06 T-RED S/C GT
Senior Member
As far as what factors you claim are not taking into account?You're all making valid points about the stock airbox providing adequate airflow for a stock 05-09 GT making 300 crank HP, but there are a couple of factors that you're not taking into account:
1. The airflow becomes reduced as the filter accumulates more dirt.
2. Quoted airflow numbers are under 28" H2O depression. Would you really want your stock 05-09 GT intake system to generate that much vacuum in order to flow 550cfm? A CAI that flows, say, 1100cfm at 28" H2O depression would only need 7" H2O depression to flow 550cfm, resulting in sharper throttle response and improved gas mileage. It would also mean that the air filter assembly is no longer the choke point in the intake system, especially if you want to add more N/A HP.
3. The stock 10 GT airbox was a big improvement over the 05-09, and one could argue that you're better off keeping it even if you're chasing after more N/A HP. It also has the advantage of being a true CAI unlike some of the others that have an inadequate heat shield thus effectively making them a HAI. You could even swap a stock 10 GT airbox with intake pipe into an 05-09 GT, though it would require relocating the PS pump reservoir and a revised MAF transfer curve written into the ECU.
4. We've all seen dyno graphs showing HP & TQ gains across the rpm range from a CAI & tune, but increased airflow only accounts for a less than 10hp gain and even that would only become significant at higher rpm. Nearly all of the HP & TQ gains, especially at lower rpm, are a result of improved optimization of fuel and timing maps. In some cases, the cam timing may also be altered.
At the end of the day if your car is bone stock, a custom tune is a great starting point.
As to the question whether you should you swap in an aftermarket CAI, definitely don't bother if it's a no tune required CAI. If it requires a tune, then decide if there's going to be a worthwhile airflow improvement. In some cases the filter is too small to flow more air than stock so pick one that has the biggest filter that'll fit in the available space. Even then, you're more likely to enjoy the intake roar and sucking sounds as you get on the gas rather than any HP gain. For some, that alone may be worth it as well as being under hood eye candy.
1. The airflow becomes reduced as the filter accumulates more dirt. This applies regardless of the stock air intake or running a huge cone filter air intake setup.
2. If the stock 3v engine is limited to 550cfm, then just how in the hell can it take in 1100cfm from a CAI when the stock heads aren't designed for it?
3. Other than relocating the intake pipe of 10 GT airbox to the front grill section, the airbox design itself was unchanged from 05-09.
4. As previously mentioned, the same HP&TQ gains can be achieved with the stock airbox and a performance tune by remapping the spark, fuel and timing parameters. Adding a larger MAF CAI for which the stock 3v engine cannot support is useless and won't gain a damn thing.
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