CHT QUESTION

[FAST FLIGHT OPTIONS LLC]

I had a JPI EDM 900 installed at Maxwell’s shop this year during my annual.  The thing is phenomenal and works great. I had all of the legacy engine guages removed.

 

On my flight home to Florida I noticed the CHT on my number six cylinder was about 70 - 80 degrees cooler then the hottest cylinder(s). All six EGT’s appeared normal and were uniform.  Interestingly enough the compressions on the #6 cylinder at annual were 78/80. This is on 1980 M20K 231 with a TSIO-360GB (1300HRS SMOH) which always runs great.

 

Does anyone feel this lower CHT reading is a cause for concern?

 

Thanks!

 

 

[Seth]

Bad probe?  different type of probe?

 

-Seth

[FAST FLIGHT OPTIONS LLC]

For arguments sake let's assume the probe is fine as it's brand new

[FAST FLIGHT OPTIONS LLC]

Don Maxwell did say the #6 cylinder is going to be the coolest...but 80 degrees?

[Cruiser]

CHTs are generated by either internal pressure or external cooling. IF all your probes are located the same for each cylinder and are reading correct you are either generating less power from #6 because of a difference in F/A ratio or you have uneven cooling.

 

If it is internal you should see a difference in when #6 peaks compared to the others (EGT vs FF) "the GAMI test". If this checks out then it is most likely a cooling issue

How are the baffles? Check for gaps and cracks and seal them or they may need replacement.

[FBCK]

I have a 1981 M20K 231 with a TSIO-360GB, with 150 hours on it.  Intercooled and with the Myrlyn waste gate and I have the same issue, if it is one.  Cylinder 2 will run 350 and cylinder 6 will be down around 260.  Egt reads about the same as the others.

[FBCK]

The others vary from 320 to 340

[Glenn]

Is the probe for the colder cylinder in the same location as the others, or is it different to accommodate the placement of the probe that serviced the factory gauge?

[thinwing]

I would suggust a bad probe or wrong type probe (k type subsituted for j type)especially since its a new installation...one test is to remove probe from #6 cyl and place in boiling water...power up and look for at least 200 f reading..another possibilty is xconnected probe ..highly unlikely coming out of Maxwells shop

[thinwing]

Ps..I am currently trouble shooting why chts are all apparently reading 100 high on all 4 cylinders on my husky(0360)...we used a laser thermometer plus factory eci guage to show cyl temps not as high as our jpi indicates

[KSMooniac]

#6 is in front, right, and #5 is next to it with an alternator in front?  If so, #6 might be getting more cooling air than needed, so perhaps a small baffle could be added to block/divert some of the cooling air going into #6.  That might help even the spread a bit.