Originally Posted by DaveV
Does anyone have one of these and do they really make a difference? If so which brands do you think are worth it or are garbage!
Contrary to what most say, I have found one circumstance where there was a documentable improvement in performance in terms of gas mileage for me - pulling high altitude, highway mountain passes, at highway speed (65+ mph). I make this trip many times a month in my TJ and after putting my K&N intake on, and using my cruise control just as I always do, I found I was getting about 1.5 miles per gallon better than with the stock setup.
Now mind you, this is obviously running the engine at the top end of its operating range, in stretches where the altitude exceeds 11,000 feet – not something most people see very often. When I removed the K&N and put the stock intake back on and made the same trips, the mileage returned to what it was previously.
So why did I take it off and go back to stock?
Because Jerry Bransford and others were able to point to a filtration study that showed that the K&N did a horrible job of filtering fine dirt particles, and the small increase of fast travel m.p.g. that I saw wasn’t worth it to me versus sucking all that crap into the engine.
Since the overwhelming majority of the engine operating hours that my Jeep sees are barely crawling along a dusty mountain mining trail at low r.p.m. where the marginal increase in air intake efficiencies I saw in a high speed, high air flow situation don’t even come into play, the K&N came off and won’t go back on.
Just my 2 cents.