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Any ideas for CHT install? - Printable Version

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Any ideas for CHT install? - raysorenson - 02-02-2014

I'm thinking about using one of these guys for my OM603:

[Image: TC3.jpg]

It can monitor 6 CHT and EGT temps at once, store all 12 peak temps in NVRAM and has an alarm output for a user-defined value.

I can't think of a good way to make a ring/washer spark plug type thermocouple work. Good suggestions welcome.

The threaded or "bayonet" type sensor seems to be the best choice. This is an example of a simple threaded style thermocouple that I'll be attempting to install into a Vespa 2 stroke air-cooled head between the spark plug and the exhaust port:

[Image: TC-K3.jpg]

It's got a 1/4"X20 thread so it's small and cost is less than $4.

I could also do a "bayonet" type thermocouple which is similar in construction but it uses a spring to push the thermocouple into the head.

[Image: alcor-86251-cht-thermocouple.jpg]

This will require a much deeper hole or a little threaded pipe to stand the body of the sensor away from the head. This would be a much more complicated, expensive and time consuming install over the simple threaded type with the only added benefit of a spring to press the thermocouple into the head.

The question is where to put it? I've got a head that I can drill into for experimental purposes. I need to get close to the heat without weakening the head.

RE: Any ideas for CHT install? - sassparilla_kid - 02-02-2014

What is CHT?

RE: Any ideas for CHT install? - raysorenson - 02-02-2014

Cylinder Head Temp :-)

RE: Any ideas for CHT install? - Simpler=Better - 02-02-2014

I've used the 1/4-20 one with an Auber readout, it did the job well. Would read out ambient when dead cold (30*F) and seemed accurate up to peaks (1100*F)

If you want intense EGT monitoring, I'd tap each exhaust runner.

For CHT you could go bananas and replace the glow plugs

RE: Any ideas for CHT install? - Jambo - 02-03-2014

Why not get the matching proble from MGL Avionics?

http://www.mglavionics.co.za/

Should be cheap given the horrendous exchange rate currently.Smile


RE: Any ideas for CHT install? - barrote - 02-03-2014

hello ray,
i would install 1 probe on the exaust gas stream as near as possible to the head. im my engine i have a EGT probe where once was the EGR exit, and i found it to be a perfect place, once i had 850Cº for a wile and the engine quited. i have exaust valves burned, so in my opinion we cant go much further without damage.
regarding CHT i dont understad why i want to install those!! i do work with aviation engines wich have that readings, but the reason is not to monitor temp , is to have a clue on how much u can lean the mixture, wich is something that in diesels make no sense.
eventhoug u want to have na idea of what is going on on each cyl, fit 6 probes on the gas steam just after the head, i mean in the runners, this will give u na aproximate idea of gas temp inside, and with time and guts u can find na equation to correct the Reading to a real value.
usually is what manufactures do, since what stresses the parts is the heat transfer from the hot gas.
regards
FD.

RE: Any ideas for CHT install? - raysorenson - 02-03-2014

(02-02-2014, 09:52 PM)Simpler=Better I've used the 1/4-20 one with an Auber readout, it did the job well. Would read out ambient when dead cold (30*F) and seemed accurate up to peaks (1100*F)

If you want intense EGT monitoring, I'd tap each exhaust runner.

For CHT you could go bananas and replace the glow plugs

Did you use the 1/4-20 probe for CHT?

Yes, the reason for using this gauge is to monitor all cylinders. Thermocouples aren't all that expensive and just one gauge wouldn't clutter up my interior. Otherwise I'd be using one of those great Auber multimeters.

RE: Any ideas for CHT install? - Simpler=Better - 02-03-2014

I ran the 1/4-20 as an EGT probe, directly in the exhaust flow

When you do your Vespa install, be sure to use or make a bottoming tap for the probe hole-that way your pilot hole doesn't have to be too deep into the head.