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Discussion Starter #1
Has anybody put the K&N 57-9027 kit on their 4.7? This kit looks more like the stock kit, not the one with the exposed cone filter. I did a search and didn't find any threads that talked about it. Even on Amazon, there are only 3 reviews. They are good reviews, but still. Anybody have one?

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Basically the small reviews that i've found online. Some people said they gained power, some didn't, but they all said they gained MPG. As you know with these V8's, any extra MPG's we can get is worth it, to me. So was wondering if anybody had any real world results.
 

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Basically the small reviews that i've found online. Some people said they gained power, some didn't, but they all said they gained MPG. As you know with these V8's, any extra MPG's we can get is worth it, to me. So was wondering if anybody had any real world results.
And they would all be wrong. I'd explain why but I can't be bothered.

There's no MPG gain and no power gain except a couple of horsepower - maybe - at WOT.
 

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I have had the replacement K&N filter in the stock housing and didn't really notice any difference. I just did it because I replace it on every car.

I just replaced the K&N with the Airaid intake. First off it sounds awesome. The throttle response is a little better. I agree with everyone that says mpg increase is bogus. I did just put larger and heavier tires on the truck so the mpg on my truck is gonna suck no matter what I do to it. The only benefit that I can really say is that the truck does seem to have a little more power and runs at a lower rpm while cruising on the interstate.

I will be interested to see how it goes when I replace the exhaust and manifold. Heard bad things about putting in high flow cats so I may just leave those as is unless I replace them with oem.
 

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Just get the K&N drop-in. It's cheaper, you get the same benefits, and a go-fast sticker to put on your filter housing.

:)
 

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Just get the K&N drop-in. It's cheaper, you get the same benefits, and a go-fast sticker to put on your filter housing.

:)
Agreed. As long as you understand the benefits are more dirt in your engine oil and a sticky intake tract. Sticker's cool though.
 

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How about because I love the intake sound of a Toyota V8 :devil:

You can throw a filter cover on for industry/dirt road travel if you're concerned about extra dirt. Just keep the filter well oiled for everyday driving.
 

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Agreed. As long as you understand the benefits are more dirt in your engine oil and a sticky intake tract. Sticker's cool though.
Sign me up for that !

I bought my Tundra 4 years ago used and it had a re-usable drop in filter installed ~ my first 'Mod' was to replace it with an OEM paper filter. Couldn't tell one bit of change in performance one way or the other. I'm not a fan of maintaining an air filter ~ I'll buy a new paper filter and change it out when the time comes.
 

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Discussion Starter #11
So why does the oil get dirtier with a K&N? Does it just let more dirt through vs a paper filter?
 

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So why does the oil get dirtier with a K&N? Does it just let more dirt through vs a paper filter?
According to my very unscientific and unproven sources, the re-usable oiled air filters aren't as capable of removing impurities from the intake air. These fellows have seen more intake tracts that I ever will so I'm taking their word for it. They claim the OEM style paper air filters are superior in filtering the air vs the K&N style filters thus the intake tracts are cleaner.
I'm not on a quest for more power or performance ~ My engine performs quite well with an OEM air filter.
 

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Discussion Starter #13
I wonder if it's a matter or letting more air through the filter but also more contaminants vs cleaner air, but not as much. I suppose leaving the air filter off would also give you more, dirty air too ;) So what's better then, more air with slightly more dirt or cleaner air, but less of it? I guess it's probably so minimal (the amount of air) it doesn't matter.
 

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I wonder if it's a matter or letting more air through the filter but also more contaminants vs cleaner air, but not as much. I suppose leaving the air filter off would also give you more, dirty air too ;) So what's better then, more air with slightly more dirt or cleaner air, but less of it? I guess it's probably so minimal (the amount of air) it doesn't matter.
Bingo! Your engine draws in air through a cross-section of a couple of square inches on either side of the throttle body plate. The power output of your engine is controlled by varying that area. Even at WOT the cross-sectional area of the throttle body is only about seven square inches. Add to that the fact that the ECU uses data from the MAF sensor and from the O2 sensors to maintain a stoichiometric air/fuel ratio.

One more thing. The ECU compensates for any flow restriction from a dirty air filter. In fact the air filter creates virtually no pressure drop, clean or dirty. And a dirty air filter is a better air filter than a clean air filter. I run my paper air filters 60,000 to 80,000 miles or more. The pressure for regular air filter changes comes from companies that want to sell you an air filter and because in the old days of carburetted engines with no computer control, a dirty air filter could cost you gas mileage. But not today.

Now you understand why aftermarket intakes are pure snake oil.
 

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The ECU compensates for any flow restriction from a dirty air filter. In fact the air filter creates virtually no pressure drop, clean or dirty.
The ECU will trim the gas flow to compensate for the reduced air mass that comes from restricted airflow, but it cannot make up for the reduced flow. The ECU meters air and fuel, but it can't do it efficiently when either one is restricted. Performance will be reduced which will effect gas mileage.

And a dirty air filter is a better air filter than a clean air filter.
This is just silly. Not only are you restricting air flow, but those particles can eventually push their way through the filter media the longer they are there.

Paper and oiled media are both perfectly valid filtering methods. Both can be made to work well, but can also be made to work poorly.
 

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The ECU will trim the gas flow to compensate for the reduced air mass that comes from restricted airflow, but it cannot make up for the reduced flow. The ECU meters air and fuel, but it can't do it efficiently when either one is restricted. Performance will be reduced which will effect gas mileage.
Almost everybody believes what you believe. And you're wrong. To be honest I don't care. I put the facts out there for the few people who have an open mind.

A dirty air filter, even a very dirty air filter, restricts the air flow very little. And the ECU doesn't know or care either way. The only effect that a very dirty air filter has (maybe) is to slightly reduce maximum power at WOT. It has no measurable effect on fuel economy.

If you're interested in the facts, read what Oak Ridge National Laboratory has to say about air filters and fuel economy.

"Results show that clogging the air filter has no significant effect on the fuel economy of the newer vehicles (all fuel injected with closed-loop control and one equipped with MDS). The engine control systems were able to maintain the desired AFR regardless of intake restrictions, and therefore fuel consumption was not increased."
 

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No one is arguing that the computer can't maintain a stoich mixture in adverse conditions. The fact remains that the driver would have to increase the throttle slightly to achieve the same HP/TQ output. Every vehicle will have different results but its simple physics. The engine is a glorified air pump plain and simple. The more air you can get in and get out the more efficient it is. Not going to dive in any further but results may vary! Also I agree with the fact that a properly serviced reuseable filter can filter just as good. JMO
 

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No one is arguing that the computer can't maintain a stoich mixture in adverse conditions. The fact remains that the driver would have to increase the throttle slightly to achieve the same HP/TQ output. Every vehicle will have different results but its simple physics. The engine is a glorified air pump plain and simple.
Thanks for signing up to make that comment. :) And yes, that's exactly what pewter05 was arguing, that with a dirty air filter the ECU won't be able to maintain a stoichiometric air fuel mixture.

Anyway, think about what you just wrote. The engine is an air pump that is controlled by "throttling" - i.e. restricting the air intake. So if the air filter is dirty and offers more restriction to intake airflow, you have to open the throttle a little more. i.e. you have to slightly reduce the restriction at the throttle plate in order to compensate for the slightly increased restriction at the air filter. The net result is the same and neither the engine nor the ECU care if the intake pressure drop is created at the air filter or at the throttle plate.

So the only effect that a dirty air filter has is to slightly reduce maximum power at WOT. My use of WOT is never.

For spark-ignition Otto cycle internal combustion engines installed in street vehicles there is just about no reason to monkey with the air intake tract upstream of the throttle plate as the engine came from the factory with an intake that was designed to provide sufficient airflow under all foreseeable circumstances. Doesn't mean you shouldn't install an aftermarket intake but the only benefit the aftermarket intake provides is a different engine sound. Oh and your MAF sensor is calibrated to the factory intake so an aftermarket intake may screw up the data your MAF provides to the ECU but what the hell. That's what the O2 sensors are for.

Note that this does not apply to diesel engines where the power output is controlled by controlling the fuel flow and not the airflow.
 

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Sorry boys, mibro is correct. Dirty filters are more efficient, and restrictions in the intake do very little if anything as far as gas mileage is concerned. I've seen test after test after test.......Its hard to digest at first, but its correct.

(If this were 1978 and we were talking carburetors, this would be a whole 'nuther discussion........)
 
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