GEN 1 Need some help

[B E N]

I'm not sure if you read the article or dismissed it out of hand, so I will spell it out.

Filter area (A):
A = (C.I.D. x RPM) / 25,500

Remember you've got an artificial displacement increase in displacement due to boost. To figure out your effective displacement:
(14.7+boost psi)/14.7+displacement.

You now have an area requirement to meet.

Height (H) and depth (D) requirements:

H = A / (D x 3.14) + .75 gives you your filtration area, it doesn't matter if its a carb type filter or a CAI filter area is area and the actual form of the filter is of no consequence, if you are using a cone D= the average of the bottom and top of the cone.

So now you know how long and what diameter the filter needs to be. I would up-size by 20% due to the environment you plan on running in. It wouldn't hurt to find a filter which has a prefilter available, it will help prevent dust up clogging and prefilters are easy to shake off in the downtime.

It doesn't matter if its in a box, as long as all faces of the filter element are exposed. Ensure the box has a large enough intake port to accommodate, I would go 1.5* your throttle body area to make sure you have adequate flow.

 

[EricM]

@EricM , with all of the Mustang blower info you have, there must be some data somewhere on how much inlet air flow is required to run well, before the air filter becomes a restriction.
The reason I ask, is the air filter, and laughable "COLD"Air Intake that both Roush and Whipple use, is not a great form of clean fresh air when in Baja.

I am looking to fab a closed/sealed air box but do not have info as to how much airflow I need. I spoke to a Ford engineer one time while at a desert race, and he claimed that the stock Raptor air box and paper filter can support 500hp.
My current 14 Roush with JDM tune put down 507 at the rear wheels which rough math says is 625hp crank. The rollers I was on gave a higher theoretical crank HP, but I do not know what drivetrain loss calculation they used.

Any theory or math to get me pointed in the right direction? Keep in mind, I would like it to fit under the hood..lol

Some more good links for you:

Boost Calculator:
https://www.modularfords.com/thread...ive-displacement-blower?p=1088426#post1088426

Mass Air flow estimator for various boost levels:
https://www.modularfords.com/thread...flow-rate-calculator-for-a-4-stroke-IC-engine

You can figure out the CFM using those two spreadsheets. Figure out what boost you can expect using the first spreadsheet, then go into the second link and see what your CFM is.

You'll need to adjust the engine size/blower size in the first one along with the pulley sizes. If you are expecting to see 8 lbs of boost, then just skip the first one and use the second one. You'l need to change the engine displacement in the spreadsheet.

Lastly, here's one you can use to size your injectors:
https://www.modularfords.com/threads/91066-Understanding-our-fuel-system/page2?p=960245#post960245
This one has a mass air flow rte calculator as well on the second tab.

Not sure how you really can accurately size the filters without testing them on the vehicle, or with some type of testing setup. Are they rated by any of the manufacturers? Standard operating procedure on the Cobras was to run the largest filter you could. Bigger is ALWAYS better when it comes to air filters. I run the biggest Amsoil cone shaped filter I could stick in the fender.

 

[EricM]

Ok, so, I want to formally apologize to EricM about my one statement about the compressor rotors.

I accept your apology. No hard feelings.

 

[Canuck714]

Thanks Eric. I hope to fab a large enough sheet metal box that I can then use a large replaceable paper element. Bigger than the stock Raptor, and hopefully large enough not to rob the engine of the required volume.
I will plan to get it on a dyno and test it. Its the only way to know how good or bad I made it ..lol
As a side note, I took one of my old Roush cone filters, cut it down the seam and unrolled it to measure the surface area of the pleated area. Surprisingly it does not have much more filter area than the stock flat filter. So I am wondering if its the box limiting the air more than the filter itself.