Originally Posted by
YNOT
A pyro gauge has a thermocouple placed in the exhaust gases as close to the cylinder head as possible for accuracy. A lot of people myself included choose to fit the thermocouple immedietly after the turbo so if anything does happen the thermocouple it won't damage the turbo. The rule of thumb is add 100 degrees to the post-turbo temps to get pre-turbo temp.
Diesels are the opposite of petrols when it comes to mixtures, an overfueled diesel will run hot.
It's interesting driving a turbo diesel with boost and pyro gauges for the first time and seeing what is happening in your engine. Lets say your cruising at 60km/h in 4th gear, about 1800rpm. Put your foot down to accelerate up to 100km/h, the boost gauge will come up very quickly (especially if you have a big exhaust fitted) but the pyro will lag behind and be a lot slower to rise. You will find you can move the needle on the pyro by lifting and pushing the accelerator. If your foot is flat to the floor the turbo will be on full boost (7psi standard) and the EGT's will rise to 500-550 if you hold you foot down for a while, but lift your foot slightly and the EGT's will start to drop without the boost gauge moving.
At other times under heavy load (climbing a long hill) you will often find that although you have the torque to maintain speed on that hill in 4th gear, the EGT's will be lower by dropping down to third and using less throttle to maintain the same speed.
Tony
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