I've never known any car that needed a tune for just an intake.
You couldnt be more wrong. You need to do some more reading
Hondas and fords, no.. Subaru has very tight tolerances for air and fuel, though. It's a gamble.
Eh, kinda. These automakers use a different type of fuel commanding technology also known as MAP based fueling. The reason why you can get away without a tune is because the KPA that the map sensor reads is, well, what it reads. if there is more air coming in then the map that dictates how much air is coming is injects the corresponding fuel that matches the fuel table. Therefore you will always get the correct AFR's that the fuel map dictates everytime without a tune.
But I'll admit, the intake = tune has always been a headshaker for me.
Let me blow your mind.
The values dictated in the tune for the stock subaru intake systems is FOR THAT INTAKE. so if you change it out then you have to alter the tune. Why? here is why. the stock box flows a certain way and has resonators built in to get the most consistent and accurate airflow that leads to the most optimal airflow for the best drivability possible. When tuning streetcars, your idle and part throttle are the most crucial parts of any tune. Subaru puts their credibility and reputation on the line and therefore go to far lengths in order to ensure they can put the best running car on the street as an answer to other competition from other automakers. Speed, looks, and power is just the icing on the cake.
Aftermarket intakes are simply made and dont incorporate all of the engineering and technology that is associated with the stock box. They are cheap to manufacture and you pay for the name. Their purpose is very simple and differ greatly from the stock system. There are alot of specifics here but im not going to go that far into it. You can research it yourself or take my word for it. stock system incorporates airflow screens, resonators, a design that dictates specific flow pattern and other engineering features that make up this system. Along with that alot of r&d testing and calibration time goes into it. They cost is minimal since there are dictated engineering teams that do this across all their vehicles that keep costs manageable. When you think of name brand intakes most of them compromise of just some metal tubing and an air filter. simple. How many do you think actually spend alot of time r&d'ing, testing, fitting, calibrating, and engineering on these? Not much. why? because in order to justify money and time spent on that would include an EXPENSIVE intake and when you look at the price of all the intakes out there and what people are willing to spend, the reason why becomes clear. and really there isnt much reason to take it that far. kids buy anything. As long as the maf tube stays the same size these brands figure it is "good enough" and for the most part it is. Is a tune ABSOLUTELY essential? no. Will the car run like stock? No Way. that is where the tune comes in. Every intake i have seen is off. just the way an intake tube bends can affect airflow and throw your trims off. CAI's are the worst when it comes to flow and FUBAR'ing trims. short rams are ok. The only intake that i have seen that has done the best is the COBB SRI. This makes sense because look at the design of it. The sensor is really close to the filter making it undisrupted by erratic flow patterns AND it has an airflow straightener built in to keep it consistent. This is the only intake i MIGHT consider not needing a tune. if your maf housing is a different size (bigger) then there is no question that you will need a tune because bigger housing means more air passes through and a slower velocity and with stock values, the amount of air read and going into the motor of a 70mm housing is not going to be the same as the amount of air that passes through at the same rate and read by the maf in an 83mm housing means more in the motor and it starts going lean (think about it) hence tune needed.
When people think of tuning they automatically think tune=get more power. This is not the case AT ALL. Tuning is another word for calibrating. Calibration ensures all sensors are working properly=a great running car. with that being said there is nothing better than the stock box and stock maf scaling (tune). There is no need to change unless you are overloading the maf due to a bigger turbo. at which point i would just suggest buying the proper maf housing that you can attatch a filter on the end with a corresponding air straightener or go MAP based. Everything else is just too shifty. can it work? sure, it just wont run like stock and drive as nice but many people seem to sacrifice that with false advertising of "AWESOME HP GAINS" which really isnt the case if you just read all of this. Is there a gain? yea, cooler intake temps are possible (tune required), maybe a little more airflow, increased efficiency of the turbo (tune required), and the like. Is it enough to get all drooling about? No, because the majority of people on here suck oil into their motors through the stock EVAP system or worn out motors and experience higher temps from the turbo anyway because they are pushing them out of their compressor range or dont know that turbo's blow hot air anyway. That is why IAT's on a subaru motor can never be trusted because they are incorporated into the maf and not placed on the IM where they should be. But now im just ranting...
