CAI .... Cold Air Intake

[47p2]

Diesel engines sometimes have a cooler built into the fuel system I wonder if something similar could be rigged up for your car.


I've attached a Range Rover diesel fuel cooling system to give you an idea

[Iyole]

Originally Posted by 47p2

Diesel engines sometimes have a cooler built into the fuel system I wonder if something similar could be rigged up for your car.


I've attached a Range Rover diesel fuel cooling system to give you an idea

Yup...that's more in line with what I am looking at.

The CAI theory appears to be along the lines of getting MORE air past the MAF.

I am looking to get cooler/denser air past the MAF as I understand it ... this has a direct influence on the ECU adjusting fuel/timing etc etc etc.....

Or am I heading in the wrong direction here ??

[ainarssems]

Well you cannot get air cooler than ambient without some type of active cooling(something like extra high power aircon for intake) but that would not be practical and possibly rob more power to operate it that you would gain. Another option would be nitrous injection.

47p2 picture shows fuel cooler which is mounted in intake, that would make intake air even hotter as it cools down fuel.

Stock A/S8 already have 'cold air intake' as does all modern cars drawing air from the front of car unlike some old cars that used hot air from under the bonnet.

Well known 'tuning' is to put resistor in place of air temperature sensor to fool ECU of thinking it gets colder air and to inject more fuel at WOT and advance ignition.

[David's8]

The system is supposed to deal with a normal range of conditions. The lambda sensors detects the amount of oxygen in the exhaust. Too much oxygen indicates a lean condition and so the vehicle computer richens the fuel to correct for this condition. Vice versa -too little oxygen indicates a rich condition and so corrects the fuel input to correct for this condition. So the fuel system automatically compensates for changes in air density. Unless you are driving in Oz (where temperature are touching 50C at the momment and possibly beyond the designed tolerances), i would have though that the system should ensure that little difference is felt.

But what do us in Scotland know about driving in warm climates!!

It would be interesting to know what conditions the system is, in fact designed to cope before performance drop-off. I would have thought that driving at altitude would have a greater effect as air density varies more with height than with temperature - I think?? I am probably wrong about all this as I am no engineer.....

[47p2]

The cooler I showed is not mounted in the air intake, the trunking only provides an airflow to the cooler not yo the engine air intake

[nakata]

Originally Posted by ainarssems

Well you cannot get air cooler than ambient without some type of active cooling(something like extra high power aircon for intake) but that would not be practical and possibly rob more power to operate it that you would gain. Another option would be nitrous injection.

47p2 picture shows fuel cooler which is mounted in intake, that would make intake air even hotter as it cools down fuel.

Stock A/S8 already have 'cold air intake' as does all modern cars drawing air from the front of car unlike some old cars that used hot air from under the bonnet.

Well known 'tuning' is to put resistor in place of air temperature sensor to fool ECU of thinking it gets colder air and to inject more fuel at WOT and advance ignition.

The main reason for "poor" performance is the low octane fuel. Try with 100+ octane fuel. With 91 or 93 octane you have too much detonation, and ECU is correct advance timing of spark's to safe engine from detonation. As cold air creates less prerequisites for detonation.
Look abaout this articile for more performance.

pp Please read more carefully about methanol. It is very toxic fuel.

[Iyole]

Thank you for all the replies and advice ...

In South Africa we only get 93 & 95 Octane so I use an Octane Booster to achieve a 98 Octane ....

Some Tech comments from the Web ....

An engine that doesn’t have a turbo charger must rely on atmospheric pressure to supply air to the engine. That ratio is 14.7:1. Now if we use our example above colder air has more molecules, more molecules means more oxygen, engines burn oxygen, so the more you can cram in there the more power you can achieve. Since there is no turbo or intercooler on an N/A engine the only way to get colder air into the intake is to extend the pipe to the fenderwell or down below the engine where the air is cooler. On this example more oxygen is getting to the engine thus creating more power. On the flip side, you have extended the intake pipe about 3X the normal length meaning it makes it harder for the engine to pull the air into the engine. So a shorter length pipe would be ideal, but that would put the filter into the engine bay sucking in hot air. You would actually LOSE horsepower here because you are pulling in a lot less oxygen. In short, people using short ram intakes on an N/A motor are actually shooting themselves in the foot. The stock airbox is more efficient.

On the NA cars, the longer the intake tube, the harder it is for the engine to pull the air. That's only true, if your intake tube is A. too small, or B. has too many tight bends in it. If it's a well designed tube, there will be no restrictions. Most intake tubes I've seen for various cars, actually outflow the engine. As for NA cars, it would indeed be more beneficial to route the filter outside the engine bay. Then again, if it's just a 4 cylinder passenger car, you're not really gaining much anyhow. There's only so much pep you can produce, from a 4 cylinder passenger engine.

Overall, most of the time, the real benefit from a CAI, is the summertime, where there is a decent contrast between under hood air temps, and outside air temps. In the winter, (if you're in a cold state like myself) you're going to get your cold air regardless. Unless of course your engine bay is jam packed.

I am not trying to gain more power ...... just constant power .... yesterday it was 32 degC in Cape Town and
the S felt really flat....

[nakata]

Sorry, but do you know about variable intake in A8? If you have long intake runner you have more power in low rpm, with longer intake is increase power in middle and high rpm. You don't need CAI in A8.Is done enough about that.
When is cooled just no need a high octane fuel. ECU is responsable for timing correcting, to safe engine of detonation.

pp look about variable intake in 40V engine.

[Iyole]

Thank you for the Link ... very informative especially all the links to DIY 's at the
bottom of the page.

I am technically challenged .... and am not looking to go the route of CAI.

What I am trying to establish is if one was able to keep the Air into the
Airbox at an optimum temperature surely the motor would run optimally and the ECU would adjust accordingly ...

I also feel that the Dastek Chip I have might have some influence in not
allowing the ECU to adjust properly when intake temps increase .... ??

I will firstly check that the intake flaps are operating properly as per your link ..


PS: Look abaout this articile for more performance ..... link not working. Thanx

[sarg]

Originally Posted by ainarssems

Well you cannot get air cooler than ambient without some type of active cooling(something like extra high power aircon for intake) but that would not be practical and possibly rob more power to operate it that you would gain.

Stock A/S8 already have 'cold air intake' as does all modern cars drawing air from the front of car unlike some old cars that used hot air from under the bonnet.

^ ^ What he said ^ ^

All cold air induction kits do is get the air from outside, rather than under the bonnet - common mod on E39 M5s, but of little or no use if air is already coming from outside