4.0 with Speedhut gauges?

[tower210]

I swapped in a 4.0 from a 94 XJ 4-5 years ago; new water pump went in with the swap. Pretty happy with it overall (another 40HP would be nice). I have the speedhut guages which replace the factory temp sensor with a more modern sender. It's always run (especially on the highway at 70MPH) about 3/4 the way to the top on the "normal range" for engine temp...

I wish the speedhut had actual temperatures on it... I have read that 4.0s under load tend to run 200-210F.

It never seems to creep higher than the 3/4ish up spot...but it does worry me a bit. Radiator is a cheap oreilys job that I had to do an emergency swap about 6 years ago before nationals...

Thinking about upgrading to a champion or similar before summer (toying with idea of heading to the national; know it will be HOT). Have the ford dual fan setup now; it's worked pretty reliably so far; but the plastic shroud isn't near as perfect as the new aluminum shrouds.... Seems a bit hard when ordering new rad not to just get new shroud and fans.....

Anyone else with a 4.0 and speedhut run in this range or know what the middle/top of the normal range correspond too?

 

[tower210]

Here is what speedhut sent me for the sensor temp vs resistance....



This was their response to me.... It doesn't make any sense in our situation; higher resistance would be lower temperatures....

Keith, I have run into this issue in the past, usually, it has to do with something adding resistance to the temp signal line. Does the signal wire run past any ignition components (like solid core plug wires, resistive plugs, or tach signal wires) or past anything else that would give off a lot of resistance like fan components as well? I will also include our temp testing procedures as well in case it is something wrong with the gauge or the sensor. I have also included a chart for temp to resistance for the sensor just in case everything else looks correct there will be a way to test the sensor itself. With the harness disconnected from the gauge at the sensor and the gauge powered on. Test the voltage between the white and black wires. You should be getting 4.9-5 volts. If you don't have the correct voltage there, also test it at the plug that is about 9" from the back of the gauge. Here the wires will be yellow/red and yellow/black. If you do have the correct voltage at either of those two points then short the white wire to the black wire (or yellow/red to yellow/black) and this should make the gauge sweep full scale. With the harness disconnected at the sensor when the engine is running the gauge should read the bottom of the scale. Thanks, Ayden Tech Support tech@speedhut.com 165 North 1330 West Suite B2 Orem Utah, 84057 U.S.A Phone: 801.221.1460 ext 112 Web: www.speedhut.com Appreciate this response · Awesome support provided by Re:amaze · View thread history​

 

[bigwalton]

Ahh, well the theory still holds that if we could find a temp sender with what looks like maybe a 10-15 ohm lower shift from these values it would put us into the right range for what the gauge is set for.

 

[FLCJ8]

could just add a potentiometer in line to change the resistance from the sender to trick the gauge... may have to look into that...

Interesting! I like this. You could dial it in, check resistance and get one to hard wire too.

This would only work for one particular value as the resistance curve of the sending unit is non-linear.

Here is what speedhut sent me for the sensor temp vs resistance....

View attachment 108927

This was their response to me.... It doesn't make any sense in our situation; higher resistance would be lower temperatures....

Keith, I have run into this issue in the past, usually, it has to do with something adding resistance to the temp signal line. Does the signal wire run past any ignition components (like solid core plug wires, resistive plugs, or tach signal wires) or past anything else that would give off a lot of resistance like fan components as well? I will also include our temp testing procedures as well in case it is something wrong with the gauge or the sensor. I have also included a chart for temp to resistance for the sensor just in case everything else looks correct there will be a way to test the sensor itself. With the harness disconnected from the gauge at the sensor and the gauge powered on. Test the voltage between the white and black wires. You should be getting 4.9-5 volts. If you don't have the correct voltage there, also test it at the plug that is about 9" from the back of the gauge. Here the wires will be yellow/red and yellow/black. If you do have the correct voltage at either of those two points then short the white wire to the black wire (or yellow/red to yellow/black) and this should make the gauge sweep full scale. With the harness disconnected at the sensor when the engine is running the gauge should read the bottom of the scale. Thanks, Ayden Tech Support tech@speedhut.com 165 North 1330 West Suite B2 Orem Utah, 84057 U.S.A Phone: 801.221.1460 ext 112 Web: www.speedhut.com Appreciate this response · Awesome support provided by Re:amaze · View thread history​

That helps a lot.
I had found the temp to resistance values for their sending unit on their website but it was only a graph.
That spreadsheet is much more helpful.

Ahh, well the theory still holds that if we could find a temp sender with what looks like maybe a 10-15 ohm lower shift from these values it would put us into the right range for what the gauge is set for.

As the gauge doesn't have any actual numerical scale the use of a higher resistance sending unit would be reflected in a lower reading on the gauge, and should also prevent the erroneous high temp warning.

This is a chart I found while originally doing some research based on the Speed Hut graph:


The OP was having issues with his older Vette showing overheating per the temp gauge.
Apparently it's an issue with older SB Chevy motors to find replacement temp sensors that display accurate temps with newer replacement sensors.

The Niehoff appears to show promise for using the Speed Hut gauge with the 4.0 (and possibly the LS swaps).

 

[tower210]

FWIW I contacted speedhut...and they will put temperature markers on the original gauge for only an "art" fee....

Kinda low key thinking about upgrading to new LEDs and selling mine to recoup half...at that point I'd just replace the clock with engine temp...