Just FYI, Savvy aviation (Mike Busch company) serves european customers with the QA service. Its purpose is to resolve specific troubles like this one.
Completely normal, about 50 r.p.m. for both left and right mag.
I finally found some acceptable weather to do some further testing after changing the new spark plugs for the old ones (after cleaning and gapping!). Unfortunately no improvement whatsoever! The engine is still running at 10.2 GPH to achieve an EGT of lower than 1.400 degrees. Leaning to the previous setting before the overhaul of 9,2 GPH made the EGT increase to 1460 degrees, which is 60 degrees higher than before. According to the Lycoming Power / Fuel graphs the fuel consumption at 65% power should be somewhere around 9 GPH, although they do not specify any EGT at those graphs.
I made some further in-flight test by doing a mag check at 2.200 r.pm. which showed a temperature rise of to 1470 degrees for both mags.
Another anomaly however showed up during run-up of the cold engine. Rev drop on both mags was 100 r.p.m. (and not 50 r.p.m. as mentioned before!). Indeed this is an increase as compared to the situation before the overhaul / timing of the magnets, where it used to be between 50 – 70 r.p.m.
We also (again) checked the timing of the magnets again and still exactly 25 degrees on both mags. We also removed some of the spark plugs, which showed a rather blackish colour, indicating a rich mixture.
I don’t know if I chasing spooks here and I may be running out of options, but I’m not satisfied before I find a reason for this weird behaviour. An EGT of 1450 degrees might be acceptable but I simply don’t see why I should accept this change after overhaul of the relevant components.
P.S. I will also cocntact Mike Bush
I understand you want to find the reason for the change, but you are not reporting anything that Lycoming would consider symptomatic or abnormal.
Assuming you have double checked all reported above and it is correct, then I would point to some change in the EGT probe…those are not usually very reliable. Also, even if the location of the p robe on the exhaust has not changed, it may have been inserted further into the exhaust than it was before driving higher numbers. Ideally you should have four probes installed and then it helps you diagnose.
BTW are you really showing 175KIAS? That’s fast! You have a two blade prop or..? Can you post a couple of pics of your airplane? It will surely bring good memories!
Oh, and the mag drop may be higher with freshly cleaned and gapped (or new) plugs and newly timed mags.
My main concern with this issue is based upon the fact that I have been a marine engineer in the long ago past. In the engine room of large tankers we became aware that changes on the gauges that we could not explain most of the time were the onset for disaster. We used to say “if something is wrong correct it at once”.
Yet another concern if fuel consumption. A high EGT automatically means that energy is flowing away through the exhaust pipe. With the exact allowable value of the Lycoming EGT there seems to be some confusion. Lycoming mentions peak minus 50 degrees, which should be somewhere around 1450 degrees. The manual of Electronics International however shows a graph relating exhaust valve life to allowable EGT. This graph shows an EGT of 1350 degrees in order to achieve 2.000 hours. So a multitude of choices!
With regard to the EGT probe it is still on the right spot, as it is a screw-in type and not the clamping type. Nonetheless I will direct my attention to the probe and measuring system. It is an Electronics International device and I found a good testing description on their site.
BTW Antonio. Do you now a Dutch guy by the name of Jos Baaner? He was working for Wings over Holland (WoH) in the Netherlands and provided builder assistance for the Lancair 360. During the nineties he left WoH and went to Spain, also helping a local company out with Lancair.
I will dig-up some more pictures of my Lancair PH-DBO and post them. This is the first one: 
I agree with you that something is odd and that you should find what it is. But I am out of ideas 
The reason why the EGT value you see is not to be taken as too meaningful is because the sensor sees the gas pulses as the exhaust valve opens, and most of the time there is nothing there – just some hot gas residues hanging around, cooling rapidly by expansion – and then for a brief % of the time the sensor sees way more than the reading you are getting. A quick google finds e.g. that the flame temperature is around 2600 F (1427 C) for a stoichiometric ratio, on an 8.5:1 engine, rising to around 2800F for a 9:1 engine. So you can see the EGT readings are not the real EGT but a value which is the average of “mostly nothing happening” and a quick burst of ~2600F gas.
Note that with a turbo engine the turbo inlet temperature (TIT) is somewhat more meaningful because the gas flow is more constant, having all the cylinders feeding in, and indeed the TIT is a limiting value for turbo engine operation.
On my IO540-C4 is see about 1500F at 65% power which is 11.7 USG/hr which is very slightly LOP. Best power is around 1300-1330F and I use that for all long climbs – the constant-EGT method described here. It works great and is simple, with throttle and rpm fully forward the whole climb.
The fuel flow is probably fine; the issue is that you are not accepting EGTs above 1400F. At 1400F you are ROP by quite a margin. Yes the plane will fly fast but you aren’t getting the MPG you could be. What is the fuel flow at peak EGT at 65% power, based on the Lyco engine charts?
It is also possible that the thicker-wall EI probes, with greater thermal inertia, are reading lower than the JPI probes. I can’t see why that should be, however.
We have many threads on EGT etc – use the Search function.
This is relevant on the JPI v. EI probe stuff.
That’s a nice plane 
We have a number of Lancair owners here, and lots of discussions of these, mainly in the Non Certified forum section.
Dbo wrote:
Do you now a Dutch guy by the name of Jos Baaner?
I do not. I did know a Dutch Lancair Salesman called Alberto Bresser if I recall correctly.
There’s not many secrets to EGT, especially on NA aircraft.
Main factors driving it are:
Power setting (MP/RPM)
Ignition timing and settings (plug and point gapping)(if checked OK, then possible
Cyl compression ratio
Air/Fuel mixture ratio
EGT measurement system
So if you are using the same power settings as before (is your MP reading accurate or could the line have clogged partially? does it react properly to throttle settings or is it slow? this could also drive FF errors) and we assume the EGT system is good and there is a probe on only one cyl:
You advised on Ign timing and plug gapping…what about mag point gapping? Is it good? Any possible leaks in your ign harness?
If ign is good then is there a leak in your cylinder? Marginal diff compression perhaps? Lower CR will drive higher EGT
If that is right then air/fuel mixture ratio could be an issue with air or with fuel.
I would first establish what is going on with your mixture on the EGT cyl: at the same cruise power setting as before, find the peak and ensure you can set stable mixture settings between 50 and 150 deg ROP. If you have a deg ROP ref from prior, use the same # of deg ROP and see what FF you get. This is much better ref than the absolute EGT. If you can set mixture using EGT peak ref the same as before, even at different FF then you know you have the same air-fuel mixture on that cyl as before.
Having that ref, if FF is higher then it can be an issue with FF indication or with airflow inside the cyl. At lower altitudes (part-throttle) an airflow change can be because of an induction leak. Look for it (both cylinder and oil sump sides on induction risers). If no leaks then airflow is substantially the same as before, and since we already established with EGT that mixture on that cyl is the same as before, then the issue is with FF indication. You could also have an airflow change with no leaks, that would be due to induction valve not opening fully due to cam wear, but that is rarer and thus unlikely and the mixture would be richer resulting in a lower, not higher EGT). We now know FF on the EGT cyl is thus the same as before, but what about total FF? You could have actual or indication FF difference, but usually it is a combination of both:
If you have a turbine-driven electronic FF indicator then you can compare both indications. A change in the difference between one and the other can point you to a failure in the turbine (they do fail) or more likely, some clogging or leak in the injection system.
Remove injectors, hook them to respective fuel lines, pLace a cup under each injector and run the boost pump with rich mixture to fill the cups and look for any obvious FF differences. Clean the offending injector.
That’s all I can think of right now. Good luck!
Hi DBO,
Increasing the advance of the ignition usually causes a higher CHT and EGT for the same RPM level. Up to a certain point it causes also an increase in power.
Did you experience, apart from consumption and temp, any change in the performance of the ACFT??
You changed back to the old spark plugs and no effect, so one can exclude them.
I don’t know how the advance of the ignition timing is made in your case (centrifugal or MAP or both) and that could cause a loss of power in high revs because the ignition just comes too late.
Just some ideas that might help.
Good luck catching the gremlin.
