Is it possible for the temperature to reach higher then the thermostat's rating before it acutally opens???

I installed a new thermostat and a cyberdyne digital water temp gauge...I tapped the sender into the upper radiator hose neck off the head...the thermostat is rated at 170 degrees...

When i drive normal/cruising its around 195-210, at idle its in the 215-220(keep in mind this is in 90 + degrees weather)...is my gauge reading wrong??? or is the thermostat not opening when it should? or is the radiator not cooling like its should...its also a brand new stock radiator (will be replaced with aluminum)...not boosting yet...but will be soon, so its running N/A currently...

The Stock integra gauge reads below the half point mark where it should be...Also when i datalogged couple months back...the thermostat would open at 170 degrees or lil before 169 or so...but its reading at a different point on the engine...so the temperature where i have the sender could be reading differently then the ecu reads...not sure...

Any experience or help would be Helpful! Thanks!

 

I use Cyberdyne gauges and they have proven to be pretty reliable, if thats something your worring about.

I wonder, and its been a while since I've been around Honda's, maybe your senders are at opposite points of each other. Like maybe the Cyberdyne sender is seeing the water right before it goes through the radiator after picking up heat from the engine and the stock sender sees water maybe after the radiator once its cooled down a bit. Just a guess.