Gtr Airboxes For Large Hp

[Kaido_RR]

Hey all,

This is a topic that hasnt been covered much for the guys upwards of 400kw that I could see.

Here's the issue;

On my GTR i have the ARC airbox with twin genuine ARC filters. Give it a squirt of full throttle and the filter gets sucked in to the actual airbox and all mangled up into a mess ($110 each, this gets tiresome quickly). It was funny the first time, but now its just plain old annoying.

This problem rose its head somewhere between 380 and 403rwkw, so im confident in saying that the limit of the (completely unmodified) ARC box is somewhere in there for at least my setup. Note; ARC dont seem to list a max HP/KW for this box

Now given that im past 403rwkw, something has to happen here as its annoying but not only that im sure its a big restriction on power if its strong enough to suck the filter in (which has allen keys on the filter bracket).

So far ive come up with;

1. Mod the ARC box with more bracing for the filters (not keen on that, its too nice as it is and the restriction will still be there)

2. Get a stock airbox and mod that but who knows how that will turn out

3. Something made from scratch using high flow commodore/falcon filters locally available and with huge surface area and filter braces

4. Use pod filters (no fkn way)

I know this thread wont apply to everyone just like the GT-RS on stroker motor thread, but id love to hear what anyone with a 400kw plus GTR has to say on the topic so please speak up

.....aaaaaaaand go!

i had the same issue with my R32 GTR and arc airbox, however mine didn't suck is at much as your but you could see the top one being pulled in and f**king the filter. (car was relatively stock, n1 turbo and around 1bar of boost untune)

I found its due to the design of the new ARC filters, as mine came with the older design filters, and when i 1st got the new ones i through i had order the wrong ones. Never had the issue with the older the design i see if i can find them and take some photos of it. If you could get a K&N filter similar to the older design it will stop the problem.

ps To me it looks like the new filters don't fit 100% thats why the problem

Edited February 15, 2011 by Kaido_RR

[N1GTR]

Steve after looking at ur airbox yesterday its a pretty poor design how they have the top filter just sitting in there. It needs to have a lip underneath the filter not just on top. If u fitted an underside lip and also a thin t bar crossing underneath also it will fix ur issue and not create any flow restriction

Yeah mate agreed but if possible id like a solution that doesnt mean changing the ARC box and getting rid of all restrictions. You should see how hard it sucks during loaded dyno sessions.

My ARC airbox had exactly the same problem ..but i was using a K&N filter instead of an arc one, which i assume was slightly different in size.

My fix was just what DVS23R mentioned as well..i tigged a cross under the filter out of 3mm diameter stainless rod..problem fixed

Although now i have gone back to a modified factory airbox because i prefer the stock look.

What kw were you at?

Wouldnt have any pics of the box once modified?

Wanna sell ur arc air box

Maybe will let you know if i do

FG XR8 Airbox and snorkel with K & N panel filter fitted to FG F6 turbo.

Good for tad over 500rwhp....maybe more. http://forum.rdpbris...ic.php?f=4&t=80

Given the long intake tract to the other side of the engine bay in a stock F6 I dare say it would be more efficient with shorter inlet tract in a GTR .

Also being plastic - less heat soak.

Can be modded to fit a pod filter inside.

I have one of these at home......so if you want dimensions just ask.

My 2 cents.

Dimensions would be fantastic thanks

not running 400rwkw but when I tested the R32 GTR box back to back with Blitz pods at 280 rwkw I lost about 20 rwkw. put the box back in, took the lid off and taped the panel filter in and the power came back. not consistent with the experience of others and both tests were done with bonnet up, but it's a big difference either way. front of box is now modified but haven't done back to back test with it in that config.

Ages ago i did M's vs this ARC box vs a stock airbox with nismo S tune filter. No difference at 262 rwkw between the 3, however i'm not talking those low number anymore and it all goes out the window with this much power

i had the same issue with my R32 GTR and arc airbox, however mine didn't suck is at much as your but you could see the top one being pulled in and f**king the filter. (car was relatively stock, n1 turbo and around 1bar of boost untune)

I found its due to the design of the new ARC filters, as mine came with the older design filters, and when i 1st got the new ones i through i had order the wrong ones. Never had the issue with the older the design i see if i can find them and take some photos of it. If you could get a K&N filter similar to the older design it will stop the problem.

ps To me it looks like the new filters don't fit 100% thats why the problem

Couldnt find a K&N filter for it, tried that already, it had one before but i threw it out thinking genuine ARC would be better - tried to find that size filter again and couldnt.

This isnt a drama for most cars, just the big hp ones

[MrStabby]

Tangomatt - 410rwkw stock airbox, nismo intake

Aaron34 - 400rwkw stock airbox

And you can make 360kw with a 3in exhaust, but as you've said before just because you can do it doesn't mean its a good solution. Does the same logic not apply to airboxes?

[N1GTR]

Exactly!

My theory on this is a massive surface area for the filter to allow the filter to not have to work as hard but still flow

[Trozzle]

You either sacrifice filtering efficiency, hence eating away at the whole purpose of an air filter, or you increase the surface area as you said Steve. It's very basic physics, if the filter is being sucked in, then it's posing a restriction by filtering "too well". It's like the cell count in a damned cat converter!

[elrodeo666]

So what do you use when you want 500kw's

[Don Dada]

4. Use pod filters (no fkn way)

???

With my measly 260kw i felt a noticeable difference goin from std 33gtr box to apexi pods AND a big ass sealed box with a 3" and a 4" pvc pipe feeding from under the guard/bumper

Pods are proven to flow more is just that you have to go thru the hassle of fabricating to seal and feed them properly as you probably already know.....but if youre going for a more or less legal look that idea is out the window

[R31Nismoid]

And you can make 360kw with a 3in exhaust, but as you've said before just because you can do it doesn't mean its a good solution. Does the same logic not apply to airboxes?

At the 400rwkw level, nothing is simple for a street car. If you want big oil coolers, keep the aircon & then throw legalities into the mix and shit gets nasty.

Indeed this is very true. But the setups are not identical.

One car has a massively larger snorkel (nismo one is noticeably bigger), piping kit etc - same result for all intents and purposes as a 10rwkw different is nothing you will ever notice.

So the only possible part is the aixbox itself, if it even is.

As usual - the dyno doesn't necessarily tell the real story especially when heatsoak comes into it and robs you of power.

Cooler intake charges are very important at this level.

If you did go to a pod based setup, it would require a fair amount of customisation and fab to get it to work to the level of a stock airbox over say a 15min track sprint etc.

A piece of tractor pipe feeding to a partially split pod isnt exactly a proper solution either

For some people also the issue when modifying the front intake piping etc for pods - is AFM reversion/surge. Now i know Steve is D-Jet now, but others have not necessarily gone down that road (two cars above).

For a dedicated track car and simply putting a pod or similar into the guards etc. No fuss, no worries that way - but different application

[Kaido_RR]

Couldnt find a K&N filter for it, tried that already, it had one before but i threw it out thinking genuine ARC would be better - tried to find that size filter again and couldnt.

This isnt a drama for most cars, just the big hp ones

i had issue with mine too and i say i would have been running anywhere between 250-300rwhp (untune so couldn't say for sure).

No idea why ARC changed the filter design the older ones seems so much better

[N1GTR]

???

With my measly 260kw i felt a noticeable difference goin from std 33gtr box to apexi pods AND a big ass sealed box with a 3" and a 4" pvc pipe feeding from under the guard/bumper

Pods are proven to flow more is just that you have to go thru the hassle of fabricating to seal and feed them properly as you probably already know.....but if youre going for a more or less legal look that idea is out the window

I'm not talking feel, I'm talking back to back dyno runs on my car on the same dyno and no difference

Still, it needs to be legal and of course fit in the engine bay which being a GTR is cramped enough as it is, so no pods here

[N1GTR]

At the 400rwkw level

That's just it, the game changes at that power level and above.

As much as I appreciate the replies and everyone trying to help, any suggestion that's from someone with 450hp atw isn't really helping cause it's all so different at 600hp atw plus.

I guess most guys with big power (450+) just stick pods in there and leave it at that

[bigmikespec]

Get a Greddy kit.

[Piggaz]

Get a Greddy kit.

Is the the pipe kit that replaces the 'twin turbo' pipe?

[Beer Baron]

I guess most guys with big power (450+) just stick pods in there and leave it at that

bingo! sadly it's the easiest way to do it. if you 'unrolled' say 2 apexi pods from the regular GTR kit you would see that they have a massive surface area combined and as such can filter very well whilst not offering much restriction in the intake. it's actually not that hard to create a good enclosure for them. you still have the same fresh air fee as you do to the stock airbox and any air from behind the headlight and just need to box 2 sides (the top and the engine side) to be effective. the inner guard creates the other 2 sides (you want those sides open anyway as that's where the cool air is coming from). the ARC airbox is just sucking air from in the engine bay anyway like pods do with it's big filter on top. yes it has another little filter on the front too but again same thing as pods and just as susceptible to heatsoak etc. the only difference really is some police may believe the arc box is more 'legal' over the pods, but if covered with a neat heat shield the pods are actually safer (more legal) as the arc filter element is exposed on the top of the box.

go for pods with an air feed, and a shield around the box. it will be the best option for the big powers!

[SiR_RB]

yeh comes with intake pipes from air filters to turbos, and turbos to intercooler

[Nee-san]

If you're smart about the design of a enclosed pod box like Beer Baron has just explained, you could probably create something substantially more effective then stuff you can buy over the shelf.

Stay away from using metals, use Lexan instead, properly shield pods in the enclosure so that the there is an air tight seal between the hot and cold air.

After this it is all about preventing or retarding the "heatsoak" and further ensuring that the enclosed area has large and dependable feeds for cool ambient air.

[Deano 1]

my vote gose to, pods and make somthing up out of fiber glass, its pritty easy and very cheap. i made a radiator shourd cost me 50bux, took along time but worth it in the end.

once my new motor is built. ill be going pods and a custom fiberglass enclosed box.

[Nee-san]

my vote gose to, pods and make somthing up out of fiber glass, its pritty easy and very cheap. i made a radiator shourd cost me 50bux, took along time but worth it in the end.

once my new motor is built. ill be going pods and a custom fiberglass enclosed box.

That's the idea !

FRP is even lighter then the usual polymers so go for it ! win win really.

[Trozzle]

Even though my car isn't a GT-R of any kind, so space is less of an issue - my pod used to be noticeably hot after driving...I bought a fibreglass enclosure off a fellow forum member, which he'd had lined with that foil skinned foam stuff on the inside...just a backyard kinda job on the foam stuff.

I drove the car around for a while on a warm day, no constant driving - plenty of traffic lights, then removed the lid of the box and felt the bod immediately after I got home - barely warm to touch,

Just get a fibreglass enclosure for pods, line it with whatever the shit is lining the inside of mine, then run some piping from behind the bar or something to feed fresh air in there.

[our12]

Hi.

If you are using a foam pad pod filter this may significantly increase your airflow.

The usual scenario is the mesh is hard up against the foam. If you trim the edge of the foam making it smaller so that there is air space between the mesh and foam when fitted you have a larger volume of air into the engine by allowing the air to go around the mesh. A simple demonstration- while you are reading this put a finger across your palm. You palm is the filter your finger is the mesh now imagine air trying to penetrate the foam through your finger- it cant. Try it and you may be surprised at the results as there is a large area the mesh covers.