2015 STI - first little up-grade

[Vixpy1]

MuscleSaloon said:

That's not good. Covered by warranty presumably? What were the issues with it?

Yes, the issue is its a st engine design

[MuscleSaloon]

Bloody shame the 2.5 seems so bad as the new WRX STi looks like an awesome bit of kit ..

[Falsey]

Ive heard that driving style also plays a big part. Ie, booting it in the wrong gear from 2.5k is not good for it. Drop a gear and get the revs up to 3.5k+ and then accelerate. The story goes that anything below that is an environment ripe for detonation. Detonation in these is a nice way to cause the piston ringlands to eat themselves.

Plus the mentioned modifications and their accompanying issues.

The poster above mentioned that running a Cosworth panel filter in the standard airbox is ok - but isnt the point of uprated filters, even panels, that they increase the amount of air flowing through? If so why would any 'uprated' panel filter be immune to MAF problems? Airbox restrictive enough to ensure you never go over the limit? Apologies if a stupid question.

[vxr2010]

There was a test on panel filters a while ago , the standard Subaru one came out on top , there was around 5 to 10 Bhp changes that includes increases and decreases of power across the range , in simple just swapping a panel filter and no remap does virtually nothing and can some times loose you power , a cold air intake does a lot more , from the earlier classic days of Subaru a map was always advised if you wanted to fit a cai

[Konan]

Falsey said:

The poster above mentioned that running a Cosworth panel filter in the standard airbox is ok - but isnt the point of uprated filters, even panels, that they increase the amount of air flowing through? If so why would any 'uprated' panel filter be immune to MAF problems? Airbox restrictive enough to ensure you never go over the limit? Apologies if a stupid question.

Sort of what I was alluding to here.

Konan said:

I don't think it's a worry that the MAF can't read airflow at higher rates, it's that change to the inlet tract can mess with the calibration.

I was purposely being a little vague as a lot of this stuff is up for debate and subject to experience (which I don't have a lot of!).

The usual route is in via the duct at the front, through a plenum in the wing, into the filter housing etc etc. Cold air kits can radically change this. A lot of people have observed the MAF giving different readings for a given amount of air flow, leading to errors in AFR (so needing a rescale). My assumption has always been this has been a change in the 'way' the air is traveling by the MAF. I guess this then gets into the realms of fluid dynamics.

[Falsey]

Makes sense, most CAI kits also bundle a larger diameter pipe too which would (I assume) disturb the flow profile enough compared to standard.