The cold air intake debate
12-21-2003, 03:51 AM
#31
Hurray, it's Ian!!
iTrader: (4)
Join Date: Oct 2003
Location: on an airplane
Posts: 3,612
Car Info: 2002 MBP WRX Sedan
i've heard all the talk, and the debates, and BAN SUV's post nd nic3krnnamja's posts sufficiently cleared up every question I've had about putting any sort of intake into my car.
thanks
thanks
12-26-2003, 11:02 AM
#32
Guest
Posts: n/a
homemade CAI
Hey everyone,
I made my own CAI from three parts. First, I removed my stock scoop and big box from under the fender. Then, I went to Lowes and bought a 3" diameter silicone rubber 90 degree bend elbow hose that is used for connecting toilets. I bought a section of 3" PVC pipe. I removed the gasket section from the stock airbox to allow the 3" elbow hose to fit into it. I then ran the other end of the elbow into the fender well. Then I cut a 12" legnth of PVC pipe and connected it to the elbow in the well. I then used a giant hose clamp to hold the assembly to the inner fender well. I also angle cut the PVC and turned the angle down towards the ground so rainwater can't enter. The end of the PVC stops about 4" back from the three side airskirt vents. I kept the stock airbox and filter. With the rubber hose forced into the airbox, it sealed it fine so the gasket isn't needed. It's also before the filter.
I noticed that with the stock air intake in place, the black funnel and the rubber intake hose after the MAF was burning hot, even after a short drive. With the mod, I can drive to my parent's house, 200+ miles, get out and touch the hose. BAM! the hose feels cold! Even after the MAF! I noticed that the car doesn't cut boost quite as much on warm days, and I do get a little extra boost on cold nights. I also bought the Forester block off plate to keep the hot air from entering the fenderwell and to make it look nice. Total cost:
$5 block off plate
$3 silicone elbow
$3 6' PVC tube
$1 hoseclamp
$12 + time 2 hours= It's been on the car for 1 year, never any problems.
Woody
I made my own CAI from three parts. First, I removed my stock scoop and big box from under the fender. Then, I went to Lowes and bought a 3" diameter silicone rubber 90 degree bend elbow hose that is used for connecting toilets. I bought a section of 3" PVC pipe. I removed the gasket section from the stock airbox to allow the 3" elbow hose to fit into it. I then ran the other end of the elbow into the fender well. Then I cut a 12" legnth of PVC pipe and connected it to the elbow in the well. I then used a giant hose clamp to hold the assembly to the inner fender well. I also angle cut the PVC and turned the angle down towards the ground so rainwater can't enter. The end of the PVC stops about 4" back from the three side airskirt vents. I kept the stock airbox and filter. With the rubber hose forced into the airbox, it sealed it fine so the gasket isn't needed. It's also before the filter.
I noticed that with the stock air intake in place, the black funnel and the rubber intake hose after the MAF was burning hot, even after a short drive. With the mod, I can drive to my parent's house, 200+ miles, get out and touch the hose. BAM! the hose feels cold! Even after the MAF! I noticed that the car doesn't cut boost quite as much on warm days, and I do get a little extra boost on cold nights. I also bought the Forester block off plate to keep the hot air from entering the fenderwell and to make it look nice. Total cost:
$5 block off plate
$3 silicone elbow
$3 6' PVC tube
$1 hoseclamp
$12 + time 2 hours= It's been on the car for 1 year, never any problems.
Woody
Last edited by Woody643; 12-26-2003 at 11:08 AM.
12-26-2003, 11:35 PM
#34
BanHammer™
iTrader: (8)
Join Date: May 2000
Location: Wagonmafia Propaganda Lieutenant
Posts: 47,585
Car Info: 2001 Forester RS2 SPEC-F
Originally posted by EJ20T
whats the difference between a cold air intake and a short ram intake??
whats the difference between a cold air intake and a short ram intake??
12-27-2003, 01:17 AM
#37
Registered User
iTrader: (6)
Join Date: Jan 2003
Location: Sunny LA West Side
Posts: 363
Car Info: Silver 2002 WRX Sedan
Originally posted by BAN SUVS
...a CAI is better because it picks up cooler, denser air.
...a CAI is better because it picks up cooler, denser air.
My advice: save your money and get mods that matter (like suspension and such...)
12-27-2003, 02:58 AM
#38
VIP Member
iTrader: (3)
Join Date: Nov 2002
Location: Lastweek Lane - Watertown, NY
Posts: 10,133
Car Info: 02WRXpseudoSTiWannabeWagon
There are simply too many 'Awesome' tuners who are split 50/50. Which leads me to believe that either the ones who are 'con' wrt aftermarket intakes have seen too much variance among the different makes of intakes. Or the ones who are 'pro' are just hucksters telling the market what they want to hear just to make a buck. That's why I think it's important to research and come up with personal conclusions.
Facts are that aftermarket intakes do allow less restriction than the stock box (snorkus or not). They also are less prone to turbulent air vs. the stock box. Do these criteria even matter, one way or the other...is more air with less turbulence good or bad.
Another fact is that the amount of heat that is post turbo (even post intercooler) is directly related to how much work the compressor side of the turbo had to do in order to compress however much boost you've asked it to. It doesn't matter a hoot what the ambient temperature is.
What is speculation (might be true, might not) is that the MAF is particular to seeing a set amount of airflow. I do believe that the MAF is a tricky mechanism for a novice tuner, like myself. But bottom line is that it simply translates airflow into voltage. I don't buy that there is some 'value' for cfm that the car or ECU is programmed to expect and recognize. Because there is more air isn't necessarily going to fool the MAF into transmitting an errant voltage. Nor is the aftermarket intake going to be any more erratic in the amount of air it sends than the stock box.
Citing Corky Bell, in reference to a restrictive intake filter vs less restrictive, he says, "So here the odd circumstance exists that flow is down, boost remains the same, and the pressure ratio goes up. Net result is that power is down and heat is up....The idea that the turbo is told to make the same amount of boost out of less air logically means it must work a bit harder to do so. The harder it has to work, the more heat it makes."
Nhluhr did his OWN testing (which is probably not the best solution for everyone, but it is still relevent advice). Here is the conclusion he came to. (hopefully you can access the link)
Facts are that aftermarket intakes do allow less restriction than the stock box (snorkus or not). They also are less prone to turbulent air vs. the stock box. Do these criteria even matter, one way or the other...is more air with less turbulence good or bad.
Another fact is that the amount of heat that is post turbo (even post intercooler) is directly related to how much work the compressor side of the turbo had to do in order to compress however much boost you've asked it to. It doesn't matter a hoot what the ambient temperature is.
What is speculation (might be true, might not) is that the MAF is particular to seeing a set amount of airflow. I do believe that the MAF is a tricky mechanism for a novice tuner, like myself. But bottom line is that it simply translates airflow into voltage. I don't buy that there is some 'value' for cfm that the car or ECU is programmed to expect and recognize. Because there is more air isn't necessarily going to fool the MAF into transmitting an errant voltage. Nor is the aftermarket intake going to be any more erratic in the amount of air it sends than the stock box.
Citing Corky Bell, in reference to a restrictive intake filter vs less restrictive, he says, "So here the odd circumstance exists that flow is down, boost remains the same, and the pressure ratio goes up. Net result is that power is down and heat is up....The idea that the turbo is told to make the same amount of boost out of less air logically means it must work a bit harder to do so. The harder it has to work, the more heat it makes."
Nhluhr did his OWN testing (which is probably not the best solution for everyone, but it is still relevent advice). Here is the conclusion he came to. (hopefully you can access the link)
12-29-2003, 07:53 PM
#39
Registered User
iTrader: (1)
Join Date: May 2003
Location: www.tristatetuners.com
Posts: 433
Car Info: www.tristatetuners.com
I had an injen and took it off. My car felt way faster after I took it off. Don't know why, and don't care.
In my opinion, the stock box works great and I am going to stick with it. The only advantage I saw in two years of having a CAI on my car was the wicked spooling sound.
Bottom line: I have never seen a dyno graph showing a CAI making more power than a stock airbox.
In my opinion, the stock box works great and I am going to stick with it. The only advantage I saw in two years of having a CAI on my car was the wicked spooling sound.
Bottom line: I have never seen a dyno graph showing a CAI making more power than a stock airbox.
12-29-2003, 08:08 PM
#40
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 t-wrexxx
Bottom line: I have never seen a dyno graph showing a CAI making more power than a stock airbox.
Bottom line: I have never seen a dyno graph showing a CAI making more power than a stock airbox.
12-29-2003, 10:37 PM
#41
Registered User
Join Date: Feb 2003
Location: busy writing log of best roads in CA.
Posts: 568
Car Info: 2002 WRX Sedan
Has anyone put the stock intake system (from the under hood scoop to the MAF) on a flow bench to see what it flows? Is it possible that it flows MORE than enough air for a 2.0 turbo?
I know from tuning, dynoing and racing air-cooled VW's, they will run the best numbers on cold, dry days, but we are talking ancient Weber 48IDA carburetors, no engine management and reading spark plugs with a magnifying glass. But combustion cycles are combustion cycles. I ask this question:
If EJ20 "A" (stock) was dynoed at sea level at 60 deg F and a barometric pressure of 30" Hg
And EJ20 "B" (stock) was dynoed at sea level at 90 deg F and a barometric pressure of 30 " Hg
Would there be a power difference??
I know from tuning, dynoing and racing air-cooled VW's, they will run the best numbers on cold, dry days, but we are talking ancient Weber 48IDA carburetors, no engine management and reading spark plugs with a magnifying glass. But combustion cycles are combustion cycles. I ask this question:
If EJ20 "A" (stock) was dynoed at sea level at 60 deg F and a barometric pressure of 30" Hg
And EJ20 "B" (stock) was dynoed at sea level at 90 deg F and a barometric pressure of 30 " Hg
Would there be a power difference??
12-29-2003, 10:47 PM
#42
Registered User
iTrader: (12)
Join Date: Nov 2002
Location: Reno, NV
Posts: 18,369
Car Info: 1993/2000/2001 GF4 mostly red
Indeed there is, because all turbo cars get stronger as the air gets colder (read: denser) right up until they start knocking from being too lean. But every good dyno takes ambient conditions into account. In fact, the easiest way to inflate dyno numbers is to allow the intake air temp sensor to touch something hot, like the radiator or manifold. Instant increase in horsepower. 
01-01-2004, 11:46 PM
#45
Registered User
iTrader: (1)
Join Date: Nov 2002
Location: LA, 91355
Posts: 352
Car Info: '03 WRX WRB
ah, good to know. I was looking into maybe getting an injen just for the sound (I LOVE a nice gulping induction sound.. and hearing the turbo), but after reading your post about the MAF calibration I'm leaning towards just de-snorkling the stock system.
if I understand your explanation of how they calibrate the MAF sensor though, wouldn't de-snorkling also throw off the signal?
if I understand your explanation of how they calibrate the MAF sensor though, wouldn't de-snorkling also throw off the signal?