The cold air intake debate
01-02-2004, 12:56 AM
#46
Registered User
iTrader: (6)
Join Date: Jan 2003
Location: Sunny LA West Side
Posts: 363
Car Info: Silver 2002 WRX Sedan
Originally posted by gordy
...wouldn't de-snorkling also throw off the signal?
...wouldn't de-snorkling also throw off the signal?
01-08-2004, 11:47 PM
#47
Registered User
iTrader: (1)
Join Date: Jan 2003
Location: Huntington Beach, CA
Posts: 306
Car Info: 03 Sonic Yellow WRX Sedan
OK, those who say cooler air has no purpose on a turbo car has been brainwashed by message boards such as this. Subaru designed the stock intake system to take in cool air from outside the car. Why go through the trouble to do this if "the intercooler is gonna cool off the intake charge anyways"?
Recently while doing R&D on EVO's, we removed the original airbox intake, w/ a similar cold air scoop like the WRX, for a conical filter. This made a 10whp increase in HP, however, the heat caused power loss after a while. A new scoop was developed to funnel cool air in and power gains stayed consistent.
Cool air intakes on turbos may or may not make power, but hot air intakes on turbos are DEFINITELY bad.
I personally have ran a cold air intake (XS-Engineering) for some time and have liked it. I have not bothered to test it, but it is faster... I have given customer's a test drive before without them knowing what I had and they have always said its faster than their car, similarly equipped, but without an intake. Its got dyno proof, confirmed by butt-dyno's of many. So, regardless of HOW that power is attained, it MAKES power and I have not seen a car equipped with a cold air intake blow up due to a lean condition. (BTW, the car runs at 10.5:1 with the intake and piping diameter measures smaller than 2.75" and there are no crazy bends before the MAF sensor.)
I have seen a car die from sucking up a ton of water however... oh and for those who modify the stock intake, all those bends and kinks and chambers, etc are designed to trap water and prevent hydrolock, as well as silence the car. I have gone through rivers and havent had an issue... though it does worry me.
Best bet? Stay with stock. But I like the extra power I get for so little money. So blah! If I go back to stock, its cuz I get tired of peeling off the mud covered fender to change my filter after each rally... OR if i decided that I wanted an off-the-shelf ECU upgrade.
Good Day!
Recently while doing R&D on EVO's, we removed the original airbox intake, w/ a similar cold air scoop like the WRX, for a conical filter. This made a 10whp increase in HP, however, the heat caused power loss after a while. A new scoop was developed to funnel cool air in and power gains stayed consistent.
Cool air intakes on turbos may or may not make power, but hot air intakes on turbos are DEFINITELY bad.
I personally have ran a cold air intake (XS-Engineering) for some time and have liked it. I have not bothered to test it, but it is faster... I have given customer's a test drive before without them knowing what I had and they have always said its faster than their car, similarly equipped, but without an intake. Its got dyno proof, confirmed by butt-dyno's of many. So, regardless of HOW that power is attained, it MAKES power and I have not seen a car equipped with a cold air intake blow up due to a lean condition. (BTW, the car runs at 10.5:1 with the intake and piping diameter measures smaller than 2.75" and there are no crazy bends before the MAF sensor.)
I have seen a car die from sucking up a ton of water however... oh and for those who modify the stock intake, all those bends and kinks and chambers, etc are designed to trap water and prevent hydrolock, as well as silence the car. I have gone through rivers and havent had an issue... though it does worry me.
Best bet? Stay with stock. But I like the extra power I get for so little money. So blah! If I go back to stock, its cuz I get tired of peeling off the mud covered fender to change my filter after each rally... OR if i decided that I wanted an off-the-shelf ECU upgrade.
Good Day!
01-15-2004, 09:53 PM
#50
Registered User
iTrader: (12)
Join Date: Nov 2002
Location: Reno, NV
Posts: 18,369
Car Info: 1993/2000/2001 GF4 mostly red
Originally posted by WickedWRX
So you would get the same or more hp gain from a k&n w/ silencer mod as you would with a CAI?
So you would get the same or more hp gain from a k&n w/ silencer mod as you would with a CAI?
01-16-2004, 04:19 AM
#51
Registered User
iTrader: (2)
Join Date: Nov 2002
Location: Lawrence, Kansas
Posts: 1,644
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
I'm curious to see what this guy shows with his graphs:
http://www.subaruforester.com/forum/...709&highlight=
http://www.subaruforester.com/forum/...709&highlight=
01-16-2004, 09:15 AM
#52
Registered User
iTrader: (6)
Join Date: Jan 2003
Location: Sunny LA West Side
Posts: 363
Car Info: Silver 2002 WRX Sedan
Hey, Peaty!
I looked at that thread and it does not make much sense...
First he says:
Then he states:
But, a stock WRX is rated 14HP MORE than an XT...
So, according to his calculations, his airbox mod on the Forester gave him extra 35 to 40 hp...
He MUST be running hella lean!
WTF!?! Over?
First he says:
baseline # on the fxt was 200hp & 219.7 torque. this was with the airbox mod
Stock wrx on this dyno on average 175.
So, according to his calculations, his airbox mod on the Forester gave him extra 35 to 40 hp...
He MUST be running hella lean!
WTF!?! Over?
01-16-2004, 09:23 AM
#53
Registered User
iTrader: (2)
Join Date: Nov 2002
Location: Lawrence, Kansas
Posts: 1,644
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
It's been shown with other dyno runs that the 210BHP rating on the F-XT is not right. Subaru low balled the HP for one reason or another. Of course all numbers are relative and need to be run on the same Dyno I think.
01-16-2004, 09:20 PM
#55
Registered User
iTrader: (6)
Join Date: Jan 2003
Location: Sunny LA West Side
Posts: 363
Car Info: Silver 2002 WRX Sedan
Originally posted by Peaty
It's been shown with other dyno runs that the 210BHP rating on the F-XT is not right. Subaru low balled the HP for one reason or another. Of course all numbers are relative and need to be run on the same Dyno I think.
It's been shown with other dyno runs that the 210BHP rating on the F-XT is not right. Subaru low balled the HP for one reason or another. Of course all numbers are relative and need to be run on the same Dyno I think.
Now, if a 227HP WRX is showing 175 to 180HP on THE SAME dyno, then a 200HP Forester would be pushing around 260 with a modded air box... Thats AT LEAST a 30HP gain!!!
For some reason I dont think it is realistic... Something is wrong...
I hope the "air box mod" the guy did will not cause him to get a new engine...
01-16-2004, 09:57 PM
#56
Registered User
iTrader: (12)
Join Date: Nov 2002
Location: Reno, NV
Posts: 18,369
Car Info: 1993/2000/2001 GF4 mostly red
The Forester is doing 5.1-5.2 second 0-60s for the media. How much power do you think it's putting out? 240-250 sounds reasonable to me, especially considering the stupefying amount of torque it is making before reaching the horsepower peak.
01-17-2004, 01:30 AM
#57
Registered User
iTrader: (6)
Join Date: Jan 2003
Location: Sunny LA West Side
Posts: 363
Car Info: Silver 2002 WRX Sedan
Hey, Ban Suvs!
Excuse my ignorance, but I am not at all familiar with the Forester 2.5XT. You mentioned 5.1-5.2 0-60 runs for the media. Are these published results? Where did you see that? I genuinly want to know, because I think the best WRX 0-60 # were like 5.5 ...
As far as I know the Forester is built on the Impreza platform, but it is a little heavier... Thus, if the 0-60 times are faster than a WRX the Forester must be WAY underrated on power. In fact, it must be quicker than a WRX.
However, the post on thw Forester forum STILL does not make sense. It is just inconsistent. Here is what I mean:
So, lets assume that STI is making 310HP at the flywheel with the resonator and muffler removed, thus based on that assumption and the following statement:
The Forester is making 228HP at the crank with the air box mod. I'll buy that, especially if the Forester power is underrated, which I think it is for marketing reasons. (8HP gain form an air box is realistic, so the Forester base power should be around 220)
that would be 240 flywheel HP max from the Forester. I'll buy this too!
However, this is where inconsistency crops up:
this implies that a stock WRX makes 200HP at flywheel. This would mean that WRX is GROSSLY overrated by Subaru...
So, my conclusion is that the data is inconsistent at best. There is a flaw somewhere. I am not trying to knock the Forester, but the numbers just dont make sense! If we take stock WRX numbers from this dyno as baseline, assuming accurate HP rating of 227HP flywheel stock (175HP dyno Wheel), then the Forester with an air box mod makes 260HP, and the STI with airbox and muffler removed makes 350HP!!!! That is just not possible! You can NOT get this kind of gains from a resonator and muffler removal! 5-10 HP, maby, but 50HP (a 17% increase in HP for the STI)? Not without a re-flash!
Excuse my ignorance, but I am not at all familiar with the Forester 2.5XT. You mentioned 5.1-5.2 0-60 runs for the media. Are these published results? Where did you see that? I genuinly want to know, because I think the best WRX 0-60 # were like 5.5 ...
As far as I know the Forester is built on the Impreza platform, but it is a little heavier... Thus, if the 0-60 times are faster than a WRX the Forester must be WAY underrated on power. In fact, it must be quicker than a WRX.
However, the post on thw Forester forum STILL does not make sense. It is just inconsistent. Here is what I mean:
on the sti the airbox resonator made a 5 hp gain...the sti best was 271 HP @ wheels
they have a dynapak dyno. baseline # on the fxt was 200hp & 219.7 torque. this was with the airbox mod
my forester best was 209 HP @ wheels...
However, this is where inconsistency crops up:
wrx on this dyno on average 175. A strong wrx makes 180
So, my conclusion is that the data is inconsistent at best. There is a flaw somewhere. I am not trying to knock the Forester, but the numbers just dont make sense! If we take stock WRX numbers from this dyno as baseline, assuming accurate HP rating of 227HP flywheel stock (175HP dyno Wheel), then the Forester with an air box mod makes 260HP, and the STI with airbox and muffler removed makes 350HP!!!! That is just not possible! You can NOT get this kind of gains from a resonator and muffler removal! 5-10 HP, maby, but 50HP (a 17% increase in HP for the STI)? Not without a re-flash!
01-17-2004, 05:45 AM
#58
Registered User
iTrader: (2)
Join Date: Nov 2002
Location: Lawrence, Kansas
Posts: 1,644
Car Info: 19' Impreza Sport Manual / 99 Miata / 13' OB
Just thought I'd share the news. It made 175 wheel hp on our Dyno Dynamics Dyno, or about 10-15 more whp than the regular WRX. Peak hp was generated by approx 5000, which is really early. IIRC, peak torque as around 180ft-lbs as well. Needless to say, the claimed power rating is understated. Assuming that SOA is honest with the WRX rating, the Forester Turbo is making at least 240bhp.
http://forums.nasioc.com/forums/show...light=Forester
A local guy got a 13.8 in the 1/4 with his stock XT Thead on that with a scan of the slip here:
http://forums.nasioc.com/forums/show...hreadid=461743
01-17-2004, 01:18 PM
#59
Registered User
iTrader: (6)
Join Date: Jan 2003
Location: Sunny LA West Side
Posts: 363
Car Info: Silver 2002 WRX Sedan
WOW! I had no idea Foresters were that quick! That is very nice! Now I know not to underestimate the qute-ute turbo bread box
!I know exactly why Subaru underestimated the Forester HP for the buying public! It is a purely political marketing move. They dont want to lose WRX wagon sales to the Forester.
01-20-2004, 10:40 AM
#60
I have heard that cai's will turn on the check engine light. The only "cai" that i have heard of that does not do any harm is the UNI Filter RAM POD. It works with the stock maf and will not inhibit the air flow. I have it. The big difference is the sound. It makes the stock bov very audible and sounds mean when you get on it. It provides a very cool induction noise. From the sidewalk it sounds like you have highly modified the WRX. I bought mine used. It is kind of pricey new. Since it has a cleanable filter that you can replace it seems ok to buy a used unit. I love mine. As for hp i don't think it does s**t. 2cents