Gami Injectors?

[Tankinbarber]

Since my top end overhaul I have noticed cylinders 3 and 4 running low temps and the others about 50 degrees higher. Is this something Gami injectors would fix? I have ran rpms up on ground to 2000 and leaned out mixture to blow any carbon out of the plugs but still consistent on those temps.

[carusoam]

Read up on GAMI spreads.  That will give you an idea of FF distribution to each cylinder.  Combine both sources of info...

Best regards,

-a-

[Tankinbarber]

Just now, carusoam said:

Read up on GAMI spreads.  That will give you an idea of FF distribution to each cylinder.  Combine both sources of info...

Best regards,

-a-

Thanks just want your personal opinions?

[clh]

Are you talking CHT or EGTs?

For EGT's the Gami's will most likely even the flow of fuel to the cylinders.  

The same is true for the CHT's if the problem is fuel distribution, but, it could also could be an airflow issue.  Make sure all of the baffling has not changed.  This includes plugging unwanted air leaks.

Fixing airflow is a lot cheaper than GAMI's.  

 

[Tankinbarber]

Just now, clh said:

Are you talking CHT or EGTs?

For EGT's the Gami's will most likely even the flow of fuel to the cylinders.  

The same is true for the CHT's if the problem is fuel distribution, but, it could also could be an airflow issue.  Make sure all of the baffling has not changed.  This includes plugging unwanted air leaks.

Fixing airflow is a lot cheaper than GAMI's.  

 

Thanks. How much are Gami's?

[carusoam]

To know what is happening in your engine, it is best to use all the data that is available.

CHTs

EGTSs

FF

 

each of these combines so many variables it becomes challenging to ferret out the answer you are looking for.

CHTs are dependent on EGTs and cooling.  If the cooling is off base because of leaky seals, the CHTs aren't saying anything about your Gamis...

If you don't have all these pieces of info, it is hard to present the facts.  Some people will actually post their downloaded data here.

We have one MSer that analyzes this data for a living.

Post some data.  Get some feedback.  Collect a set of good clean data based on that advice. Post some more data...

look up Savvy.  These are the guys that analyze the data when you are unable...

This is a PP personal opinion.  Not a mechanic or a CFI.

Best regards,

-a-

[Bob_Belville]

Have you run Savvy's Gami spread test? 

[carusoam]

Tankin,

Some back ground...

1) GAMI is a company that makes precision fuel injectors.

2) GAMI spread is a comparison of Fuel Flow at peak EGT for each cylinder.  Max peak FF - min peak FF = GAMI spread in gph.

3) doing a GAMI spread doesn't require having their precision injectors.

4) often the FIs get removed for maintenance and then put back in random places.  This would mess up the work somebody did putting the injectors in their best places.(possibly what may have happened to your plane)

5) air flow is not delivered in a well balanced way.  Each intake is slightly different.  Matching the heavier FF with the heavier air flow makes a balanced situation.

6) the tighter the GAMI spread is, the smoother the engine will run.  Especially at peak or LOP...

7) which engine monitor are you using?

Best regards,

-a-

[Tankinbarber]

No I haven't. I have never even removed the cowlings myself. Strictly a pilot not confident enough to do anything else.

 

[Alain B]

3 minutes ago, Bob_Belville said:

Have you run Savvy's Gami spread test? 

http://www.gami.com/gamijectors/leantest.php

[Bob_Belville]

Just now, Tankinbarber said:

No I haven't. I have never even removed the cowlings myself. Strictly a pilot not confident enough to do anything else.

 

Do you have an engine analyser that allows you to download data? No need to take the cowl off, the test is to carefully lean to LOP several times and to do mag checks while LOP. 

 

[Tankinbarber]

I believe it is a JPI 7 series,

[carusoam]

Their instruction manual is on line.

I was using my JPi manual today.  I printed it out.  It is simple to use, but my memory of simple things doesn't stay that long...

it has two buttons for 50 different functions.  Tap a button it scrolls through data. Tap and hold it a second, it scrolls the other way.  Tap both buttons at the same time.....

there are also some settings in there that are helpful.  Speed of the data collection vs. how much data it can hold is a good one.  Minimize the time between data points.  Six seconds is pretty long....

Best regards,

-a-

[Tankinbarber]

19 minutes ago, carusoam said:

Their instruction manual is on line.

I was using my JPi manual today.  I printed it out.  It is simple to use, but my memory of simple things doesn't stay that long...

it has two buttons for 50 different functions.  Tap a button it scrolls through data. Tap and hold it a second, it scrolls the other way.  Tap both buttons at the same time.....

there are also some settings in there that are helpful.  Speed of the data collection vs. how much data it can hold is a good one.  Minimize the time between data points.  Six seconds is pretty long....

Best regards,

-a-

Thanks!

[cnoe]

I don't believe adding GAMI injectors will provide any benefit in resolving temperature issues. As others already stated there are many variables affecting cooling problems. GAMIs are primarily useful in "fine tuning" fuel/air mixture distribution for those wishing to employ lean-of-peak operations.

I use them, love them, but for their intended purpose.


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[Zwaustin]

1 hour ago, Tankinbarber said:

Thanks. How much are Gami's?

I paid about 1k for them installed on my Tsio 360 LB

 

[Pritch]

Just bought a set for my TSIO 360lb in early Sept and they ran $1068, easy to install and then added the JPI 730. Picture below in my first test flight.  Got a ways to go before I totally know what I am doing.

Pritch

Where the Redwoods meet the Pacific Ocean

[carusoam]

Pritch, have you run the GAMI spread with your new equipment?

Best regards,

-a-

[Pritch]

2 hours ago, carusoam said:

Pritch, have you run the GAMI spread with your new equipment?

Best regards,

-a-

Not yet, have not had enough time, and the coastal Fog has not been to cooperative. 

Pritch

 

[Bob - S50]

The actual EGT values are irrelevant.  Notice on Pritch's photo that even with GAMI's there is a 91F spread between the number 3 and 4 EGT's.

Can you run LOP with your current fuel injectors?

If so, compare the cylinders, looking at how many degrees they are LOP.  That is, disregard the actual EGT.  Are they all about the same number of degrees LOP?  If so, GAMI's won't do anything for you.  Spend the $1000 on something else like ADS-B, an AOA, fuel, or your significant other.

On my J, I do not have GAMI injectors and I typically see #1 about 5-10F LOP while #3 is about 30-50 LOP.  But the engine still runs smoothly.  GAMI injectors would help make them all run closer to the same number of degrees LOP but it's not worth it to me to spend $1000.  GAMI's might allow me to run even more LOP if I wanted.  That would allow me to use the mixture to control power at low altitudes rather than the prop/throttle (not that important to me).  And GAMI's would theoretically allow me to get all cylinders into the 30 - 50F LOP that provides the best economy at my most common cruise settings.  However, the payback time is too long for me.  Let's say getting all 4 running 40 LOP saved me .2 GPH.  At $5/gallon that would take 1000 hours to save $1000 in fuel.  I fly about 65 hours/year.  The payback period for me would be 15 years (and I'm already 64).

I'm already able to run smoothly LOP.  I get close to the best economy mixture without GAMI and that's good enough for me.

[ArtVandelay]

My J has GAMIs, I normally run 50-60F LOP, helps keep my plugs clean, not sure of the cost. I assume injectors are not replaced with TOH. You might switch 3&4 with 1&2 injectors.

[NotarPilot]

On 10/6/2016 at 5:10 PM, Tankinbarber said:

Thanks. How much are Gami's?

Since you asked...

 

[Bob_Belville]

On ‎10‎/‎7‎/‎2016 at 10:32 AM, Bob - S50 said:

saved me .2 GPH.  At $5/gallon that would take 1000 hours to save $1000 in fuel.  I fly about 65 hours/year.  The payback period for me would be 15 years (and I'm already 64).

 

You're only 64? In a hurry to quit? 

[RobertE]

I don't have GAMIs but when I first ran the GAMI spread test found a pretty wide spread (can't remember exactly, but maybe as much as 1 gal/hour between the earliest to peak and the last).  Simply swapping the injectors (put the injectors that were on the cylinder that peaked first on the cylinder that peaked last and visa versa) I got it down to about .3 gal/hour.  This was good enough for me.  If I went another round (again, swapping injectors between the earliest and latest) perhaps I could get it down to an even narrower spread.  And, by "injector" I'm talking about the insert inside each injector which is what has the precisely drilled orifice.  I did this with an A&P's sign off, of course.

It sounds like maybe I saved $1K?

 

 

[mike_elliott]

In my experience, the Lycoming I0 360 will have a low Gami spread and can run LOP with "stock" injectors if everything else is correct, meaning no intake leaks, intake valves sealing well, Tempest plugs (massive or fine wire), Mags and harness in good shape, etc. One might have to "juggle" the injectors around (swap the leanest with the richest cylinder after a Gami spead test, and make sure you know the correct torque value of the injectors so you don't introduce a crack in the cyl head.) but if all else is right, you should have a nice running engine at 25 LOP.