Air intake (auto, tuning, exhaust, mileage)

[M3 Mitch]

Actually for any computer-controlled FI car, the air filter's restriction or lack of it has no effect on cruise mileage. The oxygen sensor and FI computer adjust the mixture to a chemically correct 14.7:1 (or whatever it is) during cruise conditions. If you were running at or near top speed for the car, such as on the Autobahn, you *might* get an over-enrichening due to air filter restriction, with the system running "open loop" but I don't know of any specific tests.

Consumer Reports ran a test fairly recently empirically confirming that air filter condition does not affect mileage.

It's important that the filter be *intact* of course, so it removes the dust, but the restriction, which can act like a choke on a carburator system, no longer affects MPG.

At the same time, I don't see any sense in begrudging the car a new filter every 30K miles or so. At the very least, take it out and take a hard look at it.

BTW, *never* blow out an air filter with compressed air. This will definitely damage the filter media and let dirt into yo' motor.

[Majordomo]

Originally Posted by whiteboyslo

and lastly, it just sounds good. let's not fool ourselves. the reason car people love to do exhaust work is because they love the noise. the HP gain is just icing on the cake. an intake can add a little noise, too. call me juvenile, but it's just plain fun.

That is the only reason I put on a CAI. It really does make an engine sound meaner when you're wide open. I had an underhood CAI on a Ford 3.8 with an Eaton m90 supercharger and it could make the most beautiful sound. It was like a jet engine taking off. Anyone with an Eaton supercharger from the factory that doesn't have a cold air intake is missing out.

[Omaha Rocks]

I can certainly agree that the "oil system" utilized by K&N has some advantages. The old farm tractors I grew up on (Farmall M, etc.) had oil bath air cleaners. They were phenomenal in their efficiency - and you don't get conditions any dirtier than on a farm.

But the thought that these systems are going to add noticeable horsepower and mileage is bunk. Yes, they'll be a marked improvement over a dirty air filter. No doubt. But how much will they improve your power & mileage over OEM? It's negligible.


One of the vehicles I drive is a Ford Focus Wagon (actually it's my daughter's car). The K&N Generation 2 FIPK System for that car costs $290 - and that's without shipping & handling and/or tax. They "claim" that it will give you 3.26 more horsepower at 5100 rpm. Now... show me somebody who runs his Ford Focus at 5100 rpm, and I'll show you an idiot that won't get squat for mileage anyway, and has probably already ruined his engine.


The bottom line for me personally: There is no way that K&N Systems & Filters are worth the money. I've never bought one, and I never will buy one.

[Majordomo]

Originally Posted by Donn2390

It's pretty obivious he has no idea what he is talking about, either..
I think he is trying to refute the notion that you get what you pay for, by trying to steer you to some cheap knock offs sold on ebay...

Just because you don't know what I'm talking about doesn't mean I don't know what I'm talking about. Ask any modder his experiences with the K&N FIPK and other CAIs. They will probably agree with me. I am telling you this because I don't like to see gullible people get ripped off.

[Linson]

^ i'm not sure if i agree with you or not. i will say that the K&N FIPK is over-priced. and a Moroso CAI or AIR-RAID CAI is just as good and usually considerably cheaper. not sure i would consider those brands knock-offs.

what i am seeing in this thread, however, is this: people stating that CAIs are a sham because they either have had zero experience using them or they applied one to a 4-banger economy car and expected to get some level of performance from installing a new air filter. if youre driving a Ford Festiva or a Honda Civic, you probably wont notice an increase in performance. your engine is getting all the air it needs.

however, on a modern fuel injected, V8, performance engine (especially a Mass Airflow Controlled engine - as opposed to Speed Density Controlled) i'm talkin' Mustang, Camaro/Firebird, Corvette - you cant tell me that a CAI does not produce power that you can feel or that they are a waste of money.

[M3 Mitch]

I have to agree with Linson here, and it's worth pointing out that K&N filters come in 2 general types: one to fit the factory airbox, the other is a cone-type cold air intake kit. The first one really does not have that much effect on air flow, the cold air *can* provide additional air flow that as noted can provide noticable power upgrades on the engines that can actually use the added air.

Another point - if you are not writing down *data*, logging your MPG or logging drag-strip terminal speed, or even 40 to 60 times for acceleration, you don't have any basis to say your modification did or didn't do anything. Making useful mods to a car, in terms of figuring out what works and how much it works, as opposed to following a formula handed down to you by *whoever* you decide to take a formula from (and how do you know the poobah knows what they are talking about, or are they just trying to sell you something) you are actually getting into the realm of engineering. I'm not saying that nobody who didn't suffer through the heavy math like I did ever made a car go faster, but I am saying you have to understand the basic science or you're just monkey see monkey do.

The "butt dyno" lies, and lies big time. Put me in a car that's louder but slower, and, unless I actually time it somehow, I'll agree with the numbskulls that it just has to be faster. Case in point - mechanical secondaries on a 4-barrel carb. Testing showed that the mechanical secondaries gave worse acceleration because they caused the car in question to "bog" when they snapped open. But the driver would swear it's faster because the the car would really jump when it got over the bog. Unfortunately the bog was costing more than the jump was paying back.

I hope you kids who have never actually seen a carburator except maybe on a lawnmower are not too bored by my rambling here...

[Coldjensens]

I put a K & N filter in my Z28. I saw no noticable difference in performance nor mileage. It is expensive, but you eventually break even becasue you just clean and oil the filter rather than buying a new one. The cleaner is expensive, but there is a common chemical (mineral spirits maybe?) that is really the same thing as the official cleaner and a fraction of the cost. If only I could remember what it was that cleans the same as the K & N branded cleaner. (Denatured alcohol?)

One advantage is that it does nto seem to foul up and need cleaning as often as paper filters need replacing.

[Dd714]

The K&N filter itself will have very little effect, the K&N combined with a cold air intake will have much more effect. BUT it still won't be enough to really tell a difference. Cold air is an engines friend, if you get cold air into your engine, you will get some added performance. But again, 5 HP isn't noticable in a standard 200 HP 6 cylinder engine. Neither is the slight (1 or so MPG) gas savings. It makes the car louder without the supressed factory intake. Some people like that and say it sounds more agressive, but it's a personal preference.

Now someone here wrote about puddles and "oil getting on the sensors" and I would agree that is pretty much nonsense. You are only supposed to re-oil the thing every 50,000 miles or so and that doesn't mean dunking it in a can of 10W 40. It means spraying it with a little oil. There is no risk of oil getting on sensors, etc, unless you are doing it woefully wrong
.
Puddles - again, no, unless you put the actual filter underwater. The fendors are good places for CAI's but how many times have you dunked your rear fendor up to your wheel wells in water? That's not a puddle, that's the gulf of Mexico sweeping up into your road. You shouldn't do that regardless, CAI or not. Splashing won't harm it, rain won't harm it.

I've had a CAI on my Eclipse Spyder for 6 years, pretty much put it on and forgot about it. I think they dynoed a 9 HP improvement over its 210 HP engine (probably at peak HP and RPM). Still not much of a notice, maybe a tenth improvement at a 1/4 mile drag run. I've oiled it once. I figure after 6 years I got some sort of payback in gas mileage and not buying new air filters. I have a Vette to play with for the performance aspect so that isn't even a factor for the Eclipse.

[Dd714]

Originally Posted by M3 Mitch

Case in point - mechanical secondaries on a 4-barrel carb. Testing showed that the mechanical secondaries gave worse acceleration because they caused the car in question to "bog" when they snapped open. But the driver would swear it's faster because the the car would really jump when it got over the bog. Unfortunately the bog was costing more than the jump was paying back. ..

I agree with everything you wrote except the comment above about double pumpers. If they bog, something is wrong, you don't have it calibrated properly. The jets are too small, or too large, or the shooters are missized, or float boals or the idle feeds, or the carb is mismatched, etc...
Mechanical secondaries are not the best selection for street use, they use gas like crazy, need to be tuned right, and people tend to choose carbs that are too large for the engine, and carburators are always an imperfect technology with compromises...but hell yeah they are indeed faster. If you can show "tests" that say otherwise I'd like to see the link. But they should not bog, the transition between the front and back barrels should come in like a kick, without any bog.

All this is offtopic, sorry to the OP.

[Linson]

Originally Posted by Coldjensens

I put a K & N filter in my Z28. I saw no noticable difference in performance nor mileage.

nor should you have. i did the same thing on my '96 Z28 when i first bought it back in 1999. i felt no difference in performance and wasnt thinking about mileage.

scrap your K&N filter and get a complete Cold Air Intake. Moroso sells one for under 200 bucks and it's just as good as a K&N. if youre looking for more performance, a Flowmaster or other performance muffler would be a good idea in addition to the Cold Air Intake. any increase in gas mileage would be nil because you'll probably be gunning your engine because it sounds sweeeet.

and for Godsake, man the cheapest and easiest way to get a boost in your performance is a Throttle Body AirFoil. get a used one off of eBay for 20.00 bucks. the result isnt necessarilly a huge increase in peak power, but better throttle response throughout the RPM range.

airfoil

throttle body without airfoil

throttle body with airfoil