[Darwood]

Originally Posted by Rich

I would like the needle hitting the red zone to indicate the need to stop immediately and let the engine cool down.

It all depends on the context, in general, if the engine were running at say a steady 220° F, in a situation where running hot is to be expected, I.E. heavy loads, steep mountains in the summer desert, then I think that is acceptable. A spike to 230° F near the top of a steep pass wouldn't likely cause me to stop.

In contrast, seeing 220° F on a cool fall evening driving the flats lightly loaded would merit serious attention, and that's why I mention context matters.

I'd like have the gauge setup such that having the needle near the red should be concerning and having the needle in the red should demand action, and for me, 216° F seems too low to demand stopping the vehicle when operating with high loads in very hot ambient conditions.

In general, I think that the red zone should be used to indicate that the danger of boil over is being approached, and having 240° F at the beginning of the red leaves a large margin of over 20° for that.

Hi Rich I fully agree with you. I finally posted an equation up in the development thread. I'll post some more info later.

http://forum.ih8mud.com/showthread.p...28#post1251128

I really think you might like the 150 ohm RD1 and 100 ohm R1 replacements. With this setup the needle should look like this at 238 degrees F: