I've seen descriptions and pictures of replacement filters for the PSD. I have a 2002 F250 7.3 liter diesel. Just went out and checked under the hood to be sure. The existing filter system draws in outside air through a port to the left of the top corner of the radiator. This is well off the road level and will be the coolest air you could get. Pictures of replacement filters I've seen seem to show a cylindrical cannister sitting where the old filter housing used to be. Is this cannister sucking in air from that location in the engine compartment? If so, then that air has been heated by the radiator and by heat emitted by the engine itself; it would be much hotter than outside air. I thought the idea was to feed the turbo with cool air, which will heat up when compressed by the turbo, then be cooled down again by the intercooler so that the engine gets fed the highest possible air mass. Sucking in engine compartment air would seem to partially defeat that goal, and to that extent degrade the engine performance. Comments, and please correct me if I am wrong about the replacement filter design.

 

There's lot's of kits out there that have the open air element behind a wall that shields the air filter from the engine compartment heat if you want to spend the money. I don't use that system, I simply took a NAPA 6637 air filter, removed the old filter box and put the boot over the flange on the air filter. I have in the past done the Zoodad mod so as I am going down the road I assume the air coming up the passage there would blow any heat away from the air filter. I can't say the same for stop and go traffic. At least that's what I think.
As far as performance goes, the massive additional amount of air that the filter is now letting in far outweighs any density loss due to warmer air.

 

The benefits of better flow out weigh the temp factor. The passage you looked at is restricting the air flow compared to the aftermarket filters.

 

Just a thaught for the air guys, I have an 01, F250 ,7.3. I closed off the factory air inlet with some foam glued in up by the radiater. and opened a hole to the front of the grill. Using some foam in a can I shaped the inlet so as to create a ram air effect at any speed and changed the filter to a K&N which I have to clean about once a month. I can now feel the turbo suck air at idel just slitely and I know I am getting intake as cold as it gets + ram air effect. The opening is better than 1/2 the area of the filter. There is no structual loss to the shroud and the longer intake tube keeps the rain out of the intake. Best of boat worlds I think. At least the Turbo spools up quicker. Next a big tube exhaust.
PWRPROD

 

See you even stated you can feel the suction at Idle, that is a restriction. Can you imagine what it is doing at 20# of boost. With the KwiK filter I don't feel anything at Idle. The design of the air box is to also muffle the noise. I don't think you are seeing any gains, your just hearing the noise.

 

If you want a good example of how much air these engines use, take a small screwdriver or other suitable object and prop it under the upper half of the throttle pedal so the engine is holding 3000 rpm. Then go try and hold your hand over the tailpipe.

 

I had an AFE kit on my truck...it worked very well and I was able to get one off ebay brand new with a prefilter for about $80 less than what they go for in the store.

 

I read all the time about people who "know" that thier aftermarket filters are allowing their engines to breathe better because they can "hear their turbo" or "feel the turbo spool up faster" or "feel a better throttle response", but how does anyone really know what, if any change they have made with their intake modifications other than the seat of the pants meter? Assuming thay you have decreaed restriction, the engine should pull less vacume in the intake between the filter and the turbo, right? Is there anyone who has taken something like vacume readings from their intake before and after modification to verify the percieved changes?

 

I watched two factory air cleaners go grey in less than 1000 miles each. And I live in nearly dust-free rainy Seattle, WA. No I didn't feel any difference, yes I hear the turbo (VERY good thing) and I still have the same filter that I put on 4000 miles ago, and it's barely starting to turn a little off white.

 

Quickly! Someone build an airfilter flow bench and we will see who is really right! I think what Mech2161 is saying is by removing the factory airbox you have also removed the muffler from the turbo; that is why you hear more turbo. He also mentioned that if you can feel the turbo sucking then your hole is too small. Any smaller and your turbo may begin to consume your grille!

 

What your talking about is not flow thru the filter but thru the air box. you can do what ever your little heart desires.

 

These tests been done over and over. These guy Know what they are talkin about. HP increase,NO,not much,TURBO WHINE, a little more yes, but the most thing to realize it makes your PSD breathe better and more effeicient, and ready for other mods!

 

Well said!

 

Cool, but were they pulling enough vacume to trip the filter minder? I have 20,000 miles frequently in extremely dirty enviroments, and have never pulled enough vacume to even begin to trip the filter minder on my severe duty intake system. In fact, the only time I have tripped the filter minder at all is when I had run a thin (about 1.5" pleat) stock air filter for about 8000 miles. Granted, I'm not running any performance mods. But personally, I like to see dirt on my air filters, it means they are doing thier job.

It just seems to me with as many of the aftermarket systems that are sold, someone would have some data documenting a decrease in intake vacume with the modded systems.

Does anybody know at how many inches of vacume the stock filterminder trips? My neighbor runs the bullydog big woof turbo, 4" exhaust, 100 hp chip through the stock airbox on his 2000 f450 and the filter has to "look" pretty dirty before it will trip the filter minder.
How about the Ford severe duty system, anybody know how many inches to trip the filterminder?

 

Great, maybe you could link me to some data from the tests or give me some idea where to look for it? I'm really curious about the changes.