Too Big

I installed an AFE Stage II I bought on Craigslist (I know - but it was a great price). It's the Stage 2 with the oiled filter (early model I guess).

My concern is that my mileage has gone down one full MPG since I put it on. I don't drive it any harder than before and have tried it on several 200+ mile trips and I get 17-17.5 now, when I used to get a solid 18.5.

I'm just wondering if there's something else I should check or anything I might have done wrong. My next experiment will be to take it off and measure MPG's with the stock box again (had an AIRAID filter element in it).

Thanks for your help!

nvr-enuf

worth a try to verify your assumption. Some claim that aftermarket air filters will not provide any gain and might even hurt mpg. Try it and let us know what you find out

diesel4play

I installed my Volant cold air and I do not think I gained mpg, I did not lose any. I gained a little HP & torque and that wonderful whistle but no or little mileage. Look closely at the filter to see if the guy you purchased it from put way to much oil on it while cleaning. Just a thought.

carl48

we did extensive testing on stage two afe. it is less than worthless for what you are trying to do. go back all stock parts and filter. get a psm kit and install it. do not make any other changes.

purduepurdy

Care to share some of that testing carl? More than a few of us using AFEs.

Stovetop535

I would be curious on some of the testing too. I have had the stock intake on my truck, a k&n with an oiled filter and also with a amsoil dry replacement filter, the s&b and now I have the afe stage 2. I did not notice any mpg difference between any of the units I have had on my truck, but the Afe seems to be constructed the best, by far.

Mudmohawk

I like to see some of it also. I have had and AFE StageII on mine for awhile now and have not noticed any drop in mileage or dusting in the tube.

SCCSURF

Clean the air filter, change the fuel filter, check tire pressures and ensure your exhaust is flowing normal. Just some thoughts on MPG's.

buzzard1

I gained a solid 1 mpg with the S&B intake. I hand calculate every tank including avg mph, type of driving, fuel cost,pump # among other things and have since new.

6 Shaker

I hand calculate every tank as well and I've never noticed any MPG gain or power increase with the AFE STG II intake. All I noticed was a noise increase and my passengers complaining a LOT more about how loud it is. So I've gone back to stock with the PSM and I actually saw a 50* degree drop in EGT's over the AFE.

diesel4play

Shaker, I say you need new friends if they complain about the sound of your turbo and massive air flow.

carl48

6 shaker seen what we were seeing in our testing. we tested the intake components at 2025 rpm gcw of 20,000 lbs with four temp sensors and three pressure gauges. what people are thinking are sound baffles in the tube and elbow are actually straightening vanes to reduce side shear in the turbo the 6.7's have an improved version on them.the silencer ring also helps on side shear. the afe stage two lets hot under hood air in and greatly reduces compressor efficiency. it shows up easily in the egt increase. and with the hundreds of bulletins warning of using oiled filters from every engine manufacturer, bad oil samples and pix available one would have to have his head stuck in the sand or somewhere else to use one.

purduepurdy

Ok, sounds like you are doing some crazy testing and would love to see the final output. You work for a AFE competitor? Have you considered an ISO 5011 test between stock and a AFEII?

On the silencer ring, the only thing that does it cut down on intake noise, it was a field complaint on the ISB. That comes directly from an ex-cummins ISB air systems engineer who I work with.

Not trying to bust your b@lls. I agree it does pull some hot air at idle. Just really curious and would love to see the data. We are all here to make the most power with the least $$$.

6 Shaker

Only real world driving experience speaking here, no official data. I was just responding to the original poster.

purduepurdy

Same here, never saw a mileage improvement, but it also never hurt me. I am pretty certain it did lower the EGTs at a cruise and I can feel a better spool up. I dyno'd my truck before I got it with just a plain smarty jr. I would love to do it again now with the AFE and the intake horn.

If the data looks legit it would be nice to send that to AFE, seeing they advertise the number bumps and provide 0 info.