Intake

[anabolism]

After asking questions and poking around on other threads on the board it seems that at least 3/4 of Legacy owners would prefer a drop in panel filter over an intake installed. I can't help but wonder why. Maybe cabin noise??

 

I think I will follow the consensus on this one though and go with a drop in panel filter. I plan on SPT Cat Back Exhaust and a downpipe for my 2009 spec B. No more mods after this though. Stage 2 tune is what I'm going for. No going to the track with my daily driver.

[bnguyenbb6]

Because the intake is not a restriction on a stock turbo. I run a a hacked stock airbox(to clear my FMIC piping) with an AVO panel filter on a VF39(STi turbo, larger than stock) and I'm running out of fuel not air flow.

[TSiWRX]

Noise is indeed an issue, and so is the stock turbo being fed enough air.

 

Other considerations include the potential for MAF-misbehavior (the need to recalibrate or, more concerning, unique behaviors such as the MAF-"inversions" we'll see with the old Perrin SRI and the SPT SRI), as well as higher IATs with most SRIs (even with a "heat-shield" in-place) when compared to the factory airbox (and since the IAT is our ECU's only way of determining air temperature, it starts pulling timing to protect the engine, when things get hot).

 

[anabolism]

Because the intake is not a restriction on a stock turbo. I run a a hacked stock airbox(to clear my FMIC piping) with an AVO panel filter on a VF39(STi turbo, larger than stock) and I'm running out of fuel not air flow.

What is a "Hacked" airbox? Sorry, I am a newb.

[LosAngelesLGT]

75% of Legacy GT owners do NOT want a drop in filter OR a CAI.

 

Either someone lied to you or you have not read enough posts.

EDITED: RUN A SEARCH! You got 40 posts but don't know SRI/CAI are bad/useless without a tune/on stock turbo - don't waste your money if your goal is stage 2!!!

 

IF stock to 330ish whp your stock airbox (which is a cold air intake btw) will not only be adequate - it will be superior to whatever you throw on that will cause gremlins underhood due to improper tuning for a/f ratio due to changes being read at the sensor on the intake. You already stated that stage 2 is a endgoal for you so more air is not going to help the engine breath better. If your OEM air filter is DIRTY and needs replacing, go ahead and get a washable aftermarket drop in filter, otherwise, unless you are changing turbo, injectors and FP or to a FMIC stop entertaining anything to do with intake.

 

You are planning on going stage 2. Basic Stage 2:

ERZ/CNT Downpipe ($180uncatted/$330catted)

and an INFAMOUS1 e-tune for $175 (or is it $150)...

If you want more TQ add that uber expensive SPT exhaust, not only do they look great, they sound great.

 

3/4 of Legacy owners are happy with the oem airbox and the majority of Legacy modders never go stage 3 or need more than an OEM airbox.

 

After asking questions and poking around on other threads on the board it seems that at least 3/4 of Legacy owners would prefer a drop in panel filter over an intake installed. I can't help but wonder why. Maybe cabin noise??

 

EDIT - keep in mind I am running around in a stage 3 car and only have a K&N intake because my stock airbox was sandwiching my FMIC hotside piping between the airbox and my engine timing cover causing the timing cover plastic to crack slightly. I wanted a better fit with my FMIC so I went CAI and paid for a tune.

[TSiWRX]

75% of Legacy GT owners do NOT want a drop in filter OR a CAI.

 

Either someone lied to you or you have not read enough posts.

NEWB SEARCH! You got 40 posts but don't know CAI are bad/useless.

 

I think that there should be a distinction made between a "CAI" - ©old (A)ir (I)ntake, versus a "SRI" - (S)hort ®am (I)ntake.

 

While true CAIs can still present with scaling and MAF-misbehavior concerns, they are virtually immune to the skyrocketing IAT that most SRIs will see. David Buschur, before his unfortunate departure from NASIOC (run-out by the few asshats there ), proved with a series of dyno runs that a CAI can net true gains, and that it was mainly due to getting "down" to a cooler incoming charge (he also went so far as to say that he'd never build a Subaru with a SRI, nor would ever offer an SRI for sale commercially).

 

The biggest downside of a true CAI, for most, is that as a daily-driver, "weathering" becomes somewhat of a concern - not in terms of the truly rare cases of "water-ingestion," but in terms of moisture accumulation on the MAF element, causing driveability concerns until rectified (early posts on the AEM CAI documents this very well).

[John M]

I wouldn't change the stock intake until you did a lot, including a bigger turbo and a FMIC.

 

http://moojohn.com/subaru/intake1.jpg

 

That's a $12 MAF housing with a filter long enough to actually touch the fender. Admittedly I haven't done any IAT logging yet because I'm still dialing in boost. In 98-100 degree weather I can still run 21 psi (with spikes to 23 that I'm working out) with zero knock issues on 93 pump. A great deal of that is due to the more efficient turbo and the giant WBR FMIC. I'd never recommend the same setup on a stock turbo/TMIC combination.

[LosAngelesLGT]

OP HERE IS A DROP IN K&N FILTER FOR $20 SHIPPED

http://legacygt.com/forums/showthread.php/fs-pa-oem-grille-k-n-drop-perrin-afta-maf-139387.html?t=139387

 

I think that there should be a distinction made between a "CAI" - ©old (A)ir (I)ntake, versus a "SRI" - (S)hort ®am (I)ntake.

 

You are 100% right as usual. I fixed my post to make it more clear

 

David Buschur, before his unfortunate departure from NASIOC (run-out by the few asshats there ), proved with a series of dyno runs that a CAI can net true gains, and that it was mainly due to getting "down" to a cooler incoming charge (he also went so far as to say that he'd never build a Subaru with a SRI, nor would ever offer an SRI for sale commercially).

 

Having missed that entire thing and having noted that a lot of DB's old posts are no longer up are you saying that gains are to be had on a tune with a CAI on a vf40/46? I am asking out of ignorance and to make more clear for myself and others. I went from vf40/oem airbox FMIC to vf39/CAI/FMIC so I really don't know from personal experience what a CAI could do powerwise at stage 2 levels but because fueling becomes an issue before amount of air I have a hard time imaginging the gains could be anything other than negligable from a possibly very minor drop in intake charge temp (again at stage 2).

[TSiWRX]

Admittedly I haven't done any IAT logging yet because I'm still dialing in boost. In 98-100 degree weather I can still run 21 psi (with spikes to 23 that I'm working out) with zero knock issues on 93 pump. A great deal of that is due to the more efficient turbo and the giant WBR FMIC.

 

I think that as long as you're moving, you'll be OK.

 

The problem with IATs is seen more in city-driving - I've got a GReddy Informeter on the OBD-II, so this is something that I can keep watch of, in real-time, and I really do grimace a bit, in the summertime, based on my usual commuting habits and routes.

 

The stop-and-go really kills it, and anything below about 30 MPH doesn't get much air flowing through the factory setup.

 

I've got a pretty decent heat-shield that I jury-rigged from a K&N's, and also have an intercooler sprayer (just water, nothing fancy) rigged up. Nothing really helps until my road-speed hits around 35 (and yes, I do have the factory "ram" still in-place). It then cools-off very rapidly. But this process is repeated over-and-over, as soon as I come to a stop or when I slow.

 

Undoubtedly, with a front-mount, that's a totally different story!

 

 

---

 

 

You are 100% right as usual. I fixed my post to make it more clear

 

Nah, not "right," bro, just a little more elaborate (and thus, more typing, too!!! :spin:) in trying to get everything brought into the responses, so that some knucklehead doesn't then come in and say X or Y, to muddy the issue.

 

Having missed that entire thing and having noted that a lot of DB's old posts are no longer up are you saying that gains are to be had on a tune with a CAI on a vf40/46? I am asking out of ignorance and to make more clear for myself and others. I went from vf40/oem airbox FMIC to vf39/CAI/FMIC so I really don't know from personal experience what a CAI could do powerwise at stage 2 levels but because fueling becomes an issue before amount of air I have a hard time imaginging the gains could be anything other than negligable from a possibly very minor drop in intake charge temp (again at stage 2).

I *think* that his CAI/SRI testing came *before* he switched the TR out to a larger setup, but I can't be 100% positive.

 

All I remember was how the community's eyes were opened to the difference between a true-CAI versus a SRI (and, of course, the other one was the proof that an aftermarket UP actually did yield some gains, rather than just/only shifting the curve further left).

 

And it's exactly what you're saying: that the gains are from the difference in "temperature-in." His main goal in that particular trial was to show not only that the factory Subaru intake is quite a piece of good engineering, but also that with an SRI, the problem of IAT management is unavoidable, and that with a roadgoing vehicle (i.e. something that's driven on the streets), the lack of circulation and the residual high IAT are both negatives and should be avoided, if at all possible.

 

Thank you for having me clarify that part! It wasn't until I re-read both this thread as well as your last post that I realized I'd left something out, too, in my earlier reply!

 

But even with the potential for gains, with a CAI, I think what's important for newcomers here to realize is that the gains aren't without cost - that in many cases, the CAI does indeed still have to be "accounted for" with a tune, to at least adjust for scaling, and that there are potential daily-driveability concerns to be had, too.

 

Let's say that the gain is decent, that it's 10 wHP on David's heartbreaker of a Mustang.

 

Driveability aside, is it worth the cost of the CAI, plus tune?

 

I'd say "no."

 

Instead, I'd rather put that cost towards a good e-tune or live-tune, if one's intent on staying at "Stage II" or therabouts, or to bank the dollars for a future intake, which may become - as in your case and that of John M's and many others' - necessary when the intake tract is modified due to turbo and turbo-support measures.

[LosAngelesLGT]

"as in your case and that of John M's and many others' - necessary when the intake tract is modified due to turbo and turbo-support measures."

 

Good to know tha the gains could be as high as 10hp. Makes me feel less bad about having to yank out a perfectly good factory intake to get good FMIC fitment. I can only assume that the higher the delta between the engine bay temp and the outside temp the greater the difference with the CAI. (chime in here if you know one way or other - i assume it becomes less effective as the outside temp gets hotter)

 

(PS the whole truth is that the FMIC fits with the airbox, just not in my car that has a carfax to the front end and is not 100% straight at the bumper)

[TSiWRX]

I can only assume that the higher the delta between the engine bay temp and the outside temp the greater the difference with the CAI. (chime in here if you know one way or other - i assume it becomes less effective as the outside temp gets hotter)

 

^ That's the way I see it, too, that the bigger differences would net bigger gains - or, if viewed another way, just a lesser loss.

 

But alas, I'm only a layman at this kind of stuff, and what's worse, I took "Physics for Poets" in my undergrad days. Hey, what do you expect, I'm a biologist!

 

That would seem right to me, instinctively and with a bit of reasoning, but I honestly don't know if there might be something else we're missing. Still, it should follow, given the long (and sadly lost! when the database crashed on our local Scooby-lover Forum ) post that one professional engineer made, to prove/disprove to himself that actual intake air temperature does matter (he ended up disproving his own refusal to believe that intake air temperature actually mattered he's an awesome guy).

 

 

----

 

What I say to newcomers who look at intakes - SRIs, in-particular, as they are so popular - as their first mod (or only mod) is precisely that they should not expect gains, and that they may actually see loss, or, even worse, potential danger, based on IAT concerns that arise from daily-driving as well as, for the latter, from MAF-scaling/inversion.

 

If they want one for the way it sounds, or if they want it because they think it's cool - that's fine. I just don't want them to have any delusions, nor for them to be misled, and as with you and other old-hats here, I also want them to "do it right," to at least get it accounted for, with a custom tune of some sort or another, not for any supposed power gains, but rather, to just insure that they're operating within a safe envelope, with good margins.

 

----

 

Good to know that the gains could be as high as 10hp. Makes me feel less bad about having to yank out a perfectly good factory intake to get good FMIC fitment.

 

With Buschur's heartbreaker of a Mustang, that 10 wHP truly is a good, butt-dynoable real-world gain. Stock peanut/helicopter-eye STis dyno there at 200/200 (wHP/wTQ), with variability of +/-5, consistently.

 

But as you can imagine, those gains aren't guaranteed, by any means of the word.

 

A fellow local enthusiast (who now owns an '09 2.5i BL) had his Perrin SRI-fitted WRX, with a fully-supported 18G setup, on the dyno, with Tim Bailey tuning, and they just couldn't get anywhere. Finally, they pulled off the intake, reverting to a modified stock airbox setup - IIRC, close to 30 wHP was "recovered," and the tuning issues resolved.

[TravisGT]

Because the intake is not a restriction on a stock turbo. I run a a hacked stock airbox(to clear my FMIC piping) with an AVO panel filter on a VF39(STi turbo, larger than stock) and I'm running out of fuel not air flow.

 

 

How much hacking did you have to do? I have the Typhoon intake and I was going to take it off and put the factory air box back on. Then I ordered the itsme FMIC. I decided to keep the Typhoon because the FMIC fits fine with it. Eventually I will upgrade the turbo but for now the VF40 stays. Either way, once I put the FMIC on I am going to get infamous to tune my car. If the hacking isn't that bad then I will put the factory box back on.

[TSiWRX]

^ The Typhoon is honestly one of the better SRIs out there - while I honestly don't know about whether you'll see any gains/loss, due to the IAT concerns (which in-turn will be affected by your driving practices and preferences), many here have used this intake successfully, and this is reflected in the fact that it remains one of the few SRIs which actually holds its value decently well, in the secondary market.

[LosAngelesLGT]

I am running a Typhoon (as stated before) not because of any gains but because it helps loosen up the hot side fitment of the FMIC piping where it passes the timing cover between the factory airbox and the engine.

 

Not all LGT are the same and within factory spec variance it may fit well or may not.

 

Keep the intake till you toss in the FMIC and make sure you are happy with overall fitment. If not, put in the K&N and get tuned along with the FMIC otherwise, stay stock airbox till over 300+whp.

 

I would not be running a typhoon or any intake if the fmic in my car fit well but with a carfax hit on the front end, it is just not perfect enough to fit loosely.

 

Again, factory variance could be the reason for this too. As you know, RacerX FMIC was made for the Typhoon to fit so you already know you will have ZERO fitment issues with it and you already own it.

 

Oh yeah, thanks for your lengthy and very well spoken responses TSIWRX. I enjoy your knowledge base and writing/presentation style.

[TSiWRX]

Not all LGT are the same and within factory spec variance it may fit well or may not.

 

+ eleventybillion!!!!

 

This always seem funny to newcomers to our community, but the old-hats will testify again and again to how true that statement is.

 

Heck, for those who are new, let's pick something very recent: just look at the Invidia Q300 cat-back exhaust fitment issues...look at how different things are, vehicle-to-vehicle.

 

Those of us who've been here a while and who have tried various aftermarket components on our vehicles know well that many items need a little tweak here and there, to fit properly - even if it fits like the proverbial glove on one person's LGT, it's no guaranty that it's going to be that way, on another.

 

 

Oh yeah, thanks for your lengthy and very well spoken responses TSIWRX. I enjoy your knowledge base and writing/presentation style.

 

:redface: My wife calls it "diarrhea at the keyboard!"

[m sprank]

RacerX FMIC and OEM airbox on 2008 5EAT. BNR EVO16g turbo.

[TravisGT]

I think I am going to hang on to the Typhoon for now. I have an LC-1 WB on the way too me. Once I get the FMIC and WB02 installed I will get everything tuned in (infamous). I know he can tune without a WB but I want to make sure it is right plus I will be doing more mods in the future so I wanted to go ahead and get it set up.

[LosAngelesLGT]

MSprank will tell you this is true too - Travis, Infamous1 is very knowledgeable about the Typhoon and its scaling. He gave me a very safe to drive on pre-tune when I was going stage 3.

 

Bryan made RacerX FMIC to fit with it.

MSprank checked fitment on a variety of cars.

Infamous1 has already tuned all these parts.

 

Sounds like a win-win.

[TSiWRX]

^ +1.

 

And that again goes well to demonstrate that the K&N is one of the more stable intakes available.

 

My pre-tune "safe" map from PDXT, taking what they knew of the Perrin SRI into account, ran the car unacceptably lean for Tim Bailey (then also of PDXT) when he started making pulls on the dyno - he aborted the run early, and remapped.

[TravisGT]

The WB can only be helpful so why not? Otherwise I know Infamous doesn't really need it. I appreciate all the help given to me so far by everybody. I would be lost without it. I have read a lot of your posts too Los, and they have been extremely helpful as well. I have worked on and restored a lot of vehicles but they were all NA and carbureted. Forced induction and fuel injection is all new to me. I understand HOW it works but thats it. Sorry............this post is about intakes and I turned it into how inept I am.

[TSiWRX]

^ Don't sell yourself short!!!

 

The truth of the matter is that late-generation force-fed Subarus are simply rather peculiar about how they suck air - that's all.

[TravisGT]

^ Don't sell yourself short!!!

 

The truth of the matter is that late-generation force-fed Subarus are simply rather peculiar about how they suck air - that's all.

 

Thanks. Inept might be too strong. How about "current mechanical knowledge not so helpful given the current application"? I can rebuild a hydraulic motor that spins a tank turret? Nope, doesn't apply.......dang!

[TSiWRX]

^ Hey, mount that tank turret to our LGTs...

 

Oh, wait, might be illegal....

[m sprank]

The Typhoon is incredibly stable for a LGT intake. Scaling is very consistent. Nothing wrong with having a WB. Always good to be able to keep an eye on it.

[goneskiian]

RacerX FMIC and OEM airbox on 2008 5EAT. BNR EVO16g turbo.

Do you still have the "bellows" attached to the bottom of the airbox too?

 

Really quite surprised this all fits together. Very cool.