REFLECTOR: Fuel Consumption Performance more data

Scott Derrick scott at tnstaafl.net
Tue Sep 8 08:31:57 CDT 2009


you didn't say if that 190mph was TAS,  IAS, ground speed and how you
measured it?

Brent Bourgeois wrote:
> These are the numbers from 9-3-09 for my Std RG  IO-360 200Hp
> Speed is a 2 way average from the gps.
>  
> 9500 ALT
> 2580/20.2
> 40 deg LOP
> 190 MPH
> 9 GPH
> 55 OAT
>  
> Brent
> N61VB
> New Orleans La
>
>
> --- On *Fri, 8/28/09, John Tvedte /<johnt at comp-sol.com>/* wrote:
>
>
>     From: John Tvedte <johnt at comp-sol.com>
>     Subject: Re: REFLECTOR: Fuel Consumption Performance
>     To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>     Date: Friday, August 28, 2009, 11:29 PM
>
>     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
>     <http://us.mc513.mail.yahoo.com/mc/compose?to=reflector-bounces@tvbf.org>
>     [reflector-bounces at tvbf.org
>     <http://us.mc513.mail.yahoo.com/mc/compose?to=reflector-bounces@tvbf.org>]
>     On Behalf Of Terry Miles [terrence_miles at hotmail.com
>     <http://us.mc513.mail.yahoo.com/mc/compose?to=terrence_miles@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
>     <http://us.mc513.mail.yahoo.com/mc/compose?to=reflector-bounces@tvbf.org>
>     [mailto:reflector-bounces at tvbf.org
>     <http://us.mc513.mail.yahoo.com/mc/compose?to=reflector-bounces@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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