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I want to replace my air filter. I hear you can get better gas mileage but mainly I want to be able to hear the engine note a little better without it getting too loud. But stock, the motor is pretty quiet. I hear the AFE filter is pretty loud, is this true?
How loud is it? Does it sound good or is it just loud? Any noticeable power gain? And what is this green filter I hear about? Who makes it?
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So maybe I won't bother with an air filter then, but I was reading some post about getting better mpg and people were saying they were getting better mileage with an aftermarket air filter, so go figure. Now for exhaust, whats a nice sounding one that isnt too loud, but still noticeable from inside the car. I want to be able to hear it but not have it annoying.
How about aftermarket air intakes? How loud are they and do they sound good? Also any notice in HP and gas mileage? I read an article that said air intakes unless they are cold air intakes actually can REDUCE the amount of power because its sucking in hot air from the engine that the airbox would otherwise block, but if it sounds really good it might be worth trading a couple of HP.
Zevans, what do you mean by heat problems? You mean coolant temp or the intake itself gets hot? BTW was your long trip all freeway and was it the first long trip you've taken on your 8? If that's the case then maybe the better mileage is just from all the freeway driving you did. Is the K&N really loud? I hear a lot of complaints about it and some folks even have removed them cuz of the noise. Is it loud only at full throttle or also at cruising?
In my opinion, Mazda did a really good job getting what they could out of the Renesis. Any type of "open air" filter is going to make considerably more noise than the stock air box, mainly when you are accellerating and sucking in air. It's really an opinion as far as how loud loud is. Any gains by such a filter is debatable. In fact, I've read on this forum that there are some cars that will lose power around 6000rpms and up with increased airflow. I would strongly recommend that you save your money for awhile and wait until Racing Beat comes out with something besides a drop in. As far as exhaust goes, again, Racing Beat would be my recommendation. They seem to be an honest company = no rediculous claims. More growl than several others I've heard. But, each has his own opinion, which means you'll have to find one that sounds good to you. Sound is about all you area going to get from the aftermarket, as any gains in this area will be negligible. Mazda did a heck of a job with the factory system.
If you want to see whether you will benefit from more airflow, on a nice "clean" day, take out your air filter (to simulate the effect of an open air system), and find a nice smooth road where you can stretch a bit. Take it up to third gear and just keep running up the rpms. If you have a lull at 6000rpms, don't even bother with an aftermarket intake, unless you invest in an aftermarket ECU.
I guess if I had money burning a hole in my pockets, I'd spend it on things I know would increase the performance of my car, like suspension, because, at least for right now, anyone claiming significant gains in the areas your looking (to quote ZoomZoom) is suffering from a placebo effect.
Anyone flow benched the stock rx8 intake? On the Mazda6's discusting contraption of an airbox, the airfilter itself was only worth a whopping 6% of overall restriction. (aka removing it completely only effected the overall flow 6%).
Considering most cotton gauze filters barely flow more then "current tech" paper filters...I'd consider any mileage improvements just normal variance. The increases in silicon in your UOA's however...thats a real factual negative for the less efficent (at filtering) K&N filters.
Just that intake temperatures will have climbed because the top of the air box is now open, and therefore will draw a certain amount of air from the ambient in the engine bay - which is extremely warm.
I make a lot of long trips that are mostly freeway - I meant this was the first one I have done with the K&N fitted. In fact I make the identical long trip every month or so and like I say this is the first time I've got 300+ out of a tank on the self-same trip. Therefore I'm pretty convinced it's not a coincidence.
Slightly depressing having to fill up twice in one day though...
It's really loud at full throttle over 5 - enough that I can see why people might remove it. It doesn't bother me particularly though. Cruising at any revs it's fine.
Even if you remove the intake (thus no restrictions at all), you're not going to find much improvement in power or gas mileage. So claiming anything other than very minor changes with an intake is nothing more than user error.
I think I read the removal of all air intakes will net you around 2-3 hp.
i have a custom intake that will be in the market soon, i tested the sound VS the KNN and mine came out the the same loudness i guess, mine had a deeper tone to it, the Knn was more high piched..im gona take orders soon as i get the prototype done, mine also has a silencer. when i tested it the silencer was on, so if it wasnt on im betting it would have been louder
Last edited by xxdevilzeroxx; 10-27-2004 at 10:15 AM.
ive got the Green filter on the way for mine, its free so i thought i would try it.. As a green filter distributor we have seen that gas mileage seldom increases with the use of an aftermarket filter. The theory behind this is that if your computer is seeing more air, it will add more fuel, thus any performance gain you may or may not feel. ill let you know what i think of it when it comes in