Thanks Peter! You are thinking right down the path I am currently on but
with a slightly different way to install it and to view the temperature.

So, if I negotiate with one of serveral existing manufacturers of an "oven
product" some of which I have already tested in my own turbocharged aircraft
to build it so it meets ALL the requirements of being in the cowling
(waterproof, electronics capable of handling the heat, etc. and some other
proprietary ideas...) and you could read your under cowl temperature on a
nice little digital display with an integrated "high temp" alarm in the
cockpit. What is the right price for a product that installs in 15 minutes
during your next oil change without running any wires through your firewall
or panel.

Anyone got an idea of what this might be worth to airplane owners?

$150?
$200?
$250?

Would this be something that pilot / owners would buy at their local pilot
shop or would the Internet be a more likely place to buy it, in order to get
a lot more info than can be put on the product packaging?

Interested in any thoughts anyone has on this.

George