How hot should exhaust get?

[muckypup]

I'm thinking of knocking up a simple alarm circuit to monitor the temperature of the exhausts. When on tickover today the exhausts were ice cold with the engines warming nicely - showing the water flow was doing it's job, but anyone know hot they might get?

Maplin are doing a simple temp module with alarm output for £9.99 but it will only measure temp upto 70degC - Would this be enough? Should I be setting the alarm lower than this?

S.

 

[Talbot]

ASAP sell a device that does this. I is best placed at the top of the engine rather than on the exhaust, as it will then be measuring the water temperature.

 

[Avocet]

I use the Maplin module on my boat but it's only a 12hp raw water cooled engine. I have it in the top of the head just near the exhaust port and it reads about 40-50 centigrade normally. Your system might be very different though!