MGL CHT/EGT GAUGE

Would appreciate feedback on User experiences with this instrument.( The TC-3 model)

Looking at installing in my J 170 Jabiru

Thanks a lot.

I have one fitted to my Lycoming in the RV4. Very good, but being carburetted it is not perfect for leaning the mixture, because of different mixes at each cylinder. The alarm light works well and I never fitted an audible alarm.

I have one in my J230 and the instrument is excellent, the reading spread a little less so.

A pair of the smaller TC-1 model in an engine test cell developed for engine certification. They have been tested to calibration standard for cht accuracy using calibration equipment that independently checks the probe input temperature using both laboratory-grade mercury thermometers and an IR non-contact device, and the results at the instrument were accurate to within about 2%.

However, good installation is essential; with the cold junction placed in a location where ambient temps do not vary noticeably with operation. The more sophisticated models have an intermediate data connection 'box' that incorporates ambient sensing and applies correction, but the smaller ones do not have this feature. Also, for a Jabiru engine (assuming you are using the between-the-plug sensors, not under-plug ones), the sheathed probes sold by CAMit are a good investment.

Rather than just mentioning the TC-3 temperature spread, I really should have qualified that.

EGTS vary with operating condition, but are all well within limts.

During climb No 4 CHT is always 20°C above the next nearest; if I climb at 80 Knots to 1000ft after take off it would go to above 180°C, climb at 90 Knots and No 4 CHT reaches 170°C.

In the circuit or in the cruise CHT are varied but well within limits, but No 4 CHT still leads.

The original Jabiru CHT guage (ring under No 6 Sparkplug) always stays well in the green.

The CHT sensors are fitted in between the spark plugs and are Camit supplied ones with shields (nice kit).

Non-contact temperature check shows embedded sensor approx 5°C above cyclinder head surface (some difference expected).

So, I am happy with my Jab 3300 motor. By monitoring, without being obsessive, all CHTs and less so all EGTs, the motor can be kept away from any damaging over temperature conditions.

Run only on Avgas.

Climb out at 90 knots. (Step climb in the summer as required).

Cruise revs no less than 2850 rpm (typically 20-21 l/hr, operate at less than 19 l/hr for any length of time and EGTs climb).

Keep all temps well inside limits.

Oil and filter change every 25 hours (oil analysis and Ferrography {only cause we have a lab, its not really neccessary or indicative} and filter cut and wash).

Leakdown check every 25 hours.

Engine now 385 hrs. Leakdowns all good. Currently a happy Jab 3300.

Two questions for concensus opinions -

1. The way I operate the engine avoids excessive temperatures, so I have not bothered to look at fiddling with the ducting. However, I understand that small deflectors can be fitted inside the ducts to direct airflow more evenly to all cyclinders. Is this worth trying?

2. My Engine has always had flow deflectors fitted between the cyclinders, these are fitted from below. I note that on newer engines if they are fitted at all it is on top of the cyclinders. Do I get them removed or moved to the top.

Alan

Alan:

Getting cooling airflow right is a real battle for engineers because the damn stuff just doesn't tend to follow 'what looks right' - you get unexpected stagnation points etc. . Your head cooling sounds about ok to me, unless you are prepared to (and have the gear to) measure the p-delta pressure drop across the heads, it could be a chase-your-tail job. The Jab engine Installation Manual ( e.g. JEM2202-7 )has a fair bit of useful stuff in it).

Barrel cooling - and getting decent reasonably even cooling all around the barrel - is important. NACA did a lot of work on this: see

IMPROVED BAFFLE DESIGNS FOR AIR-COOLED

ENGINE CYLINDERS

By Abe Silverstein and George F. Kinghorn

especially figure #8.

I believe that Jab. USA have a better design for the under-barrel baffles than the standard Jab. Aus design (though that is an impression gained from various posts on various sites, not personal experience) but it seems pretty clear that the 'gull-wings' on the underside have a much better chance of doing a decent job than anything on top.

Good move Roscoe. Replacing a vague steam guage with a multipoint digital temperature monitoring system is wise, as long as the installation is thorough.

I am quite happy with mine. You can easily see temperature variations and can set the alarm temperature.

The horizontal bars show the max temp reached by each channel-a handy feature.

OK, the Strato series is damn good value for money, IMHO - and if properly set up and a bit of effort in calibration is taken (and that isn't all that hard, it just requires a bit of imagination - you may have seen the 'calibration' 'Darlek' we set up for the engine test cell), will give you excellent accuracy.

One level up in the MGL range - the 'Extreme' - provides a large jump in capability, including cold-junction ambient temp adjustment via the RDAC, and to me, more importantly, recording of conditions which can be down-loaded to an Excel spreadsheet for review and record-keeping. ( I believe most Dynons have a similar capability).

I put an MGL Flight 2 and the CHT / EGT gauge in my RV with other steam gauges. Now I am kicking myself, because I should have put in the Mini Extreme and could have done away with most of the other gauges, for about the same cost.

MGL give a fairly good instruction manual with their gauges, but my flight 2 wouldn't set the date time. Eventually I found out that there was a battery inside. Absolutely no mention of a battery in the manuals.

Good move Roscoe. Replacing a vague steam guage with a multipoint digital temperature monitoring system is wise, as long as the installation is thorough.I am quite happy with mine. You can easily see temperature variations and can set the alarm temperature.

The horizontal bars show the max temp reached by each channel-a handy feature.

 

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Would you (or anybody) be able to recommend a Sydney based organisation with experience in this kind of work that could install it for me?

Unfortunately this involves cutting an instrument hole in spare space on the RH side of the Panel.

Appreciate any advice re installation.

Roscoe

Can't help with installation, except to endorse previous advice to buy probes from Ian Bent at CAMit. He supplied me with CHT probes whose leads were long enough to reach, plus neat little covers to keep airflow off the sensors.

Roscoe - is yours a 170D? If so, you'll need an L2 / LAME to do the work and sign it out, I believe ( and you may need approval from Jabiru - I'm sure there are others on this forum who can advise you there). Dent Aviation at Camden ( http://dentaviation.com.au ) is one organisation that specialises in 'non-standard' work - they maintain probably more Pitts etc. than anybody, I suspect and David Dent is very, very well regarded.

Installation is not hard. Just follow the directions with the instrument. I bought extra cable to connect to the lengts with the probes, because the distance was too long. I could have used normal co ax cable rather than the soft iron, with a slight lack of accuracy, but much easier joining of the cables. Cutting a hole for the instrument, depends on what the panel is made of. The proffessionals would have a special tool for aluminium, but you could use a small drill, cut a series of holes just within the diameter you need and then remove the centre and clean up with a file, about 2 hours work.

Roscoe - is yours a 170D? If so, you'll need an L2 / LAME to do the work and sign it out, I believe ( and you may need approval from Jabiru - I'm sure there are others on this forum who can advise you there). Dent Aviation at Camden ( http://dentaviation.com.au ) is one organisation that specialises in 'non-standard' work - they maintain probably more Pitts etc. than anybody, I suspect and David Dent is very, very well regarded.

Thanks for the info, yes ive been told that I need Jabiru approval as well.

Installation is not hard. Just follow the directions with the instrument. I bought extra cable to connect to the lengts with the probes, because the distance was too long. I could have used normal co ax cable rather than the soft iron, with a slight lack of accuracy, but much easier joining of the cables. Cutting a hole for the instrument, depends on what the panel is made of. The proffessionals would have a special tool for aluminium, but you could use a small drill, cut a series of holes just within the diameter you need and then remove the centre and clean up with a file, about 2 hours work.

Roscoe: I think Jabiru leans towards Dynon for EMS instrumentation, but since this is reporting rather than control instrumentation, I think you could very well 'insist' if they come back initially with a negative response. It would be useful to all Jab owners if you can keep us in the loop with what you get from them; I'm very pro MGL instrumentation, and it's being used on the engine certification test cell and we already have calibration run evidence; if you have problems, p.m. me and maybe I can point you in the direction of assistance.

Jabiru installed a Dynon D10 EMS in my aircraft on the right hand side of the panel with full CHT, EGT, oil temp, oil pressure, fuel level and fuel flow and tacho. They removed the analog tacho and the engine gauges. It is a neat installation and does a great job of monitoring the engine with history recording function.

They did say they were looking at some of the MGL instruments but were waiting for some more information.

Rather than just mentioning the TC-3 temperature spread, I really should have qualified that.EGTS vary with operating condition, but are all well within limts.

 

During climb No 4 CHT is always 20°C above the next nearest; if I climb at 80 Knots to 1000ft after take off it would go to above 180°C, climb at 90 Knots and No 4 CHT reaches 170°C.

 

In the circuit or in the cruise CHT are varied but well within limits, but No 4 CHT still leads.

 

The original Jabiru CHT guage (ring under No 6 Sparkplug) always stays well in the green.

 

The CHT sensors are fitted in between the spark plugs and are Camit supplied ones with shields (nice kit).

 

Non-contact temperature check shows embedded sensor approx 5°C above cyclinder head surface (some difference expected).

 

So, I am happy with my Jab 3300 motor. By monitoring, without being obsessive, all CHTs and less so all EGTs, the motor can be kept away from any damaging over temperature conditions.

 

Run only on Avgas.

 

Climb out at 90 knots. (Step climb in the summer as required).

 

Cruise revs no less than 2850 rpm (typically 20-21 l/hr, operate at less than 19 l/hr for any length of time and EGTs climb).

 

Keep all temps well inside limits.

 

Oil and filter change every 25 hours (oil analysis and Ferrography {only cause we have a lab, its not really neccessary or indicative} and filter cut and wash).

 

Leakdown check every 25 hours.

 

Engine now 385 hrs. Leakdowns all good. Currently a happy Jab 3300.

 

Two questions for concensus opinions -

 

1. The way I operate the engine avoids excessive temperatures, so I have not bothered to look at fiddling with the ducting. However, I understand that small deflectors can be fitted inside the ducts to direct airflow more evenly to all cyclinders. Is this worth trying?

 

2. My Engine has always had flow deflectors fitted between the cyclinders, these are fitted from below. I note that on newer engines if they are fitted at all it is on top of the cyclinders. Do I get them removed or moved to the top.

 

Alan

Fitted underneath they do stabilise temps.

21 lph is quite low, Hoping EGT around 700 deg? Valves can be a problem.

Cht temps to 180 is approaching permanent damage level to Jabiru heads

Theres a good instructions from Jabiru USA on these top of duct deflectors

Alan, 21 lph at 2850 is definitely on the low side, you're obviously flying the thing with sympathy for its engine management but that figure is right on the bottom end of safe... A 3300 needs to be fed around 34 lph for a max. power climb exceeding much more than 5 minutes to keep its temps. within limits, and probably around 22-24 lph at 2850.

Have you had a free-flow fuel check done recently? CAMit has been doing some research on installations, and has found that in some cases, due to fuel system installation issues (including filter types and maintenance and flow sensor intrusion into free-flow delivery), an ostensible engine fuel pump delivery of plus 30 litres/hour can drop to 22 in 10 minutes of max power running. The mechanical fuel pump spring has an effect (Jabiru use a stronger spring than standard in their pumps), but the tank finger filters, the tank vent clearance and the in-line filter(s) between the collector tank and the mechanical fuel pump can all combine to produce a serious fuel starvation and hence ultra-lean mix, killing engines. One installation audited by CAMit was only registering a free-flow to the mechanical fuel pump of 12 litres/hour!

Fuel free-flow needs to be measured with a 'climb angle' of 15 degrees applied. It doesn't need much of an obstruction anywhere in the fuel delivery system to seriously compromise the mixture being delivered to the engine - the numpty who totalled his 230 on the beach in New Zealand, had originally been forced to land due to a slight kink in the fuel delivery line (and pretty obviously, an inadequate fuel delivery check..).

I put an MGL Flight 2 and the CHT / EGT gauge in my RV with other steam gauges. Now I am kicking myself, because I should have put in the Mini Extreme and could have done away with most of the other gauges, for about the same cost.

Have you had a free-flow fuel check done recently? CAMit has been doing some research on installations, and has found that in some cases, due to fuel system installation issues (including filter types and maintenance and flow sensor intrusion into free-flow delivery), an ostensible engine fuel pump delivery of plus 30 litres/hour can drop to 22 in 10 minutes of max power running. The mechanical fuel pump spring has an effect (Jabiru use a stronger spring than standard in their pumps), but the tank finger filters, the tank vent clearance and the in-line filter(s) between the collector tank and the mechanical fuel pump can all combine to produce a serious fuel starvation and hence ultra-lean mix, killing engines. One installation audited by CAMit was only registering a free-flow to the mechanical fuel pump of 12 litres/hour!

After significant time and evaluation it seems elect pump and flow sensor are the problem, particularly the flow sensor.

Despite apperances there is almost no head differential from wing tanks to carb at AOA and long lengths of 1/4 hose burnng what there is.

EGT monitoring should pick up this problem, my experience ( totally separate issue) with low flow says if it is a problem EGT levels go very high vey quickly

I do have an issue with the way Jab plumb fuel filter upstream of boost pump in new versions.

Some time spent rooting around now sees 38 lph and scope to improve further if required.. With elect boost theres 90 lph so limited risk as it is used in most high use phases.

Withou EGT monitoring , could eaaily account for some engine losses.

I have had the MGL Xtreme for quite a while now but never used the EMS side of it just the AHRS. I have now fitted another Xtreme and use it as the EMS as well of course as a total backup instrument. I am very happy with the operation of it all . It was quite easy to setup the RDAC to all of the sensors and I made my own water temp sensors for the rotax as the MGL ones are the wrong threads for a Rotax.

 

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I do set the back up altimiter prior to run up and use primarily as a EMS. I have fitter a big red Alarm pilot light that get your attentention is something approches limits set. My plane is daytime VFR only but I would like to add a horizion reference should I inadvertantly wander into a cloud I could confidently turn 180 and exit. Do you know if one extreme can do both functions I buy the ahrs sensor pack? Full time EMS and back up horizon is all I am after. Otherwise the big slip indicator gets smaller and I have a space reserved for a turn and bank or dedicated AH gyro.

There are 2 types of MGL Xtreme...one is a EFIS and that has AHRS AND also will act as a EMS...They also sell the Xtreme EMS and that is ONLY a EMS it has no AHRS ability. I bought 2 of the EFIS but I do set the altitude on both before I fly but then turn the right hand one in EMS mode. The EFIS has a built in AHRS but its not a very accurate one...I also have the SP6 and SP7 separate units that go via the CAN bus to make the EFIS almost like a certified one...realistically they are certified quality but they cant sell it like that.