Dyno Science: "CAI" Box vs Open Cone Intake

**comengetit** · 08-31-2011

im currently using a 3" abs(black plastic) street 45* fitting n a 4" filter which fits over the hub on the 3" fitting. the street end will have the 3" rubber end connected with the 4" end connecting to the throttle body. now i was told to use 4" well i tried n there was no way i was getting the 4" filter over that street end of the 4" 45...a piece of 4" abs pipping measures about 4 1/4 od. my spectre filter wont strretch that. so ima try the 3"abs. im not doing any other mods in the near future....and intake is my only mod. im doing it for sound n looks. if i start modding itll be n aluminum 4" pipe. but for now this 3" set up has to be better than stock right? im not making my situation any worse am I?

**blueguy** · 08-31-2011

I've used 4" piping with a Spectre filter. Use your man arms.

**fubar569** · 08-31-2011

I have a 4" 45* elbow. I used thin wall "sewer" pipe PVC in white.

the 4" filter slides right on the 4" pipe. I did not try to attach it to the elbow directly. there is a small sleeve or about 2" of pipe coming out of the elbow that it connects to.

from there the 4" end of the rubber coupler goes over the other side of the 4" elbow (again a 2" sleeve) and the 3" end stretches tight over the TB and clamps down.

Visit your local Home Depot Racing/Ace Hardware Racing location for all appropriate parts

**comengetit** · 08-31-2011

wow i f***ed up lol. took everthing apart to find out my set up i planned isnt going to work...dam. ill probly go 4" polished aluminum. but for now i took the airbox out.....secured my pcm.....and slid the 4" spectre over my stock intake flex tube. that didnt work out to bad. setting my spectre filter up like this isnt going to cause harm to anything on my car will it(motor,sensors)?

**fubar569** · 08-31-2011

Nah you didn't **** up...just needed to re-engineer some portions. I literally have about 25 bucks in what you see there...IF that...counting the el cheapo filter.

The PCM mount however? that took me 4 freakin hours to secure. that was a PITA. they say you don't need to secure the PCM...i think i'd rather have it somewhat secure. GM doesn't like it bouncing around and neither do I...

literally just go to your local hardware store plumbing section. you should be able to get EVERYTHING you need in one trip. less than 20 bucks. guaranteed.

**comengetit** · 08-31-2011

i just got back from the store after buying all the wrong s**t lol. i secured my pcm with about 10 zip ties all connencted together.....i like things secure to. i put the 3.5" rubber bushing insert that came with my filter underneith the pcm...balanced it and secured it. it moves very little....pritty much whatever movment is in the rubber bushing. i have it hooked up to the stock intake tube and i secured the filter to for minmum movernt. that way it has a harder time bouncing off. it sounds good, i just hope the set up is ok for the time being.

**dmahlikGT** · 08-31-2011

I dont get how you can screw up or find makin an intake so hard lol. 4in-3in rubber coupler 22.5 or 45deg bend plastic or aluminum tubing then a filter.Thats it. Just speakin out loud

**comengetit** · 08-31-2011

i screwed it up cuz i didnt go for the thin wall pvc. and im not gonna attempt stretching my filter to fit 5/8" more than its suppose to. i plan on a 4" polished aluminum...at sum piont. i have it rigged up nice with the stock tube...and it barely has any bend to it. the pcm and filter are both secure. and it sounds great so im saticfied for now.

**fubar569** · 04-02-2012

This is what i built for my 08 GXP. there is now a plexi lid on it and sealed with foam. IAT's read anywhere from .2 to 2* over ambient. Note this car is the 5.3L V8 and not the supercharged 3.8 V6 so the colder air provided by this solution would equate to more HP over an open cone for me as this intake flows more than enough for my current level of mods. It is also built with expansion in mind to a 90mm FAST intake/TB and larger MAF. Everything inbetween is 4". I simply change 2 couplers for the MAF and go.

For those 3.8 SC owners desiring this solution it can be built by yourself for about 200 bucks counting welding supplies, sheet metal, and insulation, filter, couplers, etc.

**KeithGTP03** · 04-02-2012

$200? This cost me $35 for the filter and $25 for the acrylic and heat shield.

**fubar569** · 04-02-2012

Mine is well insulated with 2 layers of graphite header wrap inbetween 2 pieces of 28ga sheet metal. that is cost of metal, wrap, welding supplies, plus the couplers, clamps, filter, and the lid. considering the header wrap alone is 40 to 80 bucks that would be the bulk of the cost besides the couplers and filter (about 75)

**SlowNA06** · 04-02-2012

Originally Posted by fubar569

the colder air provided by this solution would equate to more HP over an open cone for me

For those 3.8 SC owners desiring this solution it can be built by yourself for about 200 bucks counting welding supplies, sheet metal, and insulation, filter, couplers, etc.

I keep seeing people say this stuff. I'm waiting for your dyno sheets. This would be a worthwhile investment if it gained 20hp over open cone, otherwise the cost is unjustifiable in light of more efficient modifications (except, of course, if the box is winning you show trophies).

**matt5112** · 04-02-2012

Colder does result in power. The op is misleading because the open cone car ran leaner.

Also my filter was $80 by itself.

Quality air filter is crucial to engine health.

for that reason I do not recommend oiled filters.

**SlowNA06** · 04-03-2012

Originally Posted by matt5112

The op is misleading because the open cone car ran leaner.

I'm gonna go with "No." The box ran similarly to the boxless. Changing the tune would have resulted in a rather un-scientific experiment. The box in my experiment provided no advantage. I want proof from someone that their box provides a horsepower advantage (or their FWI, or open cone). That's not hard to find out. I don't know why it's so hard to back up these claims with dyno sheets. I realize that makes me sound like a jerk, but I am a jerk, so the effect is entirely unintentional. I went through the effort of dyno-ing a car. I don't see why someone can't meet me halfway and do the same. Or maybe they already have and I missed it. If someone's already got hard data, please post it. This is about providing as much useful information as possible, not about proving "mine is better than yours."

**matt5112** · 04-03-2012

Having more than one uncontrolled variable is unscientific.

**SlowNA06** · 04-03-2012

Originally Posted by matt5112

Having more than one uncontrolled variable is unscientific.

Are you darkhorizon now? Explain.

**matt5112** · 04-03-2012

On my phone haha.

Afr changes power. You were richer on the cai runs than the open runs.

**fubar569** · 04-03-2012

I don't need dyno sheets to tell me what the ~30 degree change in my IAT's (vs stock airbox/stock IAT) already show. and that ~30* is cruise IAT, not in town. every 10* is said to be ~1-2hp depending on other conditions and timing tables. if the 2 intakes flow enough for the given level of mods (on a NA car) the colder one will produce more power at the same AFR. period.

Now if my AFR has changed (and i bet it has) that is another variable. my STFT and LTFT are pretty close to 0 however (within 2% usually at WOT) so i'll assume the car has already learned any applicable adjustments.