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Air Temperature Sensor Location


BillyPee

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BillyPee

I am after advice as to where to locate the Air Temperature Sensor (ATS) as part of my Omex 200 upgrade. I have Weber DCOE 40 carbs with K&N air filters fitted. I had assumed that I would drill a hole in the back plate of the air filter and poke the ATS through. However, now I look at it, there does not appear to be enough room to do this without the ATS and connection fouling on the carb body. The only possible location is at the bottom centre.

 

19740393694_e278d02f00_c.jpg

 

Just wondering if anyone has modified their K&N air filters and, if so, would mind posting photos of how that was achieved. If its not possible, would I be better off getting a different style of air filter where there is a single backplate for both carb bodies as I am thinking there would be more room between the carbs on that sort of air filter. Another thought was to just mount it separately but somewhere were the temperature it records is going to be as close as possible to the intake temperature.

 

Thanks in advance,

Bill

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luxseven

Pic shows how I did it.

There is another method somewhere here in the forum describing a more accurate solution, but mine works fine as well.

Don't forget to secure the bolt as good as you can!

Cheers.

 

Jos

 

airtempsensor.JPG

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luxseven

And just to add my first attempt, I mounted a small bracket between the airfilters to hold the sensor, but 1) it is not really in the airflow and 2) it is mechanically not a pretty thing

Cheers.

 

Jos

 

sensorair.JPG

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Chris King

Personally, I'd mount it on something non-metallic to try and avoid heat-soak. I mounted mine inside the air filter housing, but not directly to the backplate.

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When I was running throttle bodies I mounted mine outside of the air filter so try and avoid heatsoak as much as possible

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Dave Eastwood (Gadgetman) - Club Secretary

What Kingster and Dommo said. Don't worry about mounting it in the filter, it can introduce as many problems as it fixes. Heat soak from the metal filter backplate when stationary can kill any advantage it might have. Plus the tip isn't actually in the air flow near the bell mouth entries anyway. I'd mount it anywhere convenient, away from immediate sources of conducted heat, where it will get some airflow.

 

If you must mount it inside a filter, then the best way is to mount it on a bracket to lift it off the back plate and bring the tip near to the carbs bell mouths, at the same time, using fibre washers to reduce the heat getting to it through the metal will help.

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BillyPee

Pic shows how I did it.

There is another method somewhere here in the forum describing a more accurate solution, but mine works fine as well.

Don't forget to secure the bolt as good as you can!

Cheers.

 

Jos

 

airtempsensor.JPG

 

Hi Jos, thanks for this photo, that is exactly where I had planned on fitting the ATS. However, it looked as though it would not fit there because there is not enough room behind it for the base of the ATS and the plastic connector combined (it would foul on the carb body). My ATS looks bigger than your and maybe my connector is bigger too.

 

Personally, I'd mount it on something non-metallic to try and avoid heat-soak. I mounted mine inside the air filter housing, but not directly to the backplate.

 

 

When I was running throttle bodies I mounted mine outside of the air filter so try and avoid heatsoak as much as possible

 

 

What Kingster and Dommo said. Don't worry about mounting it in the filter, it can introduce as many problems as it fixes. Heat soak from the metal filter backplate when stationary can kill any advantage it might have. Plus the tip isn't actually in the air flow near the bell mouth entries anyway. I'd mount it anywhere convenient, away from immediate sources of conducted heat, where it will get some airflow.

 

If you must mount it inside a filter, then the best way is to mount it on a bracket to lift it off the back plate and bring the tip near to the carbs bell mouths, at the same time, using fibre washers to reduce the heat getting to it through the metal will help.

 

I did consider this but my thinking at the time was that mounting the ATS through the backplate would a) be a neater/hidden install, and b) get the ATS as close to the air intake as possible. I had read about the heatsoak issue and was thinking of using a rubber grommet to avoid metal to metal contact. However, I really don't think it will physically fit and I will take your collective advice and mount it elsewhere. I'm thinking I could mount it lower down somewhere around the lower wishbone mount and front chassis area as it will get plenty of airflow there and I doubt it will be too affected by under-bonnet temperatures if I mount it forward enough.

 

Thanks,

Bill 

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Welly Jen

What everyone else has said. You need it in moving air that is the same temperature as the air being sucked in to the carbs and away from hot metal objects that can soak heat in to the sensor tip when stationary.

If you do mount it inside a filter, then K&N's have the advantage that all the air is flowing in around the perimeter, so a backplate mounted sensor will be in the fast moving air stream. On filters like ITG's, where the front face of the filter flows air, a back plate mounted sensor can be in dead air and be seriously out from the temperature that the engine is seeing. You still get heat soak though with back plate mounting on a K&N. I like the idea of mounting it between the two filters, maybe on a plastic bracket.

Your idea of mounting the sensor down low by a wishbone is also good. In the air stream, but below the rising heat from the engine and radiator. My Mum's tin top had the outside temperature sensor just behind the front bumper for this reason. We found out after a supermarket car park bump damaged the sensor.

Jen

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Trevturtle

What Kingster and Dommo said. Don't worry about mounting it in the filter, it can introduce as many problems as it fixes. Heat soak from the metal filter backplate when stationary can kill any advantage it might have. Plus the tip isn't actually in the air flow near the bell mouth entries anyway. I'd mount it anywhere convenient, away from immediate sources of conducted heat, where it will get some airflow.

 

If you must mount it inside a filter, then the best way is to mount it on a bracket to lift it off the back plate and bring the tip near to the carbs bell mouths, at the same time, using fibre washers to reduce the heat getting to it through the metal will help.

Agreed. mount it away from heat sources.  I had mine mounted in the airfilter back plate. 

As soon as you stopped ( no airflow through the engine compartment). the temperature jumped from 13-15c to 30-35c in about 1 minute then took 4-minutes to drop to 13c when you started moving.

Temps reading ws from the ECU

 

Either add some heat sheild over the sensor&backplate..or just move it away from the engine.

 

 

hope this helps

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Dave Eastwood (Gadgetman) - Club Secretary

yep my data logs back up Mr Turtles experiences very closely.

 

Once the ecu thinks the air is that hot, depending on how it's set up, it can start tweaking fuel and air maps via it's compensation tables wqhich can then make the car a bit poorer to drive, specially in stop start traffic, until it's all settled back to normal again.

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BillyPee

Spent a few hours head scratching on this over the weekend and mocking up some brackets. It seems that the favoured position is going to be mounted inside the nose cone in the airflow in advance of the radiator. We have our front indicators on either side of the nose cone and these have about 1.5 cm of thread on the inside which we can mount a bracket onto. For ease of wiring it will be on the drivers side as thats where the rest of the loom is going to be located. I will keep you all posted on how I get on.

 

Thanks once again for your help and advice.

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corsechris

Given you have a hole in the bonnet for the filters and the bulk of the intake air is coming from outside, I reckon that's as good a place as any you are likely to find.

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BillyPee

Given you have a hole in the bonnet for the filters and the bulk of the intake air is coming from outside, I reckon that's as good a place as any you are likely to find.

I know what you mean and it is tempting to fashion a bracket off the carb bodies to mount the ATS. Before starting this thread, we had considered a bracket between the carb bodies the same as Jos (luxseven) has done.

 

sensorair.JPG

The problem is that back side of the ATS is quite bulky when you factor in the size of the connector on the loom. I have the underslung Weber throttle assembly which actuates the throttle between the two carb bodies and so that will be competing for space there too. I don't want to risk any of the wiring loom getting caught in the mechanism either (I've had wide open throttle jam on before and its not something I want to repeat).

I will start off with the ATS far forward in the nose cone and then monitor the temperatures to see if its prone to heat soak.

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BillyPee

Quick question:

How significant is any adjustment to timing going to be, based on the air temperature reported by the ATS?

 

I get that a water/coolant temperature sensor will help with cold starting but air temperature won't necessarilly help with that as its just (in theory) the ambient temperature, i.e. I might start the engine from cold but its 20℃ ambient.

Unlike a daily driver or tin top, I'm unlikely to ever use the Westfield when the air temperature is below 10℃ (its SORNed November to Apri) or above 30℃ (which is optimistic for summer temperatures in the North West). My thinking is if the adjustment to mapping is only applied at say below 0℃ and above 40℃ then the air intake temperature is (almost) never going to be that and so that timing adjustment will never be applied. But, if the sensor suffers from heat soak inside the nose cone, then I can see it reading over 40℃ on a hot day and the timing adjustment kicking in but the "real" air intake temperature might be 20℃. If the timing adjustment is significant, I guess that this might make the engine run worse and this would this negate any benefit?

 

So the critical question is, at what air temperatures (high and low) will timing adjustments be made?

 

I am definitely going to fit the air temperature sensor, I am just debating the merits of having timing adjustments made on the basis of it.

Thanks,
Bill

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Dave Eastwood (Gadgetman) - Club Secretary

Can you open your maps? You'll see when and how much difference it makes. On the ambient range you mention, little if any compensation will probably kick in.

 

Just out of interest on the heat soak think, directly mounted on the air filter back plate, after say 5 minutes of more or less stationary running with an already hot engine - ie queueing, or stop start traffic, I used to register around 40-45 degrees on an average day with ambients in the 10-20 degree range, on a really hot day, ie mid 20 to late 20's it would creep up past 50!

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