Airbox Vs Pod Back To Back Testing

[Duncan]

hmm those pics are interesting. The 32 inlet doesn't look so bad, but once you add the plastic extension that goes through the headlight support it is much smaller.

Has anyone measured the comparitive cross sections?

[zebra]

Geoff - did you use the holes for the factory IC piping? (i assume its a GTS-t) or cut out a bigger hole in that area? got any photos of on top of how you mounted the AFM

Also would it be better to have an air dam where it can catch the air (maybe sink the filter deeper into the box) other wise wouldnt the air bleed off around the filter rather than going through it (much like having a guide in the front bar which seals the FMIC)

not a good explanation so I hope it makes sence.

Andrew

Edited September 29, 2007 by zebra

[rev210]

no, bonnet open. i don't agree that we aren't anywhere. i think we can categorically state that the stock airbox will inhibit power due to the size of the orifice in the bottom half - bonnet up or down - but clearly the panel filter (tested up to those power levels) has the capacity to flow sufficient air if fed correctly.

i know there's a lot more to the issues of airflow and under bonnet dynamics but this shows conclusively that the bottom half of the box can't flow sufficient air.

i'm not suggesting that this is the be all and end all of tests, but it does tell us some things for sure. got to start somewhere, suffice to say i was happy with the outcome as i now know more than i did.

I can see your logic and I'd be inclined to think the same if you are using the baffle box.

However ,how well cold air gets to the pods with the bonnet down and the effects of aerodynamics on pressure based feed will effect things very significantly. It really needs a test to be conclusive.

Not a good idea in general to tune with the bonnet up, ok for initial curve but, you are missing a significant amount of road going resolution if you finished the tune bonnet up.

[WazR32GTSt]

where are the dyno graphs? doesn't mean much without them..

[Scooby]

340rwkw on stock 32 airbox, no worries.

Marcus you are getting 340 rwkw on a stock R32 GTR airbox, unmodified?

Mark, having a think about this and were any of the turbo inlet hoses constricting? If the restriction to the inlet was enough there may be some cross sectional reduction in the inlets between afm and turbo which is a sure way for the restriction to increase so limiting flow. If hard pipes were used, for example, then they would resist the negative pressure and allow the flow to continue. So just a thought.

Hi Geoff, understand where you are coming from, i watched the inlet hoses during all runs and they didn't move.

I can see your logic and I'd be inclined to think the same if you are using the baffle box.

However ,how well cold air gets to the pods with the bonnet down and the effects of aerodynamics on pressure based feed will effect things very significantly. It really needs a test to be conclusive.

Not a good idea in general to tune with the bonnet up, ok for initial curve but, you are missing a significant amount of road going resolution if you finished the tune bonnet up.

hi Rev 210, i agree but at this stage - not withstanding what Marcus has said - it appears that the stock airbox won't flow enough air for 268 rwkw with the bottom attached irrespective of the circumstances. once i've modified the airbox so that it flows sufficiently i'll start refining the tune with the bonnet down.

guys understand i'm just sharing my experiences - i'm not taking sides for either pods or stock boxes, it's up to individuals to decide what they need. in my case having seen what i've seen i'll be modifying the stock box.

cheers

Edited September 30, 2007 by Scooby

[rev210]

hi Rev 210, i agree but at this stage - not withstanding what Marcus has said - it appears that the stock airbox won't flow enough air for 268 rwkw with the bottom attached irrespective of the circumstances.

guys understand i'm just sharing my experiences - i'm not taking sides for either pods or stock boxes, it's up to individuals to decide what they need. in my case having seen what i've seen i'll be modifying the stock box.

cheers

Hi, just trying to point out that at speed the airbox gets air 'rammed' into the air box, they are designed to capture a positive pressure inside. They are also designed in this way with considerations similar to a plenum from memory, the volume of the air chamber in front of the panel filter. I think enlarging this volume might also be handy for larger power. Someone very clever may be able to explain this better.

With the baffle box off and the connecting pipe (elbow going into the baffle box) just turned around to face forward, my old GTR didn't have any problems making 276rwkw with the bonnet down. It made that power very easy.

I think it's great that you are out there giving the feedback of your tests, the more info we have the better. Top stuff mate

[Ronin 09]

Marcus you are getting 340 rwkw on a stock R32 GTR airbox, unmodified?

unmodified in that the openings are not messed with. I have a nismo element.

the ducts from under the headlight to the box are missing, as is the resonnator that is in the inner guard (needed space for oil cooler)

i.e there is no ducting at all to the box!

I want to put a feed up from the front bar to the bottom inlet

[GTRgeoff]

Andrew, I used one of the stock holes, but enlarged it a fair amount to allow the AFM to fit from underneath as well as have some tolerance for the hard split pipe it attaches to. I'll grab photos later.

I understand your thinking on the feed to the airbox however I have found that AFMs are significantly effected by water hitting them so I want to have free air traveling to the filter, but don't want a ram effect due to the water problem, especially on the racetrack so this is a straight out compromise for reliable power. If water in large enough particles or mass contacts the AFM it maxes out and cuts power significantly. I discovered this with the HKS pod directly in front of the tyre in the rain. There was enough spray to reduce my speed in a 110 zone down to 60kmh and struggling. So this way the filter gets heaps of air but there should be limited water to deal with, even from a car in front.

When we discuss Ram-Air effect in turbo cars we are really just nibbling the edges of the problem of air feed. It is more an issue of minimising negative boost or losses. In the GTR33 I'm only making 320rwkw @ 14psi and plan to lift to 18-20psi so the stock airbox in this case is sufficient for my street needs. Consider that a 3.0L engine such as in my track car at 7000rpm needs about 21000L of air per minute, but at 14 psi it now needs around twice that. So that is about 350L per second NA or about 700L per second forced induction. So we are looking at slightly smaller than a cubic metre of air every second which is almost half of the space under the bonnet. If we are lucky we might achieve about 6-10 inches of water of positive feed with a great ram effect. 10 inches of water is about .36psi so really bugger all. I'm just generalising the availability analysis right now. The turbo/s has/have a mighty job of dragging that air in so we do what we can to minimise the restrictions, but using rammed air from a stagnation point has both benefit and significant drawbacks. The fact is a turbo will pull the air in if restrictions are present, just not as well, but the ingestion problems in an AFM equipped car outweigh the benefits if there is a lot of foreign objects to be removed from the delivered charge or there is significant water suspension in the air. We can add direction changes and settling points, or if money and space are no problem then we can add cyclonic settling chambers or such, but most of us are on a hobby budget.

[sav man]

I'm thinking of putting a hole saw through the bottom of my R32 GTR airbox, running some flexi pipe to get cold air to it. What would that do to the airflow of the box?

I'm getting 311rwkw out of my stock airbox, and it's still got the funnel to the headlight, but no resonator. The inlet temps are abit high though

[Mike__]

Interesting topic and im GLAD i found it.

When i bought my 32 gtr it came with the same blitz stainless steel pods as your using scooby. My car runs ~12psi atm, has an aftermarket cat and 3.5" back & apparently had a retune. Ran 330rwhp on a dyno dynamics dyno @ 1.1bar with the previous owner and he gave me the sheets.

Upon inspection of hte filters i noticed what little filtration they offer, my intakes were covered in dust. Since the previous owner gave me the original airbox & a k&n to go in it i decided to swap over.

Results: no more hearing the turbo's spool up and a little compressor surge noise. Dead silent. Now my seat of the pants feeling. Im a believer in pods are more of a *wank wank* factor unless in high hp outputs, but i couldnt help but notice it felt slower. I coudlnt believe it so i gave it a lot of WOT and yeh, definetly slower. Felt slower getting on boost to. I drove the car the day be4 with the pods as kind of a back to back comparision.

Whats hte resonator everyone is talking about? i hooked up the snorkel from the airbox to below the headlight but removed that 'internal joiner' as it seemed a little restrictive.

I want to keep the k&n for its superior filtration (i added a little filter oil but not too much due to the afm's) but should i disconnect the stock feed to the airbox?

thanx

mike

[R31Nismoid]

Ok today ive seen testing results today... gt-ss's!

300-310rwkw R32 GTR with Airbox (32)/3" exhaust on PULP.

On the fuel, 340rwkw. Being the 3" was restricting too much, fuel sorted that problem.

So with a larger exhaust more power was possible on the stock airbox.

[Scooby]

hi mike, would like to see some dyno results with the airbox if you get the chance. 330rwhp is about what i was getting with the box but you might like to try doing what i did - remove the bottom half of the airbox and tape the filter in - to see if it improves things.

also...don't want to tell you how to suck eggs but make sure the afm elements are not getting oil on them, it will pay to check. the standard nissan paper element filters better and flows just as much.

the resonator is probably not there on your car, most have it removed. it's a box that originally sits behind the pass side vent in the front bar, roughly underneath the stock airbox location, and feeds air into the hole under the headlight. the duct going from the headlight hole to the airbox inlet should be OK in terms of flow capacity ie i don't think it will restrict flow to the airbox, but i haven't done any accurate measuring.

cheers

[zebra]

Cheers Geoff,

So I guess we allshould focus on leting the turbo breath as easily as possible with a smooth flow into the inlet rather than trying to get a ram effect happening for nealy nil efect.

Makes me wonder how much difference a decent inlet pipe would go on my car rather than the POS rubber pipe from factory, Anyone fitted Bass Junkys silicone inlet pipe and how does it go?

I was supposed to get one but couldnt get online due to work and missed the deadline.

Andrew

[Mike__]

Scooby: Was thinking bout removing the bottom half of the box prior to just checking this thread. I put minimal oil on, basically near nothing but the std filter sounds like a better idea. The k&n came with the airbox

Just checked, the resonator is still present and connected up. going to remove the duct from the airbox to disconnect the resonator effect and see what effect it has

thanx

[Mike__]

scooby: Removed the bottom 1/2 of the airbox as you suggested, but used some silicon to hold the air filter in. All i can is wow, shes back! Basically sounds/behaves exactly the same as with the pods. Maybe the induction noise was a tad louder with the pods but its back & so is a little compressor flutter .

Dyno results would have been very interesting to compare. My car was apparently retuned with the pods in place so i dont know if this is a typical result.

4got to add with the stock airbox/inlet setup running the k&n boost actually dropped. Only have the stock gauge in place and with constant checking the gauge dropped ~1.5mm from when i had the pods in, now with the modded box its climbed to the same level as with the pods. Also experienced a little lag with the stock setup, now it feels the same as with hte pods.

Least now the car feels the same as with hte pods with the added benefit of a little better filtration & a 'stock' look, but i'll be buying a stock paper filter in the future.

Every car i've owned and modded the induction ive only ever experienced differences in noise, kind of mind boggling how much of a difference its made.

[Lithium]

To dredge up an old post - this topic is something which has caught my interest after a bit of a dyno session I had with my car this weekend. I (stupidly) didn't think of popping the bonnet, but was a bit perplexed after I realised that despite tidying a few things up with my car I had actually lost a couple of kw instead of gaining - despite the boost curve looking better and the shape of the curve looking much nicer. Not to mention the car actually feeling better on the road than ever before....

I had 3 runs within the space of about 2 minutes, each successive run making about 2kw less on a car which is usually like clockwork. Air fuel ratios nice and safe, boost level consistant, and had just done a compression test finding all cylinders having healthy compression.

It only occured to me AFTER I got the car off the dyno that this is the first time I had ever dyno'd the car with the bonnet down since going to a bigger turbo etc, and for those who haven't seen the video - things get quite toasty under the bonnet of my car:

My car would be quite hard to do a cold airbox with, though I am a fan of that modication nonetheless. I hadn't bothered with it due to lack of motivation and the fact so many people don't run one and say "Thats what an intercooler is for" and the fact my engine bay is quite busy already but logic has it that the less the intercooler has to do, the better. I know with my old naturally aspirated Honda with much less power and underbonnet heat I made a 10kw @ wheels gain from changing from an unshielded pod filter to a nice cold air intake, so there are definitely applications for it.

Anyway, its over a year on from the last post on this thread - does anyone have any back to back comparisons of before and after such a modification... or should I document my expedition into doing this with before/after dynos etc?

This is the area I'd need to fit a box around

Cheers,

Dan.

[RBwhatever]

To dredge up an old post - this topic is something which has caught my interest after a bit of a dyno session I had with my car this weekend. I (stupidly) didn't think of popping the bonnet, but was a bit perplexed after I realised that despite tidying a few things up with my car I had actually lost a couple of kw instead of gaining - despite the boost curve looking better and the shape of the curve looking much nicer. Not to mention the car actually feeling better on the road than ever before....

I had 3 runs within the space of about 2 minutes, each successive run making about 2kw less on a car which is usually like clockwork. Air fuel ratios nice and safe, boost level consistant, and had just done a compression test finding all cylinders having healthy compression.

It only occured to me AFTER I got the car off the dyno that this is the first time I had ever dyno'd the car with the bonnet down since going to a bigger turbo etc, and for those who haven't seen the video - things get quite toasty under the bonnet of my car:

My car would be quite hard to do a cold airbox with, though I am a fan of that modication nonetheless. I hadn't bothered with it due to lack of motivation and the fact so many people don't run one and say "Thats what an intercooler is for" and the fact my engine bay is quite busy already but logic has it that the less the intercooler has to do, the better. I know with my old naturally aspirated Honda with much less power and underbonnet heat I made a 10kw @ wheels gain from changing from an unshielded pod filter to a nice cold air intake, so there are definitely applications for it.

Anyway, its over a year on from the last post on this thread - does anyone have any back to back comparisons of before and after such a modification... or should I document my expedition into doing this with before/after dynos etc?

This is the area I'd need to fit a box around

Cheers,

Dan.

This is what i did to mine.

I admit its not pretty but its was cheap to make and does the job just fine and keeps the pod nice and cold. I'd say you could probably do the same to yours if you not fussed about how well it looks.

And i used this for a CAI

Edited July 7, 2008 by KeyMaker

[Lithium]

That looks nice and tidy to be honest - could you tell any difference with it?

[abu]

Just had a play with this on the weekend

Standard air box on my HCR32 with HKS2535 + supporting mods on the dyno was making around 210rwkw on 16 - 17psi on the dyno

When we lifted the airbox lid about 1 cm, couldn't get it off completely because it was a tight fit and the tuner said we picked up 15nm of torque up top as well as 10rwkw

Running no sorta of CAI or duct setup, just standard airbox and intake pipe

[RBwhatever]

Well as you know you can feel a big difference between the performance of daytime and night time, so dropping the temperatures as much as you can can't be a bad thing.

I can't say whether i felt a difference because i finished it just as winter came on, and winter always makes the car fell better. I had the car retuned not long after and everything felt better after that. I'd say it would of had a contribution of some sort to making the car feel better after the tune. But one thing I do know is that the surface temperature of the pod has dropped a lot.