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Engine management: CHT/EGT

H

Helmetfire

FRIEND
Caldwell, Texas
Putting some new cylinders on the ole' cub soon, wondering what some of you have in your cubs as far as engine analyzers and such??

I don't have anything more than oil temp/pressure and feel it would be a good idea to have at least a CHT gauge installed to monitor the temps during break-in of the new cyls. Not sure I want to get all that complicated with it...keeping it light is always a factor.

I guess the upper end of the spectrum would be the EI CGR-30P. Lots of $$$ but full of functionality lets me throw out a few other gauges in the process...is it overkill for a cub?? I guess that's subjective, but kind of the point of this post. I do need a new tach also and this would take care of that problem, but a new tach is only a couple hundred bucks.

Lower end of the spectrum would be a westach cht gauge with the little selector for switching between cylinders...seems like you'd eventually get an idea which cylinder to monitor most of the time and easy enough to scan the others once in awhile during cruise or climb.

What's in your cub??
 
If you can afford it the EI CGR-30P would be great. Fuel flow is nice to have in a cub if you are doing long legs. They have some great discount deals that come up every fall and at major airshows. Anything that can give you 4 cylinder CHT/EGT is priceless when breaking in a new motor.
DENNY
 
Not contrarian by nature, garrulous at times, but I've stayed with basics and egt because my friends say I'm a bit of a perfectionist and watching everything going on in an engine would drive me crazy. I agreed.
 
Kept it light, simple and inexpensive. I use a single Westach CHT/EGT combination gauge to monitor what I think should be the hottest cyl.

-Cub Builder
 
Installed a UBG-16 on my newly overhauled 0320, on the recommendation of an A&P/Cub pilot and am glad I did. Considering the cost of the overhaul, it's relatively cheap insurance to help protect my investment. This instrument also allows for upgrades to monitor OAT, Oil Press, Fuel Flow Rate. I bought mine with a rebate so net cost was $1,300. No regrets on the purchase!
 
I'm happy with my analog tach, MP, oil temp/pressure, & amps, but a
modern instrument to monitor / record CHT's & EGT's would be great for diagnosing problems.
EI's UBG sorta fits the bill, but that one seems to have a page for EGT & another page for CHT.
I'd like something with the CHT / EGT both displayed on the same page--
the CHT/EGT display on the CGR-30 & MVP-50 would be ideal.
But I don't need all the other capabilities (and the price tag!) of either of those units.
 
If I ever get the cub project finished a simple CHT multi cylinder readout will be built using an arduino + ramps board interface, the arduino display+ 4 thermistors (.50$ each epoxied into bolts to fit the CHT holes in the cylinders. The hardest part will be the programming to get bar graphs. The 3D printer program uses digital readout of temperature. The whole thing should be less than 50$. Programming will be stealing parts of the open source program that runs my 3D printer (if I remember correctly the program is called "pronterface". That may be wrong since it's been a few years since I built my printer). It uses one thermister on the "hot end" to control when the program advances to printing after the (user set) target temperature is hit. That output would be the alarm. Copy, paste, edit the program to monitor 4 inputs instead of one and that should do it for experimental crowd.
 
The UBG does show the CHT and EGT at the same time. Look at it again. The bar graph top is EGT, THE space in the bar is CHT. The numbers below are CHT/EGT as you toggle through the cylinders.

The problem with a single cylinder CHT/EGT is you have no ideal which is the hottest until you have watched all 4 in all phases of flight (it changes)!!!! Especially at brake-in I have a buddy with 8 hours on his new motor #2 is the hottest not 3 or 4 where everyone wants to put a single CHT/EGT. The only reason he knows is he is looking at all 4!

More money up front but much safer for your motor and you will save a lot of your mechanics time if you can tell him which cylinder is giving you problems vs him just trying to guess by looking at it or pulling all off to check them.

DENNY
 
I put a JPI 730? Not sure of the # in my 185 but its color and shows all the cyl.'s egt&cht at once. I didn't think I'd use it very much but would want to fly without it in the bush. Lots of warning if something is starting to go bad. My Husky has the factory CHT-Egt but haven't flown it yet so don't know how it works but glad it's in there.
My wife's C-150 has one that you have to select the cyl. You want to see, works just fine but just doesn't give you the total information at one glance. Weight isn't a issue with modern tec. Today so they all work but money is the controlling factor as always.
 
algonquin said:
My wife's C-150 has one that you have to select the cyl. You want to see, works just fine but just doesn't give you the total information at one glance. Weight isn't a issue with modern tec. Today so they all work but money is the controlling factor as always.
Click to expand...

I've got one like this. I really wish I had one that displayed all at the same time, but I think it's way better than a single point. I have been surprised at which cylinder is the hottest in different phases of flight (climb, cruise, etc.) and minor changes such as baffle removal and re-installation have made significant changes in temps on some cylinders, causing adjustments that I ordinarily wouldn't have known I needed to make (small adjustments, everything looked tight before and and after the adjustments)
 
DENNY said:
The UBG does show the CHT and EGT at the same time. Look at it again. The bar graph top is EGT, THE space in the bar is CHT. The numbers below are CHT/EGT as you toggle through the cylinders. ....
Click to expand...

Thanks for explaining that.
I would still prefer an all-bars two-tone display like on the CGR30 & MVP50.
 
Last edited:
Both the JPI 700 and 730 have both CHT and EGT at the same time. I have the 700 in my 185 and love it. The 730 offers more options and is of newer design and is $80 more than the 700, for the 4cyl version, at $1460.
JPI has a very good reputation. There is proprietary software that allows you to see all parameters stored in the unit for many flights.
Have a friend that has a 700 in his 172. We went flying several days ago and I noticed one of his EGT's was much higher than the others. The gauge is mounted on the far right side for some dumb reason, way out of normal scan. Pointed it out to him that one appeared to be running much leaner than the others so we returned to find a very loose intake hose clamp. Once fixed the EGT's were once again mostly inline. I mention this because with a single probe EGT/CHT this would have gone unnoticed for who knows how long costing the price of the gauge.

Tom
 
Had the same issue (engine seeming to run leaner when not being leaned) due to a problem with my right tank gas cap not venting properly. My UBG-16 showed the rise in both CHT/EGT in all cylinders simultaneously, helped to quickly pinpoint the problem. I do think the "all cylinder" gauges are the only way to go. That increment in cost can really save some major $$ down the road.

Tom3holer said:
Both the JPI 700 and 730 have both CHT and EGT at the same time. I have the 700 in my 185 and love it. The 730 offers more options and is of newer design and is $80 more than the 700, for the 4cyl version, at $1460.
JPI has a very good reputation. There is proprietary software that allows you to see all parameters stored in the unit for many flights.
Have a friend that has a 700 in his 172. We went flying several days ago and I noticed one of his EGT's was much higher than the others. The gauge is mounted on the far right side for some dumb reason, way out of normal scan. Pointed it out to him that one appeared to be running much leaner than the others so we returned to find a very loose intake hose clamp. Once fixed the EGT's were once again mostly inline. I mention this because with a single probe EGT/CHT this would have gone unnoticed for who knows how long costing the price of the gauge.

Tom
Click to expand...
 
I agree,
When I bought the plane it only had the JPI 700 without FF. I added the JPI450 FF and oil temp. If doing it from scratch I would get the JPI with FF built in.
 
I have a single Alcor CHT and lead you can have for low $. You could put a probe (not the gasket style but a screw in probe) in #3 which generally runs the hottest in my experience. Then you could move it around to double check. Once you know you're good, you could take it out, but it weighs nothing. Cubs ran zillions of hours without them. Assuming your carb and baffles are correct, it's one more distraction, and mixture adjustments by ear are usually about as accurate as the gauge. Disclaimer - yes, I know there are many different scenarios, and I have a 4 cyl gauge on a banner tow ship, but that's a different game. Wayne M
 
Last edited:
Oliver said:
JPI 700 x2, with fuel flow and oil temp options
Click to expand...

I see that both the JPI & EI monitors also can include fuel flow, oil temps, manifold pressure, etc.
Unfortunately with this new whizbang electronic stuff, whether it be an engine monitor, a flight instrument, or whatever--
the manufacturer wants to put everything including the kitchen sink in it.
I'm a big fan of keeping things simple, if I got one of these I would want it for CHT / EGT monitoring only.
Just like I didn't hook up the pitot/static inputs on my Garmin G5- I just wanted the horizon & directional info.
I could do the same with a JPI 700 or EC UBG, just not hook up all that other stuff,
but I'd still have to pay for the capability which I don't want.
 
Not exactly. With the JPI the EGT-CHT is all it is until you add optional sensors and functions. If you want fuel flow the instrument itself has to be factory modified. My EDM711 is certified primary and when I wanted to add fuel flow I chose a separate FS450. A fuel flow instrument requires regular manipulation to add fuel. I prefer doing that on a dedicated fuel instrument and not the 711. I did add a carb temp sensor but that's been unimportant.

The big win of a multi-point instrument for me was to get the engine temps dialed in. With that done I rarely look at the instrument. If I feel a vibration or something just doesn't sound normal I'll glance at it but other than that it's just along for the ride.
 
hotrod180 said:
I see that both the JPI & EI monitors also can include fuel flow, oil temps, manifold pressure, etc.
Unfortunately with this new whizbang electronic stuff, whether it be an engine monitor, a flight instrument, or whatever--
the manufacturer wants to put everything including the kitchen sink in it.
I'm a big fan of keeping things simple, if I got one of these I would want it for CHT / EGT monitoring only.
Just like I didn't hook up the pitot/static inputs on my Garmin G5- I just wanted the horizon & directional info.
I could do the same with a JPI 700 or EC UBG, just not hook up all that other stuff,
but I'd still have to pay for the capability which I don't want.
Click to expand...

Then just buy the stand alone EGT/CHT. E.I. has several choices.

Web
 
On the other hand, there doesn't appear to be a financial or weight advantage to having a stand alone fuel monitor instrument, seems a bit less complicated to use the integrated system available with the JPI or EI systems. My plan is to incorporate the fuel flow into my ECI this year, which I believe is more economical than adding another instrument into my panel.
 
wireweinie said:
Then just buy the stand alone EGT/CHT. E.I. has several choices.
Click to expand...

The stand-alone EGT / CHT units (such as the US-8A, SR-8A, & C-6)
seem to be set up to display just one cylinder at a time,
and require either manual or automatic cycling to monitor all of the cylinders at once.
 
hotrod180 said:
I see that both the JPI & EI monitors also can include fuel flow, oil temps, manifold pressure, etc.
Unfortunately with this new whizbang electronic stuff, whether it be an engine monitor, a flight instrument, or whatever--
the manufacturer wants to put everything including the kitchen sink in it.
I'm a big fan of keeping things simple, if I got one of these I would want it for CHT / EGT monitoring only.
Just like I didn't hook up the pitot/static inputs on my Garmin G5- I just wanted the horizon & directional info.
I could do the same with a JPI 700 or EC UBG, just not hook up all that other stuff,
but I'd still have to pay for the capability which I don't want.
Click to expand...

Does not cost a lot to add additional feature capabilities at the time of manufacture. Costs alot to add it later if you change your mind.
I wasnt a "whiz-bang" fan either but with cub panel space at a premium and the safety/$ factor of knowing what all my cylinders are doing at a glance is comforting - Had I attempted to break in my engine as per builder recommendation w/o monitor, I would have destroyed the engine within 10 hrs, thats another story..
JPI 700 was very instrumental during break in, still is. adding fuel monitor capability adds about 3 oz to the system and was a no brainer and is incredibly accurate.
Now this 'ol dog is struggling with the idea of interfacing it with my garmin but thats getting a little too whiz-bang for now, but times ar a changin'.
 
Just following up...

I ended up installing the 4 cyl. CHT gauge from E.I. It has the little knob on the front that cycles through the cylinders, and the good bayonet style probes...easy install, nice and light too. After install, I verified the readings were very close to ambient temps, and again with a infrared thermometer.

Finished up the top overhaul yesterday and after a short ground run and a couple fouled plugs :-? , I was headed out for some break-in flying. I was really glad I installed the 4 cyl gauge...when on the shallow climb out I was watching the oil temps climb pretty rapidly, but cycling through the CHT's on the cylinders they never got above 370 degrees. Hottest cyl was number 4, followed by 3, then 2, then 1 being the coolest at 325 ish. If I didn't have that information I would've for sure thought my cht's were getting too high, given the oil temps hovering around 240 degrees. At 3000 feet and 60 degrees OAT, oil temps would stay steady at 2500 rpm, increase at 2600 rpm, and decrease at 2400 rpm. All this is with an 82/41 Borer and 31" bushwheels...I know this isn't the ideal setup for break in but it's all I have for now. Given the relatively cool CHT's, I figure Im getting enough airspeed and cooling for the cylinders.

Hopefully as the cylinders break in the oil temps will come down a bit, this engine has always run on the warm side...but most likely going with the aluminum cub cooler soon anyways.
 
Helmetfire said:
Just following up.....I know this isn't the ideal setup for break in but it's all I have for now. Given the relatively cool CHT's, I figure Im getting enough airspeed and cooling for the cylinders.

Hopefully as the cylinders break in the oil temps will come down a bit, this engine has always run on the warm side...but most likely going with the aluminum cub cooler soon anyways.
Click to expand...
Don't be afraid of pushing the throttle wide open maintaining the 2700 rpm limit. Climb to an altitude where the throttle will be against the stop without exceeding the red line. Run it hard. As it breaks in you will find that the throttle position will be reduced while maintaining 2700. When the oil temp drops, it will be broken in. I sent a friend to Wichita to pick up a new 172 which had a seaplane prop. Had him push the throttle to the firewall and fly it home. When he got here the throttle had been pulled back away from the firewall to maintain the 2700 rpm showing that the engine had been broken in. The engine loved it.
 
Good luck. My 6 month old 30P died. EI has it now. It has been repaired. I will now hold my breath every time I flip on the master.

When it dies, you have nothing.
 
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