GAMIjectors in IO360A3B6D

[PTK]

I'm seriously considering GAMI's. My AP is trying to talk me out of them. He says in Lycomings they will not make much difference as they do in Continentals. Any thoughts? 

[MooneyMitch]

http://www.avweb.com/news/reviews/182531-1.html

Just a suggestion for you.   Take a look at this Avweb ariticle on GAMI's for Lyc.  Hope that helps you make a decision.

Happy Mooney flying! 

[jetdriven]

Those are turbo engines. So is the engine is a Bravo but for some reason they won't run  LOP no matter what.    

First, check the plugs, spark plug harnesses, mag timing. Intake seals at the pan, intake tube gaskets at the head.  NO leaks. 

Do an in-flight GAMI spread test. 

Then, keep track of which injectors came from which cylinder. Use 4 separate jars to keep them in order. Clean the injectors in Hoppes #9 gun cleaning solvent or acetone overnight.  I used 3 days. I shook them and riled them up every time I walked by them. Blast them out with compressed air, then rinse again. change the solvent until there is no little specks at the bottom of the jar. Some have reported over at BeechTalk that using an ultrasonic jewelry cleaner with a stainless tub is best.  I didn't have one. Use an ear scope to view inside the injector. I must be perfectly clean. 

 

Reinstall injectors.  My #1 was leanest and my #4 was richest, I exchanged those injectors for each other. I left 2 and 3 in their original spot. 

Our GAMI spread went form something like 1.2 GPH to less than .2 GPH. 

[John Pleisse]

More fabulous claims with % power reduction never fully quantified. However, another great read, Mitch.

Give it a go Smiles. I'll follow with great interest and hope to be a convert some day. For now....... I like 155 KTAS at 8500 at 10.8. I also take great stock in flying one of the safest and most efficient engine/airframe combos in GA history.

[jetdriven]

I enjoy the same safe airframe, just with a gallon an hour less.  In 2000 hours, I save 10K in fuel costs.  I actually fly a little slower, and thus 15K, or nearly a free engine.

 

Free engine.  Run LOP.   I like that.

[jlunseth]

The problem is not that they are turbos.  I have difficulty getting mine to run LOP (231), but the Acclaim can regularly be run LOP.  The Bravo is in the middle.  The problem I think is that the induction systems are not tuned.  In the 231, it is just a tube capped at the far end, with three droppers, one to each of the three cylinders in the bank.  The Bravo is more tuned as I understand it, but not enough. 

The result in my 231 is that the pressure in the induction system varies among each of the three cylinders in the bank, and the variation between the three cylinders changes depending on percent power being produced.  I have GAMI's, but when the variation in induction pressure between the three cylinders is not a constant, GAMI's do not help that much.

I can get it to run LOP sometimes, but I have to keep an eye on it to make sure things don't change over time either.  I also lose alot of speed, at least 15 knots. 

[Shadrach]

Quote: allsmiles

I'm seriously considering GAMI's. My AP is trying to talk me out of them. He says in Lycomings they will not make much difference as they do in Continentals. Any thoughts?

Generally speaking, he is correct. Specifically speaking, you need to see how well your cylinders are matched.

All inject aircraft that I know of have constant flow injectors. Which is to say that the injection system is always spraying fuel to each cylinder.  The reason Continentals benefit from Gamis is that the air intake manifold is a "log runner type" that feeds all of the cylinders one after the other. With this set up, the first cylinder gets raw air, but the next cylinder gets some fuel from the first cylinder. The last cylinder gets a little bit of fuel from the first and second. This creates a progressively richer mixture from the first to last. Gamis tune this set up by decreasing flow of the injectors slightly from front to back.

Lycomings don't have this problem because the each cylinder is basically independent. They do hafe other issues sometimes that Gamis can correct.  I don't run Gami's because I don’t need them. Would it tighten things up a bit? probably...but it's fine as is. My spreads are close enough to run way further LOP than I need to for a given setting...

 

[Shadrach]

Quote: jlunseth

The problem is not that they are turbos.  I have difficulty getting mine to run LOP (231), but the Acclaim can regularly be run LOP.  The Bravo is in the middle.  The problem I think is that the induction systems are not tuned.  In the 231, it is just a tube capped at the far end, with three droppers, one to each of the three cylinders in the bank.  The Bravo is more tuned as I understand it, but not enough. 

The result in my 231 is that the pressure in the induction system varies among each of the three cylinders in the bank, and the variation between the three cylinders changes depending on percent power being produced.  I have GAMI's, but when the variation in induction pressure between the three cylinders is not a constant, GAMI's do not help that much.

I can get it to run LOP sometimes, but I have to keep an eye on it to make sure things don't change over time either.  I also lose alot of speed, at least 15 knots. 

[Shadrach]

Quote: allsmiles

I'm seriously considering GAMI's. My AP is trying to talk me out of them. He says in Lycomings they will not make much difference as they do in Continentals. Any thoughts? 

[jetdriven]

JLunseth:

Try adding 2" of MP back to the engine after setting LOP. Or, add the 2" before crossing over from ROP to LOP.  You should be able to run the same airspeed, and a lower FF while LOP.

Quote: Shadrach

 If you're losing speed than your not running the same hp, which in theory you ought to be able to do if well below critical altitude. It takes more MP to do it, but that in in of it self should not be detrimental.

[FBCK]

jlunseth, I have the same issue, I dont have Gamis, but my spread is only .2, When I'm lean, I find the MP and FF seem to wonder, it will be 28 and over a couple of minutes will trend down to 26 or up to 30 (the flue flow also will drift, so it needs constant monitoring.  I also find the speed loss to be in the 15knot range when flying at 28 inches, prop2600rpms (the FF being 11.2 GPH when lean).  I have an intercooler as well.

[jlunseth]

Thanks for the suggestions, they are all the same thoughts I have had, but right now I have one new cylinder replaced at annual last year and it is too far off the others to try LOP.  Hope to be back at it when this year's annual is completed in a couple months.

But the nontuned induction system is still an issue.  Raising the MP some amount (such as the 2" suggested) does not have the same effect in the cylinders at the front of the induction system as it does those in the back.  Thus, you can't simply add "x" inches and expect that all of the cylinders are going to stay at whatever your LOP setting is in degrees.  Further, GAMI/APS recommends running turbos 60 LOP if over 65%, so you have to go deep into LOP territory to protect the engine, where the chances of being able to run smoothly are not very good.

[KSMooniac]

It is probably a really rare IO-360-A3B6D that needs GAMIjectors... most of them will run just fine LOP with stock injectors so long as everything on the engine is up to par.

[Parker_Woodruff]

Check intake first on an IO-360 as it should be able to run LOP out of the box. My friend's '78 M20J wouldn't run smoothly LOP till he fixed a couple significant induction leaks. 

[jetdriven]

You could try setting 2" more MP than you wish to run, doing the "big mixture pull", then setting it 50 LOP.  You can make the power on the lean side of the graph.  We have found that 50 LOP in a NA lycoming IO-360 might be too far.  So lately, we run at 15-25 LOP. 

Side note, the advanced ignition timing lowered our peak EGT from 1585 to about 1500. So, peak EGT is the same temperature as the "Old 85 LOP".   FWIW. More reason that the EGT number itself does not matter.

Quote: jlunseth

Thanks for the suggestions, they are all the same thoughts I have had, but right now I have one new cylinder replaced at annual last year and it is too far off the others to try LOP.  Hope to be back at it when this year's annual is completed in a couple months.

But the nontuned induction system is still an issue.  Raising the MP some amount (such as the 2" suggested) does not have the same effect in the cylinders at the front of the induction system as it does those in the back.  Thus, you can't simply add "x" inches and expect that all of the cylinders are going to stay at whatever your LOP setting is in degrees.  Further, GAMI/APS recommends running turbos 60 LOP if over 65%, so you have to go deep into LOP territory to protect the engine, where the chances of being able to run smoothly are not very good.

[Shadrach]

Quote: jlunseth

Thanks for the suggestions, they are all the same thoughts I have had, but right now I have one new cylinder replaced at annual last year and it is too far off the others to try LOP.  Hope to be back at it when this year's annual is completed in a couple months.

But the nontuned induction system is still an issue.  Raising the MP some amount (such as the 2" suggested) does not have the same effect in the cylinders at the front of the induction system as it does those in the back.  Thus, you can't simply add "x" inches and expect that all of the cylinders are going to stay at whatever your LOP setting is in degrees.  Further, GAMI/APS recommends running turbos 60 LOP if over 65%, so you have to go deep into LOP territory to protect the engine, where the chances of being able to run smoothly are not very good.

[GeorgePerry]

http://www.mooneyspace.com/index.cfm?mainaction=posts&forumid=1&threadid=1698

Since LOP uses a greater proportion of air during combustion (than ROP), here's something else to think about when running LOP in a mooney with ram air.

[jlunseth]

I am suggesting that the pressures at the intake valves to 1, 3 , and 5 are all different in a non-tuned system.  That is the reason for tuned systems.

 

 

[carusoam]

Unbalanced air intakes are going to demonstrate their differences throughout the operating range.

Higher pressures/air flow rates will usually make the differences even greater.

Any air conditioning engineers here?  The AC guys use vanes and valves to balance this same type of uneven flow issues.

Ovation and Acclaim have curved, balanced intakes that are engineering art.

These curved/balanced intakes have become standard in the automotive industry.

Electronic timing, balanced runners and sequential fuel injectors would be nice.  Not too far from Lycoming possibilities?  Who asked for more HP from the io-360?

Best regards,

-a-

[jetdriven]

The newer Continentals are crossflow heads.  Only allowed for LOP operation like the IO-550G.  What a work of art.

[Shadrach]

Quote: jlunseth

I am suggesting that the pressures at the intake valves to 1, 3 , and 5 are all different in a non-tuned system.  That is the reason for tuned systems.

[PTK]

Quote: jetdriven

Those are turbo engines. So is the engine is a Bravo but for some reason they won't run  LOP no matter what.    

First, check the plugs, spark plug harnesses, mag timing. Intake seals at the pan, intake tube gaskets at the head.  NO leaks. 

Do an in-flight GAMI spread test. 

Then, keep track of which injectors came from which cylinder. Use 4 separate jars to keep them in order. Clean the injectors in Hoppes #9 gun cleaning solvent or acetone overnight.  I used 3 days. I shook them and riled them up every time I walked by them. Blast them out with compressed air, then rinse again. change the solvent until there is no little specks at the bottom of the jar. Some have reported over at BeechTalk that using an ultrasonic jewelry cleaner with a stainless tub is best.  I didn't have one. Use an ear scope to view inside the injector. I must be perfectly clean. 

 

Reinstall injectors.  My #1 was leanest and my #4 was richest, I exchanged those injectors for each other. I left 2 and 3 in their original spot. 

Our GAMI spread went form something like 1.2 GPH to less than .2 GPH. 

[jetdriven]

Yes.  Correct. It also seems fairly common so I would try that before buying gami injectors.   

[fantom]

My GAMI spread is about .3 GPH, after moving my stock injectors around. Now I don't move then at all after annual cleaning, which is probably unnecessary since 100LL is a very good detergent.

GAMI's on a Lyc 4 is usually throwing $ away in my experience.

[rainman]

Guys, I do run my 231 50 degrees LOP at 28"MP and 2500RPM (I have an intercooler). These settings are what was recommended by the MAPA article on the 231 (although he did not address LOP specifically other than to say GAMI has good data but he didn't want to get into it).  My fuel flow is consistantly below 10 GPH below 8,000 ft. The JPI shows all cylinders almost exactly the same. As I'm relatively new to turbos and LOP I'd appreciate any input. Everything looked good at the last annual and the injectors have been in place several years.

Ray