Air Charge Temp Gauge - what hose should I plumb into?

[JohnK]

Oh dear I thought one of these things would be very useful for measuring the effectiveness of your intercooler

 

 

It would be, if its accurate. Im not saying yours is, but you NEED to know otherwise its useless.

 

A lot of these things are sold as "bling"

[JohnA]

...The temp dropped while moving (open throttle) but shot up while stationary..

Of course it did.

Once the engine is at operating temp, I've found the supra bay to be at ambient+30C (winter) to ambient+40C (summer).

So once there is no air movement inside the intake manifold, it will heatsoak and tend to reach the engine bay temperature. The air-charge actually cools the manifold (at full throttle this depends on the intercooler exit temps obviously;) )

 

Same story with the airbox.

[hadyn]

A lot of these things are sold as "bling"

 

I dont know of many JDMtyte HKS/BLITZ/APEXi blingsters who run these things mate

[JohnK]

I would expect some difference but I was seeing 50c difference.

 

How do you explain the drop when out of the window?

[hadyn]

Heres a quote from the instructions I got with the kit in regards to fitting the t-piece which contains the sensor:

 

"3. Under the bonnet locate the inlet plenum chamber, from this there should be at least 1 vacuum pipe running to things like MAP sensor, boost gauge, dump valve, ECU etc, simply cut through it as near possible to the take off point on the plenum but ensuring enoguh pipe is left to fit the T piece. Insert the T piece into the now cut pipe and secure the pipe using either cable ties or small hose clamps"

 

Its this that got me thinking that I could mount the sensor t-piece in the hose by the plenum that I use for the boost gauge.

[hadyn]

*double post*

[JohnA]

I would expect some difference but I was seeing 50c difference.

Once the engine is switched off heatsoak goes through the roof.

My engine bay sensor has a max display of 70C and it always goes beyond that a bit after switching off (not now in these very cold days, but only just)

How do you explain the drop when out of the window?

what window?

if the sensor is out of the window does it display lower than ambient?

[JohnK]

what window?

if the sensor is out of the window does it display lower than ambient?

 

Yes, I let is settle at ambient wound round the wing mirror, then went for a drive, at aprox 40mph it was 5c lower than ambient.

[JohnA]

It must be humidity then, it really shouldn't be affected by the wind.

There can be no windchill effect without precipitation.

[JohnK]

Well with abient of aprox 5c im seeing 10 to 15c at WOT with the engine hot. This temp seem consistant no matter how many runs or sustained 1.3 bar pulls I do.

 

Not bad for a 10 year old SMIC.

[JohnA]

Mine has been swapped for a much younger one, but with water/methanol before and after it, the charge temps are below ambient sometimes (that's at over 20psi, lol...)

 

It makes a mockery of FMICs

[Chris Wilson]

I am still trying to work out the effect of air velocity on temprature. I had a probe just in front of the throttle butterfys, The temp dropped while moving (open throttle) but shot up while stationary.

 

I have my doubts that the reading is correct as for a simple test I let the probe settle in still air outside the car then drove down the road with it out the window, this too measured a drop.

 

So hadyn, even if you fit your sensor in the correct place you may just have another gauge with meaningless numbers displayed.

 

Expensive gauges are normally expensive for a reason.

 

Air velocity has NO effect on the temp reading, it only affects things like your hand due to moisture evaporation and transpiration. Inanimate objects aren't affected.

[hadyn]

Heres a quote from the instructions I got with the kit in regards to fitting the t-piece which contains the sensor:

 

"3. Under the bonnet locate the inlet plenum chamber, from this there should be at least 1 vacuum pipe running to things like MAP sensor, boost gauge, dump valve, ECU etc, simply cut through it as near possible to the take off point on the plenum but ensuring enoguh pipe is left to fit the T piece. Insert the T piece into the now cut pipe and secure the pipe using either cable ties or small hose clamps"

 

Its this that got me thinking that I could mount the sensor t-piece in the hose by the plenum that I use for the boost gauge.

 

Any more ideas on why the instructions for the gauge tell you to mount the t-piece sensor in the above location?

[Chris Wilson]

I just can't understand them, there's no flow as such in a pipe like that, the air is stagnant, merely undergoing pressure changes, it sounds like the istructions are for a vac / pressure gauge to me... An intake air temp probe needs to be either measuring outside air temp, mounted in fresh air, where the filter draws air from, or just after the filter in the intake duct, or, for post turbo temp, in a turbo air flow hose, or in the plenum. I doubt the instructions are correct or for that gauge