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View Full Version : Yet Another Airflow, Induction Thread



Erni902
11-06-2013, 05:47 PM
Yes guys I do apologise for bringing up this subject once again but please hear me out.

Now I have done some searching and spent many hours reading the threads on here about peoples ideas etc. The majority of these however are based on moving the standard airbox or removing the standard snorkel and re-routing the airflow.

The idea I have is different. The standard box, snorkel and Ralliart panel filter are all staying exactly where they are. This is seen to be the favoured and most beneficial setup due to air temp/pressures etc. and I get that.

The idea I have is this: rather than 'reroute' the airflow I simply want to ADD to the airflow. I want to do this by cutting a hole in the bottom of either the airbox or the snorkel (one of my questions). I will then want to route this with suitable ducting to the bumper where my fogs used to be.

First off by doing this will there be enough of a positive pressure from this position to make any sort of difference?

Then, how would I be best in getting this air into the intake? Can I feed it into the bottom of the airbox (before the filter obviously) or would it better to feed it into the bottom of the snorkel?

Now I understand the snorkel is the shape it is for a reason and that is to straighten the air etc. If I was to place the feed into the box (between the snorkel and filter) would this then undo the work of the snorkel as it would be entering the box at a 90 degree angle to it or would this be fine?

Similarly, if I was to cut the bottom of the snorkel and feed it here would it interrupt the airflow to so much of an extent that it would be detrimental and work against the snorkel?

Now I know noone has done any proper testing with different airflow routes/intake systems etc. but I am after the brains amongst you guys to try and best inform me of even the slightest theory behind what I am trying to achieve.

I believe 1 or 2 people may have put the car on a dyno with standard box and then straight back on with a cone/shroom etc and looked at the power differences but this has not been well documented. Not only that, I don't believe they have actually tested the air. I have wanted to do this for sometime under the bonnet to then design my own bonnet with vents that actually serve a purpose rather than just looking good, however this hasnt really been a priority. However, with me now getting toward the track side of things I really want to optimise airflow/temps etc as best I can so this may happen sometime soon.

I know we are all threaders with countless debates on airflow, induction etc so please if you can try and stay on topic and help with the questions I have posed we will all benefit.

Also if you are just going to post 'keep the stock setup' with no reasoning/theory/backup then please refrain from posting. I don't mind these comments in the slightest if they are backed up with knowledge and reasoning etc. Please try and be helpful with your posts guys I am trying to learn here :) lol

Nick Mann
11-06-2013, 06:55 PM
My understanding is that the airflow through the maf is the important thing. Keeping the stock panel filter ensures the flow is linear. Therefore from my point of view, any additional air prior to the panel filter can only be good.

Erni902
11-06-2013, 07:39 PM
Cheers for the reply Nick, I had the same impression until I read one comment (can't remember who by) on another thread (can't remember which one lol) that mentioned that the specific size and shape of the oval played a huge part. My thinking is, though if I still have that in place and am only adding more positive pressure then it shouldn't have any real detrimental effect.

I suppose if I twin the new feed with a suitably placed letterbox hole with a small scoop on the bonnet to direct air into the snorkel also then this will provide more direct air into the snorkel at a possibly higher pressure which can only be good right?? lol

Need to do a bit more research on airflow characteristics myself but with all the new telecomms info my brain is taking in at the moment it might have to wait lol.

bakerboy-2007
11-06-2013, 07:44 PM
I looked into this loads with my first leggie (now yours pal) in the end I went with a blitz sus with a heat shield, I did this without collecting any data !!

The thing is on the club loads of threads discussing this mod but no solid data to back up any comments ?

The only way to move forward is to dyno now to get a base read, then fit a cone, then try the modification the only thing issue I see is resetting the ecu each time pal

Erni902
11-06-2013, 08:25 PM
Hi mate, yeah I did think about the dyno test but this can get expensive when testing and adjusting for the optimum airflow pressure/temp. What I plan to do is utilise a quiet day at Santa Pod and take some readings from inside the engine bay at various points (obviously the airbox too). I will then analyse the readings and determine whether more/less, positive/negative pressure has been produced with the various mods.

The readings from various other points in the engine bay will hopefully help me to determine (with the aid of some good mathematics) precisely where to place bonnet vents and how big they should be along with angles etc. I hope to be able to efficiently remove the hot air from the rear of the engine bay thus increasing cooling and in turn timing. To do this I will need to analyse where the spots of negative pressure are and manipulate as much as I can to cool the bugger down, but thats a project for after the intake lol.

SGHOM
11-06-2013, 09:06 PM
Henry ;)

Erni902
11-06-2013, 10:11 PM
Henry ;)

Have you been drinking again?? ;) the word association thread is in the Random Pictures/Videos/Jokes (http://www.clubvr4.com/forum/showthread.php?57269-Word-Association-Continue) section.

Although, I could use a Henry as a co-pilot like in Star Wars with R2D2 :)

SGHOM
11-06-2013, 10:18 PM
Have you been drinking again?? ;) the word association thread is in the Random Pictures/Videos/Jokes (http://www.clubvr4.com/forum/showthread.php?57269-Word-Association-Continue) section.

Although, I could use a Henry as a co-pilot like in Star Wars with R2D2 :)

not at all !!

I drilled the bottom of my snorkel & fitted 2 lengths of 'henry' vacuum hose down to the front grill ;)

worked for me



edit:

http://www.clubvr4.com/forum/showthread.php?4600-I-need-more-cold-air-!!&highlight=need+more+air%3F

Erni902
11-06-2013, 10:31 PM
Aha innovative ;) but didnt that put the missus out of a job? lol

wintertidenz
12-06-2013, 09:50 AM
The N/A snorkels have a resonance box hanging off the bottom of them. You should be fine cutting into the snorkel.

I'd also run a 2-2.5" pipe into the bottom of the airbox for the extra flow and put it somewhere it'll get some good flow.

jjayokocha
12-06-2013, 10:51 AM
I just did as said above, cut an old Hoover hose in 2, drilled 2 holes into the bottom of the snorkel and feed them down to the bottom grille on bumper

Erni902
12-06-2013, 01:53 PM
Cheers for the responses/links guys, they do make for interesting reading especially Derek's thread, I seemed to miss this one! Been looking at some Ramair ducting so may buy a few lengths and a spare air box and have a play around. Think I will start by feeding the air into the snorkel then swap for just a feed into the box, then both together, get some readings and see what the sketch it. May be some time before I get proper scientific results due to other commitments but I shall strive to do this as soon and possible so we can wrap the subject up somewhat.

exevoowner
12-06-2013, 02:10 PM
From what i under stand the more cold air the better with a lot of aftermarket filters there foam which after time break up so a standard panel with cold air feeds is the way forward

Confused
12-06-2013, 02:40 PM
Once you get on boost, any real ram-air effect is lost - providing the feed is cool air and flows enough (hence the position of the snorkel at the very front of the car, behind the grill and under the bonnet)

Chris.W
12-06-2013, 08:22 PM
As stated, the colder the air getting in, the denser it is and hence the bigger bang. This is why without heat shields and ducted air flow pod/cone/mushroom filters have little effect other to increase induction noise as they are sucking up all the hot air from the engine bay.

A vented bonnet will reduce temp in the bay. I recently fitted one and the heat haze coming from the vent when stopped in traffic is large. If you were going to use a vent as a ducted path for your filter then a Naca style one would probably be ideal. Yes there are big overbearing sticky up scoop types as favoured by the scoobys and such but there is a reason motorsports teams and aircraft manufacturers use the Naca style ones.

Another way for you to reduce engine bay temp would be to get hold of/make a bonnet lifter kit, this attaches at the hinge points and raises the rear of the bonnet a few mill (dependant on spec) and allows air flowing in to the bay from the front of the car to have a second escape path (as opposed to just flowing out the bottom). The fluid flow of air over the bonnet and up the windscreen will also help to draw the hot air out. The down side of this is that your bonnet looks like it hasn't been fitted properly.

It will be interesting to see which way you go with this. My car is about to have 2 filters fitted on hard pipe with heat shielding and ducting (eventualy) where the battery used to live, so that each tub has its own air supply.

Kenneth
12-06-2013, 09:27 PM
I am not sure if you mean specifically on a VR-4 or generally.

If you could get ram-air, then you actually get more from a turbo. Because a turbo is a pressure multiplication device, any positive pressure at the turbo inlet is multiplied by your pressure ratio. If you had 0 (or atmospheric) pressure at the turbo entrance and 2:1 pressure ratio, you would have 14.5 PSI of boost. With 1 PSI of ram air at the same pressure ratio, you would end up with 16.5 PSI of boost with the same turbo speed. On our engines each PSI of boost is worth about 10kW at the wheels, net gain is 20kW at the wheels (roughly 26hp). Just from 1 PSI of ram air.

As such, ram air is highly desirable, although, at least in the VR-4s case, impracticable without some fairly serious work. It is still definitely worth while removing bottle necks in the intake pre-turbo, since any pressure drop is also multiplied.


Once you get on boost, any real ram-air effect is lost - providing the feed is cool air and flows enough (hence the position of the snorkel at the very front of the car, behind the grill and under the bonnet)

mattnz
12-06-2013, 11:21 PM
How about just cutting a vent at the bottom of the bumper where the snorkel gets it's air from currently? That's the route I am considering taking, and seems a bit more simple.

fassi1
12-06-2013, 11:25 PM
How about custom smooth air intake airbox-turbos?

exevoowner
13-06-2013, 07:38 AM
I was looking atsmoothing air flow into air box and also after to tubos

mike74
13-06-2013, 01:07 PM
i just attacked the upper front of the snorkel with a hacksaw as it looked like it had collapsed, ie cut a rectangular slot out of the top of it. definitely sounded meatier afterwards & could've been a placebo but, felt a bit perkier too. PLUS it was free :D

lateshow
18-06-2013, 07:42 PM
Using map sensor instead of maf would be a good idea. We have seen results that power and torque curves rise throughout the area(evo 5-9) . This is due to - as said - less resistance. So yes maf and standard filter will have certain max flow but this isn't the issue here. Actually you get always little more power (and peak power too) when you remove a part that restricts. Our cars have a very complex piping and many restricting parts but that is always an issue with twin turbo setups. Then with maf gone a very big cone type air filter is always the best. Hopefully someday a map mod will be there for vr4 too. It is very good with evos.