Best location for air temp sensor (Emerald Q)?
Discussion
I think most are put in the 'pipe' which replaces the AFM.
Often wondered if a little bit of MagnaParva and putting them on the plenum would be better?
Dave
Of course a custom part to replace both the AFM and the silly radius bend into the throttle would be ideal, insulated even better
Often wondered if a little bit of MagnaParva and putting them on the plenum would be better?
Dave
Of course a custom part to replace both the AFM and the silly radius bend into the throttle would be ideal, insulated even better
Edited by spend on Monday 21st January 14:19
Just about to start the install as well, the common mod is to remove the AFM and replace with a steel pipe (though have not measured the size) looking at it you can get a bracket welded to it to mount where the old AFM dose.
Pipe - Best place I can think of is find a custom exhaust builder, and get a piece of stainless pipe, then they can weld the boss and bracket as well.
Pipe - Best place I can think of is find a custom exhaust builder, and get a piece of stainless pipe, then they can weld the boss and bracket as well.
spend said:
I think most are put in the 'pipe' which replaces the AFM.
Often wondered if a little bit of MagnaParva and putting them on the plenum would be better?
Dave
I must admit that inside the plenum is where i would have put one on mine,if i had used one.In the end i ran without,due to my 'one less thing to go wrong' theoryOften wondered if a little bit of MagnaParva and putting them on the plenum would be better?
Dave
.A mate of mine is going to put his in the plenum,his plenum is an SD1 Twin,and the sensor will go where the cold start injector used to live
I guess you could mount one where the stepper is on a std plenum? Yeah, this is what I did with mine, just get some SS pipe off an exhaust builder, weld a boss into it and put it where the AFM used to be. You need some Jubilee clips as the two pipes aren't the same size but it seems to work well when clamped. I then payed a visit to Tim at ACT and got a load of heat sleeving off him to cover the whole intake from the rad all the way to the plenum which seems to keep the intake temp down nicely... All in all it was a pretty cheap fix and it works very well! 
Edited by thenick on Monday 21st January 17:54
Pupp said:
Cheers for the input all... Nick, how did your running issues resolve themselves in the end or are you still fettling?
Hi mate,I haven't actually seen the car since I last posted, it's been on a battery charger sitting in the garage back home! I just spoke to Dave @ Emerald this afternoon though and i'm going to drive it down to his place on Friday night (going to be a long day as I don't finish in Brum until 4.30!). Anyway he seems to think it might be the ECU shutting down at higher revs due to crank signal loss, and possibly there's still a wiring issue somewhere as well. He's going to work on it in the free afternoons and map it when a slot comes up as he's currently taking bookings at the end of Feb! So i'm not sure how long it'll be, but it'll hopefully be done soon and i'll get to drive it again
It's by far the longest i've not driven it since I bought it and i'm definately having withdrawel symptoms now, made worse by the fact i'm currently cycling to uni and back every day which is both tiring and gets me soaked in the current weather!
Firstly, I should say that I have no knowledge in this area.
But it occurred to me that in a faster airflow, would the sensor be subject to 'wind-chill' and therefore give a falsely low reading (overfueling?), or would it be calibrated with this into account?
Would a better place be tucked away out of airflow, like wheel arch or bumper, away from lights etc.? Or is that wide of the mark?
But it occurred to me that in a faster airflow, would the sensor be subject to 'wind-chill' and therefore give a falsely low reading (overfueling?), or would it be calibrated with this into account?
Would a better place be tucked away out of airflow, like wheel arch or bumper, away from lights etc.? Or is that wide of the mark?
Chim Chim Cheree said:
Firstly, I should say that I have no knowledge in this area.
But it occurred to me that in a faster airflow, would the sensor be subject to 'wind-chill' and therefore give a falsely low reading (overfueling?), or would it be calibrated with this into account?
Would a better place be tucked away out of airflow, like wheel arch or bumper, away from lights etc.? Or is that wide of the mark?
In fact I believe it is quite the opposite - you should place it in the high flowing air as that will chill the sensor closest to the air temperature giving a more accurate reading.But it occurred to me that in a faster airflow, would the sensor be subject to 'wind-chill' and therefore give a falsely low reading (overfueling?), or would it be calibrated with this into account?
Would a better place be tucked away out of airflow, like wheel arch or bumper, away from lights etc.? Or is that wide of the mark?
Chim Chim Cheree said:
Firstly, I should say that I have no knowledge in this area.
But it occurred to me that in a faster airflow, would the sensor be subject to 'wind-chill' and therefore give a falsely low reading (overfueling?), or would it be calibrated with this into account?
Would a better place be tucked away out of airflow, like wheel arch or bumper, away from lights etc.? Or is that wide of the mark?
Wind chill occurs when the sensor is hotter or colder than the air moving past it. The air temp sender should be at the same temperature as the air.But it occurred to me that in a faster airflow, would the sensor be subject to 'wind-chill' and therefore give a falsely low reading (overfueling?), or would it be calibrated with this into account?
Would a better place be tucked away out of airflow, like wheel arch or bumper, away from lights etc.? Or is that wide of the mark?
Isn't wind chill something dreamed up by weathermen to give an indication on a human being as to how cold it might feel on a windy day of X degC compared to a still day of XdegC? .. and presumably takes into account any chilling effects of sweat evaporation?
I can't see how the speed of the air has any bearing on what the sensor reads, other than any molecular frictional issues and of course the ability of the air to pick up heat directly from the intake pipe .. in short I don't believe the speed of the air has any windchill factor associated with it in this instance, as I believe that to be a term invented to give an indication of an event taking place not directly attributable to the temperature of the air itself, but of it's perceived temperatue on a human being (or other living form) ..
anyone care to shoot me down?
I can't see how the speed of the air has any bearing on what the sensor reads, other than any molecular frictional issues and of course the ability of the air to pick up heat directly from the intake pipe .. in short I don't believe the speed of the air has any windchill factor associated with it in this instance, as I believe that to be a term invented to give an indication of an event taking place not directly attributable to the temperature of the air itself, but of it's perceived temperatue on a human being (or other living form) ..
anyone care to shoot me down?
down?Jools is correct
Wind-chill is only felt by animals or anything else that is has its own internal heat source, otherwise it has no effect on the temperature of a part.
The best place for the air temp sensor is as close to the air that is going into the engine as is possible.
So it should be in the plenum.
The plenum body temperature will have little or no effect on the sensor reading ( other than radiative and convection - same as the air within the plenum) As the sensor 'bead' is in a plastic cage away from the mounting.
I would recommend not siting it directly above the trumpets to avoid flame damage on misfires etc, slightly below the trumpet ends is a good spot.
Interestingly at full chat you will see the plenum temp drop considerably (10-15° (so reflecting the amount of air coming in having a cooling effect on the engine intake) whereas in the pipe the temperatures will change but nowhere near as much.
I should point out that the corrections for air temp are only slight (5% max) so if you've already got the sensor in the AFM location you don't have to rush to change it as the benefits are small.
Matt
Wind-chill is only felt by animals or anything else that is has its own internal heat source, otherwise it has no effect on the temperature of a part.
The best place for the air temp sensor is as close to the air that is going into the engine as is possible.
So it should be in the plenum.
The plenum body temperature will have little or no effect on the sensor reading ( other than radiative and convection - same as the air within the plenum) As the sensor 'bead' is in a plastic cage away from the mounting.
I would recommend not siting it directly above the trumpets to avoid flame damage on misfires etc, slightly below the trumpet ends is a good spot.
Interestingly at full chat you will see the plenum temp drop considerably (10-15°
(so reflecting the amount of air coming in having a cooling effect on the engine intake) whereas in the pipe the temperatures will change but nowhere near as much.I should point out that the corrections for air temp are only slight (5% max) so if you've already got the sensor in the AFM location you don't have to rush to change it as the benefits are small.
Matt
Edited by 350Matt on Tuesday 22 January 12:47
350Matt said:
Interestingly at full chat you will see the plenum temp drop considerably (10-15° )
I'm sure that a significant part of this is from the increased mass air flow overcoming conduction through the body of the plenum, but I wonder if evaporative cooling could play a part here too. There will be a lot of fuel sloshing around in the runners under load and I expect that some will get back upstream as far as the trumpets and possible back out into the body of the plenum. Even a tiny proportion of the fuel evaporating in the plenum could be enough to pull the temperature down a few degrees.GreenV8S said:
350Matt said:
Interestingly at full chat you will see the plenum temp drop considerably (10-15° )
I'm sure that a significant part of this is from the increased mass air flow overcoming conduction through the body of the plenum, but I wonder if evaporative cooling could play a part here too. There will be a lot of fuel sloshing around in the runners under load and I expect that some will get back upstream as far as the trumpets and possible back out into the body of the plenum. Even a tiny proportion of the fuel evaporating in the plenum could be enough to pull the temperature down a few degrees.I am a layman here (no editing with a 'g' please)
But have pulled the Griffith into the garage to start to install my Emerald with new loom etc . . .
Given the volume of air that will be passing past the ATS located in the AFM position, would the air temp really be that increased at is passed throttle, plenum, trumpet, inlet tract and into the cylinder ?
I am assuming that it wouldn't and will be placing the ATS there.
I concluded that the difference as eluded too earlier would be so small that it wouldn't make at difference in normal running conditions.
Placing the ATS in the plenum however I imagine would creat heate soak in differing conditions which would negate the benefit of placing it there in the first place.
Therefore, given that I want the most accurate readings I can get, and bearing in mind I want that reading to be as close to the inlet tract as possible I see no alternative to the AFM position as putting it any near the throttle butterfly may affect air flow . .
As Pete has said before, engineering is a compromise and I think it is the best compromise we'll find. Also I believe that when DNB fitted his ATS in the front of his plenum he ended up moving it as the heat soak meant the reding were all over the place . . .
But have pulled the Griffith into the garage to start to install my Emerald with new loom etc . . .
Given the volume of air that will be passing past the ATS located in the AFM position, would the air temp really be that increased at is passed throttle, plenum, trumpet, inlet tract and into the cylinder ?
I am assuming that it wouldn't and will be placing the ATS there.
I concluded that the difference as eluded too earlier would be so small that it wouldn't make at difference in normal running conditions.
Placing the ATS in the plenum however I imagine would creat heate soak in differing conditions which would negate the benefit of placing it there in the first place.
Therefore, given that I want the most accurate readings I can get, and bearing in mind I want that reading to be as close to the inlet tract as possible I see no alternative to the AFM position as putting it any near the throttle butterfly may affect air flow . .
As Pete has said before, engineering is a compromise and I think it is the best compromise we'll find. Also I believe that when DNB fitted his ATS in the front of his plenum he ended up moving it as the heat soak meant the reding were all over the place . . .
rev-erend said:
But surely you would have less back flow at WOT than at part throttle..
Yes, but the total amount of fuel around at part throttle is correspondingly less so any evaporative effects would probably be smaller compared to the (constant-ish?) heat soak through the metal. I don't have x-ray vision so I don't know how much fuel is being bounced out of the trumpets under power, but it wouldn't need much to make a big difference.Put it like this: when mine is running on the upstream fuelling I can get the inlet manifold down to around freezing, and sometimes after booting the throttle you can literally see a wave of frost move down the manifold. More evaporation = more cooling.
Of course, somebody with a rolling road and the guts to run the engine without the plenum top could probably see what's going on and tell us this theory about evaporative cooling in the plenum is complete rubbish!
Thing is chaps
Take a look under the bonnet of a modern car, most of them have the air temp sensor in the plenum and quite often another in the inlet tract. So if the OEM's put it in the plenum then they must have good reason?
Like I said before you want to measure as close to the air going into the engine as possible, have you stopped to consider that the 'heatsoak' is real air temp? At low throttle openings plenum temps increase considerably.
An experiment I did back at Cosworth was we had temp sensors in the airbox, in the port, at the trumpet etc etc
And at idle the airbox and trumpet temps were 10-15° hotter than the air going in with the air the port 25-30° hotter than ambient
On full throttle this all evened out with the airbox and trumpet temps slightly less than ambient and the port about 20° less than ambient
Matt
Take a look under the bonnet of a modern car, most of them have the air temp sensor in the plenum and quite often another in the inlet tract. So if the OEM's put it in the plenum then they must have good reason?
Like I said before you want to measure as close to the air going into the engine as possible, have you stopped to consider that the 'heatsoak' is real air temp? At low throttle openings plenum temps increase considerably.
An experiment I did back at Cosworth was we had temp sensors in the airbox, in the port, at the trumpet etc etc
And at idle the airbox and trumpet temps were 10-15° hotter than the air going in with the air the port 25-30° hotter than ambient
On full throttle this all evened out with the airbox and trumpet temps slightly less than ambient and the port about 20° less than ambient
Matt
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