How to Add a Big Intake Pipe
Jul 3, 2011, 03:58 PM
#1
How to Add a Big Intake Pipe
I wanted to increase intake airflow and so have researched intake modification options.
Summary:
SRI sucks in hot air. This is actually reduces power. Sounds awesome.
CAI eliminates stock intake system, can suck in water, if has oiled filter then can foul MAF sensor in time, adds a bit of power, expensive for a good one that does not trigger CEL.
Stock air filter introduces basically no pressure drop, i.e. no flow restriction, so aftermarket drop-in filters are a waste of money (I have bought a few in my lifetime), and oiled ones can foul the MAF.
Stock air intake systems are cleverly designed to introduce flow resonances that help fill cylinders at certain rpms; aftermarket intake pipes do not.
The stock RA worst intake restriction is the snorkel inlet to the airbox.
I decided to stick with the stock system and add an extra intake pipe to the airbox. Research and testing with dozens of different cars has shown this mod alone will add more hp than SRI or CAI, for little money. Some tuning shops are using this method also. An excellent resource is http://www.autospeed.com/S_10/cms/section.html and search for "intake" to call up articles.
Note: I installed a mini-battery to expose the front of the airbox. If you don't do this there is no room for this air inlet mod. The battery saves 25 lb and works fine.
The stock airbox:
Cheapo 3" PVC sewer pipe:
Use this commonly available 3.5" hole saw to cut all holes:
Cut a hole into the front of the stock airbox:
This is the installed airbox:
I got this 90 degree flex pipe for free from an old wrecked Buick 6 cylinder. Many 6 and 8 cylinder vehicles have these things that accept the 3" PVC pipe perfectly. You could also use a 90 degree PVC fitting, but some flex is preferred:
Flare an end of the PVC pipe over a cone. Heat it first with a heat gun then push down over the cone. Fast moving air likes bellmouth entries and exits:
Cut straight piece of pipe to length using hacksaw:
A small piece of 2.5" long PVC to go into the airbox hole, the flex, a 12" long piece of PVC, and PVC 90 degree elbow dry fit:
Directly behind the left fog light, in front of the tire, is a boxy empty space surrounded by plastic panels. This I used as the still cold air box. Perfect! Here is the space with the vertical plastic panel removed; you can see the bottom of the white coolant reservoir:
Cut a hole out of the vertical plastic panel I removed, and insert a 3" length of bellmouthed PVC pipe. Wrap some 1/4" thick dense closed-cell foam around the pipe. This provides a perfect firm fit and flexible seal. Buy the foam at Crappy Tire in the hardware department, for sealing windows,doors and stuff. The bottom plastic panel has been removed; see the tire at the right side of the pic:
The plastic panels all put back together, and the short PVC piece sticking out the other side below the engine ready to accept the 90 degree PVC elbow:
Insert the long pipe. Dry fit at this stage:
Mark the orientation of elbow to straight pipe with a pencil mark. Glued the joint, and glued on a support tab while I was at it:
Paint it satin black:
Wrap soft open cell foam around the short piece that fits into the airbox, buy a roll with one side adhesive from Crappy Tire too. Install. Bolt the tab to a hole in the existing battery support bracket that is exposed. Done!
Results:
No extra sound at steady throttle. Deep subtle intake roar when accelerating, quite sexy. This definitely uncorked power - no kidding, very noticable new kick. I have the Hackish reflash so the ECU will not negate the effects of this mod - it will probably work without the reflash though. No CEL. I am very happy with this. Must dyno. Cost including PVC cement is $15.
Summary:
SRI sucks in hot air. This is actually reduces power. Sounds awesome.
CAI eliminates stock intake system, can suck in water, if has oiled filter then can foul MAF sensor in time, adds a bit of power, expensive for a good one that does not trigger CEL.
Stock air filter introduces basically no pressure drop, i.e. no flow restriction, so aftermarket drop-in filters are a waste of money (I have bought a few in my lifetime), and oiled ones can foul the MAF.
Stock air intake systems are cleverly designed to introduce flow resonances that help fill cylinders at certain rpms; aftermarket intake pipes do not.
The stock RA worst intake restriction is the snorkel inlet to the airbox.
I decided to stick with the stock system and add an extra intake pipe to the airbox. Research and testing with dozens of different cars has shown this mod alone will add more hp than SRI or CAI, for little money. Some tuning shops are using this method also. An excellent resource is http://www.autospeed.com/S_10/cms/section.html and search for "intake" to call up articles.
Note: I installed a mini-battery to expose the front of the airbox. If you don't do this there is no room for this air inlet mod. The battery saves 25 lb and works fine.
The stock airbox:
Cheapo 3" PVC sewer pipe:
Use this commonly available 3.5" hole saw to cut all holes:
Cut a hole into the front of the stock airbox:
This is the installed airbox:
I got this 90 degree flex pipe for free from an old wrecked Buick 6 cylinder. Many 6 and 8 cylinder vehicles have these things that accept the 3" PVC pipe perfectly. You could also use a 90 degree PVC fitting, but some flex is preferred:
Flare an end of the PVC pipe over a cone. Heat it first with a heat gun then push down over the cone. Fast moving air likes bellmouth entries and exits:
Cut straight piece of pipe to length using hacksaw:
A small piece of 2.5" long PVC to go into the airbox hole, the flex, a 12" long piece of PVC, and PVC 90 degree elbow dry fit:
Directly behind the left fog light, in front of the tire, is a boxy empty space surrounded by plastic panels. This I used as the still cold air box. Perfect! Here is the space with the vertical plastic panel removed; you can see the bottom of the white coolant reservoir:
Cut a hole out of the vertical plastic panel I removed, and insert a 3" length of bellmouthed PVC pipe. Wrap some 1/4" thick dense closed-cell foam around the pipe. This provides a perfect firm fit and flexible seal. Buy the foam at Crappy Tire in the hardware department, for sealing windows,doors and stuff. The bottom plastic panel has been removed; see the tire at the right side of the pic:
The plastic panels all put back together, and the short PVC piece sticking out the other side below the engine ready to accept the 90 degree PVC elbow:
Insert the long pipe. Dry fit at this stage:
Mark the orientation of elbow to straight pipe with a pencil mark. Glued the joint, and glued on a support tab while I was at it:
Paint it satin black:
Wrap soft open cell foam around the short piece that fits into the airbox, buy a roll with one side adhesive from Crappy Tire too. Install. Bolt the tab to a hole in the existing battery support bracket that is exposed. Done!
Results:
No extra sound at steady throttle. Deep subtle intake roar when accelerating, quite sexy. This definitely uncorked power - no kidding, very noticable new kick. I have the Hackish reflash so the ECU will not negate the effects of this mod - it will probably work without the reflash though. No CEL. I am very happy with this. Must dyno. Cost including PVC cement is $15.
Last edited by RalliartN; Jul 3, 2011 at 04:19 PM.
Jul 3, 2011, 10:42 PM
#3
Nick's car is probably the cleanest RA in Canada and the northern US, i couldn't find rust in his engine bay. She's a beauty, i felt bad driving it cause i think i wore the same pants the day before, but it also felt really good, it was a complex emotion.
Lol, look how shiny his transmission is, WTF!
I was wondering what you've been up to...It's too bad you can't make it to the track this weekend, the weather man says it's gonna be awesome, but only time will tell. I'll have to come up your way sometime and check out your handy work, looks great, and nice write up
Lol, look how shiny his transmission is, WTF!
I was wondering what you've been up to...It's too bad you can't make it to the track this weekend, the weather man says it's gonna be awesome, but only time will tell. I'll have to come up your way sometime and check out your handy work, looks great, and nice write up
Jul 6, 2011, 05:27 AM
#7
I am seriously considering getting blown. I am lucky, my daily commute is short and sweet, so I can enjoy having a hard ride - more vibration and noise from modifications is an acceptable trade-off for better handling and power. OttRalliart, it would be you guys for sure when it happens...
I will try Cranswick's ride to see if his boost figure/horsepower is what I am looking for, to give me a reference point for how much I would want. I'm thinking for a front wheel drive car with no LSD that maybe 6 or 7 psi with no intercooler might do me, since I prefer to play with handling over raw hp - just would like that extra straight line shove sometimes.
I will try Cranswick's ride to see if his boost figure/horsepower is what I am looking for, to give me a reference point for how much I would want. I'm thinking for a front wheel drive car with no LSD that maybe 6 or 7 psi with no intercooler might do me, since I prefer to play with handling over raw hp - just would like that extra straight line shove sometimes.
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Apr 5, 2012, 02:13 PM
#8
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I'm working on a mod similar to this and would like some input from everyone. I had an Injen CAI on my car originally and converted to an SRI because it was sucking water in occasionally. I am thinking about cutting the lower section that I removed and running it towards the bottom of the filter and flaring it out with fiberglass to span the entire bottom of the filter on the SRI I'm currently using. My filter is not enclosed though as this one is. Do you think it will make any noticeable difference? I am adding a 65mm TB next week and I thought this would be a nice addition to it.
Apr 5, 2012, 05:29 PM
#9
I'm working on a mod similar to this and would like some input from everyone. I had an Injen CAI on my car originally and converted to an SRI because it was sucking water in occasionally. I am thinking about cutting the lower section that I removed and running it towards the bottom of the filter and flaring it out with fiberglass to span the entire bottom of the filter on the SRI I'm currently using. My filter is not enclosed though as this one is. Do you think it will make any noticeable difference? I am adding a 65mm TB next week and I thought this would be a nice addition to it.
Apr 5, 2012, 09:56 PM
#10
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The injen cai is composed of two sections so it can be converted to an Sri. I currently have it as an Sri because the filter would suck up water during heavy rain. I want to take the lower aluminum section and run it from a hole I'm cutting in the fog light housing to the lower half of the air filter. I'm not sure if it is going to improve anything though since it's not running to an enclosed box like the stock filter shown above.
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