Who Likes the Stock Air System on their Subaru?

Charlton · 08-18-2012, 11:23 PM

I've put intakes on Subarus in the past and they sound good but I never saw any real benefit.

Who likes the stock airsystem on their Subaru? I think it is a good design on my 2002 Forester S. There is a large air reservoir behind the throttle that gives me solid low end torque but I can still get good acceleration.

I've found intakes hurt power in the powerband where I spend most of my driving. They only help when I'm smashing down the pedal which is rare. I'm not a race car driver lol.

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chazly413 · 08-19-2012, 03:20 PM

They really do not accomplish anything. The stock intake is fine.

Filthy_Mchaggis · 08-19-2012, 09:24 PM

I feel the same way. I tried the hybrid setup and since most of my driving is in the city and below 3600 rpms, it made me appreciate the stock intake more. I don't think the heatsoak issue made it any better. That aluminum pipe would get so hot, and stay hot for quite a while. I wonder how high it was raising the intake temps?

chazly413 · 08-19-2012, 09:26 PM

Quote:

Originally Posted by Filthy_Mchaggis

I feel the same way. I tried the hybrid setup and since most of my driving is in the city and below 3600 rpms, it made me appreciate the stock intake more. I don't think the heatsoak issue made it any better. That aluminum pipe would get so hot, and stay hot for quite a while. I wonder how high it was raising the intake temps?

Probably not very noticeable. The air is moving through there so quickly it has little time to be warmed.

Charlton · 08-19-2012, 11:20 PM

I looked my stock intake on my 2002 Forester this evening, same intake as the Impreza RS. It looks like a very goood system. The source of air is right behind the passenger side of the front of the car. This is a good source of "fresh air". The polymer material of the factory tubing IMO does a better job of absorbing heat than some hot aluminum tubing with some Asian prostitute marketing advertises. Immediately behind the throttle is a large air reservoir with a filter. This gives the engine a mouthfull of air vs the "tube".

Look it over sometime, it's actually a very good system since it pulls air from the coolest part of the engine bay without the risk of sucking in water, absorbs heat, and filters air immediately behind the throttle.

Go Subaru!! Thannk you for giving us an excellent intake from the factory : )

Back Road Runner · 08-19-2012, 11:44 PM

The stock intake is not restrictive at all. I mean 0% and I mean zero percent. There is no point to changing out the intake. There can be a gain, but it requires a different ECU tune. Not doing so will actually lose power in the midrange. It requires a tune to get that midrange back. Then the actual gain comes from being able to pull in colder air than stock. If you can't do that, you're not gaining. You can't gain any top end with any intake change, any. You can only lose midrange, a sizable amount too, 20 or so ft-lbs.

Counterfit · 08-19-2012, 11:53 PM

Have you forgotten about the hybrid intake thread? In the very first post, you can plainly see that the stock intake on 05-07 (and probably beyond) is not perfect from 4000-6500rpm.

Charlton · 08-19-2012, 11:53 PM

Quote:

Originally Posted by Back Road Runner

The stock intake is not restrictive at all. I mean 0% and I mean zero percent. There is no point to changing out the intake. There can be a gain, but it requires a different ECU tune. Not doing so will actually lose power in the midrange. It requires a tune to get that midrange back. Then the actual gain comes from being able to pull in colder air than stock. If you can't do that, you're not gaining. You can't gain any top end with any intake change, any. You can only lose midrange, a sizable amount too, 20 or so ft-lbs.

Agreed...from my experience aftermarket intakes decrease performance unless I live at the race track lol! Swap paper filters every other oil change and have fun : )

RaceFaceXC · 08-20-2012, 10:02 PM

The best design would be the stock layout/dimensions with a smooth, mandrel bent tube in place of the molded plastic with accordion ribs to allow flex. It just so happens that someone had already thought of that and shared it with the world years ago. Logging provides data that supports the theory that it makes small gains in the areas that need it most and liars nothing anywhere.

Counterfit · 08-20-2012, 10:52 PM

^ This.

GEE-OTTO · 08-21-2012, 08:22 AM

Stock is the best for our cars, hell even for the majority of LGT/WRX/FXT/OBXT/STi's

Boxerscoopy90 · 08-21-2012, 01:15 PM

Guys what about map sensor cars . My friend has an impreza with a map and he has an aftermarket cai and he said its very nice and much improved throttle response but i dont know why do cars with map sensor would benifit from a cai while others with maf dont

chazly413 · 08-21-2012, 01:26 PM

It's not that MAP-equipped cars benefit more from it, they just don't get the negative effects that an aftermarket intake puts on a MAF-equipped car. All of this conversation about hybrid intakes and rich down low and all the bad stuff associated with intakes is only for MAF-equipped cars.

cmiovino · 08-21-2012, 01:53 PM

I've tried the hybrid on my old MAF based '95. Didn't do crap... and it was an AEM SRI to the stock airbox. Left my '98 OBS stock with a drop in filter.

Now... my dad's '04 Forester MAP... totally different story. The Ganzflow replica made a nice sound difference and it has an actual growl to it now... for $30 shipped. Hopefully MPGs increase... that's what we're shooting for now.

Boxerscoopy90 · 08-21-2012, 06:38 PM

Quote:

Originally Posted by chazly413

It's not that MAP-equipped cars benefit more from it, they just don't get the negative effects that an aftermarket intake puts on a MAF-equipped car. All of this conversation about hybrid intakes and rich down low and all the bad stuff associated with intakes is only for MAF-equipped cars.

Yea so u mean both on both map and maf they dont provide real gains but on maf they might decrease performance while on map performance isnt hurted right ? However i've read that the cobb sri which goes into the fender provided good gains for map .Btw i have another question do a better throttle response always means more power or not always . Thanks

Charlton · 08-21-2012, 09:52 PM

From my experience the increased sound of the throttle is what makes people think they are getting more power. At least that's what I thought when I had an injen CAI on a 98 Legacy GT.

Drop a fresh, quality paper air filter in a stock NA Subaru and floor it. It might not be as loud as an intake but it will have better low end torque to get you moving and excellent high RPM performance. Can anyone really tell a 6 hp difference? The stock design on my 02 Forester is very good. It keeps a large supply of filtered air immediately behind the throttle and it pulls air from the front of the engine behind the passenger side head light.

MarcoPolo360 · 08-21-2012, 10:01 PM

Quote:

Originally Posted by Charlton

From my experience the increased sound of the throttle is what makes people think they are getting more power.

The placebo effect strikes again.

RaceFaceXC · 08-21-2012, 10:08 PM

The airbox and/or tq box it's not an air reservoir ready to open the gates on demand, it's a way to transition from a smaller diameter pipe to a square box with relatively even flow across the filter. The shape and volume may have some beneficial resonant effects, too.

lavid2002 · 08-21-2012, 10:15 PM

A lot of people just toss CAIs on their cars because they don't have enough experience to do other modifications, it's inexpensive, and their basic understanding is that factory airboxes are restrictive and that CAIs help them "Breathe" better.

Charlton · 08-21-2012, 11:28 PM

Quote:

Originally Posted by RaceFaceXC

The airbox and/or tq box it's not an air reservoir ready to open the gates on demand, it's a way to transition from a smaller diameter pipe to a square box with relatively even flow across the filter. The shape and volume may have some beneficial resonant effects, too.

This is a good explanation. It does help with low end torque in my experience.

Kopernicus · 08-23-2012, 04:52 PM

I've been reading a lot on the subject, and the stock intake system is best for all around performance...

Except for reducing intake temps. My Saab 92x 2.5i had the stock air inlet in the engine bay. After reading the williarty write ups here I was going to build the whole hybrid intake. With a scan gauge I noticed the stock intake temps would always skyrocket in traffic or after the car being parked on errands (140+ degrees) sapping power.

Then I added a used WRX style inlet horn and didn't see much improvement. In fact the temps really went south. The horn does not fully match the 2.5i snorkus so I taped it up. Still no improvement. Then I noticed two things: without the proper mount the WRX inlet sat on the radiator and in stock WRX the inlet is sealed off so it does not pull under hood air and pulls high pressure air from in front of the radiator.

Got a used WRX snorkus and a new lower hood seal from Subaru. The WRX snorkus is about 0.2" larger in diameter on the air box side (still shoe horns in!) and matches the inlet horn. It also lifts the angle of the horn to push it up against the lower hood seal and hold it off the radiator.

Problem solved! My intake temps never are over 120 in traffic or after being parked and they cool to 4-8 above ambient after a minute or two of driving. Stoplight to stoplight I have more power and a quicker throttle, it never feels heat soaked anymore.

More power, probably not much, but greater drive ability in getting the power that should be there.

Also the engine growl is pleasantly noticeable (I never heard it before) and everything is OEM. Total price: $35 in used and new parts.

Im so happy with it I may forego the rest of the hybrid.

Counterfit · 08-26-2012, 11:24 AM

You can put some heat reflecting material around the new tube, or use ABS piping.

cal_look_zero · 08-26-2012, 12:39 PM

I just replaced the stock snorkus on my OBS with a 2.5 frankenmotor and eliminated all hesitation I've been trying to diagnose for awhile now. D'oh!

08-18-2012, 11:23 PM	#1
Charlton Scooby Newbie Member#: 43038 Join Date: Sep 2003 Location: Franklin, Tennessee U.S. Vehicle: 2002 Forester S Black	Who Likes the Stock Air System on their Subaru? I've put intakes on Subarus in the past and they sound good but I never saw any real benefit. Who likes the stock airsystem on their Subaru? I think it is a good design on my 2002 Forester S. There is a large air reservoir behind the throttle that gives me solid low end torque but I can still get good acceleration. I've found intakes hurt power in the powerband where I spend most of my driving. They only help when I'm smashing down the pedal which is rare. I'm not a race car driver lol. * Registered users of the site do not see these ads.

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08-19-2012, 03:20 PM	#2
chazly413 Scooby Specialist Member#: 151079 Join Date: Jun 2007 Chapter/Region: MAIC Location: College Park, MD Vehicle: 2005 2.5RS RBP s-techs mad tyte yo	They really do not accomplish anything. The stock intake is fine.

08-19-2012, 09:24 PM	#3
Filthy_Mchaggis Scooby Newbie Member#: 275489 Join Date: Mar 2011 Chapter/Region: Tri-State Location: Philadelphia Vehicle: 2011 2.5i Premium OBP	I feel the same way. I tried the hybrid setup and since most of my driving is in the city and below 3600 rpms, it made me appreciate the stock intake more. I don't think the heatsoak issue made it any better. That aluminum pipe would get so hot, and stay hot for quite a while. I wonder how high it was raising the intake temps?

08-19-2012, 11:20 PM	#5
Charlton Scooby Newbie Member#: 43038 Join Date: Sep 2003 Location: Franklin, Tennessee U.S. Vehicle: 2002 Forester S Black	I looked my stock intake on my 2002 Forester this evening, same intake as the Impreza RS. It looks like a very goood system. The source of air is right behind the passenger side of the front of the car. This is a good source of "fresh air". The polymer material of the factory tubing IMO does a better job of absorbing heat than some hot aluminum tubing with some Asian prostitute marketing advertises. Immediately behind the throttle is a large air reservoir with a filter. This gives the engine a mouthfull of air vs the "tube". Look it over sometime, it's actually a very good system since it pulls air from the coolest part of the engine bay without the risk of sucking in water, absorbs heat, and filters air immediately behind the throttle. Go Subaru!! Thannk you for giving us an excellent intake from the factory : )

08-19-2012, 11:44 PM	#6
Back Road Runner Scooby Guru Member#: 60082 Join Date: Apr 2004 Chapter/Region: MWSOC Location: Minnesota Vehicle: 2004 Forester STI Silver	The stock intake is not restrictive at all. I mean 0% and I mean zero percent. There is no point to changing out the intake. There can be a gain, but it requires a different ECU tune. Not doing so will actually lose power in the midrange. It requires a tune to get that midrange back. Then the actual gain comes from being able to pull in colder air than stock. If you can't do that, you're not gaining. You can't gain any top end with any intake change, any. You can only lose midrange, a sizable amount too, 20 or so ft-lbs.

08-19-2012, 11:53 PM	#7
Counterfit Scooby Specialist Member#: 124254 Join Date: Aug 2006 Chapter/Region: NESIC Location: Rhode Island Vehicle: 2006 06 SGM Slowbaru "The Scoobinator"	Have you forgotten about the hybrid intake thread? In the very first post, you can plainly see that the stock intake on 05-07 (and probably beyond) is not perfect from 4000-6500rpm.

08-20-2012, 10:02 PM	#9
RaceFaceXC Scooby Specialist Member#: 165749 Join Date: Dec 2007 Chapter/Region: South East Location: stupid Florida Vehicle: 2007 No YELLING on the bus!	The best design would be the stock layout/dimensions with a smooth, mandrel bent tube in place of the molded plastic with accordion ribs to allow flex. It just so happens that someone had already thought of that and shared it with the world years ago. Logging provides data that supports the theory that it makes small gains in the areas that need it most and liars nothing anywhere.

08-20-2012, 10:52 PM	#10
Counterfit Scooby Specialist Member#: 124254 Join Date: Aug 2006 Chapter/Region: NESIC Location: Rhode Island Vehicle: 2006 06 SGM Slowbaru "The Scoobinator"	^ This.

08-21-2012, 08:22 AM	#11
GEE-OTTO Scooby Specialist Member#: 201277 Join Date: Jan 2009 Chapter/Region: MAIC Location: Arlington VA Vehicle: 2008 Legacy OBP	Stock is the best for our cars, hell even for the majority of LGT/WRX/FXT/OBXT/STi's

08-21-2012, 01:15 PM	#12
Boxerscoopy90 Scooby Newbie Member#: 309974 Join Date: Feb 2012	Guys what about map sensor cars . My friend has an impreza with a map and he has an aftermarket cai and he said its very nice and much improved throttle response but i dont know why do cars with map sensor would benifit from a cai while others with maf dont

08-21-2012, 01:26 PM	#13
chazly413 Scooby Specialist Member#: 151079 Join Date: Jun 2007 Chapter/Region: MAIC Location: College Park, MD Vehicle: 2005 2.5RS RBP s-techs mad tyte yo	It's not that MAP-equipped cars benefit more from it, they just don't get the negative effects that an aftermarket intake puts on a MAF-equipped car. All of this conversation about hybrid intakes and rich down low and all the bad stuff associated with intakes is only for MAF-equipped cars.

08-21-2012, 01:53 PM	#14
cmiovino Scooby Specialist Member#: 134005 Join Date: Dec 2006 Chapter/Region: MAIC Location: Pittsburgh, PA Vehicle: 2004 WRX Premium PSM	I've tried the hybrid on my old MAF based '95. Didn't do crap... and it was an AEM SRI to the stock airbox. Left my '98 OBS stock with a drop in filter. Now... my dad's '04 Forester MAP... totally different story. The Ganzflow replica made a nice sound difference and it has an actual growl to it now... for $30 shipped. Hopefully MPGs increase... that's what we're shooting for now.

08-21-2012, 09:52 PM	#16
Charlton Scooby Newbie Member#: 43038 Join Date: Sep 2003 Location: Franklin, Tennessee U.S. Vehicle: 2002 Forester S Black	From my experience the increased sound of the throttle is what makes people think they are getting more power. At least that's what I thought when I had an injen CAI on a 98 Legacy GT. Drop a fresh, quality paper air filter in a stock NA Subaru and floor it. It might not be as loud as an intake but it will have better low end torque to get you moving and excellent high RPM performance. Can anyone really tell a 6 hp difference? The stock design on my 02 Forester is very good. It keeps a large supply of filtered air immediately behind the throttle and it pulls air from the front of the engine behind the passenger side head light.

08-21-2012, 10:08 PM	#18
RaceFaceXC Scooby Specialist Member#: 165749 Join Date: Dec 2007 Chapter/Region: South East Location: stupid Florida Vehicle: 2007 No YELLING on the bus!	The airbox and/or tq box it's not an air reservoir ready to open the gates on demand, it's a way to transition from a smaller diameter pipe to a square box with relatively even flow across the filter. The shape and volume may have some beneficial resonant effects, too.

08-21-2012, 10:15 PM	#19
lavid2002 Scooby Specialist Member#: 226864 Join Date: Oct 2009 Location: southern NJ Vehicle: 2005 PSM WRX 18.5lb. 93 oct, DP, UP	A lot of people just toss CAIs on their cars because they don't have enough experience to do other modifications, it's inexpensive, and their basic understanding is that factory airboxes are restrictive and that CAIs help them "Breathe" better.

08-23-2012, 04:52 PM	#21
Kopernicus Scooby Newbie Member#: 328591 Join Date: Aug 2012 Location: Erie, PA Vehicle: 2006 Saab 9-2x Dark Blue	I've been reading a lot on the subject, and the stock intake system is best for all around performance... Except for reducing intake temps. My Saab 92x 2.5i had the stock air inlet in the engine bay. After reading the williarty write ups here I was going to build the whole hybrid intake. With a scan gauge I noticed the stock intake temps would always skyrocket in traffic or after the car being parked on errands (140+ degrees) sapping power. Then I added a used WRX style inlet horn and didn't see much improvement. In fact the temps really went south. The horn does not fully match the 2.5i snorkus so I taped it up. Still no improvement. Then I noticed two things: without the proper mount the WRX inlet sat on the radiator and in stock WRX the inlet is sealed off so it does not pull under hood air and pulls high pressure air from in front of the radiator. Got a used WRX snorkus and a new lower hood seal from Subaru. The WRX snorkus is about 0.2" larger in diameter on the air box side (still shoe horns in!) and matches the inlet horn. It also lifts the angle of the horn to push it up against the lower hood seal and hold it off the radiator. Problem solved! My intake temps never are over 120 in traffic or after being parked and they cool to 4-8 above ambient after a minute or two of driving. Stoplight to stoplight I have more power and a quicker throttle, it never feels heat soaked anymore. More power, probably not much, but greater drive ability in getting the power that should be there. Also the engine growl is pleasantly noticeable (I never heard it before) and everything is OEM. Total price: $35 in used and new parts. Im so happy with it I may forego the rest of the hybrid.

08-26-2012, 11:24 AM	#22
Counterfit Scooby Specialist Member#: 124254 Join Date: Aug 2006 Chapter/Region: NESIC Location: Rhode Island Vehicle: 2006 06 SGM Slowbaru "The Scoobinator"	You can put some heat reflecting material around the new tube, or use ABS piping.

08-26-2012, 12:39 PM	#23
cal_look_zero Scooby Specialist Member#: 294461 Join Date: Sep 2011 Chapter/Region: NWIC Location: Grass Pants, OR Vehicle: 1997 Outback Sport Acadia Green Metallic	I just replaced the stock snorkus on my OBS with a 2.5 frankenmotor and eliminated all hesitation I've been trying to diagnose for awhile now. D'oh!