Custom Cold_Air_Intake. Opinions?

[Andrei Rinea]

Reading many pages on cone filters, CAIs, hydrolocking, need for cold air, MAF killing by oily foam filters etc. etc. etc. I have come up with an ideea for a "CAI" :

Using stock airbox (paper filter is good enough since it is used on VR6 engines and filters finer) I would install a 5 inch plastic hose from the lower bumper grill to the airbox snorkel but not connect the snorkel with this hose. See picture below:

Why this setup:

1.Uses paper filter: better filtering (in terms of fine filtering)
2.Is hydrolock proof. Supposing a water splash onto the hose at high speed the water might be sucked into the hose but it will not go in the paper filter since the hose and snorkel are not connected
3.IT IS CHEAP
4.The cold air is driven very near to the snorkel (may ricochet from the wing) so there should be some efficiency to it.


Now there would be some problem to it... Andi TDI (also member here, on TDICLUB) told me that such improvizations might not be good since on heavy rains and/or splashes from other cars could somehow drive water near/on the paper filter (?can it in this setup?) causing it to get wet and possibly break... ouch..




QUESTION:

What do you think of this ideea of mine? Is it inefficient? Is it good? Is it worth it? Is it exposed to dangers?

 

[nicklockard]

What kind of car do you drive?

On my A4 Jetta, it comes from the factory with essentially a cold-air intake system engineered in: the cold air enters the system from just above the radiator grill (a natural high-pressure zone) turns right 90 degrees so that leaves/bugs/debris/water splash fall out of the airstream, goes through the 'snowscreen' which also filters out some of this larger debris, then goes to the paper element filter airbox.

All in all, it seems awfully hard to improve on the A4's air intake system. It accomplishes all of the goals of an expensive aftermarket well-designed system. It does not seem to offer much restriction to the intake. From what I've read, an intake pipe like the OMI is one good cost-effective way to clear up restriction (after the turbo: high pressure region of intake.)

Your design appears simple, elegant. It sounds like it would accomplish the goal of getting cold air to the intake, sans heavy leaves or bugs or debris. What kind of car is this for? Does it not have a well-designed factory intake like the A4 Jetta's?

 

[Andrei Rinea]

What kind of car do you drive?

I thought my signature was visible...

VW Passat B4 1.9 TDI engine 1Z 66kW.

B4 has a minimal CAI (or at least mine came with..) which I believe to be insufficient. Furthermore OMI (OldMan Intake) is unapplicable and unnecessary for B4s/A3s.
My "stock" CAI was made of a tiny 1 inch 90 degrees duct from the front plastic grille which points towards the snorkel. But there are 16 inch length of nothing between this plastic in the grille and snorkel.

 

[abctdi]

So 10 years old and of European usage. Could be different than released here is U.S.A.

 

[Ynot]

Andrei,

To use a term I found usfull here and spoken by KERMA a lot, is "don't know until you try it!" Let us know how it worked out. I use a vendor CAI right now, and it's intake sits in front of the drivers wheel well out of the engine compartment. I too am looking at how to use VW's basic design and trying to get a better cold air flow to it. I do not think in my 2K golf that the behind the headlight intake is optimum although the filter system is fine, and the OMI is just a link in the entire system. Let us know how you make out. An improved system will be the sum of all the parts that are matched correctly. Performance increases will qualify our improvements, other wise dynos talk, BS walks.

Ynot

 

[nicklockard]

Okay. I understand now. I'm not all that familiar with all the other variants and what the letters mean.

I think your system will improve things. Having the wing and not directly porting the intake to the snorkel will keep out bugs/debris/ etcetera.

Can you take a picture of the engine bay?

There might be an alternate way to just modify the stock system a little such that breathing is improved and bugs/debris/water don't get in there. All you really need is a 90 degree bend with an 'escape' for bugs/debris/water to fall out of the airstream--possibly two.


I think you'd be improving the breathing efficiency. Plus, it sounds pretty inexpensive.

 

[03_01_TDI]

I've done that set up with a 2 or 2.5" pipe I don't think a huge 5" pipe will fit.

 

[GotDiesel?]

You might be in for some additional intake noise with that setup. Don't know for sure.

To see if it's objectionable, you could remove the intake snorkel into the airbox before you run the pipe to bring colder air into the engine compartment.

It would be sad to do all the work and then decide you can't stand the sound of it.

Otherwise, it's an interesting bit of thinking.

 

[03_01_TDI]

I doubt sound would be an issue.

 

[Andrei Rinea]

I bought today a piece of aluminium 3.25 inch hose. It was 5$ so my project isn't too costful so far

I think it will fit. With a bit of effort I could fit 2 hoses there..
Now I will post some pics of the engine bay and of the hose.

 

[Ynot]

I've run my golf "snorkeless" as suggested by Upsolute and sound was not an issue. It was in a effort to cut down on my PP520 smoke issues with the Up II chip.

Unless you can "RAM" the cold air in, you will find that there will be quite a bit of dilution under the hood even with the wing in place. There are quite a few convection and air flow currents taking place while the car is in motion. Most high performance engines have the air intake coupled in some way to where the cold air is comming in.

Keep us updated.

Ynot

 

[Andrei Rinea]

Engine Bay pic 1

Engine bay pic 2

 

[Andrei Rinea]

Engine bay pic 3

Engine bay pic 4

 

[Andrei Rinea]

How the hose looks like (it was dark when I took the photo..)

And a last pic in the engine bay focusing on the snorkel

 

[Ynot]

I see where you are going with this now. If you can fix your intake at one of the openings shown in pic 4, looks like the lower valence there are there rectangle openings, and snake that bad boy up to the opening in your snorkle, or even in place of your snorkle, I would guess you would have some benifits of cooler air.

Ynot

 

[nicklockard]

I see. It makes sense. If you want the best source of cold air at the highest pressure gradient, couple your intake snorkel to the area where the windshield meets the bonnet (engine hood.)

This will give you:

1. Highest pressure.

2. Cold air.

3. Least likely to get bugs, as they tend to go up and over (or Splat!) the windshield. Also this is the best spot for minimizing leaves/debris entry, as it naturally has a sharp bend into your intake hose opening.

4. The shortest/straightest run of hose for minimal restriction.




This region has a higher pressure than the front of the car, because of the aerodynamic downforce effect from your angled windshield. Whenever cars are engineered with 'ram-air' intake, this is where they take the air from because of its high pressure and the other benefits.

All in all, this should be a nice, easy, cheap mod to do which will lower your IAT.


You can just route one end of the hose, directed at the snorkel opening (overlapping, but not taped or clamped together)... then route the other end to the high-pressure zone. You may have to cut a 15 cm section of that rubber gasket away, then just squash the hose into a flattened rectangle. It won't matter to the airlow, as the hose is oversized anyway and far superior to what you have now (which is sucking warm air.)

Angle the tip of the intake rectangle down sharply such that rain can't enter, and also put a 'rain escape' hole in the lowest point of the system. Finally, since your hose is overlapping, but not taped or clamped to the snorkel inlet, that is one last 'rain escape' making it nearly impossible to get water in the intake.

 

[Andrei Rinea]

First of all I must thank you all for your input !
It means very much to me. I feel I am not alone in this quest to improve the car, not only mine but the B4 in general. Probably the A3 too.

Now a few answers to propositions and ideeas formulated before this post:

a) I was advised NOT TO CONNECT THE SNORKEL (or the airbox itself) DIRECTLY TO THE COLD AIR INTAKE. At least not while I use the paper filter. Water splashes and/or water myst can wet the paper filter to the point that it will break and paper parts will go into the MAF, turbo and engine. That can cause extensive engine damage. I tend to believe this advice. Any PROs/CONs are welcome on this ideea. How about putting a foam panel filter in the stock airbox and routing the hose directly into the airbox? Water splash wouldn't be an issue since the filtering is gravitational (i.e.: the air is sucked from bottom to up in the airbox not allowing large volumes of water to pass it)

b) I cannot post the hose where the bonnet (the hood) meets the windshield because there is no space to do that except if I were to cut a large part of the bonnet, which I am *NOT* going to do. Ricey and rust prone.



SO, as a conclusion of this post, water ingestion and/or destroying the paper filter by water is my main fear in routing the hose directly to snorkel/airbox



I agree that dyno talks and BS walks but how the .. can I dyno an improvement since dynos are done statical.. i.e.: the car sits in place and air flow is not the same as in a highway run for example...

Any more input is even more welcome

thank you. I will keep you all posted and will make photos whenever applicable.

PS: It will snow very soon here were I live so maybe tests will be postponed but I will do all I can in the effort to improve intake for B4s/A3s

 

[nicklockard]

I'm only going to address the dyno issue and leave the other points for now:

Back in 1997 or so, Motorcycle magazine wanted to know just how effective 'ram-air' airbox designs were. So, they fitted a mobile dyno/computer to different ram and non-ram air bikes.


What they found was that ram-air only contributed measurably to peak power starting at around 135 mph. At that point, ram-air gave about a 3-5% boost, and at top speed (160 mph) it have 8-10% boost in peak power.

Conclusion: don't do this for the power gain (pretty much non-existant unless you go balls-to-the-wall on Autobahn every day. Do it to lower IAT

 

[gern_blanston]

Exatcly. In piston-powered airplanes, ram-air inlets add maybe an inch of manifold pressure at 150 knots. Also, you may also find that there's a stagnant, low-dynamic-pressure region around the junction of the windshield and hood. Some vehicles have a dead spot there.

 

[nicklockard]

Also, you may also find that there's a stagnant, low-dynamic-pressure region around the junction of the windshield and hood. Some vehicles have a dead spot there.

Good point.

Andrei,

You can check easily enough whether a region is high or low-pressured (in a rough, qualitative sort of way at least) by taping short (2 cm) tufts of light, bright-red yarn to different parts of the vehicle, then drive behind a friend and have him take pictures as you go different speeds--something like:

75 Kph.....moderate drag notable here.
85.........tansition from moderate to high drag
95.........high drag regime beyond here
105........where is smooth, where is turbulent, where lazy?
115........same
130........near cruising speeds (main regime of interest)
175........same


In low pressure regions, the yarn will flap about lazily; in turbulent regions, it will wag like crazy; in high-pressure, smooth (laminar) regions, it should lay relatively flat.

Gern can give a better description; this is just a rough idea...

 

[grimlock]

Andrei,

I'm considering this inexpensive mod for my B4 as well....

Although, from reading through this thread it may not be as beneficial as you would think.

I removed the snorkel and snowscreen, I'm gonna just pipe the "new" cold air near the area, but not directly into the airbox for obvious reasons. I also considered drilling several large (3/8") holes into the airbox closest to the fender, cheap & fast, and reversible with DUCT tape!

Slightly off the topic, but I'm also considering providing my air ventiliation for the intercooler, via the inner wheel well cover on the driver side -- as many have done with the TT vent plate.

Richard

 

[mojogoes]

I do not understand if the engine is sucking hard enough to make use of the cold air and a differance performance or other wise thats been fed by the pipe just because there is a gap does not mean it will not suck in any forms of particles.

 

[Ynot]

Andrei,

Pardon my sloppy dyno talk.

I did not mean anything personal. I should have said "Butt Dyno", where a Vag-Com is hooked up and you measure during a run, say 60 to 90. Other wise you are correct a fan blowing on the front of your car will not help unless the air flow increase at the intake was substantial compared to before the modification was done. (Relieved a restricted intake).

As far as particals and moisture are concerned, no offense, but the engine area of your car has quite a bit of road deposits on it as per your photos. Even up around your snorkel intake, so I would think that this would be of minor concern if you have not had problems yet. This does not mean it's OK to stick your intake down at road level. Mine is only 8" from the ground and I am uncomfortable with this myself. My filter is also at the intake point, not at the stock position. It is also a non-paper cone filter.

Alot of off road racers do put their air intakes up at the roof line to avoid deep water crossings, so I guess the ram air idea was something sold to us by US car makers during the Muscle car era.

Ynot

 

[Andrei Rinea]

No offense taken. I didn't consider important to clean the engine bay... I doubt that any of this dirt will get into intake since it is thin and well stuck to the surfaces.

I am considering removing the snorkel too and drilling a few holes in the front area of the airbox (maybe it will sound better too

) Yes moisture can pass 90 degrees bent gaps in the intake but not much, I think. How much dirt/water can pass 2 90 deg. bents? First bend would be when the hose starts from the lower bumper grille and goes up; that's the first bend.
I would also "drill" many holes in the bend so there would escape solid/liquid things.

The second bend would be when the hose finishes near the snorkel. The snorkel would be off and the hose end would be perpendicular on the airbox entering hole. I dunno how clear that was but I can draw a picture if you want. I wanted to install it today but I didn't have the time for it so maybe in the weekend I will install and take pictures of it.

I'll keep ya posted !

 

[nicklockard]

Andrei,

You're thinking process is clear and good.

The 90 degree bends are quite effective at removing water. 180 degree bends are better. Both cases work more effectively if there is an 'escape hole' for the debris or water to fall out of the airstream.

Story: I was stationed on a nuclear submarine (USS Ohio (G)) in the US Navy for a few years. On board, we had a 13.5 MW Fairbanks-Morse twin-opposed, 12-cylinder supercharged diesel as our primary power back-up, should the reactor plant fail or be offline...


We were able to operate the diesel while submerged just below the surface (periscope depth) by extending a snorkel tube a few feet above the surface. It tended to get a lot of splashed seawater in the snorkel induction unless the seas were perfectly calm (not often!) In that induction pathway was an induction ' sump' where the incoming airstream took a sharp 180 degree bend (exactly like: U)followed by a smoother one upside down.

It had a 5 inch window to keep watch on the water level. Whenever we ran the diesel, we posted a 'sump operator' watch who had to open and close the main induction valve with a hand-pumped hydraulics and keep watch on the water level. We ran that diesel in rough seas, ingesting 50 gallons at a splash, and never stalled the diesel. All of the water falls out of the airstream and is then drained by gravity through an 'escape hole.'

 

[Andrei Rinea]

Here's experimental installation pics:
(design & beauty aspects suck, I know..)

Front part:

Notice a "small" alu hose in the lower grille?

Engine bay pic:

Since it's been rather cold here (-5 deg. Celsius / 23 deg. Fahrenheit) I could not make a thorough assesment of this project. I'll leave it on for the winter and see if there are any benefits in the summer.

 

[03_01_TDI]

I had a setup like the one in the pic on a 96 cavalier. It was a nice straight shot from the front bumper to the bottom of the air box. It worked so good that it would jam bugs into the airfilter. I never had a problem with water. I can recall a 4 day pass weekend from NC to GA it was raining so bad and I was driving too fast that I missed my exit(couldn't see the signs) and wound up in SC. My point is that water was not an issue.

 

[Andrei Rinea]

But was directly ported into the airbox? Or it was just "pointing" at the snorkel like mine does?

 

[03_01_TDI]

directly to it. with tape to ensure no air leaks. I swear it made that little car get better MPG's when driven hard.

 

[Andrei Rinea]

But still that was a gasser and these seem to benefit more from CAIs than TDIs. In other words I just have a useless hose in my engine bay which (thank God) cannot hydrolock engine/destroy paper filter.
Thanks. I suppose I will leave it there IF it doesn't annoy me when I need to change the airfilter element.