I originally installed this temperature gauge in October 2006.
Reasons for Choosing a Digital Air Temperature Gauge
Digital gauges are more accurate, have greater stability over the long run (no moving parts) and have much greater resolution compared with analog models. For purposes of measuring temperature at least, they would seem to be the undisputed choice. Even in the 2 1/16" diameter size, the digital readout is large enough to be easily seen even when placed some distance from the driver.
I selected the Cyberdyne Ambient Air Temperature gauge with silver bezel. It has a Blue Ice colored 3-digit LED readout with a range of -22 to 158 deg F. The instrument is also available with an SI readout of -30 to 70 deg C. The readout scrolls ICE for one minute when temperature falls to 37 deg F (2 deg C), or below. Included with the gauge is an ambient air temperature sending unit (sensor). Also included is a set of instructions for wiring and troubleshooting the gauge and a second set describing the mounting and wiring of the sender. Both the gauge and the sender are available separately, if desired. Additionally, Cyberdyne makes amplifier, oil, transmission and water temperature gauges with the appropriate markings and sending units. For more information on the entire Cyberdyne line, go to: http://www.cyberdynegauges.net
I purchased my instrument (with included sender) from: http://www.egauges.com for US $64.75 plus shipping. The part number is: A024E351Y. Separate ambient temperature senders are available from egauges for US $13.71 each. The part number is: SENSS7E.
The current prices for both are the same.
How I plan to Use the Gauge
Of course, measuring ambient temperature air is the intended use for the gauge and that's interesting information to have available. I like that feature in my wife’s 3i. For those who want to use the gauge for its intended purpose, Cyberdyne advises mounting the sender in the front bumper as far away as possible from the heat of the engine. They go on to state that the sender can be secured in place with a cable tie.
However, the gauge can be used to measure the air temperature in any environment if the range of the sender is not exceeded. I intend to mount mine in the air box so that I can measure the actual temperature of the intake air as read by the IAT sensor. Knowing the importance of maintaining the inlet air at as low a temperatue as possible for maximum power output, I like to experiment with different air box feeds and intake types to determine which types of configurations and systems yield the best results. In other words, my main interest is using the gauge for research purposes. I'm also interested in observing how air box temperature varies with the ambient; ultimately, I hope to provide data that some of our Forum members might find interesting and useful.
This gauge could also be extremely useful for those with turbo engines. Mount the sender in the charge pipe at the outlet of the intercooler to measure the efficiency and effectiveness of various IC configurations. The temperature limitation of the sender would preclude its use at the IC inlet, so keep that in mind.
Mounting the Sending Unit
The sender is a small, sealed cylindrical object with two wires about 8" long protruding from it; a black ground wire and a white signal wire. It's ~ 1/2" (12.5 mm) long with a diameter of ~ the same dimension. Cyberdyne makes no mention of how it functions but I'm guessing it's a thermocouple that generates a small voltage proportionate to temperature that’s transmitted to the digital circuitry of the gauge. I don't think the unit is a thermistor since my understanding is that they can function only over a limited temperature range.
In any case, begin by removing the air box upper cover. Undo the clips that hold the two sections together, disconnect the MAF and IAT sensors' wiring harnesses and remove the clamp that holds the air hose to the MAF sensor. Then remove the upper cover and MAF sensor as a unit from the air hose by carefully twisting and pulling at the same time. After the upper cover comes free, remove the air filter element and the lower part of the box will be exposed. It's here that I wanted to mount the sender, on the atmosphere side of the filter, so that if it ever broke loose it would not be ingested into the engine (recall I have no MAF screen). Using a number size drill gauge, I determined that a no. 22 (.157") wire size drill bit would give adequate clearance for the sender wires. This size isn't critical - just make sure it's large enough to pass the wires without chafing them but not too large that it would be hard to close up if you're running a sealed intake system or want to prevent the ingestion of hot, underhood air that would contaminate the data sent by the sensor. Make sure the hole is low enough that the sending unit, once installed, will clear the air filter element.
There isn't much clearance in the working area so a power drill is out of the question. However, the plastic of the air box is so soft that it can easily be drilled by hand. I used a pin vise to drill up to 1/8", then switched to a drill bit holder tool (accomodates drill bits to 1/4") to finish the job. After the hole is deburred and any drilling debris removed from the box, insert the sender wires from the inside until it's positioned as close to the inner wall as possible. Then, lock it in place by using a cable tie on the wires against the outer wall of the box. If you want to insure against possible leaks, put a dab of sealant around the tie. This mounting method insures that the sender is exposed only to the intake air and is not in direct contact with the walls of the box thereby possibly contaminating the data since there is obviously a temperature differential between the two. I'm somewhat unsure if this mounting proceedure will be secure over the long run since the sender is just hanging from the wires and may be subjected to movement from the air flow that may in time damage the connection between sender and wires and render it inoperable. Only time will tell. If there should be a problem, I'll obtain a new sender and using duct tape, affix the wires to the inner wall of the box, but still keeping the sender itself from direct contact with the wall. That should solve any problem. Reassemble everything in reverse order and the sender mounting installation is complete.
Wiring the Sending Unit
Cyberdyne includes long lengths of white and black wire to connect the short leads from the sender to both ground and gauge. Using Western Union splices, rosin core flux applied with a toothpick and a Weller 40W iron, I soldered the additional lengths of wire to the sender wires and, after cleaning the flux off the joint with a small brush dipped into 91% isopropyl alcohol, covered the splices with heat shrink tubing. I then formed the wires into a twisted pair (probably unnecessary for electrical shielding purposes since they carry DC, but they look better that way) and ran them back to the main grounding point. This is where the battery negative cable is grounded and also serves as my common instrument ground point to which my previously installed tach is grounded. Using a 22-18 AWG ring terminal with a 1/4" opening, which I crimped and soldered to the black wire, I grounded the sender wire to the same point.
Because of clearance problems, I can't run a wire through the plug in the firewall from the engine bay side (I can't get my hands in there) so I fed a length of green Alpha 18 AWG with a 600V and 105 deg C rating through the firewall from the cockpit side and soldered it to the white temperature sender wire near the common ground point, again covering the splice with heat shrink tubing. Inside the cockpit, I soldered the other end of the green wire to the white sender wire coming from the OAT gauge. The reason I used green instead of white is that, already having a white signal wire running through the firewall for the tach, I wanted a different color code to make tracing easier should future problems occur. This completes the temperature sender wiring. I obtain my Alpha wire from: http://www.mouser.com
For those who don't know how to run a wire through the firewall, I’ve written a description of the procedure which I carried out when installing my digital tach. You can access it at:
http://www.wihandyman.com/forum/showthread.php?p=623835&#post623835
In the next post, I’ll detail how I mounted the temperature gauge.
Happy Motoring!
Below are photos that illustrate the wiring process:
Upper left: placement of sender and its wires exiting air box.
Upper right: twisted pair running from air box to ground point.
Middle left: sender ground wire connected to ground point.
Middle right: OEM rubber plug in firewall through which I run my instrument wires (16 AWG black ground; 18 AWG white tach signal; 18 AWG green temp sender).
Lower: view of temperature sender
Reasons for Choosing a Digital Air Temperature Gauge
Digital gauges are more accurate, have greater stability over the long run (no moving parts) and have much greater resolution compared with analog models. For purposes of measuring temperature at least, they would seem to be the undisputed choice. Even in the 2 1/16" diameter size, the digital readout is large enough to be easily seen even when placed some distance from the driver.
I selected the Cyberdyne Ambient Air Temperature gauge with silver bezel. It has a Blue Ice colored 3-digit LED readout with a range of -22 to 158 deg F. The instrument is also available with an SI readout of -30 to 70 deg C. The readout scrolls ICE for one minute when temperature falls to 37 deg F (2 deg C), or below. Included with the gauge is an ambient air temperature sending unit (sensor). Also included is a set of instructions for wiring and troubleshooting the gauge and a second set describing the mounting and wiring of the sender. Both the gauge and the sender are available separately, if desired. Additionally, Cyberdyne makes amplifier, oil, transmission and water temperature gauges with the appropriate markings and sending units. For more information on the entire Cyberdyne line, go to: http://www.cyberdynegauges.net
I purchased my instrument (with included sender) from: http://www.egauges.com for US $64.75 plus shipping. The part number is: A024E351Y. Separate ambient temperature senders are available from egauges for US $13.71 each. The part number is: SENSS7E.
The current prices for both are the same.
How I plan to Use the Gauge
Of course, measuring ambient temperature air is the intended use for the gauge and that's interesting information to have available. I like that feature in my wife’s 3i. For those who want to use the gauge for its intended purpose, Cyberdyne advises mounting the sender in the front bumper as far away as possible from the heat of the engine. They go on to state that the sender can be secured in place with a cable tie.
However, the gauge can be used to measure the air temperature in any environment if the range of the sender is not exceeded. I intend to mount mine in the air box so that I can measure the actual temperature of the intake air as read by the IAT sensor. Knowing the importance of maintaining the inlet air at as low a temperatue as possible for maximum power output, I like to experiment with different air box feeds and intake types to determine which types of configurations and systems yield the best results. In other words, my main interest is using the gauge for research purposes. I'm also interested in observing how air box temperature varies with the ambient; ultimately, I hope to provide data that some of our Forum members might find interesting and useful.
This gauge could also be extremely useful for those with turbo engines. Mount the sender in the charge pipe at the outlet of the intercooler to measure the efficiency and effectiveness of various IC configurations. The temperature limitation of the sender would preclude its use at the IC inlet, so keep that in mind.
Mounting the Sending Unit
The sender is a small, sealed cylindrical object with two wires about 8" long protruding from it; a black ground wire and a white signal wire. It's ~ 1/2" (12.5 mm) long with a diameter of ~ the same dimension. Cyberdyne makes no mention of how it functions but I'm guessing it's a thermocouple that generates a small voltage proportionate to temperature that’s transmitted to the digital circuitry of the gauge. I don't think the unit is a thermistor since my understanding is that they can function only over a limited temperature range.
In any case, begin by removing the air box upper cover. Undo the clips that hold the two sections together, disconnect the MAF and IAT sensors' wiring harnesses and remove the clamp that holds the air hose to the MAF sensor. Then remove the upper cover and MAF sensor as a unit from the air hose by carefully twisting and pulling at the same time. After the upper cover comes free, remove the air filter element and the lower part of the box will be exposed. It's here that I wanted to mount the sender, on the atmosphere side of the filter, so that if it ever broke loose it would not be ingested into the engine (recall I have no MAF screen). Using a number size drill gauge, I determined that a no. 22 (.157") wire size drill bit would give adequate clearance for the sender wires. This size isn't critical - just make sure it's large enough to pass the wires without chafing them but not too large that it would be hard to close up if you're running a sealed intake system or want to prevent the ingestion of hot, underhood air that would contaminate the data sent by the sensor. Make sure the hole is low enough that the sending unit, once installed, will clear the air filter element.
There isn't much clearance in the working area so a power drill is out of the question. However, the plastic of the air box is so soft that it can easily be drilled by hand. I used a pin vise to drill up to 1/8", then switched to a drill bit holder tool (accomodates drill bits to 1/4") to finish the job. After the hole is deburred and any drilling debris removed from the box, insert the sender wires from the inside until it's positioned as close to the inner wall as possible. Then, lock it in place by using a cable tie on the wires against the outer wall of the box. If you want to insure against possible leaks, put a dab of sealant around the tie. This mounting method insures that the sender is exposed only to the intake air and is not in direct contact with the walls of the box thereby possibly contaminating the data since there is obviously a temperature differential between the two. I'm somewhat unsure if this mounting proceedure will be secure over the long run since the sender is just hanging from the wires and may be subjected to movement from the air flow that may in time damage the connection between sender and wires and render it inoperable. Only time will tell. If there should be a problem, I'll obtain a new sender and using duct tape, affix the wires to the inner wall of the box, but still keeping the sender itself from direct contact with the wall. That should solve any problem. Reassemble everything in reverse order and the sender mounting installation is complete.
Wiring the Sending Unit
Cyberdyne includes long lengths of white and black wire to connect the short leads from the sender to both ground and gauge. Using Western Union splices, rosin core flux applied with a toothpick and a Weller 40W iron, I soldered the additional lengths of wire to the sender wires and, after cleaning the flux off the joint with a small brush dipped into 91% isopropyl alcohol, covered the splices with heat shrink tubing. I then formed the wires into a twisted pair (probably unnecessary for electrical shielding purposes since they carry DC, but they look better that way) and ran them back to the main grounding point. This is where the battery negative cable is grounded and also serves as my common instrument ground point to which my previously installed tach is grounded. Using a 22-18 AWG ring terminal with a 1/4" opening, which I crimped and soldered to the black wire, I grounded the sender wire to the same point.
Because of clearance problems, I can't run a wire through the plug in the firewall from the engine bay side (I can't get my hands in there) so I fed a length of green Alpha 18 AWG with a 600V and 105 deg C rating through the firewall from the cockpit side and soldered it to the white temperature sender wire near the common ground point, again covering the splice with heat shrink tubing. Inside the cockpit, I soldered the other end of the green wire to the white sender wire coming from the OAT gauge. The reason I used green instead of white is that, already having a white signal wire running through the firewall for the tach, I wanted a different color code to make tracing easier should future problems occur. This completes the temperature sender wiring. I obtain my Alpha wire from: http://www.mouser.com
For those who don't know how to run a wire through the firewall, I’ve written a description of the procedure which I carried out when installing my digital tach. You can access it at:
http://www.wihandyman.com/forum/showthread.php?p=623835&#post623835
In the next post, I’ll detail how I mounted the temperature gauge.
Happy Motoring!
Below are photos that illustrate the wiring process:
Upper left: placement of sender and its wires exiting air box.
Upper right: twisted pair running from air box to ground point.
Middle left: sender ground wire connected to ground point.
Middle right: OEM rubber plug in firewall through which I run my instrument wires (16 AWG black ground; 18 AWG white tach signal; 18 AWG green temp sender).
Lower: view of temperature sender
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