Different cold air thinking -

[ss2115]

Hi.
Attached up the OBDII App Torque and was surprised to see my inlet air temp wandering between 60 - 71 degree C for an ambient outside temp of 18 - 20 degrees.
I've looked at the common Cold Air Intake systems available in the past but decided them not worthwhile. Putting the cone filter in the engine bay, even with a divider wall, never felt like any worthwhile gain to me.

Indeed Ive seen a lot of forums discussing not seeing or feeling any difference other than a perhaps nicer growl seeming as if performing better. It would be interesting for someone to use any of the OBD Apps on a 'before' mod and 'after' mod to see the actual results. I'd be surprised to see more than 5 degrees difference if any.

But I'm not wanting to argue the point in this thread.
Instead, I wish to discuss an alternative.
Following my air-cleaner box inlet, its snout mates with a tube going through the fender wall into the wheel-well space in front of the front tyre, does almost a U-turn and travels over to next to the front radiators (Coolant, AC and Auto Oil Cooler sandwiched between them) where it is ends with a large opening but is open facing the rear of the car in a pocket area not open to the front of the car. ie: not lined up with the opening above or below the bumber bar nor in line with the small ducts next to the fog lights (I have the M-Sport package).
I understand the reason to face backwards is likely to try and pickup non-turbulant air, but it seems to me its picking up air from around the radiators which is heated. My coolant temp runs around 94 - 99 degrees, so with ambient at 20 degrees, the air inlet at 60 - 70 degrees would seem about right.

Before I tackle any mods on my own, I was wondering if anyone had tried taking the extension of the air cleaner out so that the air-cleaner is picking up air from the wheel well area well away from the radiators?
Further, has anyone tried modding the extension pipe so it faces frontwards and perhaps lines up with an opening to the front. I'm not thinking of any supercharger effect, but more just grabbing cold air before it passes around the radiators or anything else warmed up.

I also realise that road surface reflected heat and such can come into this, but then also the ambient temp sensor is in this same position on the other side of the car and its the one giving me the 20degrees outside temp and its only 400mm above the road surface or thereabouts.

I'd love to hear from anyone who's played around with anything other than the standard airbox removal and cone filter under the bonnet idea.

[edjack]

What is the IAT at speed?

[ss2115]

What is the IAT at speed?

It gets to around 59 - 71 degrees when the coolant temp is around 95 - 99 degrees and will only drop down to about 60 degrees after a longer continuous run. It doesn't seem to drop below around 60 no matter what the ambient temp is once the engine is fully warmed up.
So it seems to definitely be heated by the radiators or engine compartment radiant heat rather than what the ambient is. We've had a few 12 - 14 degree mornings and it takes a little longer to get up to the 60 - 71 inlet temp range but once there it stays in that range.

The only thing I haven't done is a long continuous freeway run at constant high speed. But on experience so far I don't expect it will get lower than around the 60 degree mark. On shorter inner city expressways it behaves as described already.

[jclausen]

Of course it will be ambient air temperature, the colder the air the better it is for making horse power. So when I see the cold air systems that live in the hot engine compartment, I have to laugh.

[ss2115]

Of course it will be ambient air temperature, the colder the air the better it is for making horse power. So when I see the cold air systems that live in the hot engine compartment, I have to laugh.

I always thought the same.
However, there's no reason why the Inlet Air Temp couldn't be a lot closer to outside ambient by avoiding long paths past hot engine parts. Its a matter of picking up cold air from outside the engine bay. Hence my thread.
Being cross flow, the M54 motor has the makings of a low IAT with short large ducts from air-box to Throttle Body on the "cold" side of the engine, but picking up the air right next to the radiators (heat exchangers) seems to nullify all that in one stroke.

[rdl]

I doubt very much that air entering the filter box has been heated by the radiator & A/C condenser. The engine air would have to pass through the radiator/condenser before it could pick up heat/temperature and this is impossible given the configuration of the air duct to the filter box. Rather the air being ducted to the air filter is at the same temperature as outside, ambient air coming in the grill.

I suspect the reason for the rear facing port is to prevent, or at least reduce, rain, road spray (and perhaps snow) making its way to the filter and saturating it. And a wet filter would reduce air flow through the filter - in other words partially strangling the engine.

A back of the envelope calculation finds that at idle speed a molecule of air entering the duct near the radiator reaches the inlet manifold approximately 1 second later. It doesn't seem likely that this dwell time is long enough for a ~50 C / 90 F (70C IAT vs 20C ambient) heating. Especially since a good part of the flow path won't be at underhood temperature.

But IAT has been a puzzle to me too. I have observed IATs similar to yours - so they're probably accurate. However, the intake air sensor is mounted in the inlet manifold and air the manifold has undergone an adiabatic expansion passing through the throttle: from ~1 bar absolute ambient pressure to ~0.6 bar inside the manifold. Using the formula for adiabatic expansion from 20 C ambient, the manifold temperature "should" be approximately -20 C, which is a long way from our results. Put another way, the inlet air before the throttle would have to be 120 C for a manifold air temp of 66 C after the cooling effect of the adiabatic expansion. And this doesn't seem likely either.

[JaxPlanet]

Everything you suggested I have seen tested with no gains. Remove/change the snorkel, remove the cone in the airbox, etc. Don't waste your time unless you turbo/SC the engine, which will require more air than the factory CAI can deliver.

There is a very slight air restriction from the factory air filter so replacing it with a high flow filter is a genuine improvement but not much.

Simply put, the CAI was one of the better designed systems on the e39. Your time would be better spent on weaker systems, like the cooling system.

[ss2115]

I doubt very much that air entering the filter box has been heated by the radiator & A/C condenser. The engine air would have to pass through the radiator/condenser before it could pick up heat/temperature and this is impossible given the configuration of the air duct to the filter box. Rather the air being ducted to the air filter is at the same temperature as outside, ambient air coming in the grill.

On first glance, this reply doesn't quite agree with the evidence that once the engine is up to heat for a short time, the IAT is always a constant related to the cooling system temp and much regardless of the ambient temp. The air doesn't have to be going through the radiators, although I'm probably safe to say that some of this heated air swirls about with hitting the engine block and other ancillary equipment. But its radiated heat also - the snout is right next to the hot tank of the cross flow radiator and we all know that the radiator is a heat sink as much as it is a water/air heat exchanger.
However - see my notes further down.

suspect the reason for the rear facing port is to prevent, or at least reduce, rain, road spray (and perhaps snow) making its way to the filter and saturating it. And a wet filter would reduce air flow through the filter - in other words partially strangling the engine.

Thats an excellent reason. There is quite a slope from the snout of the snorkel up to the air cleaner which would certainly drain off to some extent, but taking into account the forced air induction of facing forward I think thats a great observation.

A back of the envelope calculation finds that at idle speed a molecule of air entering the duct near the radiator reaches the inlet manifold approximately 1 second later. It doesn't seem likely that this dwell time is long enough for a ~50 C / 90 F (70C IAT vs 20C ambient) heating. Especially since a good part of the flow path won't be at underhood temperature.

But IAT has been a puzzle to me too. I have observed IATs similar to yours - so they're probably accurate. However, the intake air sensor is mounted in the inlet manifold and air the manifold has undergone an adiabatic expansion passing through the throttle: from ~1 bar absolute ambient pressure to ~0.6 bar inside the manifold. Using the formula for adiabatic expansion from 20 C ambient, the manifold temperature "should" be approximately -20 C, which is a long way from our results. Put another way, the inlet air before the throttle would have to be 120 C for a manifold air temp of 66 C after the cooling effect of the adiabatic expansion. And this doesn't seem likely either.

This is a great situation to have scientific calculations indicate what isn't possible, but the reality is opposite. It means we are missing something! ie: There IS a reason - we just haven't found it yet.

That the ambient air sensor is in the wheel well of the other side of the car and usually reads reasonably accurately the outside temperature, but the other side of the car with the air cleaner snorkel opening being close to the hot tank of the radiator I still think must have some influence even if not entirely. It would be interesting to have someone with a remote temp sensor or a data logger monitor this air temp just inside the snorkel opening for a few days to find the average compared with the ambient air temp over the same period.

But if we are to look for something else, what about the PCV (CCV) recycling internal hot air from the engine through the manifold? What about the additional fine layer of oil that deposits from the same source.
One could assume this heat source to be a constant with the heat of the engine once its warmed, and not affected by ambient air temp.
I think this could possibly be easy to test by disconnecting the pipe from the valve cover temporarily (and blocking it to prevent vacuum leak). Would there still be some hot air rising from the drain pipe to the dipstick though that might confuse the results?

I cannot imagine the air cleaner box or rubber ducts conducting heat soak to the inlet air in that short a space or time. As pointed out, the air molecules are not dwelling in this area long enough. So I don't think there's much to be gained here even if there was anything could be done short of sticking an insulated pipe straight up through the bonnet from the throttle body.

So the CCV system seems a good next logical step. Typical oil temperatures parallel cooling system temperatures or marginally higher, but also the internal air is heated by the underside of the pistons plus any combustion bypass, so we are looking at a possible cause for an IAT averaging around 60 - 71 degrees in the manifold.
And it explains why bolt on cold air inlet systems are a waste of time and money!

[TheAngryBear]

You guys are running the Siemens MS 43.0 right? The IAT is installed directly to the manifold under the engine cover? So you have a "true" heat soak where not only is the air in the manifold heated but also the mounting and sure under the engine cover is heated. Thus the NTC housing is heated... in theory you would need enough cool air to cool the manifold and housing so a lengthy stretch on the highway is needed. And you still would likely have the "insulated" 100C air under the cover to deal with. So maybe removing the cover may have a non-insignificant effect?

Makes me glad I have the Bosch ME 7.2 with the IAT integrated into the MAF. A little heat soak but generally anything more than idle will get with a few degrees of ambient quickly. Over on the "other forum" I have a table setup showing that effect.


Sent from my iPhone using Tapatalk

[ss2115]

You guys are running the Siemens MS 43.0 right? The IAT is installed directly to the manifold under the engine cover? So you have a "true" heat soak where not only is the air in the manifold heated but also the mounting and sure under the engine cover is heated. Thus the NTC housing is heated... in theory you would need enough cool air to cool the manifold and housing so a lengthy stretch on the highway is needed. And you still would likely have the "insulated" 100C air under the cover to deal with. So maybe removing the cover may have a non-insignificant effect?

Makes me glad I have the Bosch ME 7.2 with the IAT integrated into the MAF. A little heat soak but generally anything more than idle will get with a few degrees of ambient quickly. Over on the "other forum" I have a table setup showing that effect.


Sent from my iPhone using Tapatalk

So you have the V8 which makes sense to have the IAT sensor "common" to both cylinder banks.
It would be interesting because your manifold is dead in center of the two banks and more inclined to heat soak than "our" 6 cylinders would be. And if the IAT sensor is divorced from the manifold as you say, your not getting a true reading to the ECU of the air temp entering the cylinders. Even if a compensation algorithm is taken into account, its not real time is it.
Seems to me that if the air in the manifolds is hotter than measured at the MAF, your engines may well be running richer than they need to. Wasting fuel.
I write this a bit tongue in cheek because I'm very sure the engineers and designers at BMW will be way ahead of me/us on this.

Interesting point though - installing another IAT sensor upstream of the manifold and transfer the wiring loom to it so its reading air temp before getting to the manifold. In theory should richen up the mixture much the same as intended with a cold air intake. Much the same as the old trick of adding resistors to the sensor to make the ECU think the airs colder than it really is.

[TheAngryBear]

True, the temperature isn't measured "correctly" at point of use but I am not sure that is needed when thinking about it. Although the pressure and temp change through the system, the volume (or mass if we want to be accurate) stays the "same" throughout this portion of the system. The more blowby in mine the less intake. So making the measurements at a single place makes sense. But as you say: I am sure this was accounted for in both.

Actually, maybe that is why you run a CCV and I run the CVV. With your dual measurements it could account for the blowby by "seeing" the difference between the mass entering the system and the actual being used. Whereas mine just measures the incoming and it doesn't matter the reuse as the mass is fixed.

Not sure that makes sense but it feels right (always a hugely valid engineering point, lol). If the 8 is "more sensitive" to vacuum leaks this could account...


Sent from my iPhone using Tapatalk

[geargrinder]

Rdl is 100% right. "but golly gee me an cuzzin bubba eyeballed it and common sense clearly proves..." OEM intake critiques are almost always retarded. Oem intakes are highly engineered in wind tunnels and on flow benches with extensive testing. Your instincts are well meaning but wrong. I've seen it time and again with all kinda cars. Loads of shadetree dorks insist "must be that..." Then finally somebody actually BTB dynos and finds - hell - the shite looking OEM box actually works pretty great. True for the E46M3 for instance where the common sense tards miss some of the very clever velocity-maintaining engineering features. True of Audis with similar boxes to our E39...Etc.

But... On the other point by Abear... Sensor heat soak is a thing. Yes ideal IAT measurement should be IN the plenum, but catch 22 that location is most prone to heat soak... So... Yeah. Tradeoffs.

You can move the IAT into the bumper or wherever but then you're faking the sensor into an artificially cold measurement and masking actual heat transfer that might occur to the charge. E46M3 tuners do this all the time and trade-off a falsely cool measurement and prob a little more detonation sometimes in order to lose unnecessary "false alarm" timing pulls from heat soak. I'm not a fan of the approach but I understand it.

[rdl]

I made a silly mistake in some calculations in my post #6. The discrepancy in IAT is much larger than indicated there.

I used 0.6 bar as the absolute pressure in the manifold. Actually 0.6 bar is the vacuum measurement at idle, so true absolute pressure is 0.3 bar. With the correct value,
air temperature 20 C ambient => -65 C in manifold
66 C air in the inlet manifold => 205 C air before the throttle.

A note/reminder: these are calculations for conditions at idle speed. As the throttle is opened, the expansion across the throttle is reduced. At WOT inlet manifold pressure and temperature will be the same as ambient - other than for a tiny bit of pressure loss across the air filter and heating in the ducting up to the throttle.

[fullthrottle540]

OEM intakes are highly engineered in wind tunnels and on flow benches with extensive testing.

Yes, OEM intakes are highly engineered... to be cost effective (cheap to produce, last long, safe for engine), efficient, and quiet.

We're not talking about M3's here, we're talking about standard boring cars.

Stop asking for dyno sheets. It's hard to get a real cold air intake reading on a dyno because the 100+ mph air isn't there. Cold air intakes work in real life, not on dynos.

[douglawrence42]

Yes, OEM intakes are highly engineered... to be cost effective (cheap to produce, last long, safe for engine), efficient, and quiet.

We're not talking about M3's here, we're talking about standard boring cars.

Stop asking for dyno sheets. It's hard to get a real cold air intake reading on a dyno because the 100+ mph air isn't there. Cold air intakes work in real life, not on dynos.

But show your work. I have no idea whether they are worthwhile or not, but if they are worthwhile, then there should be a non subjective way to measure that. Show a faster 0-60 or 1/4 mile, or a colder engine under equal condition, or something. If it is good, let's measure it. If you can't show a measurable result, then how good can it be?


Sent from my iPhone using Tapatalk

[geargrinder]

Yes, OEM intakes are highly engineered... to be cost effective (cheap to produce, last long, safe for engine), efficient, and quiet.

We're not talking about M3's here, we're talking about standard boring cars.

Stop asking for dyno sheets. It's hard to get a real cold air intake reading on a dyno because the 100+ mph air isn't there. Cold air intakes work in real life, not on dynos.

No.

Oh... I see it's only 100+. Blow me. Who actually wants a solution for a street car that only works 100+ and blows before that? Wanker posers that's who.

Get back to me when youve actually spent time wrenching and running dynos and seeing real results in real life instead of just stroking your imaginary expertise. like I said , I know people who've tested these things properly, not just moms basement keyboard jockeys imagining what great fluid dynamicists they are.



Strike that. Don't get back to me. I need to waste less time in foolishness and fools.

[TheAngryBear]

Conversely, I focused on this:

It's hard to get a real cold air intake reading on a dyno because the 100+ mph air isn't there. Cold air intakes work in real life, not on dynos.

So I can potentially accept that, not ideal but okay. So that tells something right there: useful (perhaps) on the track but not for anything else. As I spend 95% or more under 100 mph then it is of no use to me.

Edit: and apparently took to long to type vs geargrinder....

Sent from my iPhone using Tapatalk

[fullthrottle540]

But show your work. I have no idea whether they are worthwhile or not, but if they are worthwhile, then there should be a non subjective way to measure that. Show a faster 0-60 or 1/4 mile, or a colder engine under equal condition, or something. If it is good, let's measure it. If you can't show a measurable result, then how good can it be?

I can only show you on freeway.

I have dyno sheets but thats subjective

- - - Updated - - -

No.

Oh... I see it's only 100+. Blow me. Who actually wants a solution for a street car that only works 100+ and blows before that? Wanker posers that's who.

Get back to me when youve actually spent time wrenching and running dynos and seeing real results in real life instead of just stroking your imaginary expertise. like I said , I know people who've tested these things properly, not just moms basement keyboard jockeys imagining what great fluid dynamicists they are.



Strike that. Don't get back to me. I need to waste less time in foolishness and fools.

You're arguing that youve seen wind tunnels of OEM intake tests?

My car is faster than yours and ill put up $1000 to prove it. Bring it on. Same goes for anybody willing to visit San Diego. I will race you for $1000. Geargrinder, leave the wanking and jocking at home. You dont have any supercharged cars, just stop it

[douglawrence42]

I can only show you on freeway.

I have dyno sheets but thats subjective

[COLOR=silver][SIZE=1]

That's a thing that can be measured. What is stock 100-130, and what is it with a CAI?

I agree with you that the OEM solution isn't always the best one for a given individual. All design is a compromise, and the compromises are chosen to sell cars, not to please you. But when we do mods, you either produce measurable results, or your just another dude on the interwebz with an opinion.


Sent from my iPhone using Tapatalk

[geargrinder]

I have dyno sheets but thats subjective

No they aren't.

They are possibly erroneous and bogus, if the dyno isn't well maintained and setup. But by design a proper dyno is a measuring instrument which is not subjective.

It. is. why. we. have. them.

"oh no two dynos can ever be compared" is the whiny excuse of the poser, but unfortunately is fueled by the 'grain of truth' of the not-uncommon bogus shops who fluff (and sandbag) their dyno numbers.

You're arguing that youve seen wind tunnels of OEM intake tests?

I'm not arguing anything. As already said, I've been with or know first-person real live people doing BTB dynos with CAI's vs OEM airboxes. One pro tuner bud of mine has had every CAI he's ever BTB'd has been a zero at best but most commonly a minor power killer. The only time that doesn't apply is when truly the flows start to overwhelm the stock design (almost always requiring F/I mods) so you really need bigger tubes (and usually the stock plumbing just won't work anymore anyway). I do expect the common M62 Dinan/Dinan-ripoff front-fender style is relatively harmless but if you're all bonered up about "100+" (LOL yeah... that extra 2hp at speed really helped my 110-115 acceleration! Which I use constantly!) Well, indeed thats where the factory setup probably works even better I suspect.

My car is faster than yours and ill put up $1000 to prove it. Bring it on. Same goes for anybody willing to visit San Diego. I will race you for $1000. Geargrinder, leave the wanking and jocking at home. You dont have any supercharged cars, just stop it

ROTFL. You go girl.

[fullthrottle540]

But when we do mods, you either produce measurable results, or your just another dude on the interwebz with an opinion.

Here's my dyno sheet of my (otherwise stock) 540i with Dinan intake on a dynojetP10104986.jpg



Here's a stock 540i from another member, also on a dynojet, same brand dyno before-dyno.jpg

[BimmrMeUpSnotty]

Another thing, GG's wagon is supercharged, guess you didn't know.

[fullthrottle540]

What is your deal? I'm talking about cars on a car forum, you are posting info about my family? What's your problem?

[rdl]

I'm afraid these dyno plots prove nothing, i.e. in favour or against. The fact that averages alone are different is meaningless. Measurement conditions must be strictly controlled. And standard deviation of the populations and of the measurement system must be included in the decision calculation. Even when these are strictly controlled, a proper statistical analysis (i.e. ANOVA) will often conclude that it's impossible to conclude that the "better" result isn't simple chance. It's not exactly analogous, but polling results with a confidence interval of +/- 4% may say Candidate A is more popular than B by 2%. In fact B may be the more popular a large % of the time.

Some of the concerns in the validity of the data & unknown factors
1) different dyno's. What is the calibration status of each, what is the accuracy standard deviation of each (no two devices are identical, even when new, let alone worn)
2) different engines - age and wear are different, and they probably left the factory with different actual HP
3) ambient test condition different - ambient temp & pressure so therefore air density

A valid comparison would have several before/after tests done on several engines on the same dyno.

I recall hearing years ago an illustrative fable demonstrating the danger of comparing on averages only. The story goes that a sports clothing company commissioned a study to determine the characteristics of the "average person." They found that this "average person" needed only 1/2 of a bra, and 1/2 of a jock strap. Some wags suggested that a follow-up study was unable to determine if that went right-right, left-left, right-left or left-right. ROTFLOL

[BimmrMeUpSnotty]

What is your deal? I'm talking about cars on a car forum, you are posting info about my family? What's your problem?

Stopped you in your tracks now, didn't it?
You gotta stop going full throttle on here all the time, man, relax. What's my problem? Remember back when you swore you were faster than me, saying my cars were all slow, just because I daily drive a 530 and a 528? But I also had a 540, that you obviously had no clue about? You kept wailing about my slow six cylinder E39's. Then I had to go tell you about when I want to really go fast, I can always hop on one of my motorcycles? I guess you forgot, because here you are yelling and screaming about crap you obviously have no idea about once again, that's all. Relax, it's a beautiful world out there, open your eyes, embrace it. You can do it, I've seen you do semi decent posts. Fit in, I'm trying to do the same, been trying to fit in, get along... that kind of crap.