J.P. Instruments EDM 760 Pilots Guide - Manual (Page 27)

Section 4 - Diagnosing Engine Problems
Normal Engine Limits
The follow chart lists typical normal measurement values that you
will observe for most general aircraft engines.
Measurement Normal range Comments
EGTs in Cruise 1350°F
1550°F • under 200 HP
• high performance
• EGT should drop
200°F when full
throttle is applied
EGT span (DIF) 70 to 90°F
120 to 150°F
• fuel injected
• carbureted
TIT 1600°F average • 100° higher than
EGT
CHTs 350°F(OAT 60°F)
410°F • normally aspirated
• Turbocharged
CHT span 50 to 70°F
OIL 200°F • oil cooler thermostat
opens at 180°F
Shock cooling* -40°/minute
-55°/minute
-200°/minute
• tightly cowled
• Bonanza
• helicopter
* Maintain a cooling rate of less than -60°/minute. You will find that the
cylinder with the greatest shock cooling will shift from front cylinders
(during climb out) to the rear cylinders (during descent ).
If one CHT is reading 20° to 50° above or below the others, this may be
due to that cylinder having a spark plug gasket probe instead of a bayonet
probe. This is necessary because the aircraft’s factory original CHT probe
is occupying the socket in the cylinder head rather than the EDM-760.
This is normal. If the discrepancy is greater, be sure the spark plug gasket
probe is mounted on the top spark plug. An adapter probe is available to
occupy the same socket as the factory original probe. Contact your dealer.
For Your Safe Flight Page 23