If I replace the air filter and assembly on my 2011 GS, allowing more air flow, do I have to change anything in the engine computer? Will the computer make the adjustments for more air flow? There are no other modifications. I realize that tuning the computer will help, but is it necessary. Thanks

 

Stock filter system already out flowed what the engine was demanding, so no, no tuning needed for the new air filter system.

As for tuning, it not so much the 15hp that you can pick up over stock tune, but de-crippling the TM that is holding power back to the ground now instead.

The jest of the TM, it will pull spark, limit the amount/speed in which the throttle body opens to prevent you from putting all the power that the motor has to offer to the ground.


As for a tuner, might want to find someone that is using EFI live over HP tuner to tune the car. The reason for this, with EFI live, they can get into the throttle openning rate limits/speed and other needed tables to remap the throttle opening rate limits/speed to give the car a much more linear gas pedal to TB reaction.

Watch this to get a better understanding of the difference of stock set up, verses tweaked throttle opening rates.

 

You generally want to attack the bottleneck's first. The stock air filter isn't one of them.

 

That is an eye opener.

 

more air in, more air out = tune

 

As posted,
So although the new air filter system may outflow more air over-all in the end than the stock system, the motor is not demanding more air then the stock filter was already over supplying, hence the stock filter was already out flowing more air that the motor demanded to begin with.




Simply, just because a filter system will flow a billion cubic feet of air at a low static pressure, this is does not mean that the engine will pull in more air using this air filter.

The motor has a set amount of air that it will pull in, and as long at the filter system supplies this amount of air without restriction (which the stock system was already doing) increasing the flow amount that a filter system has, means nothing to the motor.

 

Yes but supplying Cold air will make the car faster.

 

Yup. Absolutely. I have to fault the manufacturers for not being clear about the difference between a CAI and a replacement air filter assembly. They seem to imply they are the same thing which of course they are not.

 

You mean will not pull as much timing, and not make the engine have less HP.

Simply, the motor starts pulling timing when the IAT reaches 90*+, so if you keep the air going into the intake lower than 90*, then motor will not pull timing to lose HP instead.

 

There's more to it than that. Even without timing changes, colder air produces more horsepower all by itself. I believe I heard something like ~1% for every 10 degrees of temperature drop.

 

excellent write up on throttle opening speed.

 

Meth injection system will produce more real power over stock HP than any CAI system, will also keep the engine clean, and for a lot less money overall as well. The huge one here, there is already a tank on the vet that we seldom use anyway (windshield washer), and 20 below washer fluid has more than enough meth to serve the dual purpose of both meth for the engine, and fluid to clean the windshields.

Lets make it simple, unless you are staging on the line for a while to cause the engine bay/air cleaner location to just bake in heat, they any real gains or losses are not going to be that great with a CAI system (read when you Dyno, car hood is open, fan driven air to keep the motor/engine bay cool, so you will not see a difference between the two). Next keep in mind that the motor will pull timing if the temp gets above 90*. So even with a CAI, if the outside air is above 90*, then the motor will pull timing, even with a CAI.

So yes, in drag racing, pulling in cooler air, instead of sucking in hot engine bay air will make a difference, because by the time the air in the engine bay is cooled back down to start pulling in cooler air/ stop pulling timing, your already past the finish line. In a top end speed runs, its not going to make a difference, unless you are using a scope system that is gaining you some air pressure into the intake instead.

The downside to most scope systems for the vet, they are so low on the vet, that when using the Car for a DD and have to drive through wet area puddles, not hard to hydro lock a engine by sucking too much water into the system instead(read some of the manufacturers that did once make scope type system, have discontinued them due to hydro lock motors.

Bluntly, with a Meth kit, it does not really mater that air temp, since the meth/water mist is going to cool the air back down. Since the meth will allow for a higher timing advance without fear of detonation (even on standard fuel) it creates more real HP across the board (and not just what it can prevent HP lose numbers like most CAI systems instead).

Lastly, unlike someafter market air filters, the stock filter actual completely filters the air coming into the motor so you are not sucking in debris. Run the numbers on some after market oil filters, and there is a fine line of what it filtering or not, and how it flows.

To much oil, and it does not flow correctly. Same if you don't clean it enough as well. On the other side of the coin, not enough oil, and may as well just run without a filter instead.

 

Glad I keep the stock air filter! Not being original owner I replaced the filter just because of age(2009) and not knowing how dirty it would be at 22000 miles. Can they really go 50000 miles before needing to be replaced? Did I waste my money replacing filter early?
Bill

 

Depends. How long is a piece of string?

If you are in an environment, like living on a dusty road, it won't last long. If you drive on roads is China (lots of air pollution) it won't last long there as well. If you live and play in a "normal" environment, it may.

Don't forget the cabin filter! It is that door behind the battery or oil tank (on a dry sump) in the fire wall.

 

you will like the car more with a good tune period!

 

I measured the air pressure behind the air filter on a stock filter and a K&N filter. The K&N had half the pressure drop vs stock. Plugged the number into drag racing software and it was equivalent to a 400 foot change in altitude. That does make a difference. I also measured the IAT. On a 65 degree day it was 105! Seems the intake air comes over the top of the radiator. A few judicious holes and baffles dropped it to 80 degrees. But when I come to a stop the temp starts to rise. Seems the radiator fan will force the hot air past the baffles. When moving the front air intake can overcome the fan pressure. Have to do a bettrer job of sealing with the baffles.

 

Do you still have the data for the MAF between the two air filters in the same car/on the same air filter system, and are they also linked to the TB position as well?


Also, are we talking a new Wix air filter (NAPA Gold), or a used/old GM OEM filter up against the oil type filter.