[flyingriki]

Been searching for this with no luck. Had a main jet drilled out way too much so now back to stock. Wondering if this testing can help me dial it in for best performance and the cooling I need...??
What is this test?
Thanks

 

[lipper03]

Are you talking about a lean mag check? That’s done as a slightly better test of ignition system under a condition of lean and at a higher altitude, which is a more strenuous test then at run up conditions. I think you‘d want to do a “gami” check, which is a slow pull and push on mixture to record cht and egt to determine gami spread aka the balance of the cylinders with respect to their max egt.

 

[flyingriki]

Are you talking about a lean mag check? That’s done as a slightly better test of ignition system under a condition of lean and at a higher altitude, which is a more strenuous test then at run up conditions. I think you‘d want to do a “gami” check, which is a slow pull and push on mixture to record cht and egt to determine gami spread aka the balance of the cylinders with respect to their m

I thought the GAMI test was for FI. I have a carb.

 

[BH1166]

look at this thread, maybe something there might help. Look at #14 in this thread. I sent my carb to a very good FAA carb shop to dial mine in for me. It took two adjustments to get what I wanted. Very happy, now I can climb out at most any deck angle at any OAT and my chts stay below 400F.

O-320 Running too lean

It's been about 4 months since I purchased my RV6A with O-320b2c and fixed pitch sensenich. Now that I've fixed my non-functioning EGT gauge, I've come to realize my EGTs are very high on takeoff and fuel flow is too low, about 10gph at sea level. I can maybe get it to to close to 11 once I...

www.vansairforce.net

 

[lipper03]

I thought the GAMI test was for FI. I have a carb.

You can do it with any engine, you just won't get as small of a spread on a carb because of the natural imbalance of the carb, but it's still useful info knowing what your balance looks like at different settings (ie you can do the test at any power, alt, etc). With a carb you can also mess with partial carb heat and throttle position to see if you can improve the balance and spread with a little more "mixing air". Some can get very close to balanced with a few tweaks, especially Lycoming engines with the inlet manifold design.

 

[JonJay]

What are you trying to test?

If you’re not getting full fuel flow during takeoff, that’s easy to see and diagnose.

If you want to check to see if you’re capable of running lean of peak, but can’t establish what peak is - set up at cruise power, something like 60% power. Lean until engine roughness, then enrichen until smooth and a little more. That will be as lean as you can get at that power setting. Enrichen and see if your EGT’s rise. If they do, you will see them peak and then fall off as you get richer. 50deg. ROP is your max power. If the EGT’s just fall, you never reached LOP.
There are a lot of factors, mainly cylinder intake imbalances, that make it more challenging as you may have one cylinder LOP and another won’t be. You may also find that different cylinders perform differently at different power settings.
If you have an engine monitor that records data, you can fly a bunch of tests and check the numbers. Do they make sense? How do they compare to the Lycoming charts for your engine?
After all of that, you can establish what profile works best, or if you have a problem. Keep in mind it’s all relative numbers. Lycomings charts have to be factored for temp, humidity, etc….
You’re not looking for absolutes, you’re looking to see if things make sense across all the things you can monitor.

…..or, go old school….. full rich full power climb, lean to engine roughness, enrichen until smooth and a bit more….
This is what you would do if you don’t have an engine monitor and what we all did “back in the day”. Seemed to work.
It even works in injected engines. Engine roughness may not come, but you can usually determine “significant loss of power”. This will be as far LOP you can get. If you have an EMS, you can look at the data and fine tune injectors and such. I’ve never quite figured out the trick to the bottle test.

Good luck.

 

[TLockard]

Been searching for this with no luck. Had a main jet drilled out way too much so now back to stock. Wondering if this testing can help me dial it in for best performance and the cooling I need...??
What is this test?
Thanks

Savvy Aviation gives a specific protocol for doing a lean test.
https://www.savvyaviation.com/wp-content/uploads/savvy_pdf/Savvy-Flight-Test-Profile-Expanded.pdf
They do recommend full throttle but less than 65% power which means getting high enough to not be able to produce more than that power level at full throttle. They like to see a slow mixture sweep from rich to lean as far as you can go then back to rich. They have you do this 3 times and on the third pull you stay lean and check each magneto for 30 seconds to test ignition. If you have an account with them they will do an analysis on your engine monitor data as well.

TLockard

 

[flyingriki]

Savvy Aviation gives a specific protocol for doing a lean test.
https://www.savvyaviation.com/wp-content/uploads/savvy_pdf/Savvy-Flight-Test-Profile-Expanded.pdf
They do recommend full throttle but less than 65% power which means getting high enough to not be able to produce more than that power level at full throttle. They like to see a slow mixture sweep from rich to lean as far as you can go then back to rich. They have you do this 3 times and on the third pull you stay lean and check each magneto for 30 seconds to test ignition. If you have an account with them they will do an analysis on your engine monitor data as well.

TLockard

That's great! Thank you.