> lean to the "Last to Peak", not the first. The first is the leanest
>> cylinder, all the rest are richer.
>>
>> You use the "First to Peak" for ROP operations.
>>
>> Scott
>>
>>
>> Bernard Despins wrote:
>>
>>
>>> I think Terry may be arriving at the same "sweet spot of leaning" as
>>> you are Scott. He is just making all of his cylinders leaner than the
>>> sweet spot, and adding fuel until the FIRST cylinder reaches it. The
>>> rest of the cylinders are cooler than the sweet spot. The only
>>> problem with this is that when all the cylinders go leaner than the
>>> "sweet spot" (lets say 50 LOP) you may go a little too far on the
>>> lean side and the engine could run a little rough depending on how
>>> well balance the injectors are. No harm done.
>>>
>>> Scott just skips the step of making all the cylinders leaner than the
>>> sweet spot and leans starting on the ROP side of things until the
>>> LAST cylinder gets to 50 LOP. The rest of the cylinders are cooler
>>> than the sweet spot. Just like Terry's method. The only problem
>>> would be leaning too slow and lingering in the "danger zone". But
>>> once you get use to the "big pull", it is absolutely not a problem.
>>>
>>> Hope this helps.
>>>
>>> Bernard Despins
>>>
>>>
>>>
>>> Terry Miles wrote:
>>>
>>>
>>>> Al,
>>>>
>>>> Here is my cruz engine log to include this last IN to CO trip.
>>>> Westbound was full power. 10,000 will get me mid 180 Kts TAS and
>>>> 12,000 gets mid 190 kts TAS. That runs about 11.5 at full throttle
>>>> and leaning 50 LOP. Thanks to Scott I did it right and pulled the
>>>> mixture out until they were all LOP and enriched back on the first
>>>> to peak so to get 50 LOP.
>>>>
>>>>
>>>>
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>>
>
>
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