Yes ernest, we are all on the same page concerning the powercore media.

I knew I'd read several things about both filters over at TDS, took me a while to find them. Both these quotes were made by a poster named Jordan Flagstad who is supposedly an engineer for Donaldson who posts over there.

In regards to the AIS (this was in a discussion of the TYMAR filter element compared to the AIS):
"I did some digging for that data that you were looking for and came across where the new AIS was tested against the element used in the Tymar intake setup. I guess you could say that it was sort of a "Flow Bench Shoot Out". Anyway, the data stopped at 650 cfm so I would have to extrapolate 50 cfm worth of flow data to ball park the restriction at 16"H20 @ 700 CFM (Not Bad ). Incidentally, the Tymar element was yielding 16"H20 clear back at 500 cfm. "

And the 6.0 filter:
"I guess I need to know what you consider restrictive. The Donaldson filter comes in at a very low 4.9 inches of H2O at 775 cfm. I have been in the industry for many years, and this is one of the highest flowing, lowest restriction OEM air filters I have seen."

 

In my previous post #29, where I used the term boost, I should have used MAP!

Starting as before, with cfm=(0.1285)*rpm as an approximation for the flow with no boost (B=0), and MAP=15 for nominal atmospheric pressure, that cfm is increased by a factor that depends on B and on how turbulent the flow becomes for higher B.

The additional delta P drive pressure from boost (B) increases the flow (cfm), as cfm=k*(delta P)^(1/n) where n=1 for laminar flow, and n=2 for turbulent flow.

The Table below is tabulated values of [(B+14)/14]^(1/n), and doesn't include 2nd order effects like the pressure drop across the IC or filter. I can't get the table to format...n=1 (Laminar), n=1.5 (Intermediate), n=2 (Turbulent).

B------n=1------n=1.5-----n=2

5-----1.36------1.23------1.17

10----1.71------1.43------1.31

15----2.07------1.62------1.44

20----2.43------1.81------1.56

25----2.79------1.98------1.67


I'm basing my following estimate on my recollections of many years ago using my leaf blower that was rated for 200 cfm, and trying to imagine that flowing through one of the 2" rubber boot hoses going into the inlet manifold on my early 99 engine. I'm thinking that for my truck, the multiplicative factor shown in the above table for increasing cfm due to boost is closer to the 1st column for lower B=5-10, in the 2nd column for intermediate B=15, and nearer the 3rd column for higher B=20-25.

When you look across the columns on a diagonal, I think that for B>10 the factor is probably about a constant x1.7, and the increases in flow are mostly do to increases in rpm and not in boost. This helps me understand why my truck seems to tow grades better now with my special spring to limit my boost to about 20 psi. Before, when I was running 25+ psi up grades at a given rpm, I wasn't flowing any more air than I would've been at 20 psi, and I was flowing hotter air than at 20 psi.

 

Thanks for the info, if you look at my new post #32 which gives my (admittedly crude) estimate of flow rate for my early 99 which has the puny 2" boot hoses to the heads versus your 3" versions, I don't think I generate flows of even 650 cfm. At 2500 rpm I calculate about 320*1.7=550 cfm at best for my truck.

I don't know if you got around to checking the link I gave for air flow into the human lung, but now that I better understand the complicated flow paths in the AIS, they appear to be somewhat similar to a lung, with air flowing into and through small tubes, and then passing through the walls of the tubes. I see how calculating the restriction of this is much more complicated than for a conventional flat filter where all the air just flows straight through the filter element in a transverse direction.

 

If I read that right, the TYMAR / 6637 is more restrictive than the AIS filter?

 

Yes, that's what he is reporting. Since he is (at least supposedly) employed by the manufacturer of both filters, I don't know why he would make that up. The Wix web site has always listed the 46637 as a 425 cfm filter.

 

If that is true, then if I truly am seeing higher EGTs with the AIS vs 6637 then maybe it's because of all the "extra" plumbing in the AIS.

We'll see when I tow back on Thursday if it's because of the exhaust.

At any rate I'll be saving up for a 4" - any comments on how much it reduces EGTs?

 

Could the EGT be higher due to more air getting into the cylinder? More air + fuel = more heat.

 

Why not cut a 3 1/2" hole in the AIS plastic (as instructed for the fender sleeve installation) and leave out the foam sleeve? That should allow for more air, thus cooler ETGs.

 

Well, towed back yesterday with the "loose" tailpipe, trying to re-create what I had before.

Not completely sure, but I think it did make a positive difference. I had a significant headwind most of the way and then a crosswind, but where I had a wind break on the interestate (trees lining the median) I recorded the following a few times: 70mph, on the flat, EGT 900deg, boost 11psi. Of course none of these "tests" are anywhere near scientific as I had to estimate what really was "flat" and when I didn't have wind, but regardless ye old "seat of the pants" said that the truck was running well yesterday after I got out of that headwind. Just kept wanting to pass people on the road! Just as well, got home at 11pm and went to bed. I do know that if I had pulled the 10hrs with the 6637 I'd have a splitting headache (resonance). Not so with the AIS.

So I'll keep the AIS in for now, and in a few weeks when I tow again over more familiar roads we'll see again. Now I'll be looking for a 4"