Cold Air Intake

TMack409 said:

Why fool with it? It wastes energy (reduces efficiency) unless you race full bore all the time.

People just can't seem to understand that cold air is for power only; warm air is for idle and light loads. A normally driven Avalon spends a lot of time under light load and idle conditions. That's why the engineers designed a warm air system for all but WOT and power conditions. It's all a very delicate balance between radical timing advance under light load and idle /and warm air/ oh and lean mixtures.

Put a cold air box on and you screw up every factory designed parameter regards efficiency..........at $3.00 a gallon US - efficiency is something to think about. So is your increased CO2 footprint!

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The next time you tell somebody their idea is a waste of time, please use real information to back up your claim. First of all, a 'cold' air intake does not take in cold air, but rather ambient air from outside versus hot air from the engine bay. secondly, putting an intake on an N/A car is NOT going to reduce efficiency or increase the amount of CO2 your car produces. All it will do is free up the intake system from the restrictive stock system that was designed to be cheap, quiet, and to fit inside your engine bay so people don't have to go crawling under their bumpers to get at their air filters. freeing up your intake and lowering the temperature of the intake charge will mean more horsepower, and BETTER gas mileage at low throttle since the car can more easily burn the fuel due to the higher density of the air. (colder air = more dense = less fuel needed to produce the same effect)
Also why would you need to adjust your timing for a simple CAI? and there is no way that a CAI would be enough to lean out the Air Fuel Ratio enough to cause detonation or anything serious. If anything running slightly leaner will just increase the hp and mpg gains further.
So really, the only downsides to a 'cold' air intake are the time/cost factors, and the gains are more horsepower, and better gas mileage. Gains is to be used lightly in this case however, since I doubt you will net more than a few hp, and maybe 1mpg if you're lucky. but you can show all your friends your sweet intake :smokin:

Osirus9 said:

freeing up your intake and lowering the temperature of the intake charge will mean more horsepower, and BETTER gas mileage at low throttle since the car can more easily burn the fuel due to the higher density of the air. :smokin:

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Precisely my point= nobody seems to get the fact that the engine doesn't need to develop more horsepower under idle and light load conditions. (Because they are fixated on horsepower and are want to forget the resultant necessary fatness (richness) of mixture required to develop it?)
Light load and idle are not a call for power; instead, they are the conditions under which the mixture does not need more density (more O2 density that is). So therefore, mixtures can go lean with no ill effect and timing can advance dramatically - thus increasing efficiency.
Detroit, Asian and german engineers aren't stupid with regards to efficiencies and they are under tremendous pressure to meet CAFE, EPA, Kiyoto standards etc etc. If they thought they could wring another MPG out of the modern engine with cold air intake charges (ambient air if you want to nit pik), then trust me, they would be doing it.

Race efficiencies are one thing; daily driving efficiencies are entirely another. Capiche?

btw, Have you ever driven your stock Avalon with a portable OBD-II monitor connected to a Palm or Laptop and watched the conditions under which timing advances dramatically? Stick a cold air intake on the engine and you wont see this dramatic advance because the spark knock sensors will take over and retard timing.............seeing is believing!

If you want to nit pick and say that since the intake charge is VERY slightly colder than normal while the car is just sitting, and thus increasing the time for the car to warm up by a few seconds, and THAT is what increases your CO2 footprint then be my guest. by the time the car is warmed up there will be absolutely no difference since the cat is still there and working just fine.

You seem to be under some misconceptions when it comes to tuning however. The advantage a CAI has is that it lowers the intake charge, and that it allows more air to enter the engine with less throttle opening. This means you wont have to push the pedal down as far to make the same hp. Everybody knows that the less you are on the 'gas' pedal the less fuel you use. I am not familiar with exactly how the Avalon ECU will compensate for the increase in air at lower throttle openings, but I do know that the main reason to advance timing is not to increase 'efficiency' but to increase power. So what the engineers were probably doing when they advanced the timing under light load was trying to get more power out of the engine so that you wouldn't feel the need to step on the gas so hard. And for the record, lean means less fuel, and more hp. The ONLY downside to running lean is if you run TOO lean your engine will detonate, but we are NOWHERE near that point with a CAI on a conservatively tuned engine. Running rich is never good, it means you are putting more fuel in than the engine can burn, thus decreasing hp, and gas mileage. The ECU is also completely capable of compensating for the increase of air, since the exact same effect is produced every time it is cold outside.

no I've never driven an avalon with a CAI... have you? I would guess not since you seem to worship the engineers of a non-performance car, and all you want to do is argue about how if it were better for the car it would have come that way stock. This viewpoint is unreasonable, and I still believe that the reasoning behind the 'regular' intake in the avalon is the same as every other car with a similar intake. It's easy to get to, cheap to make, and easy to replace filters on. Thats why on many cars there is a tube going from the filter box to the bumper. Its to help decrease intake temperatures.

Now to address the OP, I don't think anybody makes a CAI for the avalon, but its not hard at all to make your own. You can buy intercooler piping and couplers after you take a few measurements and consider what route you want to take. A much cheaper solution is to use PVC piping though. It will look ghetto, but paint can fix that, and it will actually be better for this application since it will remain sealed unless you put on a turbo or something, and it will not hold heat like metal intercooler piping will. use 2.5 or 3 inch piping because those are the easiest sizes to find filters in. then hook one end up to the Throttle body, and put the filter on the other.

Whilst it is elementary that cool air is desirable for
maximum volumetric efficiency at full throttle this is not
so for part throttle operation when higher air temperatures
can usefully improve economy, drivability and emission control.

It should also be elementary that heated air will aid
mixture quality and will also reduce the need for
acceleration enrichment. It can also help to extend the weak
fueling limit and thereby improve minimum specific
consumption, although such an advantage is denied to engines
that have to run in Lambda feedback.

However there are other advantages from heating the intake
air that may not be so readily appreciated. Volumetric
efficiency has no importance at part throttle because if
power is insufficient the throttle just needs opening
further until it is, and for best fuel efficiency the
further open the throttle can be for a given load the
better, for reasons that will be explained.

In part throttle operation the throttle controls power by
reducing charge density but of course raising the air
temperature will do the same. It therefore follows that as
the air temperature is raised so the throttle (or idle
control valve) can be further open for a given load condition.

This has several advantages:-

1. The pumping losses will be reduced.
2. Contamination of the fresh charge by exhaust residuals
will be reduced.
3. The greater volume inflow will increase charge turbulence
and improve combustion.

Some of these effects may be quite minor but adding them all
together it should be clear that heated induction air, regardless of where it comes from, would provide some degree of improvement
of part throttle economy and improve idle quality and could
even help a car that is marginal on emissions.

There is a further slight advantage in that heated air will
help to prevent throttle icing, which can be a problem with
modern injected engines and is why engine coolant is often
circulated through the throttle body.

Osirus9 wrote:

"You seem to be under some misconceptions when it comes to tuning however. The advantage a CAI has is that it lowers the intake charge, and that it allows more air to enter the engine with less throttle opening. This means you wont have to push the pedal down as far to make the same hp. Everybody knows that the less you are on the 'gas' pedal the less fuel you use. I am not familiar with exactly how the Avalon ECU will compensate for the increase in air at lower throttle openings, but I do know that the main reason to advance timing is not to increase 'efficiency' but to increase power. So what the engineers were probably doing when they advanced the timing under light load was trying to get more power out of the engine so that you wouldn't feel the need to step on the gas so hard. And for the record, lean means less fuel, and more hp. The ONLY downside to running lean is if you run TOO lean your engine will detonate, but we are NOWHERE near that point with a CAI on a conservatively tuned engine. Running rich is never good, it means you are putting more fuel in than the engine can burn, thus decreasing hp, and gas mileage. The ECU is also completely capable of compensating for the increase of air, since the exact same effect is produced every time it is cold outside."

I want you to look carefully at the Stoiciometric chart below:

http://www.go.jeep-xj.info/Map-fic-af-emissions.gif

Maximum horsepower is not developed under lean mixture conditions... Instead, it is developed under fat mixtures at approx 12.9:1 A:F ratio. Furthermore, if you look on the lean side of the chart - nothing's going on at that side of the chart except best fuel economy - which, as I stated above, is not achievable in closed loop conditions (lambda feedback). Footnote: There is however, as I've recently read, a potential for lean running in very modern cars with Wideband O2 sensors as they can be slightly biased towards lean under special conditions. I confess, I'm not totally up on it.