Rb26 Air Temp?

[LWO]

Hello all,

I have an Apexi Djetro (in before the cries of get a Haltec/Motec/Paltronic ) on a RB26 and have been monitoring the Air Temp for a while via the hand controller.

As the standard RB ran AFM do they also have an Air Temp sensors? Or is this been added when the Apexi was fitted?

I think it may be this sensor in the front of the plenum?

I have noticed that the Air Temp does not vary wildly it stays around 45 deg when moving along. When standing it reaches 50 deg and then take 10 mins to creep back down to 45 or so. If the ambient changes 15 deg then there is no effect still 45 deg. It has a largish HKS intercooler as well as a couple of R34 N1's running 15psi so they are working hardish with all standard 32GTR piping and plenum in place.

This leads me to a few posibilities I am hoping someone can answer;

1) The Air Temp sensor installation is wrong and I am measuring plenum temperature? I need to correct this with either a different sensor or different installation?

2) The Air Temp sensor installation is right and the air temps recorded are correct? Perhaps then the RB is a candidate for a phenolic spacer between plenum and head?

I am a newbie with these engines.

[DVS JEZ]

The airtemp sensor on the GTR plenum is standard.

The issue with it is the sensor gets heatsoaked from being directly mounted to the engine via the plenum.

Best to move it to either the cold side of the intercooler core or the cooler piping after the cooler to get accurate results

[GTSBoy]

Only a couple of Nissan engines of that vintage even use IAT sensors. That's pretty much the SR20 and the RB26. The rest could have benefited from them to provide better ignition timing adjustment with temperature, which would have provided better power in cold weather (or more to the point, they could have had less conservative ignition timing and still been safe when the IAT went hot). But because they all did run AFMs, they didn't need to measure IAT in order to calculate engine load, so they cheaped out on most engines.

I strongly suspect that the IAT sensor on RB26s does little more than nothing at all. There is precious little difference between an RB20 ECU and an RB26 ECU, and precious little difference in the way the calculations are done inside. Add the fact that the IAT sensor tends to stabilise at the plenum alloy temperature, and, well, you can see what I mean.

cheers

--edit -- correction. I accidentally typed RB20 in the 2nd sentence when I meant RB26.

Edited October 15, 2012 by GTSBoy

[jiffo]

Agree, don't think it does too much until engine temp gets high.

Stock Datalogit numbers I think?

IGN V's IAT shows 0 correction at 50 degrees down to -5 correction at 70 degrees.

INJ V's IAT shows 100% at 40 degrees, 112% at 70 degrees and 120% at 100 degrees.

And the probe is always heat soaked, never seen mine less than 50 when running which is in the vicinity of the zero and 100% spots.

[linkems]

That stock sensor is really slow, inb4 haltec/motec/paltronic well... those computers can all be fitted with any modern sensor which respond much faster. So if you relocate this sensor to a less heat soaked position will it be fast enough to tune with?

Edited October 15, 2012 by linkems

[LWO]

Thanks for the responses so far... a wealth of knowledge.

Unless I am missing something, there is no accessable trim tables for air temp correction via the hand controller. I assume they are embedded into the algorthm for final ignition and final fuel pulse within the unit and setup from Apexi?

The airtemp sensor on the GTR plenum is standard.

The issue with it is the sensor gets heatsoaked from being directly mounted to the engine via the plenum.

Best to move it to either the cold side of the intercooler core or the cooler piping after the cooler to get accurate results

Does simply moving the standard sensor make the whole system run better (i.e. correct fuel/ignition for a given air temp?).

[blue_vl_t]

Thats correct, you will need to use Datalogit to change air temp correction values, so yes they can be changed, but not with the hand controller.

[LWO]

Cool..... so can the standard sensor work when relocated? Or is there an alternative sensor? Seems like buying Datalogit is the go......?

[black bnr32]

also interested in alternative locations and sensors

[blue_vl_t]

If you wish to play with the PFC your self, Datalogit is the go, I tune my own car and its very easy to use.

[Adriano]

Unfortunately i think it is the style of sensor, it is a water temp sensor mounted in the air, being that you have the adjustment tables i would try a different sensor and adjust to suit

[Moodles2]

Yep if I recall correctly, the radiator water temp sensor and the air temp sensor are the same part number.

[discopotato03]

If memory serves me correctly in the late 80s era competition teams were finding that prolonged use off high speed and boost were causing lean outs which could damage pistons etc . I think it was Murray Coote that burnt a Familiar rally engine on some event that included long stages of full speed full load running . You would expect that everything could become heat soaked particularly in hot weather and a slow reacting temperature probe could make a difference . Its hard to imagine it doing much in a road car here driven at legal speeds .

A .

[LWO]

If memory serves me correctly in the late 80s era competition teams were finding that prolonged use off high speed and boost were causing lean outs which could damage pistons etc . I think it was Murray Coote that burnt a Familiar rally engine on some event that included long stages of full speed full load running . You would expect that everything could become heat soaked particularly in hot weather and a slow reacting temperature probe could make a difference . Its hard to imagine it doing much in a road car here driven at legal speeds .

A .

Looking at my other car ecu calibration... the fuel multiplier for two different air temp breakpoints 40deg to 20deg are 1 : 1.023.... or in other words 2.3% difference in fuel - lets say we aimed for 12:1 at a particular point in the map then 2.3% difference is 12.27:1 - I know it may not look like much difference but it is.

Looks like datalogit is the go - and now to find an Air Temp sensor!

[paulr33]

the air temp sensor and water temp sensor are the same part number, its the same part and you can use either

leave the sensor where it is and leave the ecu do its job - back out timing when intake temp is excessive

dont forget you are measuring air after the compressor wheels and after the intercooler so 45deg is pretty good

imagine the air temp at the compressor wheel outlets? its probably double that so 45deg is fine

there is nothing wrong and nothing to fix. dont move the sensor

[black bnr32]

in my experience, air temp plays a significant role in power output and its worth the work to minimize it as much as possible.

[STATUS]

Thanks for the responses so far... a wealth of knowledge.

Unless I am missing something, there is no accessable trim tables for air temp correction via the hand controller. I assume they are embedded into the algorthm for final ignition and final fuel pulse within the unit and setup from Apexi?

Does simply moving the standard sensor make the whole system run better (i.e. correct fuel/ignition for a given air temp?).

it works perfectly well, there are good trim tables for fuel and air via AIT too... there is a very good reason Nissan used slow reaction sensors.

[LWO]

there is a very good reason Nissan used slow reaction sensors.

Thanks for all the help for far.... Do you have time to explain the above?

[Davets]

Hi guys,

After stumbling across this thread I remembered to post up an rb26 air temp sensor upgrade for the power fc I did a while back.

Here's the link: http://www.skylinesaustralia.com/forums/topic/412248-rb26-air-temp-sensor-upgrade-for-power-fc/

Hope it helps some people out,

Dave.

[CrimsonLey]

Good location of the intake air temp sensor: