At what point does a stock style flat panel filter ELEMENT become restrictive ?
More specifically, ACDelco A3181C as fitted to several million GMT800 Silverado, Suburban, Tahoe, etc from 2000 thru at least 2006.
flat panel filter element measures pretty close to 9" x 11.5"

Two daily drivers in my fleet
A:
Magnuson TVS1900 on top of a mild cammed 4.8LS with STOCK factory airbox, pretty sure shorty headers and 3" Gibson exhaust is as much of a power LIMITER as the FACTORY Airbox with flat panel element. Very consistent 177 kPa manifold pressure, from 3000 RPM through 6000 . Seat of pants guestimated 500 flywheel, maybe 400 wheel HP. with 4.56 gears, it's a bunch of fun.
Given my best available pump gasoline is 90 Octane Unleaded, I don't plan to run any more than 11 PSI Boost on that rig, so it's dialed in about were I want it.
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B:
Big CONE Filter on VSR78/75 next gen billet pushing 12 PSI through stock 5.3 LS, TSP 208/214 .550" Deatch 60# injectors at 66% duty cycle, 71 PSI rail pressure.
Initial set up "Hit the wall" at 4400 RPM through stock 3 inch exhaust. After Upgraydd to 3.5" pipe and a Big-*** Walker diesel muffler the Turbo 5.3 revs freely through 6000 RPM, 182kPa all the way.
Estimated 600 HP Flywheel, maybe 500 wheel HP... the QUESTION, for those who have followed this far:
"How much power will I give UP, by drawing air through the STOCK flat panel airbox top " ( I will have to cut away about 40% of the BOTTOM of stock airbox to clear my cold air pipe)
Reasons are BOTH aesthetic: ie dirty exposed CONEZ look like ***, and Flat panel stock AIR filter elements are available everywhere, and easy to keep a few in stock.

 

there are a lot more factors that go into finding your answer - stuff like:
- what's the filter media made of? (paper versus cotton gauze / woven fabric... and then even oiled fabric versus dry [often determines how tightly it's knit])
- where's it pulling air from? (drawing from the fender or a ram scoop will result in lower air temps than an open element pulling from near the engine... and cooler air makes more power)
- what's the associated tubing size / shape? (restrictive pipes will leave CFM on the table, even with the best filter)
- how much air can your engine ingest? (if you've got more vacuum on the back side of your throttle body than on the filter side, a freer-flowing intake won't help until you use a bigger TB).

 

Surface area is the best way to compare one filter to another all other things being equal.

When I put a TVS2300 on my 06 GTO I still had the stock air box and insisted on using a Wix filter mostly because I hate K&N filters. It never seemed to pull as hard as it should. I traded out the filter box for a Lingenfelter intake with a large Green Filter double cone filter and gained 34hp with absolutely no other changes. The size and type of filters can matter a lot if you are moving a good amount of air.

 

On a supercharger inlet restrictions cause pretty dramatic reductions in power. Force induction is just an air density pump, and when you have a blower with a fixed engine-to-blower speed, 10% less starting density due to a very small inlet restriction means 10% less power. Conversely, because the turbo is variable speed, a 10% less starting density due to an inlet restriction just means that your turbo needs to spin faster to make the same level of boost. This results in slightly higher back pressure which gives you a minor pumping loss (1 to 2%?) as long as you aren't way off the turbo map.

Stock cars draw that air lid from about 101 kPa to about 90-95 kPa by the top of a run. So it is already a minor restriction on a factory setup. You are moving probably 2 to 2.5 times the amount of airflow so I would expect (everything else being equal) you will probably create a 101 kPa to ~80-85 kPA inlet restriction - or about a 10-15% drop in power. As stated above, the supercharger will take this on the chin, while the turbo will probably turn that into a low single digit loss (1-2%?). Just my estimate.

 

The Magnuson TVS-1900 kit shipped WITH ( included) a K&N flat panel oilled filter element for the stock Airbox.
Never used the K&N, still new in box.
With stock element, in slightly modified GMT800 airbox ( snorkel removed ) the maggie with 3.2 inch pulley makes very consistent 11 PSI manifold pressure, regular as clockwork, year-round through a 4.8 LS. Been running it hard since 2016: Texas ( 100 degreesF), Grand Canyon 9200 Feet, Canada ( -25 F) , Alaska- year round, daily operation- pretty much drive like teenager flogging a company truck.
.............. I usually throw in a new ACDelco or MAHLE paper element every 15,000 miles.. Anyone think the K&N (element) would be an Upgraydd ?

 

Measure vaccum at the blower inlet, that will evaluate your entire intake system for you.

 

Back when I had a YSi setup on a car, I researched cone filters and the one I would have needed to run was gigantic. I ran no screen nothing and of course the blower ate a rock.

My '67 Camaro I run a Turboguard out of an abundance of caution.

 

I run a pretty large cone style filter on my car when driving on the street, Turboguard if I'm racing or plan on making pulls/logging.
Really tempted to make dyno pull with and then without when I get the car tuned for methanol to see if there's a difference.
I can't really tell a difference from seat of the pants and the pulls in the logs look the same as when using the Turboguard.
I think this is an AJE filter iirc, came with the car.

 

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An excellent idea.
Plastic intake pipe has a small hose port, routed to breather....
I'll put vacuum gauge on, and report back. my Blower truck has BIG summer tires on right now, I pulled the insurance OFF for winter.

 

Engine Masters did an episode on air filters and tested for power loss due to restriction. The results were surprising... The filters do not need to be very large before going larger makes no difference. Extrapolating from their results, those large cone filters, say the 4" dia by 8" length, are more than enough for 1000+ HP.

 

In my experience with my TVS2300 on my LS2 I'd say YES, the filter would make a difference.

And since you already have the K&N filter there is no reason not to just try it and find out.

 

This work?
Here are some formulas for K&N type filters. Found at the K&N website.
Area = (CID * RPM) / 20839
Area = (Height - .75) * (Diameter * 3.141593)
Area = Length * Width
Height = (Area / (Diameter * 3.141593)) + .75
Diameter = (Area / (Height - 0.75)) / 3.141593
CID = (20839 * Area) / R
RPM = (20839 * Area) / CID
Width = Area / Length
Length = Area / Width
Paper Flows 57.3% of K&N
Foam Flows 42.4% of K&N

 

Buy a draggy. Pull the filter and see if its any faster. If its a worthwhile amount quicker... then address the filter/induction setup.

 

Agree. The dragy is a very useful tool for things like this.

 

On a supercharger, I'd be asking more about what size air inlet tube you have on it as much as the filter. Now I don't have a ton of supercharger experience, but 1 car I tune on a lot, we actually call it the boost controller.
With the tube and filter on, car makes 14#
Take the filter off it makes 16#
Take the tube off it makes 17.7#
Car is a 5.3 LSA blower, short 4" dia tube on it

 

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That's YUGE.
Cone or Panel filter on that particular rig ? If you don't mind me asking, and since it was on ROLLERS.....
" What was the Horspower delta between 14# and 16# ? "
Any VE table changes with that ?

 

I would be more worried why you hit a wall with a 3" exhaust. IT's been proven to flow enough for 800+hp. I personally have pushed 750 crank HP through a 3" full length exhaust with a single borla offset perf core muffler and tailpipe and this is recirculating the WG back within 10" of the turbo outlet. At 16lbs with a VSR billet 70/70 next gen I was pushing 93% duty on bosch 60lb at 74psi rail pressure (aka 72lb at 58psi). 3" downpipe lots of bends out the back with the muffler. I did pick up 2psi with the cutout open. Now I run a 4" catback same 3" downpipe and cutout but added a 3" high flow cat after the cutout. I no longer open the cutout really and boost is basically the same with it open or closed due to the 4" catback even with the high flow cat.

For air filters I've run small K&N cone stubby filters, HKS clone mushroom filters, big K&N cones and AEM dryflows and none seem to really make a difference with the turbo. I guess its whatever works easiest for you.

 

Do you guys ever have connection issues with the Dragy?
I was reading reviews and there was a lot of folks having connection type issues which gave me pause on getting one.

 

Yes.
But when it works it works good.

 

My girl got me a Dragy for Christmas, it'll be fun to try out in the spring! Staying on topic here, I have a Turboguard in my Summit cart, I'm really wondering if it'll make a difference over the cone filter Huronspeed supplied in my kit. Guess I'll have to try some back to back runs as well.