3.2 in a 914, CHT times 2? Options

[NARP74]

The car I bought a little while ago had a 3.2 in it with stock FI and engine mgmt. That includes a CHT for the computer. At the last minute, the selling agent I was buying the car from decided to put in a center console with a CHT gauge. He did not have anything to drive the gauge so they hooked up a real fast solution just to get the gauge running. See the pic...

The problem is that where and how it is located, it pretty much just reads 0 or 350, nothing else. It never reads lower, never cools off. It is right by the exhaust manifold. The 3.2 has a built in CHT. Can I buy a new temp ring and tie it in under the factory CHT on cyl 3 like the factory? Is there room under the plugs on a 3.2 for the CHT ring like it would be hooked up on a 4 cyl? I have not looked into the plug area to see if there is any room. I don't think I can split the output of the factory CHT or it will change the resistance, I am guessing.

What have others done to feed a CHT gauge on a 3.2?

[barefoot]

Why not put a TC under one of the spark plugs like so much done before, don't know which cylinder on 6's get the warmest but it's #3 on the 4's
Lots of options for TC's & gauges. Here's mine:

[Montreal914]

On my /4 I have been using this one for many years.

http://thesensorconnection.com/egt-probes/...-race-series-ws

I know it doesn't answer your original question as to if something like this ^^^ could be used on your 3.2/6. (IMG:style_emoticons/default/dry.gif)

Good luck! (IMG:style_emoticons/default/smash.gif) (IMG:style_emoticons/default/driving.gif)

[Krieger]

Put the sender under the spark plug. It's a tight fit on my 3.0, but it works well.

[emerygt350]

You don't want to put it where the computer is getting it's info. Best is under the hottest plug.

[NARP74]

Pretty sure the factory put the original in the block by #3. I'll take a look at the plug situation and go down that road. Maybe some temp measurements will point me in the right direction.

[targa72e]

From the picture that is pretty much no sensor. Looks like a standard terminal tied to ground. I do not know what your gauge is expecting from a sensor but currently it looks like you have no sensor. There are a couple different types of sensors to measure temperature they work differently.

A thermocouple is a two wire device. It is made of two dissimilar metals that create a small voltage in response to temperature change. These can be very inexpensive sensors as it is literately two wires of dissimilar metal soldered together. Downside is voltage is so small any noise can cause problems. Not typically use by on cars from OEM'S. These are often aftermarket and either go in exhaust or under spark plug.

Next there is RTD (resistance Temperature detector) and thermistors. These can be a one or two wrire device. They work by having a material that changes resistance to heat. You can have positive or negative sensors. On the positive they increases resistance with more temperature and the other, negative ,decreases resistance with temperature. These are the most common type found in automotive applications. The sensor cost a little more but can work with one wire (other side is engine ground which is why engine grounding is so important) or two wire (where on side is tied to ground).
The fact that your current sensor reads 0 or 100 percent (probably ignition on or off) indicates it is most likely expecting a RTD or thermistor sensor

john.

[Justinp71]

Is there a benefit to running a CHT and Oil temp on a six? I've always just seen oil temp as the main unit to monitor. Try to keep the oil temp under 210f on the regular, but I think up to 240 is ok.

I guess it would catch if you were running lean but the oil system was still able to keep you cool?

[NARP74]

From the picture that is pretty much no sensor. Looks like a standard terminal tied to ground. I do not know what your gauge is expecting from a sensor but currently it looks like you have no sensor. There are a couple different types of sensors to measure temperature they work differently.

A thermocouple is a two wire device. It is made of two dissimilar metals that create a small voltage in response to temperature change. These can be very inexpensive sensors as it is literately two wires of dissimilar metal soldered together. Downside is voltage is so small any noise can cause problems. Not typically use by on cars from OEM'S. These are often aftermarket and either go in exhaust or under spark plug.

Next there is RTD (resistance Temperature detector) and thermistors. These can be a one or two wrire device. They work by having a material that changes resistance to heat. You can have positive or negative sensors. On the positive they increases resistance with more temperature and the other, negative ,decreases resistance with temperature. These are the most common type found in automotive applications. The sensor cost a little more but can work with one wire (other side is engine ground which is why engine grounding is so important) or two wire (where on side is tied to ground).
The fact that your current sensor reads 0 or 100 percent (probably ignition on or off) indicates it is most likely expecting a RTD or thermistor sensor

john.

I'll pull the gauge and run the numbers to see what it came with or what it needs. Thanks for the info.

[NARP74]

Is there a benefit to running a CHT and Oil temp on a six? I've always just seen oil temp as the main unit to monitor. Try to keep the oil temp under 210f on the regular, but I think up to 240 is ok.

I guess it would catch if you were running lean but the oil system was still able to keep you cool?

Probably the more is better category. The car came with just about every gauge you can cram in to tight spaces. A few were not hooked up or I doubted their readings like this one, then I started to look into it. Definitely needs a better solution.

[targa72e]

The standard Temperature sensor for 911 engines is at the front of the engine (fan end). Its in the main oil galley on the case right side (looking at fan). You have to have one in the engine or have the galley plugged it as its in the main oil galley. 3.2 used head temperature sensor for Fuel injection so you should have the temperature sender for a guage. I don't know if the calibration of 911 gauge works for 914 console gauges but it works for standard dash gauges. Might consider a triple gauge (like pictured below) if 911 sending unit doesn't align with gauge you have.



JBELL on WORLD and Pelican does custom gauges at reasonable prices and they are very nice. I had him build me a triple gauge and am planning on having another made. Also have a 10K tach from him and will probably get another custom tach built.

john