Has anyone tried K&N Engine Air Filters?

I should have been more specific about that Downey intake kit on my 1990 4Runner: it was *not* a cai kit or a ram air kit. The conical K&N filter was located directly under the hood, so it also sucked in all that hot engine compartment air

 

Being unresponsive as you are to my requests for facts, I simply repeat:

"Your insistence on disconnected analysis is leading you astray."

There was a request for numbers in my last post to you:

"In fact, show me the numbers that demonstrate no effects of flow resistance ahead of the throttle! If there is no effect then we never need change any filter no matter how clogged it gets."

I'll accept logic in lieu of numbers as argument for your position, which I understand to be "the K&N filter system does not help increase fuel efficiency in the Prius." I'll accept any logic provided it is responsive to my argument that the entire system is effected by any small change within the system. That is one condition reality can not ignore.

Here is one example of you ignoring that reality:
"With respect to optimizing for mileage for the K&N the problem is this: You have fixed load and throttle controlling the air feed to generate that load. If you understand that, the answers become obvious."

The reality; every pebble, gust of wind, grain of dust and bug, slight road contour change, etc., effects the LOAD presented to the system. There is NO fixed load unless you want to take a differential of the various temporal equations involved, and that most certainly is only a distorted picture of one non-temporal instant. (time goes to zero)

The load dynamics of the system include everything that influences power output and energy use.

Reducing air stream flow resistance ahead of the throttle plate influences the position of the throttle plate (your statement). How does that save fuel; by reducing the energy demand on the unpowered pistons engaged in creating the negative pressures at the atmospheric end of the intake air conductors.

Air conductors are the mass dust separator, the intake air conductor hose, the filter box, the filter assembly, the mass air meter, the throttle body, the intake manifold, the intake passages in the cylinder head, and the area both ahead of the opening valves and past the opening valves. Resistance reduction can be made in every one of these areas

The unpowered pistons get the energy to create that pressure difference from the powered pistons.

I repeat my Occam's statement:
"Reducing power waste in any engine causes that engine to produce more usable power. You reduce power waste by reducing operating resistances, one of which is gas flow resistance."

I'll add this; reducing power waste increases fuel efficiency!

I'll also state that K&N filters save both your wallet and the atmosphere!

 

Rusty,

You are the one making a claim about how there will be an efficiency gain. Back your claims. Walk us through that filter and throttle valve and explain how for the same acceleration and same cruise (same power output) you are going to get an efficiency improvement. Because you won't be getting more air and a higher manifold pressure, the throttle valve (via your right foot/ECU will see to that.) Same rpm...same air, same intake manifold pressure, same temp, same gasoline flow. Now if you held the throttle position constant you would indeed get more pressure and power and use more gasoline; but then your acceleration would be greater and cruise speed greater.

I've already explained that the pressure at the intake manifold is unchanged for the same load and therefore there is no efficiency gain. The throttle position is changing to eat up that efficiency you are claiming. Where things differ is at WOT. That is in line with K&N's claims where the aim is incremental increases in power.

WRONG! You are in racer mode and unable to analyze the constant speed cruise, non-WOT mode or even the same acceleration rate (not the constant throttle valve position you are stuck on.) If you were to reduce the "negative pressures" in the intake manifold that the pistons are generating you would have more air entering them. More air requires a stoichiometric amount of fuel. You get more power, but you have to burn the same proportion of additional fuel to do it. As a result you must begin closing the throttle valve to restore the same "negative presures" and acheive the same load. Poof! Away goes that "efficiency" improvement.

So, you still can't explain how you would be improving efficiency in a constant cruise, fixed load condition. Nor can you explain how it would change in a dynamic one where the same exact performance profile was repeated. Waving your hands about dynamics won't cut it as I pointed out that an acceleration case works the same way. (And when I'm confronted by someone who is having trouble with the easy part, I seek to simplify the case, rather than complicate it.)

Taking the problem a bit farther, if one knew the upper limit on power requirements (air intake) one could even further restrict the intake to the throttle body without harming gas mileage. Why? Because the throttle valve would open more to provide the needed combustion air...again acheiving the same pressures in the intake manifold. Run the same profile and get the same results up until you exceed the throttle's range.

So, you still haven't tried to analyze a case where the acceleration rate or cruise speed is the same before and after. That is what we are talking about with real world drivers (unless they run WOT habitually) and in the EPA mileage test.

K&N makes a fine product. Unfortunately, you are making snake oil claims about it.

 

You are asking for a repeat of information I have at least twice supplied.

I ask for logic and you supply intellectual insult.

Your last post, along with the imitation quote ignoring most of my last post, have convinced me.

All that baloney about gas and liquid flow dynamic analysis and me not being an engineer was simply another attempt to mislead.

To my mind you are nothing more than a troll wishing to mislead others reading this thread.

I repeat my Occam's statement:
"Reducing power waste in any engine causes that engine to produce more usable power. You reduce power waste by reducing operating resistances, one of which is gas flow resistance."

I'll add this; reducing power waste increases fuel efficiency!

I'll also state that K&N filters save both your wallet and the atmosphere!

 

Rusty, Shawn is pretty respected around here, his posts are very factual and he backs his claims with facts. You will need to prove your credibility before disputing a person who has already proven his.
We are still waiting for that.

 

Being an extremely prolific writer is proof of facts??

I have already provided an overabundance of facts to Mr. Clark, and to you about other things. It's your choice to credit those facts or not. Not doing so is usually considered less than honorable.

But then, I know that you are in Adelaide, Australia, and you know that I am in Buffalo, Wyoming. Exactly where is Mr. Shawn Clark? 'Tis a puzzlement!

 

rusty,

What facts have you provided? Your case is bogus. You've claimed an efficiency that you can't get, because the throttle is eating it up to maintain the same load.

This isn't difficult to understand, which is why I'm so puzzled that you are pushing a line of BULLSHIT so hard.

I'm in the Midwest, where really doesn't matter. Perhaps you would like to provide us with your name since you seem so interested in others' personal information? However, your name or location don't really matter to me. The weakness of your logic and inability to back your claims does.

So once again, rather than making a misapplied assumption that you misidentify as Occam's razor, walk us through how the engine efficiency is going to be different for the same acceleration and load with the K&N. This requires more than some bad assumption. It requires that you consider how the controls are going to respond, something you don't seem to appreciate. I could put several extra psi on the upstream side of that throttle and it wouldn't help if the valve was still pinching back to control the engine load. Run the EPA cycle that way and you will get essentially the same result.

Whether the restriction to produce a given load is 0.5 psi from the filter & assembly and 4.5 from the throttle, or 0.1 psi from an improved filter & assembly and 4.9 psi from the throttle is irrelevant. At sea level the intake manifold in this case will be getting 9.7 psia air and at the same temperature. This will produce the same amount of power and at the same efficiency. If instead I hold the same throttle position, more air will pass through and I'll have roughly 10.1 psia in the manifold. Sounds great...one small problem, that is more mass of air and therefore more fuel burned. Fortunately, it produces more power. Unfortunately that means I'm accelerating more quickly and cruising at a higher speed. Doing that won't improve my fuel efficiency and would instead hurt it. So...to get back ot the same acceleration rate and same cruise speed I would have to be lighter on the throttle...eating up all that efficiency in getting the air to the throttle. And we are right back where we started. This isn't the same as reducing efficiency losses in the engine itself.

You would be right if the concern was power alone. We've got no argument there, but we aren't talking open ended power. We are talking about efficiency for the same level of performance. You would be right if we could cut some size/weight/displacement from the engine to more efficiently be able to provide the same peak power on demand. But we aren't changing those things.

 

I read until I've gotten bored. And yes, I do understand what I'm reading. I'm a "non-degreed" industrial automation engineer. I do quite well so I'm not too into pedigree paperwork. Now I'll get to my point. I put a K&N on my Prius immediately after taking delivery. I have used them in the past. I only hoped to catch a little more "grit" before it gets to the engine. I'm not too sure it does that. I wasn't looking to get any more mileage out of a gallon of gas. I was thinking I might get a little more life from the engine. I paid the $50 for the filter but I wonder if I'm really accomplishing anything. To me the Prius is Toyota's engineering pinnacle to this point. This is my fourth new Toyota dating back to 1980 with some Detroit stuff mixed in. I going to assume Toyota spent some time determining how much air the engine needed and designing the intake system (including filtration) accordingly. And they did this while staying within all the various specs. mandated by the entities trying to save the planet. I would think that if Toyota could have squeezed another mile per gallon out of the Prius they would have done whatever necessary while staying within EPA requirements. The fight to push one's point could go on and on. The bottom line is third party vendors have the latest and greatest. It's up to the individual to decide if they want to keep it stock or play with it. If you got $50 extra bucks, get you a K&N. I don't know if I would again. I didn't buy it for more power or MPG. I guess the banter will go on.

 

If your objective is to keep dirt out of the engine, may I suggest you will do better staying with the Toyota-brand air filter and replacing at 15K mile intervals. K&N advocates appear to agree that more dirt will get into the intake system using that filter, but will say it doesn't matter because the engine will last "long enough" even with the presence of the extra dirt.

Since Toyota is the entity warranting the drivetrain, it has more motivation and incentive to provide quality parts, compared to a third party filter supplier.

 

Mr. Wong,
That's exactly my latest thinking. The fact that Toyota is standing behind thier product would be compelliing enough for them clean the air as best they can. I think I kept the OEM airfilter. It's a matter of finding the box I put it in. If not, I know where the nearest Toyota dealer is. Take care.

 

As I have previously stated,

"Your insistence on disconnected analysis is leading you astray."

You are NOT conducting investigations on any Prius, you are sucking disconnected, and irrelevant, numbers and conditions out of your primary vent.

The logic is very simply, and universally stated,

"Reducing power waste in any engine causes that engine to produce more usable power. You reduce power waste by reducing operating resistances, one of which is gas flow resistance."

"Reducing power waste increases fuel efficiency!"

"K&N filters save both your wallet and the atmosphere!"

You have neither disproved nor countered those logical truths.

As I previously stated,

"Trying to blind 'em with science or baffle 'em with BS doesn't work. The proof is at the checkered flag, or the timing lights, or the lap counters. Or, in this case, at the gasoline pump AND the parts counter."

 

Yes, to answer the question. But why is another product besides the original so attractive? The makers didn't know what to pick? I got the original Denso for not much money. They are a trusted source and lot of engineering went into the filter media. I doubt one can do much better than the original Denso filter.
As for power gain, just take the element out completely. The engine runs at a constant air fuel ratio, ( I think it does, like most gas engines,) so more air will give more fuel/power, but how much and at what cost? I suppose one could transplant a Yaris 100+ hp gas engine into a prius, for more power, but the result I think would be disappointing.
I am staying with the original equipment on this car.

 

And rusty still has nothing factual to say and can't provide an example to prove his point. In essence he's saying the equivalent of "trust me."

No thanks, I'll stick with things I can measure and prove, not some BS from a deluded tech. This is especially true when said tech's vague hand-waiving claims are counter to those of the manufacturer of said component.

The only one trying to baffle with bullshit here is rusty. The science and engineering are against him.

 

There appear to be varied objections to using a K&N filter.

1. The OEM knows best.

2. My buddy knows best.

3. My numbers are best.

4. I say so.

As to the objection that I have presented no facts, I repeat:

"Reducing power waste in any engine causes that engine to produce more usable power. You reduce power waste by reducing operating resistances, one of which is gas(air) flow resistance." After all, an ICE is an air pump, pure and simple.

"Reducing power waste increases fuel efficiency!"

These are FACTS, undisputed FACTS, and no amount of numerical bullsh*t will change them.

"Trying to blind 'em with science or baffle 'em with BS doesn't work. The proof is at the checkered flag, or the timing lights, or the lap counters. Or, in this case, at the gasoline pump AND the parts counter."

All gratuitous insult aside, you of course know that Edison was an "uneducated" tech. Being an artist means I accept what I see. Try things for yourself and accept what YOU see! Get yourself a pair.

 

....Thank you for your service

:focus:

 

Shawn, you're bashing your head against a rather thick brick wall mate. There are none so blind as those who will not see.

He doesn't want to understand that full throttle is such a small percentage of the running time of a road car driven normally that any improvement that occurs at full throttle is not significant. At anything but full throttle the resistance to flow in the inlet tract is less than optimal not because of the air filter but because the throttle butterfly is blocking the airflow far more than any air filter element. Rusty doesn't seem to understand that a reduction in drag through the entire inlet tract would be needed to improve (very marginally) efficiency not just a reduction across the filter.

Put a bandaid on your bleeding forehead and have a seat.

Lets try this,
at 2000RPM my 1.5 litre engine would like to gulp down a theoretical 1500 litres of air per minute. If I allow it to do this on flat level ground it would soon be running at 4000rpm wanting 3000 litres of air per minute and so on. To prevent this acceleration Mr Toyota put a throttle butterfy in the inlet manifold and through my foot (via electronic control circuits) I control the opening and closing of this butterfly to maintain 2000rpm and therefore on flat level ground I maintain my speed. There is resistance across this butterfly which can be measured as manifold vacuum, wich is actually the difference in pressure between atomspheric absolute pressure measured in the open and manifold absolute pressure. I won't use number to prevent eye glaze, lets call the difference in pressure at 2000RPM on flat level ground (X)

Now not only the throttle butterfly is resisting air flow but among other things one thing restricting air flow is the stock air filter. If while I was driving, the filter was magically switch for one with half the resistance to flow and I don't adjust my throttle butterfly with my foot the pressure difference through the inlet tract would be less then (X) and engine revs might increase to say 2200RPM, so my speed has increased by 10% also. I want to maintain my speed to where it was so I instictively raise my foot slightly to restrict the flow of air into the manifold with the throttle butterfly thereby maintaining the pressure difference at (X) and the engine speed at 2000RPM. So now, even though I have a super you beaut air filter element with only half the resistance to flow I still only have enough air going into the engine to maintain 2000RPM on flat level ground.

All this adds up to no gain at constant speed, or anything but WOT the throttle butterfly is restricting flow of air into the engine. If I had a drag car or a race car where a significant portion of driving time was spent at WOT I might get a benefit from a less restrictive air filter but as I rarely use WOT I get little if any improvement.

 

Thank you Patsparks, you present a first class analogy.

What causes the throttle change is the overall lowered drag on the system.

Reducing the throttle opening causes less fuel use at a given power output or, to use Patsparks' analogy, the same RPM. Lowered pressure in the manifold past the throttle causes less fuel/air pumped per revolution. Any mass of fuel/air will be properly proportioned by the excellent computers in the Prius. Producing the same power output from lower fuel inputs is an increase in fuel efficiency.

Curious how tangled analyses can become when the mind is closed to what is not stated. The obvious, when not stated, is ignored. Closing the throttle at constant RPM reduces fuel/air mass that will pass through the engine with each revolution, and, in other words, saving fuel and increasing fuel mileage. Revolutions are miles.

Quid est demonstrandum.

Mr. Clark is well and truly hung by his own petard, the less open throttle.

 

Wrong. You are still moving the same amount of air, the manifold pressure is the same, and the fuel addition is the same. The throttle has pinched back to do precisely that (supply the same quantity of air, and as shown by the manifold pressure.) This is straightforward as an engineering problem.

You don't get lowered pressure in the manifold! You get the same pressure. In fact, if you left the throttle position the same, you would get higher pressure in the manifold (more air.) But what you will do to get the same acceleration is to ease off the throttle, and get the SAME pressure in the manifold.

I'm counting on it. Same was true of vehicles 20 years ago equipped with O2 sensors and MAP and/or MAF sensors.

You aren't getting lower fuel input. The ratio is unchanged (as you yourself recognized.) What you fail to recognize is that the air input to produce X horsepower is also unchanged as is RPM at all except WOT (or near WOT...anything that exceeds the power output of the original configuration.)

In this case I've stated the obvious a dozen times and still you ignore it.

Wrong again! Closing the throttle to maintain the same manifold pressure will not do what you claim! (Think about what happens to an engine at 0, 5,000, 10,000 and 15,000 feet for awhile. In the higher altitude cases the manifold pressure is changing, and the throttle will have to be more open to produce the same load. I would have thought someone in Wyoming would appreciate this.) Back to unchanged elevation...the valve train, combustion chamber and exhaust still work the same way--they have not been touched and their efficiencies are unchanged. If you hold the intake manifold (throttle chamber) pressure constant the engine will have the exact same efficiency as before. That is what we are talking about but has not penetrated your skull. It is precisely what that throttle valve is doing. Call it a pressure controller if you like becaused that is what it is...an intake manifold pressure controller (or pressure regulator if you like for a given engine load.)

Nope, I can see what you are saying and how inconsistent and self-contradicting you are in your application of it. I understand the WOT cases as well as the fixed load/fixed acceleration cases that you do not yet comprehend.

 

Jeez Rusty, do you have any reading comprehension skills at all?
Go back and read again, there will be a test at the end. So far you have scored about 10% which is a dismal fail!!

I never said less pressure past the throttle I said: -

I also said: -

That pressure difference is the difference between open atmosphere and manifold pressure, my god man!

Shawn, did what I wrote make sense to you? I'm worried it was incoherent babbling now.

Did anyone else follow my logic?

 

Made sense to me. I didn't have any trouble with it.