Airbox for +T

[BuiltNotBought]

Doing a +T on my car and I’ve read the precious forums lots of mixed reviews from sometime back. 
checking if anyone has any ideas for airbox or enclosed pod filter or solutions? 
I was thinking stock GTT box but some say it’s restrictive? I seen some people try fit in a pod in the box anyone done that recently? 
not any good enclosed options ? Thanks 

[BuiltNotBought]

R34 RB25de Neo by the way ^ 

[GTSBoy]

Meh. How much power can you make from a +T anyway? I wouldn't have though it would be enough to challenge the airbox. It's not as if it's tiny compared with the turbo one.

As to putting a pod in a stock airbox .... it's not the filter element that would be restrictive. It would be the air inlet to the box that would be the narrow point, which you could open up regardless of what element was inside.

On my R32 I opened up the sort of triangular opening in the bottom front corner of the box, deformed (heated, moulded) some 4" stormwater pipe to fit to that opening and punched a 4" hole down through the inner guard to the spot where the stock intercooler used to be. This was purely in the search for a cold intake, but you could do something similar if you need to open up the inlet side of it.

The AFM tube size is the same for both NA and turbo, so the outlet from the airbox is same same anyway. If you're going to do the right thing, then an aftermarket ECU won't care about the AFM (ie, you can get rid of it). But even if it was still there, people pull >300rwkW through them all day, and I suspect you won't be going there.

[BuiltNotBought]

I get you, we’ll see I’m aiming for 200ish kw now and hopefully 300rwkw down the line after some upgrades maybe like headstuds, E85 flex fuel etc 
so trying to make it final for that now, I can get a GTT airbox for $280 so it’s not too bad but not sure if there’s better ways to spend that money. I seen online they say pod filter which isn’t enclosed isn’t good especially for a plus T.   
 

hard to say what to do

[BuiltNotBought]

Also seen this as an option 

26 minutes ago, GTSBoy said:

Meh. How much power can you make from a +T anyway? I wouldn't have though it would be enough to challenge the airbox. It's not as if it's tiny compared with the turbo one.

As to putting a pod in a stock airbox .... it's not the filter element that would be restrictive. It would be the air inlet to the box that would be the narrow point, which you could open up regardless of what element was inside.

On my R32 I opened up the sort of triangular opening in the bottom front corner of the box, deformed (heated, moulded) some 4" stormwater pipe to fit to that opening and punched a 4" hole down through the inner guard to the spot where the stock intercooler used to be. This was purely in the search for a cold intake, but you could do something similar if you need to open up the inlet side of it.

The AFM tube size is the same for both NA and turbo, so the outlet from the airbox is same same anyway. If you're going to do the right thing, then an aftermarket ECU won't care about the AFM (ie, you can get rid of it). But even if it was still there, people pull >300rwkW through them all day, and I suspect you won't be going ther

[GTSBoy]

Well you could certainly buy or build an enclosure for a pod in that corner of the bay. It is absolutely vital that there is a nice big opening to let cold air in to it from the front or underside, otherwise it will just pull air in around the edges from the bay, and if that air is hot, you gain nothing from enclosing the pod.

There is lots of good evidence around (including on here, see posts by @Kinkstaah for example) showing that pods pulling hot air from the bay is only a problem when you're static or slow in traffic, and that as soon as you get the car up and moving the air being grabbed by the pod cools down. Although that will obviously vary from car to car, whether there is a flow of cold air to the pod or if it all has to come through the radiator area, etc etc. Obviously, the whole exercise requires as much thought as anything else does. Doing the lazy thing will often end up being the dumb thing.

The stock GTT airbox has a cold air snorkel to feed it from over the radiator. Shows that Nissan were thinking.

The GT airbox is upside down compared to the turbo one, yeah? Inlet at the bottom, AFM/exit on the lid? That might make it harder to route the turbo inlet pipe using the GT airbox than a turbo one. That would probably be the main reason I'd consider not using it, not that it is too small and restrictive. I'm looking at a photo of one now and the inlet opening seems nice and large. Also seems to have the same type of snorkel that the turbo one has. Maybe all that's required is to make a less restrictive snorkel/cold air inlet, perhaps by punching down through the guard like I did.

[Kinkstaah]

If you have a turbo... then the ducting holes I used to feed the pod are not available because your intercooler likely uses them.

If you have an intercooler, your IAT's are going to be goverened by how good your intercooler setup is. I'm yet to really see anyone check IAT with a snorkel/boxed pod/proper CAI versus and unshielded pod. It would be interesting! But I suspect that the differences would not be so noticeable as if you were N/A as the intercooler is where the air is being cooled.. and out in front where the FMIC would be is a pretty good spot for it..

When I was turbo I pushed the stock GTT box as far as I could and made some pretty good power out of it, and noticed on the street I never made the same power/boost.

Then I did a before and after run with a pod filter versus the box and picked up about 9PSI from the same boost duty cycle and about 50KW instantly. I never ran the stock box again, and recently removed it for my N/A setup. The box is restrictive to a degree - Even with the V8 setup I noticed I picked up power by removing the box completely, so punching holes from the bottom of it to get air from the passenger guard *helps* but the most effective one in my case was simply having the ducts, a pod, and no box around it.

In my experience, *more* air was better than cold air. The air (with ducts) will be cooled off as you start moving, and especially if you start moving fast (a race track).

It actually moves around quite a bit as you can see.

 

[GTSBoy]

Also, I note OP is in Melbourne, which begs the question... are you aware of how illegal your car will be with a turbo, and intercooler and any sort of filter change? I don't know how you can get past the "2 intake mods" "rule" that seems to exist in Vic. Fully engineered might or might not get you there.

[BuiltNotBought]

49 minutes ago, GTSBoy said:

Well you could certainly buy or build an enclosure for a pod in that corner of the bay. It is absolutely vital that there is a nice big opening to let cold air in to it from the front or underside, otherwise it will just pull air in around the edges from the bay, and if that air is hot, you gain nothing from enclosing the pod.

There is lots of good evidence around (including on here, see posts by @Kinkstaah for example) showing that pods pulling hot air from the bay is only a problem when you're static or slow in traffic, and that as soon as you get the car up and moving the air being grabbed by the pod cools down. Although that will obviously vary from car to car, whether there is a flow of cold air to the pod or if it all has to come through the radiator area, etc etc. Obviously, the whole exercise requires as much thought as anything else does. Doing the lazy thing will often end up being the dumb thing.

The stock GTT airbox has a cold air snorkel to feed it from over the radiator. Shows that Nissan were thinking.

The GT airbox is upside down compared to the turbo one, yeah? Inlet at the bottom, AFM/exit on the lid? That might make it harder to route the turbo inlet pipe using the GT airbox than a turbo one. That would probably be the main reason I'd consider not using it, not that it is too small and restrictive. I'm looking at a photo of one now and the inlet opening seems nice and large. Also seems to have the same type of snorkel that the turbo one has. Maybe all that's required is to make a less restrictive snorkel/cold air inlet, perhaps by punching down through the guard like I did.

Yes that’s what im trying to decide. Should I do stock gtt box or enclosed or open pod. 

[Kinkstaah]

10 minutes ago, GTSBoy said:

Also, I note OP is in Melbourne, which begs the question... are you aware of how illegal your car will be with a turbo, and intercooler and any sort of filter change? I don't know how you can get past the "2 intake mods" "rule" that seems to exist in Vic. Fully engineered might or might not get you there.

Ultimately you can't - You would need engineering. The sensible option here is a good no-cut FMIC, the GTT box, a highflow or stock manifold mounted turbo and aim for the best 280rwkw you can get in 2025.

It's sensible for many reasons!

[BuiltNotBought]

18 minutes ago, Kinkstaah said:

If you have a turbo... then the ducting holes I used to feed the pod are not available because your intercooler likely uses them.

If you have an intercooler, your IAT's are going to be goverened by how good your intercooler setup is. I'm yet to really see anyone check IAT with a snorkel/boxed pod/proper CAI versus and unshielded pod. It would be interesting! But I suspect that the differences would not be so noticeable as if you were N/A as the intercooler is where the air is being cooled.. and out in front where the FMIC would be is a pretty good spot for it..

When I was turbo I pushed the stock GTT box as far as I could and made some pretty good power out of it, and noticed on the street I never made the same power/boost.

Then I did a before and after run with a pod filter versus the box and picked up about 9PSI from the same boost duty cycle and about 50KW instantly. I never ran the stock box again, and recently removed it for my N/A setup. The box is restrictive to a degree - Even with the V8 setup I noticed I picked up power by removing the box completely, so punching holes from the bottom of it to get air from the passenger guard *helps* but the most effective one in my case was simply having the ducts, a pod, and no box around it.

In my experience, *more* air was better than cold air. The air (with ducts) will be cooled off as you start moving, and especially if you start moving fast (a race track).

It actually moves around quite a bit as you can see.

 

I’m only using 1 of the Intercooler holes as it’s cross mount Intercooler. So maybe I could have some sort of pipe feeding air into the pod from the bottom hole for the Intercooler and link to front bumper open area. 
 

Was thinking of doing open pod and also leaving the stock snorkel there to help feed air also, but remove the airbox. Not really sure, it’s not a track car but not a daily driver either but I will face traffic and im Worried about the hot air going in at stand still.

[Kinkstaah]

Ultimately with that, all your air will be going through the FMIC.

No matter what, any tune needs to be able to compensate for changes in intake air temperature. In your situation you could duct air using the hole that isn't being used.

Did you cut the chassis to get a cross mount intercooler? At this point - open pod, cut chassis for intercooler, and the whole 2 intake mods, and car *not* registered with a turbo motor means legality (visually or otherwise) is fully out the window here.

[BuiltNotBought]

12 minutes ago, GTSBoy said:

Also, I note OP is in Melbourne, which begs the question... are you aware of how illegal your car will be with a turbo, and intercooler and any sort of filter change? I don't know how you can get past the "2 intake mods" "rule" that seems to exist in Vic. Fully engineered might or might not get you there.

Yes that’s another issue, I always have a front mount, plus will be turbo plus intake will big hasstle. I’ve been told if it looks stock they’re fine with it by a couple others who have done it ahahaha. 
 

I know @Kinkstaah said the stock gtt airbox is limiting but I might just have to do that to avoid a defect so it atleast looks legit. Or an enclosed pod so it’s hidden away and feed air from the snorkel and below Intercooler holes like kinstaah mentioned. Hmm what to do 

[BuiltNotBought]

1 minute ago, Kinkstaah said:

Ultimately with that, all your air will be going through the FMIC.

No matter what, any tune needs to be able to compensate for changes in intake air temperature. In your situation you could duct air using the hole that isn't being used.

Did you cut the chassis to get a cross mount intercooler? At this point - open pod, cut chassis for intercooler, and the whole 2 intake mods, and car *not* registered with a turbo motor means legality (visually or otherwise) is fully out the window here.

I haven’t yet cut the chassis, maybe I switch to a reverse flow. I’ve got the Intercooler mounted as I already had it but not cut yet. Might have to speak to an engineer 

[BuiltNotBought]

3 minutes ago, Kinkstaah said:

Ultimately with that, all your air will be going through the FMIC.

No matter what, any tune needs to be able to compensate for changes in intake air temperature. In your situation you could duct air using the hole that isn't being used.

Did you cut the chassis to get a cross mount intercooler? At this point - open pod, cut chassis for intercooler, and the whole 2 intake mods, and car *not* registered with a turbo motor means legality (visually or otherwise) is fully out the window here.

There is a guy who said he can weld me piping without having to cut chassis, maybe I do that ? Or do I just go reverse flow but isn’t reverse flow very limited once again? 

[GTSBoy]

By "reverse flow", do you mean "return flow"? Being the IC having a return pipe back behind the bumper reo, or similar?

If so... I am currently making ~250 rwkW on a Neo at ~17-18 psi. With a return flow. There's nothing to indicate that it is costing me a lot of power at this level, and I would be surprised if I could not push it harder. True, I have not measured pressure drop across it or IAT changes, but the car does not seem upset about it in any way. I won't be bothering to look into it unless it starts giving trouble or doesn't respond to boost increases when I next put it on the dyno. FWIW, it was tuned with the boost controller off, so achieving ~15-16 psi on the wastegate spring alone, and it is noticeably quicker with the boost controller on and yielding a couple of extra pounds. Hence why I think it is doing OK.

So, no, I would not arbitrarily say that return flows are restrictive. Yes, they are certainly restrictive if you're aiming for higher power levels. But I also think that the happy place for a street car is <300 rwkW anyway, so I'm not going to be aiming for power levels that would require me to change the inlet pipework. My car looks very stock, even though everything is different. The turbo and inlet pipes all look stock and run in the stock locations, The airbox looks stock (apart from the inlet being opened up). The turbo looks stock, because it's in the stock location, is the stock housings and can't really be seen anyway. It makes enough power to be good to drive, but won't raise eyebrows if I ever f**k up enough for the cops to lift the bonnet.

[Kinkstaah]

It would be well worth deciding where you want to go and what you care about.

Reliability of everything in a 34 drops MASSIVELY above the 300kw mark. Keeping everything going great at beyond that value will cost ten times the $. Clutches become shit, gearboxes (and engines/bottom ends) become consumable, traction becomes crap.

The good news is looking legalish/actually being legal is slighly under the 300kw mark. I would make the assumption you want to ditch the stock plenum too and want to go a front facing unit of some description due to the cross flow.

Do the bends on a return flow hurt? Not really. A couple of bends do make a difference but not nearly as much in a forced induction situation. Add 1psi of boost to overcome it. Nobody has ever gone and done a track session monitoring IAT then done a different session on a different intercooler and monitored IAT to see the difference here.

All of the benefits here are likely in the "My engine is a forged consumable that I drive once a year because it needs a rebuild every year which takes 9 months of the year to complete" territory.

It would be well worth deciding where you want to go and what you care about with this car.