The CLT sensor is only going to be used for a gauge. I had planned on tapping it into my thermostat housing, but the sensor is a bit larger than I had thought, and I am afraid that it will impede flow too much. I ordered a radiator hose adapter last night but already changed my mind, I would rather not hack it like that. Are there any spots that I am not thinking of? The engine is already back in the car, otherwise I would have tried to find a spot on the back of the head near the stock sensor.. Maybe I am just over thinking this.

 

The heater core hoses are a good place...and they're mostly out of sight.

 

Is the sensor the same size as the stock sensor? If so, the bolt behind this tube is a place for a sensor to go. Should thread right in i think.

 

Back of the head is going to give you and idea of temps after the coolant has complete it's job before it's had an opportunity to start cool down upon exiting the engine. That's where the ecu and OE gauge pick it up.

 

The sensor is 1/8"NPT but maybe that bolt hole is small enough to tap. Is that picture the back of the head?

 

Yes

 

In-line with the upper radiator hose is actually pretty decent... I like that position for the sender because it's accurate for what temp is coming out of the motor after it's run all the way through the motor just like the stock sensor that is behind the head - the coolant flows out of the motor, through a tube, through the thermostat and then into the sender before the radiator cools it back down, so you're seeing the max temp the coolant is seeing.
Also, having it plumbed after the thermostat helps w/ troubleshooting cooling problems - if the stock water temp gauge rises to normal operating temp range and the aftermarket gauge doesn't follow a minute afterwards, you know the thermostat isn't opening - you don't have to wait until you're overheating to realize there's a problem.

 

Is this the same type of temp sensor originally on the back of the head (at least on the 1.6's) -- ie: the sinlge-clip sensor for the temp gauge on the dash?

I have a CLT for my TEC3 plumbed into a "T" just before the heater core. I've done a BBundy-style coolant re-route, however, so the coolant going to that line is coming from the bottom of the intake manifold. IMHO, like M2cupcar said, it's going to measure the hottest temps, after it's gone through the block/head completely.

BEGI has a nice billet "T" piece that splices into the upper rad hose as well.

 

Its not the same size as the stock CLT sensor if thats what you meant. I think I am going to T into a heater line, it will be out of sight that way.