LOL I remember some of those old threads. Ernest and I didn't exactly get along too well.

 

Ah yes....the classic Gene posts. The A,Bee and Cs of air flow was a classic post. Funny how everyone locks into CFM and completely forget how density is all that really matters.

 

After reading a lot of his stuff, I think I see what was taking place. The guy is a wiz with numbers, and he scoured resources to get them... but there was information overload and X-factor overlook. That is not a criticism, just an objective observation. We need people like ernesteugene to make things work as well as they do, and to keep improving upon them.

In that vein... I don't want to engineer the engines fuel-to-air ratio, or even the filtration performance - I just want to collect the information the vendors give us and make a simple graph that anybody would understand.

Interesting tidbit of information I discovered today (while on my Donaldson AIS research): The 7.3L AIS mod outperforms the 6.0L, the 6.4L, and the 6.7L intake systems. So... for those of you scheming to modernize to any of those, I wouldn't put my time and money into it.

 

The problem is, nobody wants to bang on a calculator all day to come up with air density (including myself). CFM is a component of air density (if you figure how much air at xyz density passes through the engine per minute), and CFM is an easy number to grab/calculate with... so CFM is not an invalid number. I concede it can be over-simplified, but CFM is a better number to use than say... boost pressure.

If the filter capacity is exceeded... the backpressure drops, the boost plateaus, the EGTs go up, the turbine speed goes up, and the CFMs just inch up incrementally.

 

Just be very careful and try not to assume that density is constant because that will skew all your hard work.

 

I'll put a disclaimer at the bottom... something along the line of "This data is a scenario in Death Valley at 62 degrees F with 50% humidity, when the moon is in the seventh house" or something like that. I doubt I'll have all the data I need to make the graph scientific-accurate, but it would make a great quick-reference cheat-sheet.

 

Have you ever monitored under hood temps during the summer? I see 165 degrees at times. I have often wondered how air density is affected for those folks that draw air from under the hood vs in front of the grill.

My wife's 2000 Lariat F250 has the factory air box.
My soon-to-be ex 2000 Lariat F450 has an Airaid cone filter that still utilizes the factory cold air snorkel but it doesn't have a lid for the filter. Instead, it has a 3 sided baffle that is cut in such a way that it seals up against the hood...sorta. One day I ran both trucks and left them idling side by side in a parking lot and I checked the air intake temps. The truck with the Airaid reported temps that were almost 10 degrees higher. I think the ambient was 113 at the time. Both trucks had engine oil temp readings that were nearly identical (I think they varied by 1 degree...)

I wanted to compare intake temps while driving but I couldn't convince my wife to drive the 450 home that day...

 

I am one of the few humans nerdy enough to look at the Air Intake Temperature on AE, this is how I found my engine makes a different noise when the AIT crosses a threshold.

Anyway... I've never really seen my AIT get much above ambient, yet I have seen the air under the hood easily reach 150-160 degrees F. This kills the air density, and one of the key reasons why I stick with cold air intake... plus the noise issue. I don't talk about the air density to 6637 lovers on the forum because I've known for a long time about that dead horse needing a decent burial.

 

Right there with you buddy....

That is interesting about the change in noise at a certain point.

Ya know we have two air temp sensors under the hood but as far as I know only one is monitored by the PCM. I presume it's the one next to where the MAP elbow is located but I haven't checked that for certain. Have you been able to pull up both sensors on AE at the same time? If so, what is the PID identifier? Is the sensor in the spider called Air Intake Temp while the sensor in the air filter box called Ambient Temp sensor?

I plan to crack open the hood on the 450 to do some preventive maintenance wrenching this weekend....maybe I'll connect up AE and then start unplugging sensors to see what is what.

 

MAT...mass air temp 'delphi TS10098'

 

Rich I am liking the direction this tread is going. I myself have had heated discussions over the years with my friends that I feel that a lower cfm with a higher air density can get the job done as good if not better than a high cfm sucking in hot air charge. It is a pet peeve of mine when it comes to a intake charge sucking in hot engine compartment air. I am a firm believe that any gas or diesel engine always likes a nice cool dense air!

So now that I am trying to get the best I can out of my stock E99 and have no goals of ever getting to the point that you are at. I get alot of guys saying get rid of my modded stock air box with a K&N and get the 6637. Everyone is like the K&N is junk. It isn't the K&N it is the stock air box that is junk. Well actually until I can afford the AIS set up it works fine, I have no dusting since I modded the stock box and I have reports from Blackstone to prove it. So for my needs I feel a AIS will work very nicely.

But as far as this tread goes and collecting data I think it will be hard to do. It would be nice to be able to do a controlled study with side by side testing. So good luck coming up with results.

Honestly for guys looking to make huge hp and a nice quiet intake. I would think the real answer would be to make a REAL air box with twin cool air intakes for the 6637. I like the cfm's of the 6637 I just don't like that it is noisey and it sucks hot air.

Greg I am very interetsed to see what you come up with as far as what sensor is what. Since I don't have AE to compare or see what is actually going on under my hood I really apperciate when guys like yourself or Rich take the time to collect the data. I have always felt that the under hood temp affects the intake charge and density negatively. That is where I have been working on getting all my exhaust wrapped, thinking about wrapping my IC pipes and I am a firm believer that a cool air intake is better than higher cfm sucking hot air. So please let us know what you find out.

 

I had such a time trying to parse out which filter would suit my needs, I thought I would try to make it easier for the next guy... but the task is too daunting for one person who has a life outside the forum. I thought it would be cool to recruit some help and get this done, but I totally get that other people have lives as well.

An enclosed pair of 6637s has merit, but consider this:

Every 1000 miles of my driving has enough air passing through Stinky to fill the latest model of the Goodyear Blimp - about 297,000 cubic feet. From that, a lot of dust is either caught by the filter, or let through. The claim to fame for the 6637 is its price, but I have yet to verify its filter efficiency. This needs to be verified before choosing a WIX 46637 over a Donaldson B085011.

My AIS is recognized as being a solid performer for providing plenty of clean dense air to a stock-to-lightly-modded 7.3L - but at the initial cost of about five 6637s. The AIS goes 20K miles before cartridge changes on a tuned stock truck in my environment, I don't know about the 6637 - and never will.

 

When it comes to intakes, it goes in this order:

- filtration
- flow
- money

At that point, pick your poison. If you can crack open your intake tube, run your finger in there, and it comes out squeaky clean, then you've accomplished the most important aspect.

Next comes airflow. If you're able to go WOT without sucking down the filter minder, then you've accomplished point #2.

Last is the cost. Once you factor in the cost of the system, the replacement filters, or the cleaning supplies (for reusable filters), and you are able to get away with #1 and #2 at a reasonable cost to you, then congrats - you've found the perfect intake.

It really is that simple folks.

I've run quite a few different intake setups back in the day, including stock, stock with K&N (big big big big big mistake), AIS, 6637, and the current (for many years now) AFE Stage II with Proguard7 filter.

All of the setups, except for the K&N, filtered just fine. 6637 and AFE provided the balance of great filtration along with great airflow. AFE I got for super cheap, so it met the final criteria that tipped the scales.