REFLECTOR: Fuel Consumption Performance

[Rene Dugas]

Great reference John

Rene' Dugas
Sent from my iPhone 3G

On Aug 28, 2009, at 11:29 PM, John Tvedte <johnt at comp-sol.com> wrote:

> Terry,
>
> I think Scott is saying... as you lean, the first cylinder to peak  
> is the leanest - the last to peak is the richest... if cruising ROP,  
> you lean by the leanest cylinder (first to peak), but if cruising  
> LOP, you lean by the richest cylinder (last to peak) - because you  
> are on the other side of the Red Box.
>
> www.eaa42.org/misc/gregs_show.ppt
>
> Note, I do not claim to have any practical experience.
>
> John
>
> ________________________________________
> From: reflector-bounces at tvbf.org [reflector-bounces at tvbf.org] On  
> Behalf Of Terry Miles [terrence_miles at hotmail.com]
> Sent: Friday, August 28, 2009 11:31 AM
> To: 'Velocity Aircraft Owners and Builders list'
> Subject: Re: REFLECTOR: Fuel Consumption Performance
>
> Well I appreciate your patience.  I did read the below articles, and  
> several
> books now on related engine operations and mixture settings and we  
> are in
> full agreement on the concept.  I am not running ROP.  I am running 50
> degrees LOP.  The question between us is which cylinder should be the
> reference cylinder.  My choice in this is that I will use the first  
> cylinder
> to peak.
> Thanks again.
> Terry
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]  
> On
> Behalf Of Scott Derrick
> Sent: Thursday, August 27, 2009 21:01
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Fuel Consumption Performance
>
> Terry,
>
> Below is my reply of a month ago when you indicated you were leaning  
> to 50
> LOP on the first cylinder to peak.  All the rest being richer.   
> Which as I
> stated a month ago is BAD!
>
> Maybe I misunderstood and you are now running ROP?  Leaning until  
> the first
> cylinder reaches peak, and then enriching it until it is 50 ROP?
> That would be the old school acceptable  method.  If you decide to  
> read the
> articles below, you will read that  GAMI recommends 75 ROP because  
> 50 ROP
> may be stressful to some engines  at high power settings and low  
> altitude.
>
> But, since you were running at 10K or above you can run at any mixture
> setting and be fine, as far as detonation is concerned because the  
> engine
> cannot produce more than 75% power at full throttle.
>
> I once again recommend the articles below by  John Deacon about how to
> safely  operate these big bore aircraft engines.  They are expensive  
> and
> easy harm.
>
> Scott
>
>
> **********************************************************
>
> Terry,
>
> running the first cylinder LOP can put some of the richer cylinders  
> right in
> the BAD zone. Thats well... bad!  Thats why you always lean to the  
> last
> cylinder when running LOP.  Thats also why you lean to the first  
> cylinder
> when running ROP, so all the other cylinders are rich of that point.
>
> you said
>
> "I was afraid my coolest cyl could be 150 LOP before the last cly  
> peaked and
> that I could burn that exhaust valve."
>
>
> Thats exactly backwards. Once a cylinder reaches peak EGT and goes  
> on the
> LOP side it will run cooler and cooler the leaner you run it. The  
> absoluter
> worst mixture is about 25-50 degrees ROP in terms of detonation and  
> the
> timing of peak power pulses.  If your coolest cylinder was running  
> at 150
> degrees leaner than the last cylinder to reach 75 LOP it would  
> probably not
> be firing due to the too lean mixture.
>
> How to operate your engine is a complex topic.  Here is a great set of
> articles by John Deacon, I consider a must for any recip operator,  
> whether
> you run LOP or ROP.
>
> part 1
> http://www.avweb.com/news/pelican/182179-1.html
> part 2
> http://www.avweb.com/news/pelican/182176-1.html
> part 3
> http://www.avweb.com/news/pelican/182583-1.html
> part 4
> http://www.avweb.com/news/pelican/183094-1.html
>
>
> Here's GAMI's lean test,  a great thing for anybody to do, to see how
> balanced their injectors are.
>
> http://www.gami.com/gamijectors/leantest.php
>
>
> Scott
>
>
>
>>
>
>
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