CHT Temp, What is the upper operating limit? Options

[ericread]

Based on the converstaions here,I drove over to Corona, CA (Aircraft Spruce) this afternoon and purchased the Micro 1000 CHT, a sensor and a 15 foot extension cable. It's all installed and looks great in my original center console.

So where is the danger point? Some posts say that hitting 400 degrees will cause a valve seat to fail. Others say they regularly see 375 to 400 degrees on their longer, higher speed drives. Where is the point that indicated engine heat danger? BTW: 74 2.0L all original FI w, standard exhaust.

My thanks.

Eric Read


NOTE: Please note that this was originally posted in a CHT topic post. After about a day, I received no responses, so I am re-posting it as a unique topic.

Cross-Posting Disclosure: Cross-posted to the "other" BBS (Saturday, 10/11/08) as a result of no response on this BBS.

[Jake Raby]

Sensor location is key! You must install the sensor under the spark plug, no where else!

I keep heads under 400F for longevity, but you can run over 400 for short periods of time.

Past 400 if you have not updated the valve seats with a procedure and component enhancement like ours a failure can be experienced at any time. At 420 seats start to fall out.

315-385 is the sweet spot for expansion, wear and MPG. The key is to keep the temps as stable as possible, huge CHT differentials are what necessitate more frequent maintenance, valve adjustments and head re-torques. The heads on my 912E have NEVER went over 375 and due to that the engine hasn't needed a valve adjustment since February 2003, 125K miles ago.

[ericread]

Sensor location is key! You must install the sensor under the spark plug, no where else!

I keep heads under 400F for longevity, but you can run over 400 for short periods of time.

Past 400 if you have not updated the valve seats with a procedure and component enhancement like ours a failure can be experienced at any time. At 420 seats start to fall out.

315-385 is the sweet spot for expansion, wear and MPG. The key is to keep the temps as stable as possible, huge CHT differentials are what necessitate more frequent maintenance, valve adjustments and head re-torques. The heads on my 912E have NEVER went over 375 and due to that the engine hasn't needed a valve adjustment since February 2003, 125K miles ago.

Jake;

Your article in the 914 info section is really appreciated. My main concern was running in the 375-390 degree range during my high-speed freeway runs (~75-80MPH). From what I can see, I am in the "sweet spot" for head temperature.

My thanks for your advice, and for sharing your experience with us.

Eric Read