Intake Question

[jude26]

Hi, I'm new to this board. I plan on buying a Legacy GT, but it will probably have to wait until the 2006 model comes out next year. I've test driven the car and all I have to say is that its freaking awesome. Now for my question, I read a post somewhere saying that its better to leave the air filter stock instead of upgrading to a cone filter. Is that true and why? I like the sleeper aspect of this car. I own a 99 Maxima SE 5spd, which also has a bit of a sleeper aspect, considering that only 6% of Maximas at that time were coming out with stick. My best run stock was 15.7, but after installing an intake, it went down to 15.2. Is it possible to see this kind of improvement on a GT if an intake was installed? Thanks.

[Drift Monkey]

[quote name='jude26']Hi, I'm new to this board. I plan on buying a Legacy GT, but it will probably have to wait until the 2006 model comes out next year. I've test driven the car and all I have to say is that its freaking awesome. Now for my question, I read a post somewhere saying that its better to leave the air filter stock instead of upgrading to a cone filter. Is that true and why? I like the sleeper aspect of this car. I own a 99 Maxima SE 5spd, which also has a bit of a sleeper aspect, considering that only 6% of Maximas at that time were coming out with stick. My best run stock was 15.7, but after installing an intake, it went down to 15.2. Is it possible to see this kind of improvement on a GT if an intake was installed? Thanks.[/quote] I'd say it is pretty true. Turbo Subarus tend to lean out when a intake system is installed. Besides, your money is better spend elsewhere (like an ECU flash).

[RobY]

Yep its true. Vishnu tuning actually showed a 5 hp LOSS to the wheels when the stock filter was replaced in a WRX. Most staged stetups for the WRX are done with factory boxes and filters.

[SUBE555]

The N/A models tend to be able to work with inproved intake flow, but as the others have noted, most U.S. tuners don't use intakes for this reason, at least not on their non-extreme packages. Subaru's are a different breed.

[jude26]

It should be ok to put on a K&N Panel filter, right?

[SUBE555]

It's really not needed and shouldn't garner much of anything. Really just a waste of money. I've also seen recommendations against filters you oil because it could damage the MAF sensor. Spend a bit more, get a reflash and you're making better power.

[awdG35killer]

its the same with the turbo vw/audi's... cai/wai/filter = noise + oil in maf(many ppl have to either clean or replace the maf, and those bastards are expensive) but on N/A engiones they are great.

[RobY]

Dont put in a panel filter... Dynoed and tuned with a panel filter some people report Losses.

[outahere]

The Australian tuner MRT seems to like oiled cone filters. See this thread: [url]http://www.legacysti.com/viewtopic.php?t=1782[/url]

[kanoswrx]

If you don't have engine management don't get an intake, simple as that. On WRX's little to no hp has been gained by doing an intake even after tuning. I personally don't think its worth the time/money or trouble. You deffinetly won't feel any increase in power. If all you want is the noise, take off the little snorkel piece in the fender wheel well, that will let you hear the intake and turbo more.

[meier motor sports]

[quote name='kanoswrx']If you don't have engine management don't get an intake, simple as that. [/quote] now my question is. do u get engine managment before or after an intake? woudlnt u want the intake on and then the engine tuned to it?

[BoxerGT2.5]

You are going to get next to nothing out of an intake. Now a days manufactures have put alot of design into a cars intake. I found this out with my Rx-8. Many are VFAD and/or utilize helmholtz resonant tuning....not something you can reproduce with a CAI or SR. I found just putting a greenfilter in to help it breath better was more than the SR.

[SUBE555]

Intake mods on many cars don't garner the results they claim. In many ways it is a fad. Intakes, Boost Controllers, things like here in the states we generally recommend people stay away from unless they know full-well what they are doing with them. I've heard of quite a few instances of people doing serious damage because they don't know what they are doing. First rule of thumb, make sure you can get the air out effectively before you stuff more in. I'd do an ECU reflash & exhaust work first.

[wunderkind]

so when come time to change the old air filter, do you recommend going back to subaru's paper filter or something else? I didn't know Subaru reverted back to MAF. It was a problem for the 1999 RS and Subaru switched to MAP for 2000+ RS. So it was intake heaven for those owners never to worry about spoiled MAF sensors.

[Drift Monkey]

[quote name='wunderkind']so when come time to change the old air filter, do you recommend going back to subaru's paper filter or something else? I didn't know Subaru reverted back to MAF. It was a problem for the 1999 RS and Subaru switched to MAP for 2000+ RS. So it was intake heaven for those owners never to worry about spoiled MAF sensors.[/quote] I always stick to Subaru filters. NO comprimise in filtering abilities for me.

[Max Capacity]

On my 00GT I removed the snorkle that hung from the intake and installed a Green filter. I feel the car gained a little midrange power. I never dynoed it so there is no ture way to prove it. But I have been diving for over 30 years and used to drag race so I have a good idea what the power curve feels like. My son and I may try a home made manual boost controller this Sunday. He made one for are Civic and is happy with. It cost about $12.00 to make one.

[SUBE555]

Wunderkind, I believe it is because all of their turbo motors had used MAF sensors. Their 2.5L N/A motors haven't reverted back at all, not that I am aware of at all. MAF sensors are more sensative to non-WOT conditions, conditions where the turbos need the most amount of input.

[Drift Monkey]

[quote name='Max Capacity']On my 00GT I removed the snorkle that hung from the intake and installed a Green filter. I feel the car gained a little midrange power. I never dynoed it so there is no ture way to prove it. But I have been diving for over 30 years and used to drag race so I have a good idea what the power curve feels like. My son and I may try a home made manual boost controller this Sunday. He made one for are Civic and is happy with. It cost about $12.00 to make one.[/quote] I would recommend against this.

[Boostjunkie]

[quote name='Drift Monkey'][quote name='Max Capacity']On my 00GT I removed the snorkle that hung from the intake and installed a Green filter. I feel the car gained a little midrange power. I never dynoed it so there is no ture way to prove it. But I have been diving for over 30 years and used to drag race so I have a good idea what the power curve feels like. My son and I may try a home made manual boost controller this Sunday. He made one for are Civic and is happy with. It cost about $12.00 to make one.[/quote] I would recommend against this.[/quote] Why? I believe that some WRX owners use a manual boost controller. The famed Hallman valve and Gillis valves are simply homemade boost controllers that are made from parts you can get at a plumbing supply store. They are not high tech at all, but I have an 8 year old Hallman valve in my Merkur XR4Ti that still works perfectly. Obviously, I would hope that the poster making the valve knows what he is doing, and is conservative in cranking up the boost. Regarding intakes, most cars see minimal gains, but my wife's Mazda 6s has an Injen CAI which has been independantly proven to yield over 10 whp. It is most certainly noticable. Intakes do work well on a few cars. I do find it odd that Subarus tend not to respond well to intakes. While it is definately old-school tech, my XR4Ti benefited greatly from a K&N cone filter as well. The total power increase wasn't everwelming, but it definately helped spool-up. Of course, if the stock air cleaner in the WRX and LGT have enough capacity so as to not present any kind of a restricition, then opening the intake would serve no purpose.

[Drift Monkey]

[quote name='Boostjunkie'][quote name='Drift Monkey'][quote name='Max Capacity']On my 00GT I removed the snorkle that hung from the intake and installed a Green filter. I feel the car gained a little midrange power. I never dynoed it so there is no ture way to prove it. But I have been diving for over 30 years and used to drag race so I have a good idea what the power curve feels like. My son and I may try a home made manual boost controller this Sunday. He made one for are Civic and is happy with. It cost about $12.00 to make one.[/quote] I would recommend against this.[/quote] Why? I believe that some WRX owners use a manual boost controller. The famed Hallman valve and Gillis valves are simply homemade boost controller that are made from part you can get at a plumbing supply store. They are not high tech at all, but I have an 8 year old Hallman valve in my Merkur XR4Ti that still works perfectly. Obviously, I would hope that the poster making the valve knows what he is doing, and is conservative in cranking up the boost. Regarding intakes, most cars see minimal gains, but my wife's Mazda 6s has an Injen CAI which has been independantly proven to yield over 10 whp. It is most certainly noticable. Intakes to work well on a few cars. I do find it odd that Subarus tend not to respond well to intakes. While it is definately old-school tech, my XR4Ti benefited greatly from a K&N cone filter as well. The total power increase wasn't everwelming, but it definately helped spool-up. Of course, if the stock air cleaner in the WRX and LGT have enough capacity as to not present any kind of a restricition, then open the intake would serve no purpose.[/quote] Too risky, especially in the hands of inexperienced folks. Search on nasioc for "partial throttle full boost." The car's A/F conditions become dangeously lean under partial throttle.

[SUBE555]

BoostJunkie, your wife's Mazda6 is a naturally aspirated and as noted, Subaru turbo engines just don't react the same with CAI's. We're hitting redundancy here. Thanks for jumping in on MBC's first DM. The reason we don't recommend them is because not enough people know how to use them and for the reasons Drift Monkey noted. That can be very dangerous if not compensated for. [u]If you know how to use them on Subaru turbocharged engines, great![/u] If not, stay away from them if you want to distance yourself from a greater likelihood of problems. So instead of taking it case by case, we just recommend against them. Those who know how to work with them already don't even ask. We say the same for Manual Boost Controllers (MBC) and Intakes.

[Boostjunkie]

Fair enough guys. I realize your stand on the intake issue, and really don't dispute it for Subarus. I was just stating my experience that for at least one car out there, CAI's can be more than just a gimmick or fad, the whole FI vs. NA issue aside. I obviously have no previous experience with Subaru's and MBC's, but I do have quite a few years tweaking turbocharged cars. Frankly all I want to do with my LGT when I get it is an ECU reflash, catless uppipe and maybe a turboback exhaust. I don't have the desire to really mess around with the car. I do feel that those who have a solid understanding of tuning turbocharged cars shouldn't be afraid of MBC's.

[John M]

Will someone please go into further detail on the whole PTFB issue? If it goes lean just because there's more airflow than expected at part throttle, that's the crappiest engine management I've ever heard of. What is the MAF for? It's telling the ECU how much air is coming in. Why does it ignore this reading? Is it knocking at this point or is there just a high EGT? Besides, if it's really a big problem, I'll throw in an aftermarket FPR and dial in a few extra psi base fuel pressure. Having said that, I know of several WRXs with MBCs and they do nothing special to modulate boost. They've each driven over 20k miles with the MBC and had no trouble. That's exactly what I plan to do with my car. Oh, and throw me into the "been tuning turbos for many years" crowd. DSMs since 1992; Stealth twin turbo since 2000, and I bult my brother's single-turbo 94 Supra. Get ready to see what an original DSMer can do on an original DSMer budget! To me, a reflash is a great solution but stupidly priced at $1k for your first time. That's pure "because we can charge it" pricing. I promise if the price was cut in half, more than twice as many people would buy it, thus making more profit for everyone.

[Xenonk]

[quote name='John M'] If it goes lean just because there's more airflow than expected at part throttle, that's the crappiest engine management I've ever heard of. What is the MAF for? It's telling the ECU how much air is coming in. Why does it ignore this reading? Is it knocking at this point or is there just a high EGT? [/quote] If you ever looked at a maf sensor, you'll notice it only takes a SAMPLE or PORTION of air based on the STOCK intake pipe sizing.. when you change the intake pipe sizing to say twice the size, the engine management wont know that (and most likely it's not even part of it's parameters to calculate such size) and it would lean out. Proper Engine Management is the best thing to do with today's cars based on the billion amounts of electronic to run and monitor the engine. Just the ETC (Electronic Throttle Control) has a few issues I would like to address so that I dont get that delayed rev-match pump... remember, it's all in the parameters of the ECU's programming that will limit and hinder our goals of performance. Keefe

[John M]

I'm fully supportive of the actual intake issue. It makes sense that if you have more air bypass the sensor then of course it'll give false readings. That's the same with any MAF-equipped car, as all of my previous vehicles have been. I was more concerned with the PTFB issue. It's actually deserving of its own thread - I hate to hijack this one but since it was brought up I thought we might as well expand on it. It's silly that you should have to worry about your turbo spooling up *too well*.