Oil Temps Again

[Kyler]

cylinder head temps

Cylinder head temps were 397 in practice 1 and 411 in practice 2. DNF race 1.

Oil seems to be cooler and I assume this because the temps are not spiking as soon meaning exceeding the limit of my inaccurate gauge.

We ran pretty hard too. I was bouncing off the rev limiter this year. Time for a smaller sprocket.

[mmattockx]

Cylinder head temps were 397 in practice 1 and 411 in practice 2. DNF race 1.

Those seem quite high to me. Does anyone know what is a typical head temp for these air cooled motors? Is this data from a spark plug washer thermocouple or a different sensor?

Oil seems to be cooler and I assume this because the temps are not spiking as soon meaning exceeding the limit of my inaccurate gauge.

How long did it take to run off the gauge? In your OP you said 4 laps previously. I am surprised the temp is still that high with the ducting. What were ambient temps? Humidity? Where is your gauge taking the reading from?


Mark

[posplayr]

Those seem quite high to me. Does anyone know what is a typical head temp for these air cooled motors? Is this data from a spark plug washer thermocouple or a different sensor?




How long did it take to run off the gauge? In your OP you said 4 laps previously. I am surprised the temp is still that high with the ducting. What were ambient temps? Humidity? Where is your gauge taking the reading from?


Mark

200-220 degC (392-428 degF) is about what I read off of my 1166 header (thermal couple strapped to header and data logger)at 6" from the exhaust port.

[mmattockx]

200-220 degC (392-428 degF) is about what I read off of my 1166 header (thermal couple strapped to header and data logger)at 6" from the exhaust port.

That I will believe with no problem. I once saw color (ie - dull red) on the header just outside the head on my '86 GSXR750 after a spirited run at dusk. That indicates the outside of the header tubing was approaching 800F.

Hopefully we can get some data from someone with a spark plug thermocouple as a reference point.


Mark

[posplayr]

That I will believe with no problem. I once saw color (ie - dull red) on the header just outside the head on my '86 GSXR750 after a spirited run at dusk. That indicates the outside of the header tubing was approaching 800F.

Hopefully we can get some data from someone with a spark plug thermocouple as a reference point.


Mark

A little discussion on he topic.

http://www.ebay.com/gds/CHT-Gauges-for-Air-Cooled-Engines-/10000000007206732/g.html

http://www.ulpower.com/engines/faq/monitor-cht-egt.html

On the second link it shows CHT much lower than EGT. It suggests without an external oil cooler the CHT is pretty close to steady state oil temp. At least not 100 deg above.

http://xlforum.net/vbportal/forums/archive/index.php/t-50006.html

This link suggest 400 deg F as an absolute maximum and that the oil temp and CHT are only remotely related. The bigger the oil cooler the more this is true.

[Kyler]

How long did it take to run off the gauge? In your OP you said 4 laps previously. I am surprised the temp is still that high with the ducting. What were ambient temps? Humidity? Where is your gauge taking the reading from?

It is a spark plug washer thermocouple on the #2 cylinder.

Ambient air was 86 with 88% humidity. I didn't top out on temps till the 5th lap. The rev limiter is set at 9,000 RPM and I was bouncing off it a lot (more sprockets on order with 2nd day delivery - race again this weekend at the same track). The motor was getting flogged hard.

[Kyler]

200-220 degC (392-428 degF) is about what I read off of my 1166 header (thermal couple strapped to header and data logger)at 6" from the exhaust port.

off the header and not at the plug? hmmm. Isn't EGT hotter at the exhaust due to post combustion?

[Kyler]

a new oil thermocouple was in the mail when I got home. It came from the same folks that make the gauge. I also got a 1/8" NPT weld-in bung for my adapter which is just visible in front of the left knee tray in this picture. Last time I swapped the thermocouple I noticed the threads were a bit soft and I'm worried about stripping it out. I wish I had installed a bung when I made it instead of just tapping the tubing wall. Oh well, live and learn. Not sure if I have enough time to get this fixed and the new thermocouple installed before I race again this coming weekend. I'd really like honest oil temperature readings.

[Kyler]

Here's the latest oil sample report

[posplayr]

off the header and not at the plug? hmmm. Isn't EGT hotter at the exhaust due to post combustion?

Yes very much so. My measurement is suggesting your head is running as hot as the hot part of the header pipe on my 1166. In other words you have reached the diminishing returns on oil cooling. You need more air across the motor to cool it down.

[Kyler]

I finally found time to install the new thermocouple and it seems to be accurate. It at least shows ambient temp when it comes on.

I relocated the oil filter but am running out of time making new ducting. Next race in 2-weeks at Summit Point. If nothing else, I'll be using my period-correct political signboards as ducting.

[mmattockx]

I finally found time to install the new thermocouple and it seems to be accurate. It at least shows ambient temp when it comes on.

Good deal. If you want to check it at higher temps you can place it in a pot of boiling water and see what you get for a reading.


Mark

[posplayr]

Good deal. If you want to check it at higher temps you can place it in a pot of boiling water and see what you get for a reading.


Mark

This temp gauge is accurate only when mounted in certain places.

[Kyler]

I moved the oil filter to the right side of the motor to get it out from in front of the cooler. I should have put it there to start with. The new locatiuon will make it much easier to change the filter.



and another view



then, using period correct political signs, I enlarged the ducting.





and from the back side



If this works as expected, I'll get with a buddy who has sheet metal tools and we'll bend up decent ductwork.

After countless hours of research, I believe Nessism has it right, temps should run closer to 180-220 F. With the new thermocouple I'm hoping to see temps in that range next weekend.

[qcktvr]

Hi Folks, I have been following this thread with interest, had a feeling that you were worrying too much about your oil temps and trying to get them toooo low, so went looking for some facts relating to the subject; found this which I think puts a few myths to bed:

http://www.speedtalk.com/forum/viewtopic.php?f=1&t=31363

A dry sump system would be nice, although no doubt costly and add weight, but it would eliminate any pick up problems from cornering G forces and let you carry more oil, which would extend the time / laps for it to reach the peak temp.
Anyway, this article makes running upto 300F a few times over a couple or more race weekends look not too worrying.. (and will let you select a good oil).
Now trying to get more air over the motor.... probably a v good thing to do
Wishing you an enjoyable and safe racing season