4 Probe EGT

[MooneyBob]

Hi,

 

I just got my M20J and I have a question about the 4 probe EGT gauge that is installed in the plane. I can't find any manual or even model number of the instrument.

I'd like to find out how to determinate what cylinder I should go by to lean my engine, how often to switch the cylinders to get the most accurate reading, etc.

Anybody with any experience with this type of the EGT? I have attached a picture of the instrument.

 

Thanks

[Bob - S50]

We had a similar gauge in ours but it also had OAT on it.  We got rid of it and installed a JPI EDM 730.  EI and Insight also make good monitors.  What the EGT does is not nearly as important (almost not important at all) as what the CHT does, and with the factory setup you can only see what one of the 4 cylinders is doing... and it may not even be the hottest.

 

With that said all I can suggest is:

 

1.  Ignore it.  Pretend you don't have one.  Just lean until it runs a little rough then richen to smooth it out or...

 

2.  If you really want to know which cylinder is the leanest on that day with that power setting, and you want to run ROP...

 

a.  Start with #1 and lean until it peaks.

b.  Go to #2 and lean a bit more.  If the EGT goes up it was still ROP if it goes down it was LOP.

c.  Pick the leanest of the two depending on what you found in step b.

d.  Re-lean that cylinder to peak EGT.

e.  Go to #3 and lean some more.

f.  Pick the leanest of the two and lean to peak.

g.  Go to #4 and lean some more.

h.  The leanest of the two is your leanest cylinder.

i.  You can then richen to your desired ROP setting.

 

3.  If you want to run LOP and you want to know which is richest that day... do the same as above, but instead of picking the leanest cylinder each time, pick the richest.  Once you find the richest you can lean however much you choose.

 

Once you get it set, I wouldn't bother looking at it anymore unless I changed power settings.  I'd be looking at the one CHT indication you have instead.

 

Bob

[Marauder]

Hi,

 

I just got my M20J and I have a question about the 4 probe EGT gauge that is installed in the plane. I can't find any manual or even model number of the instrument.

I'd like to find out how to determinate what cylinder I should go by to lean my engine, how often to switch the cylinders to get the most accurate reading, etc.

Anybody with any experience with this type of the EGT? I have attached a picture of the instrument.

 

Thanks

 

 

What you have is an original Alcor manual EGT gauge. There is another version of this which I had in my plane. It was set to measure only on the #3 cylinder (the one expected to peak first).

[Marauder]

Some of these units had a red movable indicator that allowed you to mark a temperature point and then switch to the next cylinder to move it if the temp was higher on that cylinder. You basically started leaning and watch the exhaust temp (I would start with cylinder 3 or 4) climb and mark when it got the highest point before the engine started running rough or the the temp started dropping off. Then you move to the rest of the cylinders to find the one that peaks first and then enrichen the mixture.   If memory serves me correctly, it was 25 degrees per mark.

[MooneyBob]

Thank you everybody for the responses.

I

[KSMooniac]

You really ought to consider putting a modern engine monitor in there...they are very high bang-for-the-buck, and there are used ones popping up on the secondary market now regularly as people upgrade.  If you are mechanically-inclined, you can also do a lot of the tedious installation work routing the probe wires and save money.

[MooneyBob]

What brand / model number should I look at if I decided to go with one for my M20J?

I will do my research but any advice will help.

Thanks

[carusoam]

There are three modern manufacturers that I have seen installed in Mooneys....

JPI - https://www.jpinstruments.com/

EI- http://buy-ei.com/

Insight - http://www.insightavionics.com/strikefinder.htm

They all have the latest in electronic, color options. JPI was most popular back in the day. EI is known for there excellent customer service. Insight is better known for their strike finder.

All can record data, graph data, and have alarms. Others have that, plus include additional data collection skills. Some can integrate with their GPS for mpg and fuel to destination.

Some models have nice flush mounts.

Some models have the ability to act as primary data such as rpm and MP.

None have the ability to measure %HP at ROP that will satisfy everyone...

Four CHTs and four EGTs are the preferred minimum instrumentation for modern Mooney flying. Adding fuel flow will get you the full data set for informed LOP operations.

For comparison, the manual Mooneys have the Alcor single probe EGT. Some people just don't want digital in their favorite Mooney. http://www.alcorinc.com/index.php/sensors/

Good luck,

-a-

How was that?

Welcome aboard...

[KSMooniac]

My plane came with a JPI EDM-700 with the fuel flow option, and I think it is a great instrument.  I'm debating my eventual upgrade path to the EDM-900 or -930 so I can remove all of the old engine instruments.  In the mean time, I might install a -730 that I have from my salvage plane, but it doesn't do anything additional...just looks pretty and shows more info at once.  

 

The -700 pops up on ebay, barnstormers, or sites like this one from time to time, and can be had for ~$1500 with probes I believe.  

 

Any modern monitor is valuable for proper leaning of course, but more importantly, for trend monitoring and troubleshooting.  My own personal story involves a dead spark plug at a fuel stop.  Without the monitor, all I would know is I had a very rough mag check and no idea which cylinder was likely not firing, and some troubleshooting would be required.  Instead, I knew exactly which cylinder and plug was bad, and fortunately found a mechanic at the field that loaned me tools, tested my plug (it was dead) and sold me a new one.  30 minute delay vs. potentially hours of troubleshooting.

 

www.advancedpilot.com can teach you all you should know on the subject too!

[MooneyBob]

Thank you very much.

I will take a closer look at those. It looks like a reasonable investment. I like integrated systems and as much parameters as possible to be monitored.

I hope for the better and warmer weather soon to start flying and working on the plane.

[MooneyBob]

Thank you Bob. It looks like it makes sense to get the modern engine monitor or something better and more sophisticated.

[Bob - S50]

Some of these units had a red movable indicator that allowed you to mark a temperature point and then switch to the next cylinder to move it if the temp was higher on that cylinder. You basically started leaning and watch the exhaust temp (I would start with cylinder 3 or 4) climb and mark when it got the highest point before the engine started running rough or the the temp started dropping off. Then you move to the rest of the cylinders to find the hottest one and then enrichen the mixture.   If memory serves me correctly, it was 25 degrees per mark.

Just a small point.

 

It really doesn't matter which cylinder EGT gets hottest.  What matters is which one peaks first or last as you lean the engine (depending on whether you want to run ROP or LOP).  EGT is not a reliable indicator of how lean a cylinder is running.

 

That's probably what you meant, but not the way I read it.

 

Bob

[Marauder]

Just a small point. It really doesn't matter which cylinder EGT gets hottest. What matters is which one peaks first or last as you lean the engine (depending on whether you want to run ROP or LOP). EGT is not a reliable indicator of how lean a cylinder is running. That's probably what you meant, but not the way I read it. Bob

I corrected my post. To be honest, I'm not even sure how easy it is to do with a manual EGT gauge. Mine was the fixed Alcor (on the #3 cylinder). When I installed my first engine monitor, a GEM 602, I learned that my #1 cylinder peaked more frequently than the #3. That still holds true to this day with the JPI 830.

[MooneyBob]

The bottom line is that the modern electronic engine monitor is way to go. Thanks

[Marauder]

The bottom line is that the modern electronic engine monitor is way to go. Thanks

Exactly, you will get all of your cylinder head temps as well. That is going to critical information as to how hot you are running them.

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[Bob_Belville]

I replaced a nice JPI 450 with a really great JPI EDM 930. I sold the 450 to a fellow MSer for $300. and I think the buyer is happy with it. As mentioned above I would think you could find something similar for a similar price.

 

The 930 allowed me to get rid of a lot of very old instruments.  

[MooneyBob]

This is one sweet panel. Is that Garmin 750? I will do something similar.

[Bob_Belville]

This is one sweet panel. Is that Garmin 750? I will do something similar.

Bob, yes GTN750. Here's the rest of what I have in my '66E. (a GDL 88 is remote.) Aspen PFD 1000, STEC50, Stormscope 900, The GPS 696 is sync'd to 750 and has Sirius/XM)

 

It will do everything for me except flare and pour coffee.

[MooneyBob]

That's awesome. Can you share with us the cost including installation? That will be interesting number.

[Bob_Belville]

I already had the STEC, the Stormscope and the #2 NavCom. The rest including a new panel and the installation of the engine monitoring transducers, etc was $48,000 after deducting $6000 for stuff I sold to Mooniacs and on Ebay. 

 

Would you believe there are some on this forum who do not believe I could get my money back @ resale?! For some reason they have not been able to cite a comparable sale.

[MooneyBob]

I am a strong believer in adding value to the property. It is much easier to sell a house with running water and electricity than similar house without it.

You can do some serious and safer flying now.  Good job.

[kevinw]

Bob, My J is going into the avionics shop next week with HSI issues. Been down this road before when I replaced a bad Century NSD360 with a used one he had on hand less than a year ago. He sold it to me cheap and told me I was on borrowed time. He's telling me the Aspen PFD is the way to go. Just curious how you like it and if you have any regrets.

[Marauder]

Kevin -- I have been flying behind an Aspen for a year now. Absolutely love it with no regrets. I went one step further than Bob and stuck in the MFD 1000. Integrates with my older Narco NavCom and with the GTN 650. Very easy to use.

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[Marauder]

Kevin -- What would you be connecting it to? Sent using Tapatalk

[Bob_Belville]

Kevin, like Marauder I love my Aspen and the whole panel. I'm on my smartphone now but I'll answer in more detail later.

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