J.P. Instruments EDM 740 Pilots Guide - Manual (Page 32)

Page 32 Engine Data Management
Section 3 - Diagnosing Engine Problems
This chart lists typical EDM indications for most G.A. engines.
Parameter Normal range Comments
EGT at Takeoff
1200 to 1300°F 
EGT is approximately
200°F lower than
cruise when full
throttle applied.
1350°F

under 200 HP
EGT in Cruise
1550°F

high performance
70 to 90°F 
fuel injected
EGT span (DIF)
120 to 150°F

carbureted
TIT 1600°F average 
100° higher than
EGT
350°F (OAT 60°F)

normally aspirated
CHT
410°F

Turbocharged
CHT span 50 to 70°F 
100° with gasket
probes
OIL 200°F 
oil cooler thermostat
opens at 180°F
-40°/minute

tightly cowled
-55°/minute 
Bonanza
Shock cooling
(CLD)*
-200°/minute

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).
NOTE: 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. 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.