[Bimmer_Bro]

Hello,
I know this DCI Vs OEM airbox topic has been beaten to death, but I am curious how many people run stage 2+ with the oem box? I currently run DCI with my stage 2+, and it works fine, but I am starting to get a little tired of the induction noise.
Does the OEM box flow enough for 18 psi? I am not too concerned on the hot vs cold aspect as that has been proven enough.
I just don't want to starve my turbos of air if I put the stock box back on.
Anyone running this with a tune or is everyone DCI or CAI?

Thanks

[type-dRew]

I'm on 21-22psi through stock air box.

I lose trap speed with open inlets/dci. So I prefer stock box until I find a necessity in the upgrade. That will probably be if I do relocated inlets.

[Jeff@TopGearSolutions]

Although it may feel fine, top end suffers greatly with OE box. It's been proven in the real world, controlled test and at the track. After several DCI's I'm using the AFE Momentum GT.

[type-dRew]

Originally Posted by Jeff@TopGearSolutions

Although it may feel fine, top end suffers greatly with OE box. It's been proven in the real world, controlled test and at the track. After several DCI's I'm using the AFE Momentum GT.

yeah, i lost top end with open inlets compared to stock box. idk

id love to find more power and definitely more top end with stock turbos, so maybe ill try something like this eventually

that said, id be all in on this intake if it gave you a mr. 5/dinan style snorkel down to the bumper for more air flow.

[Ilma]

Originally Posted by Bimmer_Bro

Hello,
I know this DCI Vs OEM airbox topic has been beaten to death, but I am curious how many people run stage 2+ with the oem box? I currently run DCI with my stage 2+, and it works fine, but I am starting to get a little tired of the induction noise.
Does the OEM box flow enough for 18 psi? I am not too concerned on the hot vs cold aspect as that has been proven enough.
I just don't want to starve my turbos of air if I put the stock box back on.
Anyone running this with a tune or is everyone DCI or CAI?

Thanks

I am running Stage 2+ on OEM airbox. I had DCI's in the past but came to dislike the induction noise.

But Jeff is right - the DCI's did feel like they breathed better at higher rpms. But the difference is not that great in terms of power. It's a little easier on the turbos though.

The important data point to watch is your WGDC's. The more restriction in airflow, the higher the WGDC's will be to hit the same boost.

With the stock box I am hitting 70% WGDC by 6K rpm's and that is when I shift. I don't like to see much higher than 70% as I feel the turbo shaft speeds are spinning too fast at that level to maintain reliability.

I bought a used Z4 airbox for $40 in the Z4 forums recently. Supposedly the lid is more open and provides more airflow. But I have to wait until the borders are open to pick it up.

I will be sure to see what happens to the WGDC's.

I love the GT Momentum box Jeff sells and I would have gotten it, but it's like $700 once converted to Canadian dollars. But I think that is one of the best cold air sealed boxes on the market.

[Bimmer_Bro]

Thanks for the info! There are some nice intakes on the market, but as mentioned, the price is crazy once in Canadian.
What were your duty cycles with the DCI if you recall? (if 70% was with OEM box)
I have heard of those Z4 lids being larger. I tried to find one for a while but gave up.

[type-dRew]

Originally Posted by Ilma

I am running Stage 2+ on OEM airbox. I had DCI's in the past but came to dislike the induction noise.

But Jeff is right - the DCI's did feel like they breathed better at higher rpms. But the difference is not that great in terms of power. It's a little easier on the turbos though.

The important data point to watch is your WGDC's. The more restriction in airflow, the higher the WGDC's will be to hit the same boost.

With the stock box I am hitting 70% WGDC by 6K rpm's and that is when I shift. I don't like to see much higher than 70% as I feel the turbo shaft speeds are spinning too fast at that level to maintain reliability.

I bought a used Z4 airbox for $40 in the Z4 forums recently. Supposedly the lid is more open and provides more airflow. But I have to wait until the borders are open to pick it up.

I will be sure to see what happens to the WGDC's.

I love the GT Momentum box Jeff sells and I would have gotten it, but it's like $700 once converted to Canadian dollars. But I think that is one of the best cold air sealed boxes on the market.

My wgdc went down with stock air box.

It went up with open inlets and went slower. I'm sure my car is the just the exception to the rule but I hear this all the time and it is just the opposite for me.

That said I have wanted to find a z4 box. Do you need the whole thing or just the lid?

[Ilma]

Originally Posted by Bimmer_Bro

Thanks for the info! There are some nice intakes on the market, but as mentioned, the price is crazy once in Canadian.
What were your duty cycles with the DCI if you recall? (if 70% was with OEM box)
I have heard of those Z4 lids being larger. I tried to find one for a while but gave up.

It was years ago, so I don't remember the exact %. But I do recall that the difference with DCI's was about a 5-7% lower duty cycle over the stock box at higher rpms.

I was watching IAT's as well and found they were about 5 degrees hotter with the DCI sometimes (like at stoplights where you have no airflow over the intercooler).

On WOT I spray meth and that cools things down to ambient for intake temps. But I have read a number of posts where people at the drag strips say they lose power due to heatsoak.

I do notice better low end torque with the stock box though.

[Jeff@TopGearSolutions]

Originally Posted by type-dRew

yeah, i lost top end with open inlets compared to stock box. idk

id love to find more power and definitely more top end with stock turbos, so maybe ill try something like this eventually

that said, id be all in on this intake if it gave you a mr. 5/dinan style snorkel down to the bumper for more air flow.

Open inlets? Can you elaborate?

[type-dRew]

Originally Posted by Jeff@TopGearSolutions

Open inlets? Can you elaborate?

i was at the track and in between passes I took out the air box to test if i was losing power

did a pass with airbox, then pass without, then next pass with

car was faster with the box with nearly the same 60ft on each pass, several tenths and mph were lost without the air box and wgdc went up

[Sgop335]

Originally Posted by type-dRew

My wgdc went down with stock air box.

It went up with open inlets and went slower. I'm sure my car is the just the exception to the rule but I hear this all the time and it is just the opposite for me.

That said I have wanted to find a z4 box. Do you need the whole thing or just the lid?

Just tle lid. You get more height above the filter. But below the filter its all the same, where there is also a bottle neck. I had it sold it, honestly don’t remember if it made much improvement. Have to dig old logs

[studio54]

Now running Stage 2+ MHD with OEM airbox too here. I remember asked MHD directly if stock airbox was ok for stage 2+ and he said for OTS tunes, the OEM airbox was enough.
(Enough may not means the best about WGDCs number concern)

Anyway I prefer the way my car feels (low end) to drive with OEM than with DCI. Sometimes i switch back to DCIs without the cowl when i want the big intake sound for fun, but overall i prefer the stock airbox.

Originally Posted by Ilma

I bought a used Z4 airbox for $40 in the Z4 forums recently. Supposedly the lid is more open and provides more airflow. But I have to wait until the borders are open to pick it up.

I will be sure to see what happens to the WGDC's.

40$ is a good deal ! Curious to see results when you did the test, will you make a post ? I searched too for a used Z4 airbox but can't find it yet in my area. Was planning to make a combo Z4 lid + mr5 and see if it feels any better over stock.

Originally Posted by Sgop335

Just tle lid. You get more height above the filter. But below the filter its all the same, where there is also a bottle neck. I had it sold it, honestly don’t remember if it made much improvement. Have to dig old logs

I guess that if you sold it, it wasn't a noticable improvement ? If you find your comparing old logs it could be interesting to see.

[roadkillrob]

I am also someone running MHD Stage 2+ and had. been running. and Injen dual cone went back to stock airbox and really don't notice much difference feels a little better low end and I don't run a lot of high rpm's.

[blown07]

Originally Posted by type-dRew

i was at the track and in between passes I took out the air box to test if i was losing power

did a pass with airbox, then pass without, then next pass with

car was faster with the box with nearly the same 60ft on each pass, several tenths and mph were lost without the air box and wgdc went up

Are you talking about a comparison between an air box with no filter vs no air box? I have thought about running the filter box at the track with no filter as I'm sure it would be better than DCI but keep forgetting to do it lol.

[mweisdorfer]

Originally Posted by Bimmer_Bro

Hello,
I know this DCI Vs OEM airbox topic has been beaten to death, but I am curious how many people run stage 2+ with the oem box? I currently run DCI with my stage 2+, and it works fine, but I am starting to get a little tired of the induction noise.
Does the OEM box flow enough for 18 psi? I am not too concerned on the hot vs cold aspect as that has been proven enough.
I just don't want to starve my turbos of air if I put the stock box back on.
Anyone running this with a tune or is everyone DCI or CAI?

Thanks

I run an AFE momentum CAI. Great air box.

I got mine on sale on Black Friday.

[type-dRew]

Originally Posted by blown07

Are you talking about a comparison between an air box with no filter vs no air box? I have thought about running the filter box at the track with no filter as I'm sure it would be better than DCI but keep forgetting to do it lol.

No just the box removed completely. Open inlets.

[Jerain]

What works best for me is stage 2+ with Z4 airbox lid, airscoops en K&N drop in. According to my logs and feeling, the car likes it best overall.

[Smgs1992]

I'd imagine with a drop in filter performance wouldn't suffer too badly

[Bimmer_Bro]

Thanks for the info! Maybe I will give my stock box another try. I do have a drop in filter for it too. Wish I could find a z4 lid but they have been hard to come by. Anyone modded their box by removing all the fins in the lid to smooth it out? Doubt it would make much of a difference. Cheers !

[Sgop335]

Originally Posted by studio54

Now running Stage 2+ MHD with OEM airbox too here. I remember asked MHD directly if stock airbox was ok for stage 2+ and he said for OTS tunes, the OEM airbox was enough.
(Enough may not means the best about WGDCs number concern)

Anyway I prefer the way my car feels (low end) to drive with OEM than with DCI. Sometimes i switch back to DCIs without the cowl when i want the big intake sound for fun, but overall i prefer the stock airbox.



40$ is a good deal ! Curious to see results when you did the test, will you make a post ? I searched too for a used Z4 airbox but can't find it yet in my area. Was planning to make a combo Z4 lid + mr5 and see if it feels any better over stock.



I guess that if you sold it, it wasn't a noticable improvement ? If you find your comparing old logs it could be interesting to see.

Yea that may be the case, but i was running much less boost at that time lol, so may be others can log the difference...

Originally Posted by Bimmer_Bro

Thanks for the info! Maybe I will give my stock box another try. I do have a drop in filter for it too. Wish I could find a z4 lid but they have been hard to come by. Anyone modded their box by removing all the fins in the lid to smooth it out? Doubt it would make much of a difference. Cheers !

Yep, all fins are gone in mine...

[Ilma]

Originally Posted by Bimmer_Bro

Thanks for the info! Maybe I will give my stock box another try. I do have a drop in filter for it too. Wish I could find a z4 lid but they have been hard to come by. Anyone modded their box by removing all the fins in the lid to smooth it out? Doubt it would make much of a difference. Cheers !

There was some debate that the fins are there to keep the air stream linear and cut down on turbulence. You don't want air tumbling around in different directions - you want it flowing in one direction.

I doubt removing them would add any benefit since they run parallel to the direction of airflow and don't introduce any bends or turns which create resistance/drag.

[Boosted12a]

Are any of you running larger inlets with the stock air box? I think at that point the stock box would become the bottle neck. When I first got my car I put the dci on and the only difference I noticed was the sound.