K&N Performance Air Intake/Filter

[paulcarson]

I am trying to improve the MPG on my Type C motorhome. I am considering installing one of K&N's performance air intakes on my motorhome. Was wondering if anyone has done this and what results were achieved with this. I rarely drive over 60 mph, keep the tires properly inflated, use synthetic oil, etc. I replaced the stock filter with a K&N filter when the motorhome was new. The engine is V-10 Ford.

[wolfe10]

Answers may be a little difficult.

Some, like you may have the K&N filter with OR without the K&N's performance air intakes.

Perhaps someone has a MPG history of "Before and After" (1) filter and (2) fitting the K&N's performance air intake.

Might also ask about any change in performance as that is where I would suspect a change-- far more than an MPG change.

Note: at least all the diesel engine manufacturers recommend AGAINST the oiled cotton element filters. They do let in more air, but also more dirt.

Brett

[shields]

As Brett indicated, a lot of OEMs advise against K&N type filters. The air passing through the filter can pick up oil from the filter membrane. If that oil gets onto the mass air sensor, the computer misadjusts the air-fuel mixture. My brother had exactly that trouble with his Ford pickup. We eventually went back to the factory intake system.

However, since you are already using the K&N filters without problem, adding the streamlined K&N intake piping might not create trouble. I would look and see where the mass air sensor is mounted in the K&N intake and compare it to your present set up.

Good luck saving fuel !

Tim

[MikeCanter]

The heavy duty truck and RV filters do NOT use oil on the filters.

http://www.knfilters.com/HDfilters/heavy-duty-air-filters.htm

but smaller K&Ns for gasoline motors do use oil on the filter. I have used K&N for 30 years on all my cars and have never had the oil from the filter get onto the MAP or any other sensors. People pass that story around but very few people that tell it either have used a K&N filter or have had a problem.

[paulcarson]

Thanks, Mike, for the info. I too have used K&N for years on all my vehicles and had never experienced or even heard of the problem of oil in the mass air sensor, but who am I to question?? I appreciate the website you shared. None of my engines are diesel......Paul

[MikeCanter]

Try this at Camping World.

http://www.campingworld.com/shopping/product/kn-air-filters/676

I am a big gearhead and tune professional drag racing cars and I feel that I know a lot about engines after starting to do it in the 1960's. I have found that in a lot of cars there is oil that gets into the air intake system from the closed crankcase ventilation tube that is normally comes from the valve cover and is attached to the air filter box on the engine side of the air filter. For some reason or another some cars seem to pump a lot of oil mist or oil fumes through this hose into the air intake system. These oil fumes or light oil mist will coat sensors after a period of time and also coat the throttle body throat around were the butterfly(s) rest in the closed position. When this happens one just has to clean the sensors and/or the throttle body. There are special spray cleaners made for doing this. If the K&N filters are oiled correctly with the special K&N oil and NOT over oiled then there is not enough oil on the filter to cause a problem. After one cleans a K&N filter and re-oils it the air flow during the first few miles will clean off any excess oil if it happens to be there and then there would not be anymore oil coming off the filter. Somebody that doesn't like K&N filters or does not understand were this oil normally comes from may incorrectly try and blame it on the K&N filter. One my three cars with K&N filters I NEVER find any K&N oil residue on the air filter box immediately after the air filter.

[ClayL]

I added a complete Banks system to my last motor home. The system included a K7N air filter. I kept very good records before and after the installation and saw absolutely no increase in MPG.

In tests the K&N filters have not been shown to be very effective filters

:

HERE

There was another test done by DuraMax per the SAE test procedure that also showed poor performance:

HERE

Also you might want to what Consumers Reports says about air filters and MPG:

HERE

Scroll down.

[MikeCanter]

I have seen that test before. The question I have is who is Ed Hackett? What is his resume? How did he conduct the tests? I maybe be wrong but my guess is that he sells Amsoil and Amsoil filters (just got the feeling,lol)

[paulcarson]

I really appreciate everyone's reply and info shared. But, I have now decided to keep the stock air intake configuration using the K&N filter. I decided the results would not be sufficient for the cost of the custom unit. I will just be happy with my 7.5 - 8.3 mpg and live life to the fullest. Thanks again everyone....Paul

[shields]

Mike,

Thanks for the input on the oil issue. I checked and you're right. While K&N's filters for gas engines (like Paul's V-10 and my brother's truck) use oil, the filters for larger diesel applications do not. Good to have you in the forum.

Tim

[desertdeals69]

I have been using a K&N filter on my diesel pusher ISB 275 for a year and it works fine. I have a 32 ft and pull a Chevy Silverado 1/2 ton. On our trip from Az to Perry FMCA we traveled 2150 miles a got 11.003 mpg. Its about the same milage as with the stock paper filter. I don't see changing the filter has any positive effect on milage unless the old one was plugged.

[MikeCanter]

I agree with you that driving at a steady cruising speed a free flow air filter of any kind is not going to show you an improvement in gas milage. Any non plugged air filter is going to let in enough air to make the required HP to run the weight of your MH down the road. The only way a high flow air filter is going to improve performance is at wide open throttle when your turbo is making max boost.

At cruising speed you only need a enough air to mix with the fuel at the correct air fuel ratio. That mix is controlled in a gasoline motor using the O2 sensor and ECU and with a diesel is controlled by the MAP and the ECU.

[Spike45]

I agree with you that driving at a steady cruising speed a free flow air filter of any kind is not going to show you an improvement in gas milage. Any non plugged air filter is going to let in enough air to make the required HP to run the weight of your MH down the road. The only way a high flow air filter is going to improve performance is at wide open throttle when your turbo is making max boost.

At cruising speed you only need a enough air to mix with the fuel at the correct air fuel ratio. That mix is controlled in a gasoline motor using the O2 sensor and ECU and with a diesel is controlled by the MAP and the ECU.

Diesel engine OEM companies like Cummins, CAT, Detroit Diesel provide application engineering specifications to the chassis builder. They will provide the maximum air flow requirements so that the chassis builder can spec an air cleaner system that will sufficiently provide that amount of air and usually more for the standard HP rating on the engine. Standard paper media air filters from companies like Baldwin, Donaldson, and Fleetguard have products that can meet the air flow requirements of the air filter housing as installed on that chassis. The maximum air flow occurs at peak HP. On a Cummins ISL 400 the peak air flow is 672 CFM at 2100 RPM while the ECM is delivering sufficient fuel rate to produce 400 HP.

Attached is the ISL 400 Engine Performance Curves. Scroll down to the 'Maximum Rating Performance Data'. You can read air flow at peak torque, peak HP and maximum governed RPM.ISL 400 RV Engine Performance Curves.pdf

Having a K&N or any similar product does nothing to increase this air flow. The above data was generated at the Cummins tech center engine test lab with no air cleaner. For a K&N to have any effect you would have to modify the ECM with a chip to provide fuel delivery above the map points in the ECM. More fuel requires more air to burn it efficiently. While cruising (not maximum load) you are no where near the maximum air flow requirement. The K&N and similar products provide "psychological HP"........you think it is doing better!

An earlier post had links to air filter testing. The absolute best link on that post was to the one on the Duramax diesel. There is a lot to view there and for the untrained, it may be confusing. The real telling data was the maximum trapped dust capacity, the overall efficiency and the air flow of each filter. The air flow was the same for all the filters as the testing was done at the air flow requirement of the Duramax diesel with standard ECM fuel delivery map. The K&N had the least trapped dust volume compared to standard paper media air filters. In the long run, that will dust the engine. All engines will ingest dust even with the correct air filter and stellar air system maintenance. More frequent air filter changing allows more dust to get in sooner. Air filters with low efficiency (<99.7%) will allow more dust in. At Fleetguard, an air filter for a midrange or heavy duty diesel engine that tests at 99.7% overall efficiency would be considered to have failed. They should test at 99.8+% and usually come in at 99.99x%.

With a given envelope of space considerations for mounting air cleaners, many RV and other applications have no room for larger air filter housings to accommodate the increased air flow demand of a diesel that has had the fuel system and turbo altered to increase HP. The K&N and AFE type filters can allow more air in the same space.....but at a cost to engine life and reliability.