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Discussion Starter #1
Hi,

I have a Gruppe M fitted to my FN2 but have been told these can be restrictive. Can anyone tell me what is restrictive about them please as I thought the ram air affect would be better than a cone just sucking air in and the cone surface area is much bigger than the OEM panel filter.
Is it because of the smallish gap from the bonnet scope to the air box? Air box size?
Would a second air feed into the box remove this restrictiveness if it is restrictive?

Thanks for any answers and advice.
Cheers
Dave
 

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Enjoying life
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I only think in comparison to maybe a 3.5" cai, it's a good bit of kit. It's my old one too :D
 

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Discussion Starter #3
I only think in comparison to maybe a 3.5" cai, it's a good bit of kit. It's my old one too :D
lol, it curtainly is mate. When you refer to 3.5, is that the size of the in diction pipe leading to the throttle body?

Cheers
 

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250bhp.... finally :)
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As I've said before it's not resricting until you get up into 250bhp territory with cams and a 3" mate.

Below that there's zero difference between intakes other than flat spots, noise, throttle response and heatsoak etc
I've paid a fortune in dyno costs changing bits around so take my word for it and enjoy it :lol:

People jump on fitting a skunk2 without supporting mods and are just wasting money and effort. Until you fit cams & a 3" decat I've had HKS, GM, Teg box and HR and all were exactly the same until I had pretty much maxed out NA tuning where the HR took over.

If you're charging then I'd get a 3.5" CAI personally.
 

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250bhp.... finally :)
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As for it's restriction Paul at TDi said it's the top of the cone, the rubbery/plastic bit that holds the fabric. It takes up potential intake surface area of the closed box that's essentially a dead zone which is much less in a closed box as this is around the outside of a panel filter.

Again the actual useable surface area however is plenty enough all the way up to 250bhp
 
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Discussion Starter #6
As for it's restriction Paul at TDi said it's the top of the cone, the rubbery/plastic bit that holds the fabric. It takes up potential intake surface area of the closed box that's essentially a dead zone which is much less in a closed box as this is around the outside of a panel filter.

Again the actual useable surface area however is plenty enough all the way up to 250bhp
Cheers @musegroove, just trying to get my head around the reason it would be restrictive, completely believe that it is good for up to 250bhp (never doubted you mate :) )

It was part of a discussion with Paul at TDI regarding charging and that it would be restrictive, so got my brain thinking on how I could improve it as I like the ram air concept.
So if charging, the intake pipe and filter would need to be of a solid nature to prevent collapse from the SC sucking the air in?
Stupid question time, when you refer to 3.5", is that the diameter of the cone and pipe that leads to the inlet manifold?

Cheers for you help, as usual, very much appreciated.
Dave
 

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250bhp.... finally :)
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Only noticed you was thinking of charging from your TRO post as then I would advise going bigger definetly.

I'd probably go skunk2 over HR for charging just from worries of it collapsing as once it's kinked it's never going to be right again.

The whole intake pipe from the end of the filter to the MAF housing is 3.5" then reduced down unless you have a big TB then the big coupler can be used.
 

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Discussion Starter #8 (Edited)
Only noticed you was thinking of charging from your TRO post as then I would advise going bigger definetly.

I'd probably go skunk2 over HR for charging just from worries of it collapsing as once it's kinked it's never going to be right again.

The whole intake pipe from the end of the filter to the MAF housing is 3.5" then reduced down unless you have a big TB then the big coupler can be used.
Thanks mate, yeah, considering the SC route but won't be for a while. For what I'll be doing short term the GM will be fine. But I'm thinking ahead and stock pilling parts if they come up cheap second hand so something to add to the shopping list.

next stop is Longlife for a stainless B-Pipe with cat welded in like yours :)

Thanks for you help.
 

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Discussion Starter #9 (Edited)
Only noticed you was thinking of charging from your TRO post as then I would advise going bigger definetly.

I'd probably go skunk2 over HR for charging just from worries of it collapsing as once it's kinked it's never going to be right again.

The whole intake pipe from the end of the filter to the MAF housing is 3.5" then reduced down unless you have a big TB then the big coupler can be used.
OK, sorry about this mate. What are your thoughts on this? What I trying to do as I like the GM set up (Carbon fibre bitch) is keep it if and when I do SC. SO;

Looking at the skunk CAI, which is nice and not as expensive as I thought it would be. The cone filter doesn't seem any different or any bigger that the K&N with the GM.
As you can buy skunk spares, would fabricating a 3.5 feed from the GM air box to TB be beneficial and remove the restriction or as you've said above, its the air box that is the limiting factor here?
If the air box was the limiting factor, would a second cold air feed into the box resolve this?

You may have by now gathered I'm a tinkerer and don't believe the wheel being round should not be questioned >:)

cheers
 

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Can't see it making a huge difference, I had a stainless intake pipe which was a tad over 3" and didn't really affect much other than fit correctly to the RRC angle.

The 3.5" filters are girthy by the way, especially the HR one. It's huge.
 
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Discussion Starter #11
Can't see it making a huge difference, I had a stainless intake pipe which was a tad over 3" and didn't really affect much other than fit correctly to the RRC angle.

The 3.5" filters are girthy by the way, especially the HR one. It's huge.
Just looked at a vid of the HR set up, that filter is big. The GM one is quite big tbh. Don’t think it’s as big as the HR, the internal opening of the filter is 4.5” across, and filter section is 4” tall and 5 & 3/4” at widest point.
I think the solid body of the Skunk2 is what’s needed for the SC so it doesn’t collapse.

Let’s face it, GM looks nice but if SC-ing it’s about power so looks like the GM at some point will have to go :frown2: but let’s face it, I should get near to the price of the Skunk2 if I sell the GM.

CHEERS
Dave
 

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Be interested in the gm if you sell :) not yet like
 
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Discussion Starter #13
Ok @Danith will bare you in mind, but I have found a
thread on the internet where a guy fitted and supercharger with a gruppe m and got over 300bhp out of it and I’m not going to be looking for much more tbh, so with a bit of meddling it may be ok to keep. ?
 
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[Removed quote of post above. See HERE]

Ha yeah not able to afford one yet but do fancy trying one out. Itch to scratch and all that.
 
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I understand concerns but I don't think you'd have an issue with the HR intake, it's the one I'm using just now and I've had the Gruppe M, Tegiwa and Skunk2 previously. The HR pipe is really thick so if would take an incredible amount of force to choke it and make it collapse, the Skunk2 is more likely to collapse IMO where the composite meets the rubber insert near the top as the rubber is fairly flimsy
 
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