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Gami injectors


Danb

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I read Don's entry when the Bravo forum started and stated he had gamis and after a mag change stopped running lop but stated that putting the gamis in was a great move. My Bravo goes in annual in June and I was going to have Weber install the Gami injectors, would you still consider this a good thing to do, I am going to take ths aps course to acquire some engine knowledge(not to bright in this area) I seem to be one of those Bravo's that do 5-7 knots better than book?? I've been flying mostly at 30" 2400 since joining the forum at tit 1625 I don't know why. My main question after studying the gami site and aps is that this installation is of great value. Just looking for a positive for doing what my plan is...

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GAMI injectors are merely individually modified fuel nozzles designed to balance the fuel/air mixture of each cylinder.

Some advantages are better overall power from the engine when all cylinders are producing nearly the same output.

Smoother operation, the roughness you feel when leaning is the unbalanced power output between cylinders.

Better efficiency by maximizing the ability to run at stoichiometric mixture and not wasted fuel.

 

GAMIs cannot get the flows between cylinders perfect. Anything below 0.5 gph is about as close at you can get. Although some report better balances.

Do a GAMI test to determine your current condition. IF it is greater than 1.0 gph, GAMIs will probably be able to improve your performance. If you intend to run >100°F ROP, GAMIs will not help you and will be a waste of money.

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Tom, thanx.. I looked up the GAMI test and plan on doing it. My engine actually runs quite smooth but there seems to be quite a bit of info. Out there recommending the change, as stated I have no clue (I'm a CPA though not a nerd and do certain amount of my own maintenance) I appreciate your input, do you used them and run lop?

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I don't need them. My engine is balanced from the factory.

 

Yes, I run LOP. I want the most efficiency I can get.

 

What you are after is balanced fuel flow. The GAMI test will tell you how well your engine is doing.

IF you fuel/air mixtures are not balanced across all your cylinders GAMIs can help improve that. (Assuming all other sources that can cause an imbalance are performing properly) Air leaks, spark plugs, wires, mags.

IF you are already balanced (do the GAMI test) you don't need them, they will not give you any benefit. 

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Running the spread test will help determine if Gami's will help.  See when each cylinder peaks.  The readout afterward will help make the determination. 

 

After a Top Overhaul when I had two cylinders crack on an overhauled engine (warranty repair) the local mechanic who pulled and replaced the cylinders didn't put the fuel injectors back on in the same order.  I could not get it to run as smooth as I wanted, and when I took it to my MSC once flying again, they noted the injectors were not where they were supposed to be, switched it around (they were Gami's) and boom, smooth engine all peaking at the same time.   

 

If your engine is already set up well, you don't need Gami's.  If they fuel flows are not peaking at the same time, get some Gami's.  Even if you don't run LOP your engine will perform better and smoother.

 

-Seth

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That brings an interesting point Seth.

Question - if your injectors are well balanced - say to 0.2gph - will they remain balanced if you get a top overhaul or do you need to rebalance the injectors ? (Assuming you do not randomly permitted them by mistake obviously!)

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I would not think there's a connection. My well balanced IO-360 remained well balanced after the engine tear down OH. Cam and lifters were replaced but not valves or cylinders. New rings. Mags were replaced but fuel distribution system, injectors, were not effected.

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That brings an interesting point Seth.

Question - if your injectors are well balanced - say to 0.2gph - will they remain balanced if you get a top overhaul or do you need to rebalance the injectors ? (Assuming you do not randomly permitted them by mistake obviously!)

My experience was that they remained generally well balanced (maybe .5 GPH) but the first and last to peak changed.

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Where the Bravo comes up short is not so much leveling fuel flow...

But the balance of airflow into each cylinder...

The Acclaim and other 550s handle this challenge by having even length, nicely curved intake tubes for the six cylinders.

I believe you can find smooth LOP ops with a Bravo engine, unfortunately it occurs at a lower power setting than the pilots are interested in being at.

Yes, it is good to have GAMI or other balanced injectors for ROP, but without sexy curvy intake tubes there is no additional capabilities readily available.

That's my understanding, from a fluid flow / chemical engineering sort of way.

For examples seek out pictures of the engines Bravo vs. Acclaim.

Best regards,

-a-

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I read Don's entry when the Bravo forum started and stated he had gamis and after a mag change stopped running lop but stated that putting the gamis in was a great move. My Bravo goes in annual in June and I was going to have Weber install the Gami injectors, would you still consider this a good thing to do, I am going to take ths aps course to acquire some engine knowledge(not to bright in this area) I seem to be one of those Bravo's that do 5-7 knots better than book?? I've been flying mostly at 30" 2400 since joining the forum at tit 1625 I don't know why. My main question after studying the gami site and aps is that this installation is of great value. Just looking for a positive for doing what my plan is...

Interesting question, I have a Bravo, and took the APS course. I already had GAMI injectors on my airplane, but if I did not have them, I would have had them installed, here are my thoughts.

First, our Bravo engines do not do well lean of peak. Without getting into a huge discussion over this, although it can be done, it takes perfectly balanced GAMI injectors to do it, and if they're not, will be very hard on our engines.

- the advantage I see of having GAMI injectors that it should balance fuel flow on all of your cylinders, which should decrease fuel consumption a little bit but more importantly cylinder longevity by not having such a spread between cylinders.

- yes, you absolutely should take the APS course and you'll have the answers to these and more questions you haven't yet thought of. Even though you won't likely do LOP operations in your Bravo, there's a ton more valuable insight into things that will increase your knowledge of your airplane

- your power setting of 30" 2400 is a bit higher than what I run (29"/24 number = 53) and you are running a higher %BHP which is probably not too bad and will give you that extra 5-7 kts speeds, but the course will teach you about internal cylinder head pressures and you can then make your own judgements about where you wish to run your engine.

- but the question of whether you should add GAMIs if you're not planning on running LOP is a valid one, and would be interesting to hear other potential benefits than the ones I mentioned above from the APS guys when you go there, (or if they're any around here)

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John..thank you for your response, The next course is not for a few more months. I was considering taking the online course in that I have limited knowledge re internal engine mechanism. I've had 3 Mooneys since 1988 without ever having a problem. I pay strict attention to all temperature management and feel that is one reason I've never had a cylinder or valve problem in 3000 hours. If I could acquire more knowledge the better. There are many on this forum that feel if your not a competent mechanic your not a competent pilot.Like I mentioned I've never had a major problem. Luck I guess other than say vaccum pumps or maintenance issues. Thanx again. Happy and safe flying

Dan

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No worries Dan,

I did both the online and the live course, at least when I took it, the online was free when you bought the course as it's VERY helpful to go over all of the graphs and info now before the live course as you'll get more out of the live course when you do. Just ask about it and I'm sure they'll give you access if you've registered for the live course. Happy Flying!

John

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So I just checked out GAMI's site because I'm considering putting on some of "their" injectors at annual this year. I am puzzled to find that there is a $250 core charge!! So, I guess you pay $700 to have them rebuild your current injectors. I thought for $700 you would get all new injectors! Kind of a rip off really. If you've ever fiddled with the injectors on your engine, there's probably only about $2 worth of material for all the cylinders. I guess that's why they don't have a gallery section on their site showing sparkling new GAMI injectors, at least part of the injector would look old and crusty. Why don't they tell you they are offering a modification or rebuild service?

 

The site implies that they are selling you new injectors. It should say something like- "We take your injectors, modify them and rebuild them..." but it doesn't. It just says "GAMIjector R" , sort implying that you're getting a new product. Kinda swindly IMO. Oh, and wow! $250 for a set of used injectors!!?? Where else in the world is a set of used injectors worth $250? I guess there's a lot of engine shops sitting on a gold mine!

 

Oh well, rant off. Carry on.

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  • 1 month later...

The GAMIjectors have a completely different nozzle design. The Lycoming has an insert with a hole drilled in the end, which sprays fuel out the open end of the injector body.  the GAMI has a one-piece injector with the engine end shaped like a cone.  I'd suspect it has a bit better atomization as well.

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The GAMIjectors have a completely different nozzle design. The Lycoming has an insert with a hole drilled in the end, which sprays fuel out the open end of the injector body.  the GAMI has a one-piece injector with the engine end shaped like a cone.  I'd suspect it has a bit better atomization as well.

 

Then why do they want my old injectors so bad?? :huh:

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  • 1 month later...

I have to revisit this thread. Last week I finished my annual and I installed the GAMI injectors. I was still puzzled and concerned about the whole "core deposit" thing, so I called them and inquired. They told me that indeed, the injectors were 100% brand new and they did not rebuild Lycoming's injectors. The reason for wanting them was to get them out of customer's hands.

 

I guess they had experienced problems with customers mixing and matching their injectors with the Lycoming injectors and it must have caused them headaches. I'm guessing of the legal variety. Anyhow, the website sounds very menacing, but on the phone they were kind of nonchalant about it. I have yet to send my old injectors back and I bought the GAMIs about a month ago. No threatening notice yet.

 

The good news is, I did notice a difference on the first flight. The EGTs were much more even and the engine ran a little bit smoother LOP. It has only been one flight, so the I have to do some more flights for a better review.

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  • 1 month later...

Where the Bravo comes up short is not so much leveling fuel flow...

But the balance of airflow into each cylinder...

The Acclaim and other 550s handle this challenge by having even length, nicely curved intake tubes for the six cylinders.

 

 

I think this is where you are still one step behind…    The OWT we were all taught is that the airflow was imbalanced (especially engines like the TSIO 360), hence the imbalance in power, different cylinders reaching peak etc.  Continental spent millions designing the 'spaghetti' intakes to balance the fuel flow, first used in the 252, which was a whole lot better, but more expensive and heavier.

 

The brilliance of team GAMi, was to identify that with a constant flow injection system, there is fuel carry over from the one cylinder to the next when the valve is closed.  Its not hard to understand that if you are injecting a contionious stream of fuel behind a closed valve it is going to vaporize and expand, thus 'contaminating' the air going to the next cylinder.  Solution is to give the next cylinder slightly less fuel, and the last cylinder in line even less.  All are getting the same amount of air.  

 

I theory the 252 engine is balanced - in practice the calibration of Continental fuel injectors is nowhere near as good as GAMi.  Do the GAMi test (with continental or GAMI injectors), then tell us how well balanced your engine is.

 

For those who say that their engine is balanced form the factory, I call BS.  Do the GAMi test and then tell us its balanced…

 

And yes, GAMI want the old injectors just to take them out the market, kind of like Continental used to want a cylinder core to get it out of circulation and the repair market.

 

 

Don

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Don,

When you say "I am one step behind"...

It sounds somewhat personal.

Aside from that...

Do your best...

1) balance your fuel flow...

2) balance your airflow...

3) balance your EGTs...

4) balance your CHTs...

5) balance your power output of each cylinder...

These are extremely challenging engineering concepts. They include non-continuous flows, of non-ideal fluids, with non-ideal variations of temperature and pressure. Throw in a few elbows in pipes and tubes...

Two cases of Mooneys with very nice motors have difficulty going LOP.

The C has a carburetor and the Bravo has a challenging air intake.

Neither has a fuel injected IO360...

I enjoy the informed discussion of how to get these two engines up to being able to be so balanced that they are able to run LOP.

Fortunately, running LOP is icing on the cake.

Realistically, ROP is what is in the POH and is plenty reliable enough for most pilots.

There are a few pilots that would like to have the icing on their M20M, but cannot find it by adding the finest available fuel injectors.

They report that by the time it runs smoothly LOP, they are not producing the power that they are seeking.

There is another thread of people discussing the Continental TC'd motor and how the learning curve is best handled in the 231, 252 and Rocket...

See if you can bring me up to speed with the OWT you are referring to.

I am only a PP, not a mechanic. It is possible that I have missed something or I AM one or two steps behind...?

Through open conversation at MS, and a bit of shared experience, I have a chance to keep up...

I'm good with that,

-a-

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As for how well 'balanced' my engine is...

The GAMI spread is as tight as a I can measure it. All six peak within .1 to .2 GPH?

At intermediate alts... It runs LOP smoothly past 80dF until it shuts off...

At higher alts... It runs LOP smoothly past 40dF

If there was any additional balancing work, it was done prior to my ownership.

Realistically, I use altitude to safeguard against high %hp output while operating LOP.

A few degrees LOP at altitude, maximizes speed, and minimizes fuel waste at these conditions...

I don't think anyone goes this deep LOP, accept to define how well things are set up...

These numbers are from old fuzzy memories. They are not exact, but they do illustrate the point fairly well...

Any chance your engine on the PA18-150 goes LOP?

Best regards,

-a-

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