Cooling: Tweecer vs. Glow Shift sensors/gauges

[DonMaximo]

I've just recently got my fresh/dyno tuned crate engine fired up.

Set timing, Fuel pressure, and DC Controller for my Mark VIII fan.

In the beginning, I used an aftermarket (Glow Shift=GS) Water Temperature gauge to set the fan for startup around 185 degrees. The GS sensor for this gauge is located in the lower radiator hose return. After the fan starts up, the temperature according to the GS gauge is maintained at 180 degrees.

The sensor for the DC controller is located at/near the lower left hand side of the radiator... where the lower hose enters the radiator...and was pushed in the fins as instructed.

What I've noticed however is that when my GS gauge reads ~185, the tweecer is reporting 210-215. Even after the fan has cooled the engine to 180 (GS gauge)...the tweecer is still reporting ECT of 210.

For what it's worth, ACT is somewhere around 195+/- a few ticks.

All sensors are new.

Can someone help me understand this disparity...and comment on which gauge I should use to set my fan controller to ( Tweecer vs. GS ) ?

Thanks in advance.

-D

 

[HISSIN50]

The ECT measures coolant before the rad cools it. The GS sensor (and DCC, by design) are seeing coolant temps after they've been through the radiator. And that spread you're seeing is just about right.
If you moved the GS sender to the stock temp gauge sender location, you should see a reading real close to the ECT.

The DCC takes into account the probe location and the unit accomodates this.