Cold Air Intake (CAI) vs Fender Well Intake (FWI)

AA wrote:

CAI: Cold Air Intake
Another theoretical problem with the FWI is the positioning of the air filter nearer to the ground, possibly exposing it to the elements more so than a CAI. This fact raises fears with some that water may splash up into the air filter, but this has yet to happen in the case of a Riviera using a FWI design. There is little chance of the filter being exposed to water unless driven through a flooded street, or if by chance the fender well became damaged or disconnected. Even so, the filter in a FWI will receive more exposure from the elements because it is less shielded from the outside. Expect to clean/change filters more often than with a CAI design, and expect that to be a chore, as the fender panel must be removed to service (works best with the wheel removed).

It has now. I sucked water into engine through FWI on Chrismas Eve. The fender panel was modified though, so no Riviera with stock fender panel has sucked up water yet still. The car was going about 55mph on level highway, really bad storm. It had the rpm surge a bit, likley due to water hitting maf sensor, a little water would read as alot of airflow. Someone not paying attention to gauges with radio on may not have noticed anything was wrong. Next day checked for source of problem, oil lucked like milkshake and there was standing few inches of standing clean water around insert in UIM.

Do not modify the fender panel without doing something to prevent water getting on air filter.

I put a short ram on temporary for winter till I get problems fixed. On a 33 degree day with strip behind hood removed I hit 91 degree intake temp. Short rams are defiantly HOT air intakes. I wouldn't want to see the IAT if it was 90 outside. If it was 90 out the intake would be 150? That would probably make the pcm pull some timing, and then some more from the KR it would cause.

Thanks for the report. I can see that happening with the removal or modification to the fender well panel. It really depends on how you modify the panel. I've cut a hole in mine and placed a shield/scoop over it to block any splashes. Also have mounted an aluminum panel protecting from heat and water from the engine bay area. More info here:

Link

Using a short-ram in summer will easily create 150ºF intake temps. I have measured 135ºF with a FWI on a 95ºF day sitting idle - before making modifications to the fenderwell - now that is improved. For supercharged engines, short-rams are almost a suicidal mod for summer use.

In your case, being an L36, the 150ºF will mean less power, and possibly retarded timing, but I don't know if it would cause knock for the N/A engine. It usually has to get really hot for that to happen. I wouldn't worry really - lots of N/A cars use short rams with success. The increase in air flow seems to offset the higher temps, especially when at cruising speed.

Perhaps AA should edit that old post a bit... How is your fender modified?

Until you get into cams, rockers, etc. I think the opening in the stock Air Box is fine. I cut the red restrictor out of my AB lid and left the resonating chambers alone because they're not hurting airflow. Nor do I feel any improvement if I take the snorkel off of the air box and run wide open...
My IAT @ highway cruise is only 4 or 5 degrees above ambient.

The fender is cut away from where the fender well opening the filter was in down. I had it come loose at one point from breaking to many platic pins and the tire chewed it up. I trimmed off the jagged edges straight rather then replace it. So it was probably water flung off the tire.

Before the filter goes back there I was going to make a splash shield, put a filter sock, and AEM Bypass valve in(switches air intake to short ram when water starts getting sucked up). It would probably have been fine with anyone of the three. Even with most of the fender panel gone there was no problem for about a year.

Short ram temps would pull 3-5deg timing from '00 L36 Bonneville( closest vehicle I have table for).

since the weapon r dosnt work what can be easy instead of cutting up my fender and all can i just put a kn cone on it or what.. i have done to many mechanical things to cars... i wanna hear he supercharger whine more and get sum more power... if i just take the air box off and replace it with a cone what bout air sensor?

Dylon, please read the links provided above. The questions you are asking have been answered before, and we've saved the information so that others like yourself can learn from it.

There is another thing to be cautious about with a fwi. I recently replaced my radiator due to a crack in the drivers side tank and when doing a routine check up of the airfilter I found coolant in the bottom of the airbox. Now all three designs stock, cai, and fwi, draw air from the same area in the fenderwell but only the fwi would be directly exposed. As it was the stock box pulled just a little coolant up into the filter, and none into the intake tube itsself, but I can only imagine how much worse it would have been had the filter gotten sprayed directly.

Interesting. Do you think the amount of coolant that reached the air filter in would be harmful to the engine? Water has its way of getting through a filter (humidity), but how much actually gets through, and is it significant to cause any real problem. Compare to the fact that you're loosing coolant, I think that's a far greater concern. Glad you got that fixed!

I would also think if there was coolant in the bottom of the airbox, it surely hit the air filter first, and some probably got through to the intake. So, CAI and OEM designs are not immune to this, but I do agree the FWI gets more exposure to the elements. I put a shield up to protect mine from moisture and heat:

Link

Might as well throw some of my experiences in here for what its worth.

I have a FWI, with a 9 inch K&N cone stuffed into the fender-well. I also had the customary leaking Riv rad on the intake side belching coolant everywhere. Some got onto the filter, but a close look showed it didn't get past K&N's "sticky oil". I also at the time checked the MAF sensor to see if it got anything onto it. It was perfect.

On a related note, I did once accidentally end up on a flooded street with my FWI, like a foot of water, and of course my first instinct was to
goose it to get through the water. Everything seemed to be ok, but I pulled the fender later to inspect the filter. Half-way up the filter was bone white from the water washing off the K&N oil. Not a bit of moisture was up the tube. I suspect if it was a 7" cone, it might have snorkeled up some water, but the giant 9" had plenty of other surface area to get air from. Just FYI....

Glad I got a giant K&N on mine! (it's a 7.25", still pretty darn big).

I'm still not sure how I got the 9" to fit into the fender on the 95, there looked to be less room in the wife's 98(she has a 7.25" too).

I tried 3 filters, but the 7.25" is the max I could fit. Much better than the 4" cone I used to have.

I agree with Andrews finding that the coolant did NOT get thru the kn filter but it could be possile with a dryflo or paper filter. Judging from the spray pattern the stock airbox seems to direct a large majority of the incoming air thru one corner of the filter, so flow rates may have dropped but weren't cutoff entirely.

I'll post some pics of my setup. It's just a 4x7" cone filter on the end of the stock duct. If memory serves, the duct in the Riv's had a larger diameter than the Regal so I didn't need to change that.

I went to home depot and found a PVC coupler that fit inside the duct and filter opening. Scuffed it, painted it semi-gloss and drilled a hole in it for the IAT sensor to fit in. I had a grommet laying around to make a good seal around the sensor. You can see that better in the second pic.

How does that sound??

No complaints here. Anything past 2700rpms and the blower starts a whinin'.

That's with stock pulley.

Only posted it because of how easy it was to install. You can get fancy with these but there's really no need to.

Ya thats what im looking at. I have the filter and wanna do a quick intake. Where do I look for those lil couplers that you have the IAT running into?

Be sure and read this before installing a hot air intake: http://www.kennebell.net/techinfo/general-info/HotAirWARNING.pdf

Oh man! 23PSI loss thats crazy!

It seems that most of the w-body guys dispelled the myth that a CAI or FWI is really anything better than an open cone on our engines. FWIs can be more restrictive, thus negating any benefits from running cooler air to the motor. CAIs don't really provide much of a barrier to hot engine bay temps. I've seen people wrap theirs with that ugly heat reflective stuff and it still doesn't do much. The way I see it, when a car is sitting stagnant in traffic, there will be heat soak in the engine bay. But as soon as the car is moving, cool air is circulating around. . Ambient air is rushing into the bay from the grille and underneath the car.

From experience with my Regal, I've seen a loss of PSI with a FWI. There has not been a difference in IATs between the FWI and open cone, especially when the car is moving.

Not trying to sound like a jerk but just sharing what I've learned from the various posts and arguments on ClubGP, RegalGS, local L67 guys and my own personal experience.

There's a lot of misinformation at all of those forums, as well as a lot of useful info. But the concept of the cold air intake isn't really open for discussion, it's not a myth to be dispelled. The fact is, all modern cars come with a cold air intake source from the factory, and if you look at OEM turbo and supercharged set-ups, they go through great lengths to isolate the intake air from the engine bay. For example: my brother's S4 had a snaking tube from the TB routed around the front of the radiator, pulling in air through the grill. Nissan/Infinity VQ engines do the same thing for a couple extra HP.

Everyone can make their own choice, but I'm going to believe Kenne Bell and every auto maker in the world - companies that spend millions on R&D - before I take the advice of the W-Body forums. I've done my own testing with IAT readings, and I do see benefits from isolating the intake from the engine compartment. I also picked up a lb of boost switching to my FWI tube from the OEM ribbed one.

anyone try or have feed back on the K&N apollo cai?

Well the whipple riv has a hot air intake then whats he thinking?

Consider that your car and the Whippled Riv are totally different animals.

The Whippled Riv shows that if you really know what you're doing, you can get away with things that don't seem right to the onlookers. When you consider that car has an intercooler AND nitrous, the intake air could be 200ºF and it ain't gonna matter with more than a 150º temp drop after the blower. It does not mean you will see the same results with your car.

A similar example would be tuning a supercharged car to turn 1/4 mile runs on 87 octane gas. It takes a lot of work, but it can be done. But none of us should try, as it would knock severely, probably damaging our engines. Just another case where the rules can be bent in very specific situations.