OTR Temps vs Standard Airbox temps on E3 GTS

[crackelaktor]

The E3 GTS now has just over 2000kms on it so I decided to go with a VCM OTR yesterday. Did not get a tune done as I plan to do this once the car loosens up at 5000-6000kms. So stock standard GTS E3 with a VCM OTR and what did I notice.....

1) Awesome induction roar under heavy throttle. Totally awesome.
2) Air Inlet Temps go from hot to cold and vice versa much quicker than they use to.

When the standard air box was on, I would often keep an eye on the AIT's and see a slow rise in temp once the car warmed up and the temps would stay consistently much higher (2 to 3 times) than ambient. With the OTR, in traffic, AIT's were hitting in the 60's, and then once the car picked up some speed, it would drop 20 degrees in no time.

Am I happy with the OTR and WHY? Hell yes for the induction roar and what appears to be a stronger car (could be the induction roar playing on me).

I'm sure once I get my tune, things will improve, but the AIT's I assume will be all over the place as they currently are due to the nature of the OTR.

So my questions here:

1) What impacts will the OTR have on everyday driving as I suspect the rapid rise in heat when standing still will be due to it being much closer to the engine (because of the MAF position).

2) Whilst the ECU will manage timing to suit AIT's, will it be as dynamic as the changing air temps? My concern is I will lose too much timing when in everyday traffic.

3) I assume the AIT sensor in the MAF is being impacted by its location and proximity to the engine therefore why the air temps rise and drop so quickly at idle and when the car is moving.

4) Where does the W427 AIT sensor sit (I assume in the MAF)

5) Can and should a MAF version with an OTR have the AIT sensor moved to somehwere further away from the engine (ie, inside the front of the OTR)

Interested in other EDI equipped vehicles as without the EDI showing me what the AIT's were doing, I would have no concerns.

PS - Have also posted this on the HSV Forum so you may see it there as well.

Cheers:)

[Martin_D]

Interested in other EDI equipped vehicles as without the EDI showing me what the AIT's were doing, I would have no concerns. Cheers:)

What is the compensation in your engine calibration for ignition timing and fuel delivery impact versus 'AIT' ?

[crackelaktor]

The car will be tuned once it has a few more kms. At the moment, it just has the bolted on VCM OTR.

[Wonky]

I and others have done a fair bit of measuring and experimenting with IAT (inlet air temp) sensors, myself mainly on my previous SSV sedan, from memory I think starting with standard airbox and MAF, then to Orrsom OTR with MAF tune and various attempts at heat shielding and then to moving the IAT sensor, all measured using a scangauge permanently plugged in to the OBD2 port.

In summary, the standard setup suffers an incredible amount of heatsoak, especially once it's sat in traffic for a while and once the motor is warm IAT will virtually never come down to any less than 10 - 12C above ambient.

With the MAF moved to behind the OTR the situation improved somewhat, which heatproofing between the radiator and OTR further improved, but it was still far from ideal.
http://i122.photobucket.com/albums/o274/gcovo/Misc/OTRShield02.jpg

We then moved the IAT so it was in the incoming airstream (drilled hole where the red squircle is in the pic below and removed heatshielding) and that made it run at ambient except when stopped at lights etc.. Even then, it might typically get to only 10 - 15C above ambient (about the best the standard setup ever achieves anyway!) but would typically be back at ambient within a few hundred metres of normal driving. :goodjob:
http://i122.photobucket.com/albums/o274/gcovo/Misc/orssomIAT.jpg

I know of people who even go further and mount their IAT sensor far away from any potential heatsoak eg. down behind the front bar, but I'd at least like to know the temp my IAT sensor is measuring at least bears some resemblance to what is going into the motor. Of course the air will heat in the few milliseconds it takes to pass through the OTR, but I'm relying on the fact the heating effect will be pretty negligible. :yup:

DUS OTRs (as I have on the ute) now come with a preformed hole ready to insert the IAT sensor into in a somewhat similar position to where we drilled the hole in the Orrsom.

[Soopy]

I'd have thought the best place possible would be as close to the throttle body as possible to be the go.

The information you get back may not be what you want to see, but I'd guess at it being pretty accurate.
Happy to be told otherwise.

[Wonky]

Probably correct, but the problem is how do you then avoid our old mortal enemy heatsoak?

[Soopy]

Well in my mind, if you're putting the IAT sensor in some place where its telling the PCM that its not hot, you're still not avoiding it.
If the IAT is getting hot readings, its probably for a reason.

The heat shielding on the radiator is a good idea. I wonder if there is some way to apply this to the intake track its self. I know carbon fiber is supposedly very heat resistant and wont transfer heat to the air charge.

[Wonky]

Sorry, but based on our testing I disagree, except in the case of those people who put their IAT sensor far away from the incoming air flow eg behind the front bar.

The problem with the standard setup is not that the incoming air is hot, but that the IAT sensor is being artificially heated by heat transfer from the MAF and the intake pipe all being heated by the motor and radiator. If you touch the MAF or intake pipe when the car has been running for a while, especially in traffic, they can be quite warm and even hot (get a laser temp probe and check as we've done). Therefore, in that set up your motor is pulling far more timing than it needs to because the IAT the ECU sees is not the actual air temp but indirectly the temp of the heated plastic. Admittedly, given the design of the standard airbox and twists and turns the air is forced to do on its long path there will be some heating effect but to my mind from the testing we did the reading will still be artificially way too high in that setup.

By putting the IAT sensor directly in the flow of incoming air you are measuring the actual air temperature and not heatsoaked metal/plastic/fibreglass. As I said in my original post, in the few milliseconds it takes the air to pass through an OTR there will be some heating effect, but I'm relying with confidence on that being negligible, so with the sensor where I now have it (in the incoming air stream) I believe my ECU is getting the most accurate reading I provide, not influenced artificially by massive heatsoak.

[Soopy]

Yeah I see where you're coming from there.

What is the cause for the heating of the intake material?
Is it absorbing the heat from the motor its self or from the hot air temps under the bonnet?

The later I would presume.
If so, does that mean using some form of heat shield will stop it?

[Wonky]

Especially when you are sitting in traffic on a hot day your motor and radiator both radiate heat which heats everything under the bonnet. The problem is with a standard airbox setup once the IAT gets high it will probably never come down to anything even remotely like ambient, even with lots of freeway driving. I can't remember exact figures now because it was getting on for four years ago but I do remember on a hot (mid 30s) day in traffic in Melbourne my IATs were well over 60 with the standard airbox and even once we got onto the freeway it struggled to get below 50C due to heatsoak.

I'll see if I can find the thread(s) I wrote about it in for some more precise figures.

[Soopy]

Through my own Datalogs I've seen what you mean.
40deg+ IAT's on a 10deg ambient day.

Although I'm using a VY with an LS1, I do see that the IAT's drop reasonably quickly once i get so speed up. Say 30seconds and its back down to 20-25c. Still not great given ambient temps.

[macca_779]

I've tested external measuring of IAT. Infact I still have mine setup that way due to the DUS OEM layout. Took alot of time to get it working adequately and even then I've lost alot of resolution to control certain aspects. Is it better. Hell no. Besides the way it totally screws with the airflow model from actual varying inlet temp with loss of measured variance. Just watch fuel trims at idle jump all over the shop if you have any doubt. You have to bias further towards ect to fix it and I can garantee few tuners do it or even know how to.

The almost total loss of IAT spark control is somewhat concerning for a ragged edge tune.

Heatsoak 100% does influence the inlet charge. Believing it doesn't is just plain ignorant. Anyone that's got any idea about tuning would of seen the airflow dynamics tables and how much influence coolant temp is biased towards the airflow temp calculation at lower aircharge volumes.

Yes there are better places to locate the IAT in the box than some intakes come with. But outside is not one of them. Capturing accurate IAT is achieved in a high airspeed area. You'll still see the REAL heatsoak. But you'll maintain accurate readings at the same time.

[duke5700]

Bah just 0 it out.. if its not pinging its not singing :lol:

[Soopy]

I've tested external measuring of IAT. Infact I still have mine setup that way due to the DUS OEM layout. Took alot of time to get it working adequately and even then I've lost alot of resolution to control certain aspects. Is it better. Hell no. Besides the way it totally screws with the airflow model from actual varying inlet temp with loss of measured variance. Just watch fuel trims at idle jump all over the shop if you have any doubt. You have to bias further towards ect to fix it and I can garantee few tuners do it or even know how to.

The almost total loss of IAT spark control is somewhat concerning for a ragged edge tune.

Heatsoak 100% does influence the inlet charge. Believing it doesn't is just plain ignorant. Anyone that's got any idea about tuning would of seen the airflow dynamics tables and how much influence coolant temp is biased towards the airflow temp calculation at lower aircharge volumes.

Yes there are better places to locate the IAT in the box than some intakes come with. But outside is not one of them. Capturing accurate IAT is achieved in a high airspeed area. You'll still see the REAL heatsoak. But you'll maintain accurate readings at the same time.

In the ideal world Macca, where would you place the sensor?

[duke5700]

In the inlet manifold?

[Soopy]

In the inlet manifold?

So, in reality the most practical place we could locate it would be as close to the TB as possible?
(don't mean to repeat myself, just clarifying)

[macca_779]

In the ideal world Macca, where would you place the sensor?

At the trailing edge of a reverse NACA duct formed at the leading edge of the OTR right behind the filter.

Till someone in the industry actually adopts basic aerodynamics to otrs were stuck with what we have so stick it at the snorkel near the tb.

[Soopy]

At the trailing edge of a reverse NACA duct formed at the leading edge of the OTR right behind the filter.

Till someone in the industry actually adopts basic aerodynamics to otrs were stuck with what we have so stick it at the snorkel near the tb.

Fair enough.
Next question, WTF is the NACA duct, and how would you improve apon the OTR's we have?

[macca_779]

Fair enough.
Next question, WTF is the NACA duct, and how would you improve apon the OTR's we have?

It's basically a low drag inlet. Use it in reverse to channel bulk air over the sensor. Google it for a pic

Big question. Ducts are one way. But a few other aero tricks I've thrown around in my head to improve turbulent air could also be applied. I can't fabricate or use cad to save myself though

[Soopy]

Interesting dude. I shot you a PM.

[crackelaktor]

The E3 GTS now has just over 2000kms on it so I decided to go with a VCM OTR yesterday. Did not get a tune done as I plan to do this once the car loosens up at 5000-6000kms. So stock standard GTS E3 with a VCM OTR and what did I notice.....

1) Awesome induction roar under heavy throttle. Totally awesome.
2) Air Inlet Temps go from hot to cold and vice versa much quicker than they use to.

When the standard air box was on, I would often keep an eye on the AIT's and see a slow rise in temp once the car warmed up and the temps would stay consistently much higher (2 to 3 times) than ambient. With the OTR, in traffic, AIT's were hitting in the 60's, and then once the car picked up some speed, it would drop 20 degrees in no time.

Am I happy with the OTR and WHY? Hell yes for the induction roar and what appears to be a stronger car (could be the induction roar playing on me).

I'm sure once I get my tune, things will improve, but the AIT's I assume will be all over the place as they currently are due to the nature of the OTR.

So my questions here:

1) What impacts will the OTR have on everyday driving as I suspect the rapid rise in heat when standing still will be due to it being much closer to the engine (because of the MAF position).

2) Whilst the ECU will manage timing to suit AIT's, will it be as dynamic as the changing air temps? My concern is I will lose too much timing when in everyday traffic.

3) I assume the AIT sensor in the MAF is being impacted by its location and proximity to the engine therefore why the air temps rise and drop so quickly at idle and when the car is moving.

4) Where does the W427 AIT sensor sit (I assume in the MAF)

5) Can and should a MAF version with an OTR have the AIT sensor moved to somehwere further away from the engine (ie, inside the front of the OTR)

Interested in other EDI equipped vehicles as without the EDI showing me what the AIT's were doing, I would have no concerns.

PS - Have also posted this on the HSV Forum so you may see it there as well.

Cheers:)

Absolutely loving the VCM OTR and it seems to be doing a good job of reducing air inlet temps. The induction roar is the best feature of this upgrade and I now cannot wait to get the car tuned. For anyone with an E2/E3 HSV with a Bi-Modal exhaust, add the OTR to the car and you'll think you've upgraded the exhaust just by the change in sound under heavy acceleration. Under normal driving, you don't even hear the OTR so you get the best of both worlds.

[crackelaktor]

So what VCM need to come out with is a modified insert to where the GTS silver bits on the bonnet are. These can be removed easily but would look ugly. By removing this piece of plastic or at least making vent holes in it, the VCM OTR would get cold air blasting into the little vents under the bonnet which i suggest would provide an even colder airflow. attachmenthttp://tapatalk.com/mu/7c957bf0-d915-0b80.jpg