IAT Sensor Location w/ Alcohol


Active Member
Dec 9, 2004

I have been pondering the location of the IAT sensor for some time now, And wonder what your take on it is.

You mention in other threads how the inlet temperatures are lowered using alcohol. I understand this to be because methanol converts to a gas at 150degrees F and takes heat energy to do so, therefore lowering the amount of heat in the surrounding air.

OK so where to place the IAT sensor?
For EMS tuning you want to place the IAT as close to the intake valves as possible so the computer knows the temperature of the incoming air and can calculate density. So for us that means doghouse.
However, do you think the IAT sensor reading can be compromised and and result in a false reading if the cold methanol spraying from the nozzles lands on the sensor that is down stream?

If the air entering the motor is less than 150degF, then the methanol is still in a finely misted liquid form right? Is is not until it lands on the surface of the surrounding surfaces before it totally becomes a saturated vapor.

I have my IAT placed in the up pipe before the IAT, but this is not good because A: the distance from the intake valves is not ideal and the air could change temperatures before entering the motor, B: the cooling affect of the methanol is not measure by the IAT which could result in the computer thinking the air is less dense that it actually is = lean. However the methanol is providing fuel, so I just tune 10.8:1 A/F.

Do you see what I am getting at?
OH sorry if this has already been answered.
The boiling temp is 155. Flash temp is 70

Me.. IAT inside intake manifold
Others like it in the up-pipe
Others leave it in the stock location

All three locations work in one way or another
mine is pretty far from the intake. Close to the maf. at idle it climbs up to about 90 and then starts dropping to reflect outside air temp. I have a cold air set up behind driverside headlight.
On a MAF-less EMS system the ideal spot is as close to the intake valve as possible.

When you guys say intake do you mean the lower intake?

If it is in the Dog house I wonder if the methanol is being sprayed on the IAT sensor and cooling down beyond what the temperature of the air entering the motor.

Could anybody post a picture of where they placed the IAT using methanol.

Much Appreciated
stock ecu chip it really doesnt matter but on a aftermarket or speed density that calculates fuel based on inlet temps you want the sensor after the nozzle

mine is in the rear driverside of the dog house under the trans cable behind the cable bracket , and the stock iat wires will reach there without splicing if you slide them out of the loom back to where they come out of the plastic raceway on the valvecover

if you have the intake out you could install it at the rear under the coil pack, youll need an iat extender harness or extend the wires to reach that location
Might want to go to this thread. Part way through, I hijacked the thread from a fellow Okie Buick club member and changed it to this subject. It is a very good discussion about IAT location with input from Julio, Eric Marshall, Brian Bissonette and some tuners/installers on different makes of cars.

BTW, the OP forgave me because I helped him with some tuning matters at Noble and his car ran much faster.