Hey,

I have noticed that my new engine has some differences in EGT across cylinders, as shown below (in degrees Celsius):


The differences become larger as I lean the engine towards peak EGT, it looks like cylinder #2 is running a lot leaner than the rest and peaks first, while others run a lot cooler and take peak at a leaner position.

I am a student of the Mike Busch line of thinking, and I plan to run LOP whenever the opportunity exists. So - two questions:

Does the range of temperatures I'm seeing actually give any cause for concern? I mean, I can already run the engine back to 9 Gal/hr and it seems to be OK, nothing outwardly changes except the fuel flow and power output. Back around 8 things start to get interesting - temps end up all over the show, with some still hot and some much colder, and by 7 Gal/hr I've lost too much power to bother investigating further - but the engine still seems to run smoothly even at that mixture setting, although I suspect cylinders 2 & 5 are hardly pulling their weight by that point.....

Then, provided you do think the temps should be more evenly balance than they are -
Is it be worthwhile trying to swap the injector nozzles around, to get the flows more evenly balanced, or will that just result in moving the same problem to a different location?
In which case, I just buy a decent set of Airflow Performance injector nozzles and be done with it.

Battson wrote:Hey,

I have noticed that my new engine has some differences in EGT across cylinders, as shown below (in degrees Celsius):


The differences become larger as I lean the engine towards peak EGT, it looks like cylinder #2 is running a lot leaner than the rest and peaks first, while others run a lot cooler and take peak at a leaner position.

I am a student of the Mike Busch line of thinking, and I plan to run LOP whenever the opportunity exists. So - two questions:

Does the range of temperatures I'm seeing actually give any cause for concern? I mean, I can already run the engine back to 9 Gal/hr and it seems to be OK, nothing outwardly changes except the fuel flow and power output. Back around 8 things start to get interesting - temps end up all over the show, with some still hot and some much colder, and by 7 Gal/hr I've lost too much power to bother investigating further - but the engine still seems to run smoothly even at that mixture setting, although I suspect cylinders 2 & 5 are hardly pulling their weight by that point.....

Then, provided you do think the temps should be more evenly balance than they are -
Is it be worthwhile trying to swap the injector nozzles around, to get the flows more evenly balanced, or will that just result in moving the same problem to a different location?
In which case, I just buy a decent set of Airflow Performance injector nozzles and be done with it.

GAmi injectors!!

M6RV6 wrote:
GAmi injectors!!

The best news is, the big EXPERIMENTAL sticker means I don't have to pay $$$$ for certified injectors

Then all you need to do is get the drill bits out and start with the smallest ones after you change them around!!

Yup! Do what you need to do to get your Gami spread at least below .5 gph. After swapping three injectors, mine went to .2 gph and it now runs nicely 65 degrees LOP.

Be VERY CAREFUL moving injectors around, and please understand that M6RV6 was joking about drill bits.....I hope

Easiest plan: Buy a set of balanced injectors....certified or not, whatever suits you. Make certain you install them in the specified order.

If you can't balance out those EGTs, I'd be reluctant to run LOP.

MTV

mtv wrote:Be VERY CAREFUL moving injectors around, and please understand that M6RV6 was joking about drill bits.....I hope

Easiest plan: Buy a set of balanced injectors....certified or not, whatever suits you. Make certain you install them in the specified order.

If you can't balance out those EGTs, I'd be reluctant to run LOP.

MTV

Maybe I should have used the ,

mtv wrote:Be VERY CAREFUL moving injectors around, and please understand that M6RV6 was joking about drill bits.....I hope

Easiest plan: Buy a set of balanced injectors....certified or not, whatever suits you. Make certain you install them in the specified order.

If you can't balance out those EGTs, I'd be reluctant to run LOP.

MTV

Damn, I had my 3/16" bit all ready to go

What do I need to be careful about when moving injector nozzles around - damaging the fuel lines? Getting debris in the nozzles? Using the right compound when reinstalling them?

What sort of EGT spread would you expect to see from a balanced set of GAMI's?

First, what flavor engine are you talking about, and what vintage?

The GAMI Injectors are different nozzle size for each cylinder, to compensate for length of induction runner. So, switching those will be a bad idea. Continental has now gone this same direction as well....stealing some of GAMIs thunder.

Lycoming uses a better balanced system from the git go.

With balanced injectors, you should see EGTs VERY close all the way across. In my experience, once leaned out, they'd nearly always be within ten or so degrees, though EGT instruments are a relative measure, as opposed to specific temp.

MTV

It's a 'mostly new' IO-540-A4 experimental.

I have done a bunch more flights and tried the "GAMI lean test" for fuel flow.
Much to my surprise, all the cylinders actually peak within about 1.5 L/h fuel flow (less than 0.5 gal/h) despite temperatures being all over the patch prior to that.

The cylinders all peak at different temperatures, but not wildly different, maybe less than 20-30F between the widest two at peak. As I lean, the temperatures shoot all over the place. At certain mixtures just rich of peak one cylinder's EGT can suddenly shoot a long way up, even at 55% power setting. I think that's a warning sign, so I am not keen to leave it there long enough and see if the CHT follows suit and confirm it's what I think it is!

The engine runs very very smooth at 35 L/h (9.25 gal/h) just lean of peak, all the EGTs (and CHT too for some reason) settle to almost exactly the same value - certainly within 5 degrees of all other cylinders. So I feel good about running it there.

I am left wondering if I really need to do anything to the injectors, "if it ain't broke" kind of thing.

Man that 9.25 sounds good to me. I'd leave her alone.

A difference of .5 gph is the point at which gami says "leave em alone". Anything higher than that and they can help. I fly a big continental io550 and fly lop all the time getting 160 knots at 12 .5 gph in the bonanza.

When we determine balance (gami lean check) we compare ff as each cylinder peaks. We are not so concerned with comparing egt between cylinders. They are their own little individual powerplant. When we fly lop, we typically do the "big mixture pull" to get to gross lop (safer) then fine tune degrees lop from the lean side depending on % horsepower being run

For us it's either lop or SUFFICIENTLY rop. ( avoiding the red box)

It was fun learning about this from APS.

Idahomike wrote:When we fly lop, we typically do the "big mixture pull" to get to gross lop (safer) then fine tune degrees lop from the lean side depending on % horsepower being run

For us it's either lop or SUFFICIENTLY rop. ( avoiding the red box)

It was fun learning about this from APS.

Thanks IdahoMike, glad to hear 0.5 is close enough!

We follow exactly those procedures too, and love it. It's great leaning with confidence ae.

I carry a .pdf Red Fin diagram on my mobile device, just in case I decide to cut it close.

I'll apologise in advance for this...

Great. Works well when ff is balanced to each cylinder. I've been looking at the bear hawk ( I see you have one) I want to expand to a bush plane but need room for the Labrador and assorted firearms/carcasses. Looks like your plane would fit the bill.

Idahomike wrote:need room for the Labrador and assorted firearms/carcasses.

Hahaha - sounds like my kind of problem

I say leave it alone, my $$$ GAMI's won't even do that. Still waiting on another couple of tweaked injectors from GAMI after initial purchase Sometimes it feels like we are put in the too far away, too hard basket down here everyone forgets about us. Except Wup at ABW's of course, nothing was a problem to those guys.

Battson wrote:Hey,

I have noticed that my new engine has some differences in EGT across cylinders, as shown below (in degrees Celsius):


The differences become larger as I lean the engine towards peak EGT, it looks like cylinder #2 is running a lot leaner than the rest and peaks first, while others run a lot cooler and take peak at a leaner position.

I am a student of the Mike Busch line of thinking, and I plan to run LOP whenever the opportunity exists. So - two questions:

Does the range of temperatures I'm seeing actually give any cause for concern? I mean, I can already run the engine back to 9 Gal/hr and it seems to be OK, nothing outwardly changes except the fuel flow and power output. Back around 8 things start to get interesting - temps end up all over the show, with some still hot and some much colder, and by 7 Gal/hr I've lost too much power to bother investigating further - but the engine still seems to run smoothly even at that mixture setting, although I suspect cylinders 2 & 5 are hardly pulling their weight by that point.....

Then, provided you do think the temps should be more evenly balance than they are -
Is it be worthwhile trying to swap the injector nozzles around, to get the flows more evenly balanced, or will that just result in moving the same problem to a different location?
In which case, I just buy a decent set of Airflow Performance injector nozzles and be done with it.

I must admit that I am just a little concerned about your LOP operations, but it may be due to my lack of understanding about your methods. Your comments about things getting "interesting" at various fuel flows does not include information about what the fuel flow was at peak EGT and how many degrees lean of peak you are at various fuel flows. If you haven't already done so, you may benefit from taking the online engine course offered by Advanced Pilot Seminars so that we can speak the same language.

When you say your temps are all over the show, does this mean that your temps are oscillating with time or are they just different between cylinders? Rhythmic oscillation of EGTs could indicate valve problems, but it is not clear what you mean. As was mentioned in a prior post, the specific values for EGT are not important as EGTs do not need to be "balanced" when compared against each other.

If you have performed a GAMI lean test and have determined that your GAMI spread is 0.5 gal/hr, then you are in the ball park.

Perhaps you could include data from one of your lean tests and indicate what you mean by the #2 cylinder being the leanest and what that effect has on the EGT.

Hope to have more conversations about LOP operations as you get your 540 dialed in and feel comfortable with how you are running it LOP.

I thought of this thread while listening to The EGT Myth webinar from Mike Busch. You probably already watched it but if not I think it is worth while.

whee wrote:I thought of this thread while listening to The EGT Myth webinar from Mike Busch. You probably already watched it but if not I think it is worth while.

Thanks for thinking of it!
I have watched / listened to a lot of his stuff, several times for some of my favourites. Very interesting and practical. Good to refresh regularly.