Tit probes. Have two which one do I really read.

[warrenehc]

Hello,

I have two tit probs on my Mooney. One at the intake and one 2-3 inches back towards the wastegate. My understanding is that the tit probe should be located 2-4 inches aft of the intake towards the wastegate. 
The first probe is on a stand alone JPI tit gauge on the panel. The second is on a JPI 930.

I can never get to peak tit regardless of the power setting before hitting 1650. 
 

The second probe is always 100 degrees cooler than the first. 
 

My CHT’s never get above 365 regardless of power setting speed or altitude based on a 1585-1590 tit reading off the first probe. 

I feel that is extremely rich considering redline for the cht is 500. I fell 380-390 to probably be the right cht temp for a standard cruise setting to be around best economy/power range.

So is the first tit probe in the wrong position. Or was that recommended location after the Bravo update and I’m not seeing that information.
 

 

 

[N201MKTurbo]

The one by the wastegate is obviously the factory position and should be used for your TIT limit. The one near the turbo exhaust inlet is clearly an afterthought.

[LANCECASPER]

2 hours ago, warrenehc said:

Hello,

I have two tit probs on my Mooney. One at the intake and one 2-3 inches back towards the wastegate. My understanding is that the tit probe should be located 2-4 inches aft of the intake towards the wastegate. 
The first probe is on a stand alone JPI tit gauge on the panel. The second is on a JPI 930.

I can never get to peak tit regardless of the power setting before hitting 1650. 
The second probe is always 100 degrees cooler than the first. 
My CHT’s never get above 365 regardless of power setting speed or altitude based on a 1585-1590 tit reading off the first probe.  I feel that is extremely rich considering redline for the cht is 500. I fell 380-390 to probably be the right cht temp for a standard cruise setting to be around best economy/power range.So is the first tit probe in the wrong position. Or was that recommended location after the Bravo update and I’m not seeing that information.

No additional location was ever recommended after the Bravo conversion.

I would get that other probe out of there, do whatever you have to do to make sure there is no exhaust leak in that area and disconnect whatever indicator it's attached to. (Unless that's where they put your #4 EGT probe.)

Make sure the correct factory location probe is displaying on your JPI930 since that is your official instrument now that the original instruments are removed. Pull the other supplementary JPI TIT indicator or clearly mark it INOP. 

Looking at an incorrect lower TIT indication is a good way to cook a set of cylinders on this engine and at the same time burn up the turbo and the exhaust system and maybe even the occupants. There were a few incidents of the exhaust system getting so hot that it took out the "Y" in the tailpipe and blew 1650 or higher exhaust like a blow torch through the fire wall. That didn't end well.

This is a great airplane but running it with the POH numbers will burn up the engine. I keep preaching to the choir on this but . . . 

 

[Fritz1]

The upper probe closer to the cylinder appears to be an EGT probe, TIT probes live in a hostile environment and have a service life of 200-300h at best even if the engine is run correctly, i.e. max TIT 1600 dF. Best way to test the probe is to run a lean test below 60% power, first cylinder EGT to peak and then go 100-110 degrees rich on that cylinder, TIT should come in at about 1580 dF, if your probe reads significantly less, replace it, fuel flow in cruise, in my engine 2250 rpm 30.5", comes in at 18-18.5 GPH at 17,000 ft, TIT around 1580 dF, max CHT 375-380 depending on ambient, tempest fine wire plugs help in the Bravo engine

[Rick Junkin]

I'm curious as to why someone drilled into the turbo transition casting to install a second TIT probe. From the picture it looks like the second probe has been there for a while, judging from the build up at the base of the probe. It shouldn't be there, but someone obviously thought they needed it. Do the log books shed any light on when and why it was installed?

To my knowledge that casting is no longer available except through salvage and plugging the hole after the probe is removed might be problematic. But I'm not a mechanic so someone else here probably has a solution to share. I had mine overhauled with the rest of the exhaust earlier this year and it came back looking like new.

Just to make sure we're all talking about the same probes, I've put a green circle around the OEM probe location and a red square around the added probe. The #6 EGT probe is in the riser above the transition, right about the same place mine is.

[Fritz1]

yes, see it now, the factory probe is green, probe marked red is unusual, have never seen anything like it, thought it might have been an early Bravo engine, probably best to shut that probe down and put new probe into factory location, think the only probe available with the thread is made by Alcor, installed one about a year ago, KS probe was not available at that time, Alcor probe held up well, about 100h on it, no drift from new so far

[LANCECASPER]

8 hours ago, Rick Junkin said:

I'm curious as to why someone drilled into the turbo transition casting to install a second TIT probe. From the picture it looks like the second probe has been there for a while, judging from the build up at the base of the probe. It shouldn't be there, but someone obviously thought they needed it. Do the log books shed any light on when and why it was installed?

To my knowledge that casting is no longer available except through salvage and plugging the hole after the probe is removed might be problematic. But I'm not a mechanic so someone else here probably has a solution to share. I had mine overhauled with the rest of the exhaust earlier this year and it came back looking like new.

It's a Special Order item and Aircraft Spruce lists it for $11818.00. https://www.aircraftspruce.com/catalog/eppages/lycomingexhaustpipe_07-15169.php

[Fritz1]

Jesus!

[kortopates]

Installing a second TIT probe is a standard practice whenever one installs an engine monitor that isn’t approved for primary like a JPI EDM 830. You can’t replace the primary factory TIT for your panel but you want your engine monitor to log TIT along with everything else. Quite common.


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[Rick Junkin]

8 hours ago, kortopates said:

Installing a second TIT probe is a standard practice whenever one installs an engine monitor that isn’t approved for primary like a JPI EDM 830. You can’t replace the primary factory TIT for your panel but you want your engine monitor to log TIT along with everything else. Quite common.


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Thanks for this info. Never would have occurred to me to drill into the turbo transition casting where this one is located. Makes sense that a second TIT probe would be required to get it displayed on a non-certified monitor.

Having said that, here's a pic of my transition during installation of the overhauled exhaust. It has a second TIT probe mounting point cast into it. I thought it was odd, but now I understand why it's there. Thanks Paul!

 

[warrenehc]

Was told by the machanic he did so after a lot of experiment's he did flying the plane back in the 90’s. Even running at 1650 or under on the tit people were still burning up cylinders and turbos using the factory tit location at that location running at 1600-1590 he found best performance and longevity out of cylinders and turbos. 

I have been running that from that probe. 15k-17k running 27/22 fuel burn is 17.2-16.8.

Here below is a picture 14.5k running 27/22 16.8 a gallon. TIT from inlet (red box from upper picture) shows 1588 from manufacture probe location 1495(green circle from upper picture). CHT’s between 341-360. EGT show low on the graph. Cowl flaps complete closed.
 

Would gladly take anyone’s thought and opinions on that..

[LANCECASPER]

32 minutes ago, warrenehc said:

Was told by the machanic he did so after a lot of experiment's he did flying the plane back in the 90’s. Even running at 1650 or under on the tit people were still burning up cylinders and turbos using the factory tit location at that location running at 1600-1590 he found best performance and longevity out of cylinders and turbos. 

I have been running that from that probe. 15k-17k running 27/22 fuel burn is 17.2-16.8.

Here below is a picture 14.5k running 27/22 16.8 a gallon. TIT from inlet (red box from upper picture) shows 1588 from manufacture probe location 1495(green circle from upper picture). CHT’s between 341-360. EGT show low on the graph. Cowl flaps complete closed.
 

Would gladly take anyone’s thought and opinions on that..

My guess is that the probe displaying on your JPI 900 has an older probe and has probably been burnt up a long time ago and is showing a much lower, incorrect reading and that the supplemental gauge has a newer probe. If you really want two readings they should both have their probes changed out at the same time to make it an apples to apples comparison.

[Rick Junkin]

20 hours ago, warrenehc said:

Was told by the machanic he did so after a lot of experiment's he did flying the plane back in the 90’s. Even running at 1650 or under on the tit people were still burning up cylinders and turbos using the factory tit location at that location running at 1600-1590 he found best performance and longevity out of cylinders and turbos. 

I have been running that from that probe. 15k-17k running 27/22 fuel burn is 17.2-16.8.

Here below is a picture 14.5k running 27/22 16.8 a gallon. TIT from inlet (red box from upper picture) shows 1588 from manufacture probe location 1495(green circle from upper picture). CHT’s between 341-360. EGT show low on the graph. Cowl flaps complete closed.
 

Would gladly take anyone’s thought and opinions on that..

How do your individual EGTs compare to the TITs from the two probes? My TIT, as measured from the OEM location, is about 75-100Fº higher than the average of my EGTs. 

From your pictures it appears the OEM location probe is fairly new, while the other one shows signs of erosion at the tip and buildup at the base. I would expect, as @LANCECASPER pointed out, that the worn probe would be reading lower than actual. The fact that they are reverse of this, with the newer probe reading lower, is puzzling. This is a guess, but it may be possible that the buildup of gunk at the base of the second probe is retaining heat and causing the probe to read high.

I agree with Lance, installing new probes at both locations would provide a more accurate basis for comparison. If the OEM probe is indeed fairly new you may only need to replace the secondary probe, which is looking a little worse for wear.

I'm not a mechanic, just a maintenance-involved owner.

[tls pilot]

I have owned the plane since 1993 and when we installed a GEM then JPI we used a second TIT

probe. A few engines later still have a second TIT