REFLECTOR: Running LOP

[Chuck Jensen]

But if the probes are trimmed to give even results, then yes, the
display (graphical and/or digital readouts) may be equal, but due to the
trimming process, they don't tell you the state of each cylinder.  Is
each of the 4/6 cylinders LOP, ROP or at peak?  All you know is they are
reading the same.

Brian, your last two paragraphs are spot on.  Different mixtures will
peak at different temperatures and different cylinders have different
air flows.  However, that's why we balance the injectors instead of
trying to change the air flow (which is not practical other than porting
and polishing during an engine teardown).  Balancing the injectors is an
attempt to compensate for air flow differences so that the richness of
the mixture being fed to each cylinder is the same--hence the cylinders
will reach peak EGTs at the same time and fuel flow.  But the absolute
peak temperature may not be the same, since readout is dependent on a
number of variables including TC accuracy, efficiency and placement.

Finally, the 'normalizing' function of the EIS will allow all of the
EGTs to display the same temperature, but this is useful only for
trending during a flight.  If one cylinder's EGT goes up or down, then
something is going on with that cylinder, but it doesn't tell us
anything about whether the injectors and fuel flow is balanced across
all the cylinders.

We're probably just saying the same thing with a little different
perspective or spin on the terminology.  Given their relatively low
cost, running any engine 180hp or greater without an engine monitor
seems a little foolhardy.

Chuck


Brian wrote:
Well, they mean something.
Assuming the probes weren't "trimmed" to give even results and are 
reporting actual EGT's, then even EGT's mean even power across
cylinders.

Uneven EGT's can be caused my two things:  Uneven mixing of the 
air/fuel, and uneven airflow to the different cylinders.  Cylinders that

breathe better will make more power, and thus higher EGT's.

Different mixtures will result in peak EGT's at different temperatures.
Different airflow will result in different cylinder to cylinder EGT 
measurements.

Chuck Jensen wrote:
> Joel,
> If you are using a 'normalizing' function with the VM1000, then even 
> EGT bars mean nothing.  If you are not using a 'normalizing' function 
> with the VM1000, then even EGT bars mean nothing.  Either way, even 
> EGT bars mean nothing.  However, as you progressively lean out your 
> engine, if all of your EGTS peak at the same fuel flow (well, within 
> 0.2-0.5 GPH
> anyhow) then you are good-to-go.  In that case, you don't need GAMI,
you
> need to thank your lucky stars.
>
> As Scott will advise you in spades.  The peak temperature of each 
> cylinder is totally irrelevant!!  The only thing that counts is the 
> fuel flow at which each cylinder reaches its peak temp, irrespective 
> of what that temp is.
>
> Chuck Jensen
>  
>
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] 
> On Behalf Of Dr. Golf
> Sent: Monday, January 01, 2007 8:58 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Running LOP
>
>
> Thanks Kieth.
> If using the VM1000 engine monitor, all the cylinder
> bars are at the same level after leaning, what would
> the advantage be if I changed to the Gammi injectors?
> Joel
>
>
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