Anyone ever test between air filter in and out of engine bay on dyno?

[turboglenn]

Just wondering as i can't find much info on this, but when i was looking at the vid of the 9 second DD 2g car i noticed it's filter is in the OEM location and the car is making great power. I however have my filter mounted where the OEM side mount use to be and have had it there for years (and it cost me an engine last sept by sucking up water when a storm grate backed up)

So i was wondering if anyone with a dyno had done back to back pulls with the filter in and out of the engine bay and with the hood closed? I know that's an odd request, but I'd really like to know what i stant to loose if i put mine back in the bay.

I found several dyno comparisons of atmospheric vs. re-routed wastegates and the results were impressive enough that i decided to keep mine external dumping (i only wanted the car quieter as i get older ) But anyway, i saw people claiming gains of 30 - 42hp by going from re-route to atmosphere. and i don't want to loose 10hp, let alone close to a possible 30

But like i said, I can't find any info on filter location that has dyno numbers to back it up compared to "it felt better"

I guess i could still use methanol injection or my n2o for cooling if underhood mounting is worth going back to, but i like having the filter in "open air"

 

[ApexVIII]

i have no experance with this on the dyno, but...

but i would think that aslong as you are usign methanol injection or something else to cool the intake charge below ambient, that an intake mounted out side, (like a CIA or somethign) would not have much effect, becase that CIA will get you what, 10*-30* intake temp difference befor the turbo, then once its heated by the turbo then cooled by the intercooler and methanol i cant see ther ebeing much of a gain.

i would stick with it not CIA,

i have methanol and im going to keep it in the stock location.

oh also on a dyno the hood is open, so unless the hood is shut i cant see it being a fair way to compaire the two.

 

[turboglenn]

oh also on a dyno the hood is open, so unless the hood is shut i cant see it being a fair way to compaire the two.

That's why i said it was a weird request since most dyno sessions have the hood open for RPM pickup at minimum.

But the problem is i'm trying to not HAVE to use any aerosol or nitrouse cooling on a dialy basis, the car runs E85 already, and has nitrouse and methanol injection mounted and ready to go, I jsut flip the switch to arm them and the ECU takes over control of them, but as stated i would LIKE to not have to use them 100% of the time.

I noticed in logging i went from 120-150* average intake temps to 75-85* average intake temps from the filter relocation outside of the engine bay (these numbers are as measured at the TB elbow during idle/cruise once the car is fully warmed up)

The only reason i'm going this in depth on filter location is because i'm about to build either aluminum or SS intercooler piping and use a new route to comply with my daily driving needs such as fans, filter not being able to suck up water etc..etc.. So a little compromise doesn't bother me, but if the difference is anywhere near what the wastegate tests yielded i'd rather take the chance and just not drive in the rain when i don't have to

My old setup allowed me to move the filter where i wanted it so i could put it in the bay on a rainy day by just loosening a T-bolt clamp and turning the filter upwards. But there's been many changes in the setup since then and now i have to pick one or the other for the final piping and don't want to loose many more horsies than i have to ( i won't comprimise daily driving for power so that's why i say loosing more than i have to ) But i'm well within my goal for power anyway at this point so if it's only a 5hp diff or so i'll stick that puppy back in the engine bay i guess..

 

[94awdcoupe]

When I built the intake on this car I was measuring post and pre intercooler temps on 25G turbo at 29psi. There was a huge difference from just having the filter open to suck in hot compartment air. There was 25 degree drop pre intercooler. felt like it gained 12-15whp. well worth a little effort. hot air is big, cold air is small. turbo can suck in more cold air.

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[turboglenn]

^^ nice engine bay...love that plug cover.. I've been thinking about a box like that IF i put mine back in the bay (and plasma cutting a HUGE hole under it for cool air) But somehow i like not having it in the bay because it's less clutter that way... Plus it's funny to see some one's face when you're on a stand alone and the stock MAF meter is laying under the hood, plugged in but hooked to no piping at all...then you tell them..."i don't know, i just get a lot more power that way with the big turbo" and see if they ever call BS on you..most don't :

But anyway, Still curious if there's any dyno numbers.I understand air density and the effects of temperature, I just don't know the scientific way to say how dense the air gets with how much temperature decrease. I know i can "feel" the difference especially on hot days, but all variables being the same i guess i'm looking for "X" amount of power lost when temperature rises "X" amount of degrees or something ...hell i don't know, just looking for data..like johnny 5 said..."need input...need input....."

P.S. What intake mani is that? Is that the evo 3?

 

[slowgsr]

Glen, I don't know if this helps.. I run my filter though a basic FP 4" intake tube and it sits in the passenger side front lower area of the engine bay (just above the crossmember).

My IAT's are always very close to ambient when cruising, maybe 2-3 deg above. After pulls I get maybe 2-3 deg increase during pulls but it drops back down to where it was. Untill I begin to experience any sort of heat soaking.. This only usually occurs at the track, I don't hot lap the car but if i do 3-4 passes or so with only 5-10min brakes my IAT's were around 95-100 at the top of the track (80deg day).

This is with a 'large' jet that comes with the AEM water/meth kit.. Im running a 75/25mix.


You could assume that lower IAT's will lead to more power, and IAT's are most likely related to air filter placement and heatsoaking.. as well as other things that aren't directly related to this discussion.

As far as dumping your wastegate to atmosphere, the main thing here is that it dumps behind the oil pan, so your engine dosen't end up sucking in exhaust gases.. I can see this being an issue for guys who don't run much of a dumptube, especially on dyno's when the car isn't moving (sure you have fans), but at the track it will be nothing worth worrying about.

So yeah.. My 0.02 says out of the bay would be better because it would give you cooler IAT's, and less chance to suck up any lingering exhaust gases from a open dump.

I have no dyno comparisons, or even if it 'felt' better. I just know when my IAT's are good and cool I 'feel' its safer. IAT's and power have a direct relation and, air filter placement and IAT's have a direct relation, so do air filter placement and HP have a direct relation? I would consider it an indirect relation, but you can figure that one out

 

[Defiant]

Bench racing dyno results.

Bizarre.