question, about OE CHT sensor Options

[bd1308]

now that i have carbs, i have no use for my CHT....is there any way to get a CHT guage to work with the stock sensor rather than having to buy a setup........

[scotty914]

you might be able to use a big POT to adjust it so its is close to where you want it. i dont know if it will be accurate over a wide range but you should be able to tune it so the middle range is close

[Cap'n Krusty]

Since it reaches it's minimum resistance somewhere short of full warmup, and doesn't move much after that, it isn't gonna be of much use, IMO. The Cap'n

[bd1308]

right


(IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif)

[bperry]

With the CHT gauge setups I've used, its not the sendor that is the
expensive part. It is the CHT gauge. The actual sensor is like $10.
You can get a complete VDO Gauge & sendor kit for around $60
from places like CB.

Since complete kits start at around $60,
personally, I wouldn't mess with trying to rig up something that used
the stock sendor because due to its design and sensing location
(you want to measure the temp at the spark plugs) you won't
get any sort of true representation of how hot things really are.


--- bill

[Dave_Darling]

The common aftermarket CHT gauge uses a thermocouple to measure temperature. The thermocouple puts out a very very small voltage which varies depending on the temperature difference between the two ends of the TC.

The FI's CHT sender is a Negative Temperature Coefficient thermistor. It changes resistance with temperature, and does not put out any voltage on its own.

The principles are completely different; you cannot mix/match the senders and gauges between the two.

You can, however, hook up the FI's CHT sender to the stock oil temp gauge. It will be only marginally less useful than the stock oil temp gauge, telling you "hotter" and "cooler" but not hotter or cooler than what. And, as the Cap'n pointed out, it will max out its reading somewhat before full operating temperature is reached. But at least it'll show something during warmup. Not sure how much of the gauge it will cover, though.

--DD

[tat2dphreak]

the CHT sender goes under sparkplug #3, not in the stock place... the stock sender is like a switch... it reads "hot" or "not" and that's about it... a CHT gauge and sender kit is pretty accurate... but needs to be in the right spot, under the #3 plug.

[Mueller]

QUOTE (tat2dphreak @ Jul 13 2005, 07:13 AM)

the CHT sender goes under sparkplug #3, not in the stock place... the stock sender is like a switch... it reads "hot" or "not" and that's about it... a CHT gauge and sender kit is pretty accurate... but needs to be in the right spot, under the #3 plug.

If you go to the Megasquirt site and do some google searches, you can find the conversion charts for the Bosch CHT sensors.

I am using a stock CHT with my aftermarket FI, normal operating temp that would shut off extra fuel on a D-jet is a CHT of I think 300°, my laptop reads it as 180° (the stock CHT has the same resistance curve as a Chevy or water cooled Bosch sensor)


The CHT has a curve so you could heat it up and measure and plot the curve.

only problem is is that the temperature is really only relevant to you and your setup, you cannot compare your numbers to anyone elses unless they are running the same combo/calibration.

if you just want to see the temperature change, you could use a Chevy or possibly a german water cooled temp. gauge