Aftermarket filters K&N or Simota?

[Baltothewolf]

Originally Posted by Frank Lee

I think you could diddle with it all you want and at the end of the day you will still have to make that downshift.

This ^. The only mod I have ever done to prevent a downshift when climbing a hill, was swap the rear end from 2.73's to 4.10's in the stang. However, that in itself lowers mpg due to higher RPM (2500 instead of 1700 @70mph).

[niky]

Originally Posted by Eddie25

It just doesn't make sense. I am aware of the resonator but getting info on exactly what it does is hard. however common sense will tell you shorter pipe means less restriction = les suction motor has to do to get air in. my plan was to delete my air box completely. then modify it like in the first image. but that result showed cars performing better with the standard air box? so what if I do the mod showed in pic 2. still using the airbox just putting the filter at the end? but just improve cold air circulation.


Attachment 17095

Attachment 17094

A resonator resonates. An intake resonator tunes the length of the intake pipe, making the column of air in the intake tract "longer" without it actually having to be longer. This means you can tune out annoyjng drones at certain rpm by changing the natural pitch of the intake noise.

It can also help "pulse tune" the intake, where the intake air moves faster at certain rpm/loads, but change anything else in the intake and you can throw that tuning off.

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A short intake tract technically should liberate more high rpm power. Technically... and only if the intake itself is the big restriction... but a long intake tube typically works better at medium to low rpms. In my case, it works better at high rpm, too. It's on a case-to-case basis, though.

What applies to a tiny Daihatsu engine fitted with an overly large aftermarket filter that most likely causes flow stagnation (something they didn't mention in the MCM video because... duh... doesn't fit the script) can't be generalized to your (Focus?).

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Still, even the best intake won't keep you from having to downshift. Only an ECU tune or a good exhaust manifold will have enough of an effect for that.

[Shawn D.]

Resonators in the external portion of intake tract are solely for reducing (or sometimes enhancing -- seriously) intake noise. This is common knowledge in the hot-rodding/tuning community. If resonators made more power, there would be aftermarket parts to add them to non-resonated intake tracts.

[some_other_dave]

Originally Posted by Eddie25

... common sense will tell you shorter pipe means less restriction = les suction motor has to do to get air in.

In this case, common sense is wrong. Or rather, it is only right in some circumstances.

If you've done research on exhaust systems, you'll have seen that the shortest, fattest exhaust pipes possible are generally not what you want on most engines. Short and fat pipes have a higher maximum flow, but at lower flow rates they don't do anything for you. Conversely, a long skinny pipe limits the maximum flow, but at lower flow rates the inertia of the moving gas in the pipe actually pulls more exhaust out of the cylinder.

The intake works the same way. Except the inertia is pushing the air into the cylinder, instead of pulling it out.

There are also more complex effects, like the resonances set up in the system of pipes. (Google "Helmholz resonator" for way too much info on the subject.) If you design the lengths of the pipes correctly, at some RPM/flow conditions, air will get packed in even more strongly by pressure waves in the intake than it would with just open air pressure.

OK, so with that all said: The typical low-restriction intake or exhaust will help flow at high flow rates--that meaning, at WOT and high RPMs. Guess where anyone driving for fuel economy hates to drive? Yes--WOT and high revs.

Stick with the stock intake, and just deal with the downshift is my take-away from all of that.

-soD

[cyclopathic]

Originally Posted by Eddie25

Anyone rate these K&N filters or are you just paying for the name? Here a K&N cost 6 times more than the Simota. I am not worried about the re usable or washable or those gimmicks. I just wan to know which one wil give me better increase in power? I keep having to gear down to climb some long hills around where I stay and it really hurts my FE. There are other things u can do to improve my FE but I want to start here.

There are might be some MPG gains with K&N, but they are "special case". I have tested K&N on Prius C, and the manifold vacuum had dropped from 1.2-1.6 psi by 0.3-0.5psi on average. This is with RPMs in 1-2,5k normal operation range. That would indicate 2-3% better volumetric efficiency.

Note that this is hybrid, so ECU runs ICE at low vacuum with throttle plate open enough to keep intake pressure close to barometric. Most of conventional designs run engine with higher intake vacuum, so any improvements you'd see will have to come from situations which dictate low vacuum.

2nd I am not sure how the higher intake pressure will and if translate into MPG gains as this is function of ECU programming.