Just fyi, I bought the 5"opening S&B velocity stack. Outer Diameter is 6.75" so I also ordered a Filterwears 7.5" outer filter for a little extra protection driving around. They say go a size larger on the Filterwears. I figured I'd share, probably a few people looking for decent filtration but don't have the space or maybe want something they can pull off quick when its go time.

https://sbfilters.com/products/turbo-screen


https://filterwears.com/products/fil...rbo-horn-cover

 

Had a lot of people say those kill airflow to the turbo.
The website claims an increase in airflow over an open turbo (not sure how that's even possible) at 1,000cfm, I feel like a 7875 turbo is moving more than 1,000cfm at full song.

 

A correctly shaped velocity stack will definitely help flow. This has a velocity stack built in so I'd say that their claim is plausible but probably inflated. I think these have to be better than a turbo guard etc that doesnt have a velocity stack built in. For me I want a filter of some sort, even if it hurts power a little. I'd even prefer a real filter like a kn eventually if I can fit one.

 

Check out how the s&b flares out and has more surface area than the turbo-guard. Price is comparable too.

 

There is Math involved in a Velocity Stack. The best is an Elliptical Profile. A great read is " The Best Bell" by Gordon P Blair.

 

Those filter wear over sock are VERY restrictive. I put 1 over each of my throttle bodies and the car would barely idle. Took them off and the idle jumped back up to normal.

 

Steve Morris just had a video where he added a bellmouth and it picked up HP on a Procharger. I would imagine same result on a turbo.

 

If anyone just wants a velocity stack I found some on Amazon for cheap.

 

Engine Masters tested various air filters to see what kind of horsepower they would support and found some with basically zero loss. I forget the horsepower level but it was boosted application. Thats what I eventually would like but this will do for now.

 

Can confirm now the 7.5" Filterwears fits the S&B velocity stack.

 

The issue is the mesh filter. It probably covers 50% of the opening with metal wire. The math ain't mathing.

 

Imagine pushing all that mesh up (South to North) until each piece is touching. Then do the same E to W. It will cover a large portion of the entry. Mesh is horrible for flow. Its why air filters are pleated. That setup will flow poorly with the mesh installed, even the coarse mesh. Whether its flowing poorly enough to show up on a dyno depends how hard you are leaning on it.

A flat filter like this would work much better. But is still restrictive. But at least it filters the air and is easily removeable at the track.

 

My buddy has one on a 4” tubed ram air (Chris1313 Pro Stock) on his 4th gen, on a back to back dyno pull the Filter wear installed it dyno’d 15 less rwhp. This was on a NA car though.

 

that's huge for a NA car.

 

I had one on an S480 and a 4.8. The OG guards with the porch screen, not the new ones that allow marble sized rocks in your compressor. What's the point if there is zero filtration?! lol

Anyway... Car wouldn't make over 8lbs it was so restrictive. Would make 20+ with out it.

Also FWIW. I have my turbos hung out in open air. Velocity stack VS no velocity stack (no filter media of any kind) back to back runs made zero difference in ET/MPH or fueling. Not saying velocity stacks are some imaginary thing. I know they work to some extent. I'm just stating they did absolutely nothing for me on this setup. SO likely not worth it for most. Esp on setups pulling air from under a hood.

Also did back to back pulls with and without 6" K&N pod style filters on. Saw no diff in performance.

 

My thought is if it allows debris in large enough to damage the turbo, what's the point? I think the "porch screen" style and filterwears are only good for cruising around. If you are going to be getting on it they should be removed. I think the one I bought looks more promising because it flares out and therefore has more surface area. But I will try it with and without. Eventually I want to get a short length of 4" piping and a large air filter on my car to help IAT. Not much room though so its going to take some trial and error. And having bends in the system is also a restriction so it may not be worth it.