quick question about sensors

[FJ 280z]

hey guys, im about to drop my intercooler piping at the welding shop, just wondering where the best place to put an IAT sensor is. i got the 3/4" aluminum bung for the GM IAT sensor, im wondering is it best to put it on the hot pipe before the intercooler, or the cold pipe after the intercooler, and if i put it on the cold pipe (which is short) would it affect airflow to the throttle body(as in causing turbulence before the throttle blade), or be affected any bit by the Blow off valve which isn't that far away? i don't have a MAF sensor, i have a air filter mounted right on the turbo so there isn't any room to put the IAT sensor between the air filter and turbo......so pretty much where is the best place to put it?

[rztmartini]

technically it should be as close to the intake valve as possible for the most accurate reading, most put it on their intake manifold, some put it in front of the throttle body (what i will be doing).

[280Zone]

but where did you get the aluminum bung?

[RTz]

A quick search revealed these... happy reading.

 

http://forums.hybridz.org/showthread.php?t=115937&highlight=%22air+temp%22+iat

 

http://forums.hybridz.org/showthread.php?t=107628&highlight=%22air+temp%22+iat

 

http://forums.hybridz.org/showthread.php?t=105195&highlight=%22air+temp%22+iat

[z-ya]

You want a 3/8 NPT bung, not 3/4. I've had good luck mounting it in the intake plenum, but others have mounted it elsewhere 8^)

[RTz]

Hi Pete,

 

I did that thing I told you I don't do.... I mounted one in the plenum I put it right behind the TB (in the bottom), with no insulator.

 

I decided to try this for the following reasons...

 

1) The car has ceramic coated headers and intake manifold. I'm hoping this reduces the peak heat soak temperatures it see's during extended light loads.

 

2) I'm also thinking locating it at the inlet would do a couple things, due to getting 6 cylinders worth of air at all times (instead of 2 or 3 at times). This should also help lower the peak heat soak temperature a bit and it *should* cool it down to 'reality' much faster.

 

3) if I'm wrong, a simple 'plug and relocate' is all it will take to 'fix' it.

 

I'll let you know how it works out.

[z-ya]

Ron,

 

I put them in the top of the plenum, usually close to the brake booster fitting. Most L28 manifolds have an extra large hole in that area. I just drill out the old threads and tap it to 3/8 NPT.

[trwebb26]

I mounted mine in the old cold start injector hole (just behind the throttle body). I get pretty bad heat soak (especially when the car is sitting at idle for more than a few minutes). I'm thinking about trying to make a phenolic spacer for that location.

[z-ya]

Are you are using an open air type sensor? The sensor is already thermally isolated from the threaded collar. Not sure if any more isolation would help. I'm also not sure why people having problems with heat soak, but we've been there before. Every install I've done, I put it in the intake manifold, and none of them show any signs of heat soak. Even when using the CLT sensor as an IAT (no thermal isolation).

[Tony D]

I installed mine in the spacer between my 60mm T/B and the manifold. If this plate was made of Phenolic or lexan like pallnet was originally doing, there would be no heat-soak. I get some, but having the dual gaskets isolating it form the big manifold proper seems to help somewhat. I lined the sensor up inline behind the throttle shaft, so it's not getting hit with air directly, but turbulent air off the shaft at WOT.

 

My cold-start hole is where my idle bypass runs back into...

[trwebb26]

I'm using the GM open air sensor (3/8 NPT). I assume I have soak problems because it can be 30 degrees F outside and if the car sits long enough the sensor can read up to 130 degrees F. Before I start the car - the IAT and CLT numbers are equal.

[twoeightythreez]

I had mine installed in the stock rubber TB boot where the hose nipple went for the cold-start valve. I have a different provision for cold idle.

The IAT was pirated from a 1989 grand prix w/ 3.1 v-6. (it pushes in)

Since then I've done a turbo swap, so I took the same boot, made a short pipe to connect it to the air filter, and bolted the whole shebang to the intake side of the turbo.

Works great. I was sure that's the best place to put it, as it's compensating for intake air temperature, not intaked-then-compressed-then-sent-thru-intercooler temperature. (let me know if it's in the wrong place )

[z-ya]

trwebb26, it's OK that your sensor is reading 130 deg, because that is most likely the actual intake manifold air temp. With the butterfly closed, and engine not running, there is no air flowing through the intake manifold so the IAT can increase greatly. I don't consider this heat soak. The IAT sensor is reporting the correct IAT to the MS. The MS uses it's IAT compensation algorithm to modify the mixture so that it is correct for all air temperatures. That is why I have a problem with locating anywhere but the intake manifold. If it is not mounted in the intake, it will give a false IAT reading to the MS.

[woldson]

ya know my brother bought a gasket that is spoposed to help isolate heat from the head into the manifold,,,,add that to heat shield and wrapped headers (i know thats not the best for turbo) but that can help too??

[trwebb26]

z-ya: But if you put the car in WOT - the IAT number doesn't go down very much. I doubt there is enough convection taking place in the sub-1-second time that it takes for the air to go from the air filter into the head for the temperature to rise from 40 degrees F to 120 degrees F.

 

By no means am I saying you are wrong. I just want to make sure I fully understand what is going on by asking questions.

[z-ya]

I still beleive that the closer the sensor is to the intake port on the head, the more accurate the measurement. Anywhere upstream of that will be less accurate IMO.

[pallnet]

Tony

That's exactly what Warren (customlock) did with one of my spacers. He loves the setup and has "0" complaints about the location.

[woldson]

hey tony pic?