Intakes?

[wleehendrick]

So what's been done for intakes? Obviously nobody's going to use the OEM airbox. Does a standard aftermarket short ram intake with cone filter fit in the engine compartment?

[SixStar]

Keep in mind that EVERY aftermarket intake will require a tune to be correct with the exception of the COBB. We have dyno tested several makes and they are all lean. Just a heads up.

[Xusia]

I have a Perrin (came with the donor).

EDIT: I should add my donor made very good hp on the dyno before being wrecked.

[wleehendrick]

Keep in mind that EVERY aftermarket intake will require a tune to be correct with the exception of the COBB. We have dyno tested several makes and they are all lean. Just a heads up.

Thanks for the input, but that applies to pretty much any 818, since I doubt anyone will try to fit the Subaru box. I'm thinking of getting a Cobb access port v3, and so the Cobb short ram would be a natural, since I could start with an OTS tune. I know discussing intakes can be a can or worms, and I don't want to go into performance issues; My main concern is fit/interference in the engine compartment, and if anyone who's installed their motor yet can comment on clearance.

Thanks,

Lee

[NISMO_RB25]

Good to know on the Cobb intake as that is the one I just ordered along with the COBB Sylicone hose. They are on sale and it appears to be valid wherever they are sold.

[D K]

Why would you want an intake that doesn't require a tune?

Get one that makes the car run the leanest. Then correct with fuel.

[Rasmus]

Even with the OEM intake pipe (it's a pipe not a tube), the part where the MAF sensor sits, it is a good idea to get tuned for it. That is, update the MAF table. That way the ECU has a better idea of how much air is actually getting to the cylinders. Same goes for the Cobb or any other MAF pipe. Run too rich and you're leaving power on the table and just wasting fuel. Run too lean and, boom.

Get a tune, even if your just going 100% stock. There's additional power and fuel economy to be found just tuning the ECU.

[wleehendrick]

So I went ahead an ordered a Cobb short ram intake on a black friday special... hopefully it won't interfere with anything in the engine bay.

[Scargo]

I am waiting on my kit, and I haven't thought this through, but there is something to be said for isolating where the intake air comes from and having the air as cool as possible. In my STI I picked up my air from in front of the right front wheel.
On the 818 I think air might be directed into a custom box, much like the stock setup...

[wallace18]

I have a Cobb short cold air intake for sale in the parts section. Save $65 over a new one.

[NISMO_RB25]

Why would you want an intake that doesn't require a tune?

Get one that makes the car run the leanest. Then correct with fuel.

I plan to have it tuned, but I may drive it some before then and I would prefer not having it run lean during that time.

[Scargo]

Cobb tunes, especially their basic canned ones, for mild mods, tend to be rich; like real rich. If that is not good enough, get your tuner to send you a tune for driving to him to have it tuned. It should be a safe, conservative tune that will not get you in trouble. They should know what to give you. From a Cobb tune to a dyno-tune my gas mileage went 4 mpg to the better.

[D K]

If you want power obviously you need it tuned.

Why not wait for the install until you get it tuned?

[DodgyTim]

Interesting info from MRT on intakes as part of their staged builds.
Apart from dealing with cars with the steering wheel on the correct side, the right:cool:, the info should be relevant
cold air intakes are the first thing to replace on 2001 to 2005's, but not so important on 2006 and 2007's ????
http://www.mrtperformance.com.au/files/stories/products/power_kits/PowerKit-Subaru-WRX-MY01-05.pdf
http://www.mrtperformance.com.au/files/stories/products/power_kits/PowerKit-Subaru-WRX-MY06-07.pdf

[HelluvaEngineer]

I have a 2005 Legacy GT. There has been a lot of testing and tuning on intakes and basically Subaru did a fantastic job on that intake. There have been a few instances of actually losing power after changing intakes (With a compensated tune) Basically put a K&N filter in it and you are done. Most of the other intakes allow to much extra heat to get in and that is the primary loss of power. I thought I read it was about 350-400 WHP where you may be able to start seeing any difference for an aftermarket intake on the Legacy GT.

[wleehendrick]

Basically put a K&N filter in it and you are done.

Well, that's what I typically do (just put a K&N panel in the factory airbox) but the 818 is clearly a different case. First, I don't have my donor's airbox, and I don't think this:

23895

would be practical in the 818 anyway!

I'll use the CObb short ram intake, and may build a box, or add ducting from the fender intake to feed it fresh air. This may or may not be necessary, since in the 818 the radiator won't be heating the air in front of the intake.

I started the thread to hopefully get some input and photos from builders that have already gotten to this point and see what they've done.

[billjr212]

is there room in the 818 to keep the main box for the panel filter (part 7 in the diagram) and ditch parts labeled 9 and 10? Then maybe just route ducting to the circular intake in part 7 from one of the openings in the right side of the car?

On my 2002, I had removed parts 9 and 10 anyway (part 10 is a silencer that was eliminated in later years, not sure exactly when).

Or, perhaps part 9 could somehow be attached directly to part 7 and line up with one of the intakes on the side of the car (with some creative trimming to part 9, of course)

(hopefully if you read this twice it will make sense)

[wleehendrick]

I get what you're saying, and that would be a nice resuse of parts. But it's hard to tell from photos if it'll fit, and I haven't installed the motor or body yet to see how much room is left.

[jontexas]

Even with the Cobb, you need a tune. In my case, this is via Eric of Torqued Performance, who tuned my '13 WRX.

[tirod]

There's an interesting generational difference these days - ask someone over 35 about intakes, they start talking aluminum manifolds bolted to the engine. Younger, it's about the air filter box and tubing leading to the MAF.

Here's the older perspective on intakes: http://forums.nasioc.com/forums/showthread.php?t=2229576

Just suggesting there's more to it than the air cleaner.

[Scargo]

There's an interesting generational difference these days - ask someone over 35 about intakes, they start talking aluminum manifolds bolted to the engine. Younger, it's about the air filter box and tubing leading to the MAF. ... Just suggesting there's more to it than the air cleaner.
I've run into that so much on STI forums; getting back into cars after a hiatus. I always thought headers were what comes off the heads. Now it seems like they're exhaust manifolds; not to be confused with up-pipe, down-pipe, mid-section and rear pipe.
For me, right now it's suspension parts. People throw around all kinds of descriptors. Is it a knuckle, a bearing mount, an upright or a wheel bearing housing. I could go on... Which one wins? The one with the most Google hits?

[tmoretta]

Interesting how everyone is confirming the need for a "tune", but no one has answered the question of whether or not there is room around all the 818 frame rails for an intake.

[Scargo]

Interesting how everyone is confirming the need for a "tune", but no one has answered the question of whether or not there is room around all the 818 frame rails for an intake.
See if this helps. (http://thefactoryfiveforum.com/showthread.php?10507-And-it-begins-quot-The-Flash-quot-Build-Thread&p=128499&viewfull=1#post128499) He says he extended the intake tube so it puts the filter right in the vent on the passenger side. There's a picture of the CAI.

[longislandwrx]

There's room for the intake on the side. I think Metalmaker has some pictures showing how it fits.

I have a Cobb too if anyone is interested. Filter needs cleaning but i'll let it go for cheap.

[BrandonDrums]

Why would you want an intake that doesn't require a tune?

Get one that makes the car run the leanest. Then correct with fuel.

This should be: "Get the one that flows the most air then re-scale the MAF sensor appropriately." You want an accurate MAF reading so you always hit your targets even in varying weather. Just spot-tuning the fuel maps to target lower AFR's than you want to read on your wideband O2 sensor isn't going to remain accurate in all conditions. I.E. trying to target 10.9:1 AFR at WOT so that your wideband reads 11.5 is not a viable solution to leaning out due to popping on a different intake with a bigger MAF housing. Re-scaling the MAF sensor tables so that when you target 11.5:1 you hit 11.5:1 IS THE viable solution as it will be more accurate when weather/pressure/temperature/humidity change. Those can have a very large effect when you're shoving tons of compressed air into an engine.

There's actually an automated tool for doing this on RomRaider.
http://www.romraider.com/forum/viewtopic.php?f=33&t=5404&sid=894e0e33b02dd7ae867d1f36df096a45

Not sure about Cobb but they have a fairly good database of MAF scale values for different intakes, even if it's from the Cobb forums.

[pt00323i]

my donor came with Injen per owner it was tuned, all forum and wrx owners said intake will loose low end torque but gain high end, I'll just keep it on the car for now.

but since the intercooler is off is good idea to replace the hoses, and stick with Mishimoto or Samco, helps the turbo spool up faster

[DruOdil]

What do you think about this flexible/ custom intake from K & N?
Dru
http://www.knfilters.com/search/product.aspx?prod=RC-5052AR

[wleehendrick]

What do you think about this flexible/ custom intake from K & N?
Dru
http://www.knfilters.com/search/product.aspx?prod=RC-5052AR
Looks interesting if you want to try ducting from the fender intake. You would need a way to mount the MAF sensor somewhere, though.

[Scargo]

What do you think about this flexible/ custom intake from K & N?
Dru
http://www.knfilters.com/search/product.aspx?prod=RC-5052AR
If you note in the description it says it is rated for 350 bhp (for a turbo motor), so it seems small if you are looking for over 300 hp at the wheels.

[uk_beginner]

rekindling this thread - Is the requirement to retune based on the fact the internal diameter (I.D.) of the inlet hose changes when you install an aftermarket intake?

I have just completed my (second hand) 818, with a mishimoto silicone turbo intake, connected via 76mmO.D / 74mm I.D aluminium MAF sensor tube to cone filter. I doubt my engine has been mapped previously. With this setup, short-term fuel trim STFT / learning always goes high to +25% (I think this means the ECU is considering this as lean) , and the inevitable long term trim following with enough time.

I experimented with inserting various bits of silicone hose prior to the MAF, to make the 74mm I.D. narrower. In fact I chopped the end off the stock intake and pushed that inside my MAF tube - that reduced STFT to much more sensible numbers around 7%. inserting a thicker-walled silicone hose instead makes the STFT go negative.

so a few questions:
So has anyone else done such work-arounds?
Could it be prone to unravelling different problems?
With a larger I.D intake, would a tune just increase the fuel-usage to cater for the increased input air, and therefore reduce MPG?

Thanks all in advance.

[driveslikejehu]

I was unaware of this as a potential issue. I hadn't seen this thread and didn't know enough about Subaru's to be concerned.
I built my kit in '22-23 based on an '06 STi. The donor had an aftermarket MAF tube and cone filter. It runs great, plenty of power, beautiful color on the plugs. Never did a tune, etc.
Mine is mostly a track car, so lots of WOT.
Doesn't really address your questions I guess, just another data point.

[uk_beginner]

Yeah, well actually mine also drives OK (02 donor), and at some point I got a P0171 (lean) error code after running for 10 minutes.

I'm not sure if that was due to a vacuum hose leak, or from just the intake being aftermarket. In any case, at the moment, its running OK, but with the OBDII reader graphing STFT, it goes to +25%, and fuel consumption goes quite high. But it drives OK. With my filler padding material (careful not to insert anything that has risk of moving, or shedding bits of rubber / silicone into the turbo!) - I get the more sensible STFT values, and it still drives OK (at least on the brief time I had to test).

I just wasnt sure if this could be considered a 'safe' workaround prior to a tune-up.
Cheers

[lpmagruder]

Retuning for a new maf tube is relatively simple. The hardest part right now is getting the USB to OBD2 interface.

Guessing from your username you're in UK. Lookup RaceDynamix, he can either do it for you or even better, teach you. There's a discord full of folks that should be somewhat local to you.

I don't recommend shimming the inside of your MAF. That's a total hack that at best is going to limit power and more likely, fall apart over time and take out your turbo and maybe more.

[uk_beginner]

The hardest part right now is getting the USB to OBD2 interface.
Yeah - I noticed the Tactrix website does not have stock of the openport on their site. Is this down the to EPA clampdown on such devices (Cobb, etc)?


Yes UK, and thanks for the tip. I'll definitely by getting more experienced eyes to do the tune (first, at least!) . From the guide here (think someone else on this forum also linked to this) : https://www.romraider.com/forum/viewtopic.php?f=33&t=5404&sid=7ac435fb58c048a0e2827d2e912a3315 and https://www.romraider.com/forum/download/file.php?id=5305 , it appears the MAF re-scaling is just 'pre-loading' the fuel trims based on accumulated MAF readings and STFT trims, so after flashing, the STFT / learning trims are closer to zero? If this is the case, I don't understand how this would be considered 'normal' operation, but an un-mapped but high STFT / long term trim giving the same fuel response is considered lean. I'm clearly showing my limit of understanding here/

[lpmagruder]

It's modifying the curve that equates MAF voltage to mass airflow of air. Changing things in the intake tract near the MAF will change that relationship.

The car will only correct within 25% or so, it throws rich or lean codes once it hits that rail. But, it only corrects in 4 "bins" and the curve has way more than 4 points, so it really is best to get your MAF curve scaled correctly.

If you're across the board lean or rich you could also make a coarse adjustment with injector scaling.