Underhood Conical K&N vs. Stock Airbox with K&N

jimberg · 08-28-2001, 12:56 PM

If any of you guys remember the little debate we had in the Blue Oval Lounge about the stock air box vs. a conical filter, there was a relevant and interesting dyno test in the October 2001 issue of 5.0M&SF.

They tested the new C&L Performance 76mm Mass Airflow System on a pretty much stock 5.0. The results were interesting.

With their full installation, the 76mm MAF sensor, underhood conical filter, and cast aluminum air pipe they were able to pickup about 9 hp and 10 ft-lb of torque over the base pull. When they replaced the conical filter with the stock airbox and a dirty panel type K&N they were able to pickup 11hp and 16 ft-lb over the base pull.

Without getting into all the nuances of whether the car is moving or sitting still on the dyno, I think it is important to note that the stock air box is not restrictive and IS already a very decent cold air intake system. The real key, however, to making good power with whatever type of filter you use is the rigid, smooth intake tube over the flexible, wavy walled stock intake tube.

------------------
351W 89 Mustang GT Convertible

TJR · 08-28-2001, 01:03 PM

Can you buy just an intake tube?

------------------
1989 lx notch
89,000 miles
bolt-ons,stock heads/cam
60'- 2.07, 8.90@78, 13.93@99

jimberg · 08-28-2001, 01:12 PM

Word on the street is that you can. I have an e-mail into them to find out for sure. I will buy one if they will let me.

------------------
351W 89 Mustang GT Convertible

RED92LX50 · 08-28-2001, 02:26 PM

What about the stock rubber hose going from the MAF to the Throttle Body - it has about 5 ribs...should this be replaced too?

dinomite · 08-28-2001, 03:02 PM

anything that has ribs on it is going to cause turbulent, and therefore slower and more restrictive flow. perhaps pvc piping would due? what are the diameters? i may take a trip to home depot.

Rick 91GT · 08-28-2001, 03:20 PM

I can speak from expeirence that the stock airbox runs better then the sheilded K&N on my set-up. I talked with Lee Bender owner of C&L and that air box flows over 800-850cfms which is good for over 700HP. I know it's ugly but it works. I am working on a idea that will relocate a similar box to the inner fender well and it will be connected to my ram air and the 3.5" or 4" Power Pipe I am working on. Jim let me know what C&L says about that pipe, I heard you could buy it for a decent price but never posted as I did not hear it from the source..Lee Bender. I have a e-mail into him as well on other issues.

------------------
Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension, SPEC stage III clutch, Lakewood SFI bell, S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon! <B

[This message has been edited by Rick 91GT (edited 08-28-2001).]

PKRWUD · 08-30-2001, 04:54 PM

Jim-
This is very interesting info! I know my 4.9L runs better with the FIPK. I tried reversing the top of the factory airbox to allow for a more direct flow, which was an improvement over stock, but lacked the extra power under load the FIPK provided. A friend with a 4.6L noticed similar gains, as did his wife's Civic. All three first tried K&N replacement filters first (which are now for sale

) ). I haven't done any testing on 5.0 Mustangs though. Good info. Thanks.

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

elma22 · 08-30-2001, 06:52 PM

Hi
Thought I pitch in a little. There was a simular test done using MAC cold fender intake and the underhood conical intake. The fender intake provided more horsepower throughout the band with about 9-11 horsepower at the wheels, I can't remember exactly, where as the conical filter under the hood provided top 8 horsepower at the wheels and faded down to 4 HP at higher RPM.

------------------

jimberg · 08-31-2001, 11:24 AM

elma22, that test is interesting, but I think the flaw with it is the fact that the car is sitting still on the dyno. When you're moving, air is flowing through the engine bay and able to remove some of the underhood hot air.

There were two points that I was trying to make. The first is that the stock air box flows as well if not better with a K&N panel filter than an underhood conical. The second is that any gains you see from a cold air kit come from the less turbulent, rigid intake tube as opposed to the location or shape of the air filter.

The stock airbox, by the way, is a cold air induction kit.

------------------
351W 89 Mustang GT Convertible

PrplMonster · 08-31-2001, 11:36 AM

my .02 is that anytime we run a motorcycle on the Dyno, there is ATLEAST 1 huge fan blowing on the bike/ air cleaner/ram air(sport bikes)

.dave

jimberg · 08-31-2001, 11:47 AM

Quote:

my .02 is that anytime we run a motorcycle on the Dyno, there is ATLEAST 1 huge fan blowing on the bike/ air cleaner/ram air(sport bikes)

I would guess that that is more for cooling the air cooled engine. A fan still couldn't possibly simulate traveling at 60+ miles per hour and its effect on the performance of an engine. You're right, though, I would hope that they at least had a fan on the front of the car.

------------------
351W 89 Mustang GT Convertible

Mr 5 0 · 08-31-2001, 02:36 PM

I run a Moroso cold-air induction set-up with the conical filter in the upper fenderwell.
I replaced the factory rubber (upper) intake tube with a rigid smooth-metal intake tube from a place called 'Tiny Avenger' at a cost of $70.

Moroso claims a 3 1/2 to 4 HP gain with the rigid (plastic) intake tube and fenderwell (K&N) filter over the factory airbox. Sounds reasonable as you're getting slightly cooler, denser air and eliminate the ribbed intake tube. The smooth metal upper intake tube is probably worth another 2 or 3 HP.
I rate the whole setup at a conservative 5 HP. Not much, but on a basically stock 5.0 you get what you can any way you can.

08-28-2001, 12:56 PM	#1
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	Underhood Conical K&N vs. Stock Airbox with K&N If any of you guys remember the little debate we had in the Blue Oval Lounge about the stock air box vs. a conical filter, there was a relevant and interesting dyno test in the October 2001 issue of 5.0M&SF. They tested the new C&L Performance 76mm Mass Airflow System on a pretty much stock 5.0. The results were interesting. With their full installation, the 76mm MAF sensor, underhood conical filter, and cast aluminum air pipe they were able to pickup about 9 hp and 10 ft-lb of torque over the base pull. When they replaced the conical filter with the stock airbox and a dirty panel type K&N they were able to pickup 11hp and 16 ft-lb over the base pull. Without getting into all the nuances of whether the car is moving or sitting still on the dyno, I think it is important to note that the stock air box is not restrictive and IS already a very decent cold air intake system. The real key, however, to making good power with whatever type of filter you use is the rigid, smooth intake tube over the flexible, wavy walled stock intake tube. ------------------ 351W 89 Mustang GT Convertible

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08-28-2001, 01:03 PM	#2
TJR Registered Member Join Date: Apr 2001 Location: Bowling Green, OH Posts: 270	Can you buy just an intake tube? ------------------ 1989 lx notch 89,000 miles bolt-ons,stock heads/cam 60'- 2.07, 8.90@78, 13.93@99

08-28-2001, 01:12 PM	#3
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	Word on the street is that you can. I have an e-mail into them to find out for sure. I will buy one if they will let me. ------------------ 351W 89 Mustang GT Convertible

08-28-2001, 02:26 PM	#4
RED92LX50 Registered Member Join Date: Aug 1999 Location: Fairfax, VA Posts: 220	What about the stock rubber hose going from the MAF to the Throttle Body - it has about 5 ribs...should this be replaced too?

08-28-2001, 03:02 PM	#5
dinomite The Dude Join Date: Feb 2001 Location: Arlington, VA Posts: 1,262	anything that has ribs on it is going to cause turbulent, and therefore slower and more restrictive flow. perhaps pvc piping would due? what are the diameters? i may take a trip to home depot.

08-28-2001, 03:20 PM	#6
Rick 91GT Procharged! Join Date: May 1999 Location: Hanover, PA Posts: 1,539	I can speak from expeirence that the stock airbox runs better then the sheilded K&N on my set-up. I talked with Lee Bender owner of C&L and that air box flows over 800-850cfms which is good for over 700HP. I know it's ugly but it works. I am working on a idea that will relocate a similar box to the inner fender well and it will be connected to my ram air and the 3.5" or 4" Power Pipe I am working on. Jim let me know what C&L says about that pipe, I heard you could buy it for a decent price but never posted as I did not hear it from the source..Lee Bender. I have a e-mail into him as well on other issues. ------------------ Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension, SPEC stage III clutch, Lakewood SFI bell, S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon! <B [This message has been edited by Rick 91GT (edited 08-28-2001).]

08-30-2001, 04:54 PM	#7
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Jim- This is very interesting info! I know my 4.9L runs better with the FIPK. I tried reversing the top of the factory airbox to allow for a more direct flow, which was an improvement over stock, but lacked the extra power under load the FIPK provided. A friend with a 4.6L noticed similar gains, as did his wife's Civic. All three first tried K&N replacement filters first (which are now for sale ) ). I haven't done any testing on 5.0 Mustangs though. Good info. Thanks. Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

08-30-2001, 06:52 PM	#8
elma22 Registered Member Join Date: Jul 2001 Location: Montreal Posts: 45	Hi Thought I pitch in a little. There was a simular test done using MAC cold fender intake and the underhood conical intake. The fender intake provided more horsepower throughout the band with about 9-11 horsepower at the wheels, I can't remember exactly, where as the conical filter under the hood provided top 8 horsepower at the wheels and faded down to 4 HP at higher RPM. ------------------

08-31-2001, 11:24 AM	#9
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	elma22, that test is interesting, but I think the flaw with it is the fact that the car is sitting still on the dyno. When you're moving, air is flowing through the engine bay and able to remove some of the underhood hot air. There were two points that I was trying to make. The first is that the stock air box flows as well if not better with a K&N panel filter than an underhood conical. The second is that any gains you see from a cold air kit come from the less turbulent, rigid intake tube as opposed to the location or shape of the air filter. The stock airbox, by the way, is a cold air induction kit. ------------------ 351W 89 Mustang GT Convertible

08-31-2001, 11:36 AM	#10
PrplMonster Registered Member Join Date: Mar 1999 Posts: 88	my .02 is that anytime we run a motorcycle on the Dyno, there is ATLEAST 1 huge fan blowing on the bike/ air cleaner/ram air(sport bikes) .dave

08-31-2001, 02:36 PM	#12
Mr 5 0 Conservative Individualist Join Date: May 1997 Location: Wherever I need to be Posts: 7,487	I run a Moroso cold-air induction set-up with the conical filter in the upper fenderwell. I replaced the factory rubber (upper) intake tube with a rigid smooth-metal intake tube from a place called 'Tiny Avenger' at a cost of $70. Moroso claims a 3 1/2 to 4 HP gain with the rigid (plastic) intake tube and fenderwell (K&N) filter over the factory airbox. Sounds reasonable as you're getting slightly cooler, denser air and eliminate the ribbed intake tube. The smooth metal upper intake tube is probably worth another 2 or 3 HP. I rate the whole setup at a conservative 5 HP. Not much, but on a basically stock 5.0 you get what you can any way you can.