3in intake mod concerns [Archive] - SaabCentral Forums

: 3in intake mod concerns


lowbudgethero
18th February 2007, 10:14 AM
well i was bored so i decided to try it out and in the end i ended up with a 3" pipe that was too big to be put in the air box so i had to butt it against the airbox with epoxy, this makes me worried about it just braking off from bumps and vibrations.... should i just rip it off and get another pipe, and worry about having made a too big of a hole?

redrum
18th February 2007, 11:24 AM
It should be fine if you prepped the surfaces well for the epoxy. Even if it ends up breaking off it wouldnt do any damage. You could just re-do it then.

lowbudgethero
18th February 2007, 01:13 PM
my worries got the best of me, i decided to use flexible aluminum tubing instead

hunt.dogshome
18th February 2007, 02:02 PM
I guess you jammed it over the existing spigot? Plastic drainpipe also works well like that :cool:

Old Goat
18th February 2007, 03:25 PM
When I did this I used PVC ID 3". It was a little too big so I cut the sides a little, then I "welded" it together with a soldering iron. Everything sprayed with flat black paint. I also put an end joiner on it to give it a wide bell shape. The weld is pretty strong, I tested it by twisting and pulling, it didn't budge.

SPATL
19th February 2007, 09:19 AM
When I did this I used PVC ID 3". It was a little too big so I cut the sides a little, then I "welded" it together with a soldering iron. Everything sprayed with flat black paint. I also put an end joiner on it to give it a wide bell shape. The weld is pretty strong, I tested it by twisting and pulling, it didn't budge.

The reason that it didn't fit is that you probably tried to use schedule 40 pvc which has too largeof a OD. Thin walled pvc is the correct stuff to use. I have only found this stuff at Lowes. Home Depot does not carry it.

I would worry about it breaking off being that it is pre-filter, but if you want to do it right, get the thin walled pvc.

lowbudgethero
19th February 2007, 09:43 AM
i highly recommend getting flexible aluminum tubing after my little mishap ;oops: you can shape it, elongate it, and it's really easy to fit ill get a picture up later

SPATL
20th February 2007, 09:11 AM
It is probably a negligable difference but something to consider...

The aluminum will be corrugated whereas the 3" pvc tube is smooth. Air travels better in smooth tubes than rigid tubes. The bell on the end of the tube is an important, often overlooked part of the tube.

I will explain further...

Here was my initial attempt at the 3" duct. I added a 4" to 3" bell on the end...
http://im1.shutterfly.com/procserv/47b3d722b3127cce9bffd48d301200000026109AYtWTNy1aw
After installing this, I noticed a lot more intake noise, almost turbulent so I cut the 4" section of the tube off and sanded the inside to make a smoother transition...see pic below:
http://im1.shutterfly.com/procserv/47b4df24b3127cce9bffd57653da00000016109AYtWTNy1aw

After this minor change, I noticed less noise(still more than the stock tube, but then again the 3" tube does not extend through the airbox as far as the stock tube.)

Noisy air is more turbulent and doesn't flow as well.

If you do use the aluminum, make sure you create a bell simialr to the stock bell.

Like I said above, the difference might be minimal to nothing gained but something to consider.
You can also see in the first pic the gasket I made at the airbox to seal the tube well. This pic will show how far I was able to get the net tube up inside of the airbox.
http://im1.shutterfly.com/procserv/47b4dd22b3127cce9bffd57799e700000016109AYtWTNy1aw

Just some food for thought as you make yours.
Hope this helps.

hunt.dogshome
20th February 2007, 01:52 PM
Pic no#1 looks like a seagull swallowing a herring :cheesy:

G96nt
21st February 2007, 09:13 AM
I went to my local exhaust shop, and had them cut me an 11" piece of 3" exhaust tubing, and flare one end out as much as he could. cost me $5.

when I got home, I did what everyone else does and made the box, but on the inside, I cut out about a 3"x2" run of the pipe along the top to help direct the air directly out the pipe and up into the filter. the pipe still has a bottom, and makes it less likely to pull up water and stuff.

I ultra-blacked the pipe into the box, and flat-blacked the pipe so it looks "stock".


seems to be working well-enough, these days.
:cheesy:

lowbudgethero
21st February 2007, 01:00 PM
i dont really notice a lot of noise increase, also in some race applications turbulence is actually created by the intake, the aluminum worked for me :)

http://www.youtube.com/watch?v=8k1lyinPo1k

^it doesnt even seem loud at full throttle

Marks900SE
22nd February 2007, 03:22 PM
I had 3" ID PVC pipe laying around when I did the same mod. The OD, like yours, ended up being too big so I just thinned it up to fit in. Its now been on the car for close to 3 years and havent had a problem.

the part that goes into the airbox is thinned like the top. Just make sure you flare the end to smooth the air otherwise the turbulence will probably negate the effects of a bigger intake.

http://memimage.cardomain.net/member_images/2/web/458000-458999/458565_23_full.jpg