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Discussion Starter · #1 ·
I installed a RS air box and K&N air filter. Does it make sense to install the snorkel too or does having a open top/front RS air box lid work against it?

When travelling at highway speeds does the intake snorkel help even with the RS air box lid?
 

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Just my .02, but if I had a snorkel I would put the stock lid back on. I don't believe an open lid would build any positive pressure at high speed, but like @Lou64 said any extra cool air in there is a good thing.
 

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If you're worried about intake temps, stop wasting money on boxes and snorkels and spray the house down with nitrous.

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Discussion Starter · #6 ·
I ordered the Ford Racing Snorkel and will revert back to the ST air box lid to take full advantage of the snorkel.
 

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The rs air box lid seals up against the underside of the bonnet anyway. Plus if you're running an aftermarket air filter they have an open end, so regardless your gonna lose some air whichever lid you have on


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The rs air box lid seals up against the underside of the bonnet anyway. Plus if you're running an aftermarket air filter they have an open end, so regardless your gonna lose some air whichever lid you have on


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Not all aftermarket filters. I recommend the K&N closed end with the RS box. That way you're only sucking fresh air that's being forced past the headlight.
 
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The snorkel is going to do much much more for ambient air than the open airbox will. The RS airbox is for induction noise and appearance.

You ordered something from the dealer? ARE YOU NUTS?!?! :furious:
I can get the RS airbox for $51.40 after tax picked up from my dealer. Seems like a good deal to me.
 

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Stock Lid and Green (open end) filter is much noisier than RS Lid and AEM dry flow (closed end).

As long as I am moving, the lid of the airbox and the open/closed end side of the filter is always cool.

But, I have a 2013 so we sport the infamous hood gap of the pre-facelift models, which definitely lets in air over there...

Hope that helps,
Mark
 

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Ayada - That is actually very helpful. It kind of confirms my thinking.
If you go to the trouble of getting the snorkel in there to increase cooler air, why expose the box to the hot air under the hood?
 

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RS airbox opening was designed for dyno use with the hood open according to an article in a UK car magazine. I don't think the box was engineered to be used with the snorkel system, I know mountune has a quad x4 box that makes use of all available openings without a snorkel. The point of sealing the box when using the snorkel is to reduce pressure loss and increase efficiency at the turbo plus keeping Temps closer to ambient. If you don't care about maximizing efficiency (at the expense of sound & cool looks) then you can still use the snorkel with whatever box/filter setup you choose, however it was designed to be used with a closed box sealed system (CAI/FRPP tune) per Ford Performance (I called them). I asked about using the RS box & open filter and they advised against since they had not tested the flow dynamics on that particular setup. Who knows maybe it will work better but I can say the the idling Temps were higher with the RS lid & open filter which is why I went back to the stock lid and capped the open end on the filter. I will eventually install the K&N closed filter that came in the kit.

I think when moving at speed the temps are fine with the RS lid & open filter but that still doesn't address the potential loss of pressure and efficiency across the intake vs having a sealed + ram style system. MountuneUK makes a low loss pressure box for the rs500 and a quadx4 box for the RS but these do not incorporate a ram style snorkel (which is a FRPP product), although the Quadx4 does run a hose to a hole in the fog-light grill plate plus utilizes the open end fliter design for maximum air volume. Either way, I would also wrap the box & intake tube with heat reflective tape for all applications.

Here are links to where I got my info, cobb & strat are a good read:

https://cobbtuning.zendesk.com/hc/en-us/articles/200026104-COBB-Initial-Focus-ST-R-D-Findings

Blog : A Technical Discussion of Intakes and Turbocharging : Stratified Automotive Controls

R&D

https://www.mountunestore.com/products/focus-c307rs-x4-quad-entry-induction-kit

https://www.mountunestore.com/collections/mk2-focus-rs/products/focus-c307rs-airbox

https://www.evolutionm.net/forums/evo-engine-turbo-drivetrain/385943-heat-reflective-tape-gold-vs-silver.html
 

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Not all aftermarket filters. I recommend the K&N closed end with the RS box. That way you're only sucking fresh air that's being forced past the headlight.
K&N closed end filter comes with the CAI kit.
 

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So this is just from today while in a fast food drive-thru, no line, with the snorkel, stock lid and a open end filter. I took the cap off the filter just to compare temps again. 50°F temp diff between ambient and intake in less than 5 minutes. The open end just started pulling in all that radiant under hood hot air.
 

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