Gtr Air Intake Temp

[Don Dada]

Since the search engine has gone to shitz i'm forced to start a new thread.....

What you guys think of using a teflon washer, maybe two between the air intake temp sensor and the plenum instead of the copper one it comes with inorder to get a more accurate reading instead of picking up heat transfer from the plenum?

[blind_elk]

If you are getting heat transfer into the sensor, then you are getting heat transfer into the air in the plenum. And I suspect that the sensor is actually registering the heat-soaked air in the plenum rather than sensing heat transfer from the metal of the plenum.

[R31Nismoid]

The sensor is affected by the heat of the plenum, not the air.

You need to use a Gizzmo Gasket, or move the sensor to get an accurate reading.

[paulr33]

what sort of temps are you seeing on the intake temp?

i think greg is right, nissan would have tested the crap out of it, given that the stock sensor provides correction to the stock ECU mapping

there would be some tolerance to a hot plenum and it would likely be taken into account so as greg said, you may in fact be seeing high intake temps which are actually true

after intake and compression from a pair of turbochargers its probably reasonable to some fairly high temps - what are you seeing?

[Don Dada]

Im seeing up to 60* if driving at a slow pace in traffic and not much lower probably about 55* normal driving so i'm thinking it has to be heat soak off the plenum bearing in mind we only experience 30-35* days here

[paulr33]

i reckon that sounds reasonable for intake temp

[paulr33]

the GTR powerfc has mapping correction for air temps at 50, 60 and 70+

each step retards timing and i assume stock ecu would be pretty close to this

50 - no correction

60 - -3 deg

70+ - -5 deg

so i reckon what you are seeing is correct

[Don Dada]

I'm checking out the demo version of datalogit and realized that by 60* it has already pulled 3* out of the map so that is why i was concerned about temp being so high

I'm not sure if the default in the pfc has the same setting so probably some one can confirm until next wk or so when my datalogit arrives......Cant wait so Im tinkering from now!

[Don Dada]

^^^^^

guess you beat me to it!

And thats the thing.....We might be driving along a few degrees retarded when the air temp in fact may be well under 60* because i know i can hold my hand against the cold side of the intercooler.....trying to do that on the plenum is a different story!

[GTRNUR]

Air temps are one of those unfortunate realities of tuning a performance car in a tropical climate. An accurate tune during the day can massively change come night fall. What it comes down to though is that you should aim to keep the tune safe. Which means tuning the car at night when the air is more dense. This will mean that during the day the car will just run a tad rich and on average the ignition will be retarded a degree or so.

Keeping the air temp trims where they are is good insurance against detonation, though its been my experience with mildly tuned RB26's that you can drop the 60 degree temp range back to 2 safely, and 1 if you monitor it closely. While still keeping the 70 degree setting at 5 to quickly pull ignition back when it starts to get really hot.

Its mostly the stop-go traffic situations that result in the heat soak issues. If your intercooler is getting cool to the touch then you'll also find that once you are out cruising at 80+km/h you will have enough air flow at the plenunm to see the temps start to drop.

[GTRsean]

I have another intake air temp that is mounted to outlet of intercooler (v spec) and that shows a fairly accurate indication of the temprature of the air going into the engine (on the MFD screen). Typically shows 6 degrees C hotter than ambient temp cruising along, and up to 10 degrees hotter when idle.

I also did a test long ago with my 32GTR with a temp sensor that I slipped in under the rubber joiner into the plenum and had it in the airflow, not touching metal. Results were pretty much the same as the R34's MFD sensor.

Also changing the plenum sensor to read a cooler temp (modding it) will mean that the ecu will see a different value (thinks that it's a nice cool day going off old temp values) and the engine will need a retune to get the values correct again.

[R31Nismoid]

Trent i think posted up about the difference in the sensor when using a Gizzmo gasket.

Now if there is a good 10-15 degree difference just by insulating the plenum, then IMO the lower temp is then the more-so accurate one.

[Adriano]

IMO nissan did a half arsed job on this, they used the same sensor as the water temp sensor, which is very slow to respond, and as noted is affected by the temp of the surface it is bolted to. Do r34's have the same sensor just in a different location?

[GTRNUR]

IMO nissan did a half arsed job on this, they used the same sensor as the water temp sensor, which is very slow to respond, and as noted is affected by the temp of the surface it is bolted to. Do r34's have the same sensor just in a different location?

All the RB26's have identical sensors. The R34's just have an additional sensor in the intercooler. The data for it is only displayed on R34's with a vspec2 or higher MFD version.

[Don Dada]

I have another intake air temp that is mounted to outlet of intercooler (v spec) and that shows a fairly accurate indication of the temprature of the air going into the engine (on the MFD screen). Typically shows 6 degrees C hotter than ambient temp cruising along, and up to 10 degrees hotter when idle.

I also did a test long ago with my 32GTR with a temp sensor that I slipped in under the rubber joiner into the plenum and had it in the airflow, not touching metal. Results were pretty much the same as the R34's MFD sensor.

Also changing the plenum sensor to read a cooler temp (modding it) will mean that the ecu will see a different value (thinks that it's a nice cool day going off old temp values) and the engine will need a retune to get the values correct again.

So let me see if i got this....

The R34 vspec has 3 air temp sensors? One on the plenum,one on the intercooler and one somewhere to tell ambient temp???

You have a pfc right? If so what is the difference between the plenum temp (pfc) and the intercooler temp (mfd) ?

[Don Dada]

Air temps are one of those unfortunate realities of tuning a performance car in a tropical climate. An accurate tune during the day can massively change come night fall. What it comes down to though is that you should aim to keep the tune safe. Which means tuning the car at night when the air is more dense. This will mean that during the day the car will just run a tad rich and on average the ignition will be retarded a degree or so.

For some reason i always thought tuning when the weather is hot was better in that due to the temps already being high you know the max timing that can be dialed in before it pings as the likely hood of it detonating is worse due to high temps and during the night yes it would run a little lean but the cool intake temps would hold down detonation ?

[paulr33]

yeah the ECU (GTR with working airtemp) will back out timing when airtemp goes up, but it wont ever add timing when airtemp is cool

so tuning in cold may be ok as ECU will back out timing as it should when its hotter

[GTRNUR]

For some reason i always thought tuning when the weather is hot was better in that due to the temps already being high you know the max timing that can be dialed in before it pings as the likely hood of it detonating is worse due to high temps and during the night yes it would run a little lean but the cool intake temps would hold down detonation ?

Its not uncommon to see air temps in the 60 degree plus area when tuning in the tropics, especially if your stuck in 60km/h traffic. Even at a cruise speed of 80-100 it will still hover around 54-55 degrees in the middle of the day.

So if you factor in the ignition retard vs air temp, plus the fact the air is a lot less dense, it will run richer and with less ignition during the day. There is more chance of detonation at night as the air is more dense, and there is no ignition retard in effect to keep it 'safe';