[QRF968]

How much of a difference does the shroud from RS barn make when modifying your airbox?

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[Waylander]

Its all about the colder air, and keeping the engine bay heat out of the intake air,

 

all depends on the ambient temp

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[94SilverCab]

The RS Barn shroud is roughly equal to the shroud cover. But, it is currently available if you can't find a shroud.

 

Also, RS Barn has the Stage 1 chip that was developed with the air box modification in mind.

 

As Waylander pointed out, the trick is cool, still air.

 

 

Regards,

 

Jay

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[az968]

And a really nice cat back exhaust system.

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[94SilverCab]

It can be a VERY steep slope  

 

One phone call for an airbox mod shroud can lead to $25K in "Standard Maintenance Parts"  :ninja:

 

Jay

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[RS Barn]

The Airbox shroud keeps air temps very close to ambient. Without I was seeing 20 to 30 degrees above ambient measured at mass Air flow sensor. Also in traffic I was seeing closer to +40 and it took 3 to 4 miles to drop. With shroud air temps dropped in less than a mile.

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[Waylander]

I would take a guess that 10 degrees in air temp is worth a few horses, maybe 5-10,

The best is ice cold damp air for max power,


If the air is really wet you even get a few extra oxygen atoms to help out

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[Kaj Hallstrom]

I upgraded my air box by drilling two holes instead of three. Just slightly larger than the recommended. I then sealed them with soft rounded rings for the flow. Replaced filters with K&N,,,,,,,and WOW what a difference.......I am not sure that this project needs to be handled too scientific.

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[MCL968]

Try cutting out the entire front, covering it with Plexiglas and adding velocity stacks. Looks cool and works good!
 

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[RS Barn]

Very cool stacks but you are still sucking in hot engine compartment air, just more of it. Use the factory plastic cover or my Airbox shroud

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[MCL968]

Hey Pete,

 

I just had the cover off to show the modification, I don't drive it like that.

 

Matt

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[az968]

I used the same velocity stacks that Matt used but I followed Flash's original design for spacing, just drilled the four 2-1/8 dia holes where Flash's design recommended they go and the stacks installed easily .

 
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And I do use the original front engine compartment cover to keep the engine temp air from the intake..

 

Kaj, I disagree that it doesn't need to be scientific, Flash published a pretty extensive analysis of how he came up with his recommended design.

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[ds968]

Kaj, I disagree that it doesn't need to be scientific, Flash published a pretty extensive analysis of how he came up with his recommended design.

I agree with Bob on this , a lot of research and testing of multiple variations of the mod was performed by Flash ; larger holes, fewer holes, more holes, different rings shapes, etc, etc.. the final design tested to be the most effective of all those other variations. Not that the other options were useless, but the biggest difference by far was noted with the design of the mod most of us used . It's not necessarily aligned with the intuitive inclination ; bigger holes, better air cooling effect .

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[MCL968]

It is interesting how much testing Flash did on this seemingly simple modification, but the holes and the rings really do make a difference, and removing the snorkel helps as well.

 

Understanding the reasoning for the snorkel (German noise laws) made it make a little more sense. In one of the many threads on this, Flash mentioned that someone should try adding velocity stacks and see what happens. I took a page from the motorcycle engineer handbook and modified the airbox to be a larger version of a sportbike airbox. It seems to work, but I have no idea if it works any better than the holes and trim rings design that Flash tested.

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[az968]

I don't know if the velocity stacks work any better but they look way cooler, so that in and of itself makes it faster  

 

Also remove the snorkel and the gasket that surrounds the snorkel opening in the bumper. Its all about getting more air into the airbox and under higher pressure, thus the decreasing opening caused by the shape of the "rings". The factory shroud, or a replacement shroud, reduces the amount of hotter engine compartment air getting into the airbox and engine.

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[94SilverCab]

The air needs to be cooler, but also not turbulent...

 

Jay

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[az968]

Right about that, faster air but "quiet".  Anyone considering this mod really should read Flash's article, it explains the logic and design very well.  It's posted somewhere on this site. (search).

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[ds968]

Just so you guys know, the original air box shroud design based on which Flash, or Pete or anyone else engineered their own versions originated at the FIAT factory many, many decades ago . It's widely known as " the shroud of Turin " . Automotive history . Or maybe that was the first car cover, I'm not sure ..

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[Waylander]

Ha ha

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[Roboman]

"Shroud of Turin" - very funny!!


I've looked through this and other threads about getting more air into the box, and have read Flash's article. Thanks to all for the hours of hard work and taking the time to report on their efforts.


I note that the concentration of effort was on getting more air into the box, was any mod done to the inside of the box? Any "walls" put inside to create lamina flow up to the filter?


We all know that only 50% of the filter is used. Walls/rounded corners inside the box that guid the air up to the filter would, I would have thought, reduce interference/turbulence below the filter, but unfortunately may just pass the problem to the chamber above the filter where creating lamina flow to the MAF would be much more complex...... mmm now that I've written this .....

 

where to find an air-box base on which to experiment   :unsure: 


Anyone had a go inside the air-box?

 

Cheers,

 

Robert

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