- #46 of 50
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Re: MPG---UPDATE [greyfox1]
by coolrunning
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Apr 04, 2008 (2:57 pm)
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Replying to: greyfox1 (Feb 10, 2008 1:38 pm)
You are so correct. There are a lot of so-called "econoboxes" made by Japanese manufacturers that get the same mileage. 25 mpg HYW from a Toyota Rav4 is not near as impressive as a 5.7L HEMI doing the same thing! 
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- #47 of 50
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Re: 25.3MPG in 300 Touring. [xtec]
by coolrunning
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Jun 23, 2008 (11:43 am)
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Replying to: xtec (Sep 05, 2007 2:19 pm)
I also installed a K & N air filter on my 5.7 HEMI, and have not noticed any improvement in mileage or performance. If anything, I think the mileage is a bit worse, but I attributed that to the weight of my right foot... I had a discussion recently with someone about the high flow air filters and learned something. These filters really make a difference on carbureted engines where you can get more horses from more air/fuel. On modern engines with computer controlled injection and the combustion air intake controlled with mass airflow sensors and oxygen sensors in the exhaust side, you could take the air cleaner off completely and never change the amount of air allowed into the engine. So, what is the point? If anything, the filters don't clean as well and can allow dirt to flow into the micro-sized orifices that meter air/fuel into the cylinders, etc. I am definitely considering going back to stock filters!
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- #48 of 50
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Re: 25.3MPG in 300 Touring. [coolrunning]
by shipo
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Jun 23, 2008 (2:09 pm)
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Replying to: coolrunning (Jun 23, 2008 11:43 am)
"I am definitely considering going back to stock filters!"
I'm thinking that that's a good move.
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- #49 of 50
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Re: 25.3MPG in 300 Touring. [coolrunning]
by brit5
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Jul 24, 2008 (5:44 am)
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Replying to: coolrunning (Jun 23, 2008 11:43 am)
Fuel injection engines do not work the same way that carbureted engines do.
With an intelligent fuel injection system, the increased airflow from reduced air filter obstruction results in the metered introduction of additional fuel to compensate for greater air mass-flow. The engine will make more peak power but will burn more fuel doing so.
Maintenance warnings about dirty air filters negatively affecting performance on EFI engines are quite correct, but the performance parameter that is most affected is power output, not economy. A really dirty airfilter not only significantly reduces power, it can also result in air bypassing the filter altogether, carrying grit into the engine with obvious implications for engine life.
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- #50 of 50
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Re: 25.3MPG in 300 Touring. [brit5]
by coolrunning
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Oct 10, 2008 (12:16 am)
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Replying to: brit5 (Jul 24, 2008 5:44 am)
You are absolutely correct. If I owned a 1960's muscle car, I wouldn't hesitate to use a K & N air filter. They are a well designed and constructed product. They are such a risk to modern engines, they are even banned from use by Dodge on any DIESEL engines according to the dealerships. They claim the stock OEM filters do a better job of keeping the dirt out of critical areas. Since I can see daylight when I hold my K & N filter up to the sun, I am inclined to agree. Besides, the whole point was to improve my fuel economy which it did not. 
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