I must say... Do you think I would still have 470hp with a stock air box on there and still be able to keep my EGT's below 1300???

For a chipped truck there might not be a huge gain from going to a bigger filter set up, but you also have nothing to loose. They all filter as good if not better then 99% of the air boxes out there. There cheaper, and last longer then the factory filters...

Whats the down side again???

 

Well actually if you switch from a stock 7.3L FA-1750 filter to say a 7.3L AFE filter (Part Number 40035) you "gain" as in you "gain an additional 3.39 grams of dirt" in a standardized ISO 5011 "Dust Loading" test because as can be seen here... http://www.thetruthaboutfilters.com/...andAFE_Dry.pdf ...the AFE passed far too much dirt in the "Dust Loading" test. It passed 4.70 grams of dirt compared to only 1.31 grams of dirt for a stock FA-1750!

This same link shows that when you "play" you have to be prepared to "pay" and here "pay" means eating an additional 3.39 grams of dirt to get the measured 12" H20 restriction of the AFE at 950 CFM compared to the measured 37.5" H20 restriction that's required to get a 950 CFM flow from a stock FA-1750! There's no such thing as a "magic" air filter because you always have to eat more dirt to get a lower restriction at a higher CFM period!

If all of the 6637 advocates on this forum would donate $1 each they could commission an independent lab to perform a standardized ISO 5011 "Dust Loading" test on a 6637 filter and then we'd all know for sure just how well it filters! To kick off the fund my wife will write a $20 check to whomever wants to lead this effort! I tried for a $50 offer because I probably want the data more than most users do but the wife limited me to $20!

Well let me do some calculations to see how much CFM is required to get what I assume to be 470 RWHP which is about 565 FWHP, and I'll post those results later.

 

OK, Gene... I'm investigating the option of taking you up on your offer. Check out my reply in the "other" 6637 thread ... you know which one I'm talking about

 

How many $1 donations do we need to get the test done? I'll pitch in.

 

I hope to be able tog et a feel for the cost of this kind of project on Monday, but it may honestly take a week to get an accurate estimate. I'm sure that the companies I've talked with preliminarily will want need to have the details of how many air filters, how many conditions, exactly what tests performed, etc..

 

My planned departure has been delayed due to a forecast of enroute snow so I've got time to run some numbers. Lets calculate the required CFM at the air filter inlet to accommodate 565 FWHP and see if a stock filter can handle that much CFM.

There's enough chemical ENERGY in each gallon of diesel fuel so that when a fuel flow of 1 GPH combusts with air it releases 51.08 heat ENERGY equivalent HP and about 65% of this heat ENERGY equivalent HP or 33.2 HP is converted into piston power stroke HP and about 57% of this piston power stroke HP or 18.9 HP is converted into FWHP. So it takes a fuel flow of (565)/(18.9)=30 GPH to produce 565 FWHP and in the process about (18.9)/(51.08)=0.37 or 37% of the fuel's chemical ENERGY is converted into FWHP.

Since each gallon of diesel fuel weighs 7 lb a fuel flow of 30 GPH=(30)(7)=210 lb/hr=(210)/(60)=3.5 lb/min. Since it takes 15 lb of air to combust each lb of fuel you need a MAF=(3.5)(15)=52.5 lb/min to make 565 FWHP! If the temperature at the air filter inlet is 70 F then the air density is 0.075 lb/ft^3 and this gives a required air filter inlet CFM=(52.5)/(0.075)=700 ft^3/min.

Here's the measured data for a stock air box with a stock filter...

CFM......Inches H2O Restriction
000.0.. .0.000
314.5. ..4.436
471.1.. .9.598
627.7...16.660
786.5...25.775
929.8...35.705

...so if your turbo sucks hard enough you'll get 785 CFM at a 25" H2O restriction with a clean stock filter which is more than the bare minimum of 700 CFM required and a 785 CFM provides a MAF=(785)(0.075)=58.9 lb/min and a AFR=(58.9)/(3.5)=16.8 and that should keep your EGT below 1,300 F because a AFR=18 typically gives an EGT in the 1,200 F to 1,250 F range.

However you'd be operating a clean stock filter at 157 CFM higher than its maximum rating of 628 CFM where the restriction is only 16.7" H2O and you'd be within 1" H2O of the cut-off restriction for a fully restricted dirty filter operating at 628 CFM. So a clean filter might be good for a couple of dyno runs of a few runs down a 1/4 mile strip but then you'd need to switch in a clean one!

Based on what I've read so far I think the S&B 7.3L Cold Air Intake below might be your best bet for your high HP application. The S&B has a "Dirt Filtering Efficiency" of 99.69% which is almost as good as the 99.76% for the stock filter and at a 785 CFM the S&B only has an 11" H2O restriction instead of the 25" H2O restriction for a stock filter.



As shown below S&B tests the complete cold air inlet system by connecting it to a suction chamber and then the resulting CFM airflow is measured at various values of Inches H2O Restriction.

 

Well even though no one has expressed an interest in hearing the rest of this story I'll at least give a brief outline of it so I don't leave the mistaken impression that simply comparing the 2.11 HP parasitic drain on the engine caused by a stock filter with the 0.7 HP parasitic drain on the engine caused by a K&N filter for a net difference of 1.41 pumping loss HP is the only way a lower restriction K&N filter can increase an engine's net HP.

In order to establish the 580 CFM air flows through the respective air filter elements used in the above example a considerable HP needs to be applied to the turbine shaft in order to spin the compressor wheel hard enough to suck this 580 CFM air flow through the air filter elements and then pressurize this air flow to a high boost pressure in the intake manifold so the turbo itself is a considerable parasitic HP drain on the engine.

Of course if you play your engine's ECM tuning cards correctly by adding the appropriate amount of extra fuel to combust the additional air flow provided by the turbo you can get back more HP than the turbo's parasitic drain HP and this gives a net gain in engine HP by using a turbo. So what happens if instead of simply pocketing the net difference of 1.41 pumping loss HP when switching to a K&N filter and calling that the increased engine HP with a K&N filter you instead "reinvest" that 1.41 HP as additional turbine shaft drive HP to make additional boost so that a chip can add more fuel when using a K&N filter versus a stock filter?

At this point the story gets sufficiently complicated that equations are required to get a numerical answer but the above outline is probably sufficient to see how the investment of the 1.41 pumping loss HP as additional turbine shaft drive HP to increase boost coupled with a retuning of the ECM to maintain the same AFR as with a stock filter might give a net pay back of up to a 5 HP net increase in overall engine HP but the equations show you don't get anywhere near the 15 HP net increase claimed in the K&N advertising.

 

Here are the ISO 5011 test results for s&b intake I found. Maybe someone can fill me in to what they mean.It really sounds like a good intake.I'M asking because I want to upgrade from the 6637 . John
http://www.sbfilters.com/pdf/iso_5011_2927_ISO%205011%20Test%20Results%20for%20 75-5028.pdf

 

I explained ISO 5011 test results in posts #74 and post #83 here... https://www.ford-trucks.com/forums/8...uestion-5.html ...

 

So simple, even a caveman could understand it!

Stewart