Hi new and proud Prius owner - Wondering if anyone has tried the K&N Filters for PIP and if they had any luck seeing an MPG increase or any other benefit? Thanks!
Back when cars had carburetors, K & N filters may have been a good idea. Specific worries in the Prius is that the filter hangs straight over the throttle body and excess oil may foul the mass air sensor, and the Prius intake air makes a u turn where excess oil pools up.
I had a K&N filter setup on my Ford T-Bird. I don't doubt the sales claims that it cleans the air much more efficiently than a paper filter, and I don't doubt that it's marginally better for the engine to be breathing cleaner air. I do doubt the claims that it will increase mileage in any car with fuel injection. In the days of carburetors (long past) any increase in air-flow to the carburetor would result in a leaner fuel-air mixture, which may or may not be beneficial to the engine, but it would probably increase fuel economy, therefore a K&N filter would probably make a measurable difference. In a fuel-injected engine, the fuel-air mixture is unaffected by increased or reduced airflow. The airflow sensor determines how much fuel to mix with the air, and it doesn't vary with less air; the ratio is the same, therefore fuel economy is unaffected. Similarly, at higher altitudes, the fuel-air ratio remains constant, even though the oxygen available to the engine is reduced. No special air filter can help that. That's where a turbocharger makes a big difference by increasing the airflow. I also doubt the claims that it will significantly extend engine life, because I've never encountered engine damage due to microscopic particles of dust getting into the engine, in all my 40 years of owning and using many types of engines. So bottom-line; it might give you 1-2% more power at the top end, so my advice would be to get a bigger engine instead. It may or may not extend the engine life by a few miles, but I haven't seen any evidence of that, therefore personally, I wouldn't waste the money.
I've been using k&n filters for more than 15 years. I never noticed a lick of difference in power and fuel economy. My sample size is too small to comment on engine longevity. I continue to use it for the simple reason that I can clean and reuse it. I save some money and I save the landfills from x number of dirty filters. iPhone ?
+1 I bought them for my '06 Prius and my '02 Lexus in order to save on the costs of replacing the regular filters. IIRC, the service interval for K&N filters is 50K miles vs replacing the OEM filters at 30K. Buying a couple of those will more than cover the cost of the K&N filter. I sold my '06 before I got close to 50K, and my low mileage, little used Lexus has a long way to go. No problems with either car, but no noticeable differences in power or mileage that I could see.
