CAI vs. FWI

[Alibi]

As the title suggests, what are the pros and cons to each method? I'm just wanting to clarify this for myself before I go with method or another. Perhaps I should clarify myself a tad first:

FWI: Fenderwell intake as in sucking air in from inside the fenderwell and using a flexible hose
CAI: Using a rigid pipe with a flexible pipe to TB connection to suck air in from behind the headlight

From what I've been seeing the FWI is the way to go these days. The kit from Intense is affordable for what you get, but even without a kit its pretty easy to set up. Just hook a hose on the TB and stick it into the fender well to a filter. No heat shields to mess with, no worries about the engine moving in the bay and hitting anything, etc. The only cons I see is the filter is going to get dirty *slightly* faster and it doesn't have the *bling* factor that a shiny rice pipe has.

At this point, I think the biggest advantage of the CAI are the looks of the rice pipe and whatever shielding you can come up with. IMO, most attempts to make it look clean allow for too much heatsoaking and attempts to keep it cool make it look like a tool on its way to the moon (covered in foil and whatnot).

In my own experience its much, much easier to rig a FWI than a CAI, even on my '88 and '89 (I found a clever way to mount the filter). I've fiddled with several setups for a CAI but I've always had problems with heat shielding or supporting the filter or with finding the correct diameter pipe with the correct bends. On the FWI, the hose, filter, clamps, and couplers can all be sourced from Intense for a reasonable cost (probably less than $100 to get everything I'd need for an 87-91 style bay since I don't need a PCM holder)

Am I wrong in saying that CAI is obsolete? Its just not nearly as efficient or simple as the FWI? Does my reasoning make sense?

Edit: CAI is probably a blanket term for any induction that sucks in cool air (including FWI), but in this instance I've defined a difference.

[allensteiner]

i thought about putting in a fwi in mine but the stock setup doesn't look restrictive enough to bother, and doesn't it suck air from inside the fender anyways? i wonder if a k&n or a dryflow filter replacement wouldn't be the same as fwi - airflow wise.

[willwren]

Read the topic I just posted about intake size. A FWI is probably preferred in most cases, but make sure it's not overly-large for your application.

[Alibi]

Airflow wise, the stock setup is bad. The accordian hose reduces laminar air flow. And the stock box is also sucking air from behind the headlight... but from behind the fender the air is going to be much, much cooler. Cooler air means more power. IIRC, every 10* temperature drop in intake air yields 1hp.

[Alibi]

Condensed from the other thread:

Parts used:

-K&N cone filter, no clue what the # is as its just an old one I had laying around
-$20 rice zone flexible intake tubing that I bought a couple years ago
-3" exhaust coupler with hole drilled in it for the IAT sensor
-two eye hooks
-random clamps

I need to get some longer hoses so that I can properly re-mount the evap canister. I was going to feed the hose down behind the headlight like most other versions, but I don't think I have enough clearance between the back of the lights and the frame so I stuck the filter down the evap canister hole.

The accordion hose is going to be replaced with INTENSE hose in the near future, but as-is its got LOTS more power according to my butt-dyno :D

See any major flaws otherwise?

[willwren]

I think once you've got smoother tubing, you nailed it. That's almost an Intense FWI.

[psburtis]

so he's right in saying that the FWI is better than a regular CAI?

[Alibi]

In just seat of the pants tests, the FWI seems to give me better performance than my previous CAI system. I'm using the same hose and filter for both setups. Let me look for a pic of my CAI setup...

I figure 3 feet of Intense hose and I'll be set... that should be about $30-40 so not bad. Assuming I do the same thing to my other T, I'm going to source the clamps, junctions, filter, and hose from Intense as well. Should all be about $100 so not too shabby.

Edit: Old CAI setups.

Version II (most recent before the FWI, shielded with a peice of plywood.... it actually worked pretty well)



Version I (used a couple 45* elbows covered in tape, shielded with carboard for a while )

[01bonneSC]

OK, one disadvantage I may see to a FWI would be flooded streets/roadways. What is the possibilty of a FWI sucking up water? Water would atleast probably get on the filter getting it wet and needing a re-oil. Would the engine be able to suck water up the hose to the intake or is the angle to steep for the water to make the climb? Its been raining a lot more here in N. IL. the past few years and I am glad I have my CAI setup. But what are the possibilities of water/moisture getting on the filter?

[willwren]

We have never seen any water problems whatsoever, and many of us run them year-round. The entire engine would have to be immersed in water to get the filter fully covered, especially on a 2k.

Not only that, but unless you're at WOT half submerged, your motor will stall from lack of air before the water gets there.

Filters sucking water is a bagged and slammed ricer problem.

[MadMike]

i have a custom made CAI
heres wat i used;
intense 4" intake pipe
"highflow" air filter from Murray's Discount Auto Parts
ReflectEx as the heat shield

[willwren]

That spectre filter is the worst filter on the market for flow. Your stock paper filter flows more. In addition, the next biggest problem is that accordian adapter on the TB. Turbulence is killing what little flow that filter allows through.

FYI, many 'ricer brand' filters actually hold WATER.

[MadMike]

lol, well it looks like im buying a new filter

oh and the acordian thing, is from the stock intake, i just used it cuz im to lazy to make a new one

i spose i should tho

[Roadtech195]

^ Mr.wren I am not sure I follow you on that statement. "FYI, many 'ricer brand' filters actually hold WATER." I am curious as to how so. I would not think that there would be a difference in absorption rate as they both have a cotton fiber element. I agree spectre makes junk filters because they don't use stainless steel mesh. so after 2 months they begin to rust and the rubber components seal very well. A CAI vs a FWI pretty much depends on what you hoping to gain. I have a CAI that is better suited for my needs and I feel is more practical for my car. in my case a FWI would not give me any more power than the CAI I have now.

[smellbird]

Not only that, but unless you're at WOT half submerged, your motor will stall from lack of air before the water gets there.

This is true, I had it happen to me after I went through a big puddle after a downpour.
A FWI is safe as long as aren't fording any rivers.
A K&N is coated in a oily solution that repels water. Cheaper brands don't do this(or not good enough) and when water comes in contact it stays in the filtering material.

[Roadtech195]

that answers my question about holding water. makes sense now, thanks

[willwren]

Years ago, while up in WA with DrJay building his intake, I had a hunch and filled his spectre filter with water in his kitchen sink.

It was brand new, and he claimed he'd noticed no increase in performance when he installed it.

One hour later he had a brand new K&N.



The spectre took probably over 3 or 4 minutes to drain out slowly. How's that for airflow?

[01bonneSC]

For MadMike...
Intense makes a Throttle body adapter that has a IAT sensor bung. Not sure if you can get it without getting a kit though. I think Im gonna save up for a FWI....
You can see the adapter in the pics...
http://intense-racing.com/Merchant2/mer ... _Induction

[Roadtech195]

"The spectre took probably over 3 or 4 minutes to drain out slowly. How's that for airflow?"
Its not, its water flow. I am sure the viscosity of water over different kinds of filter media will act differently as opposed to air but I see your point. spectre filters are just as effective as coffee filters, I have used K&N on every car I have owned since 1992. FWI is the way to go for any boosted car. The shielding for a CAI with all the heat from a supercharger would not work very well IMO.

[Blownville]

I don't want to get in the middle of a debate so I am just going to post my expierence with the Spectra filter.

Does it rust like stated? Yes and no! I have one that did and one that didn't. The 93 SC didnt the 95 SLE did.

Did it make a difference? Yes and no! On the 93 SC yes it made a huge difference in felt power over the stocker. on my 95 SLE it made a tiny bit less power.

Is it cheap? Of course.

Is it recommended? No

IMO Stay with the stocker until you can afford a K&N and the Intense tubing.