B6 Guard venting (SMIC airflow improvement)

[cpitts]

Well, as we all know, the poor little SMIC setup in most Audi's doesn't let a lot of air flow THROUGH the IC, and here's my attempt to show why that's the case and how to address it (somewhat).

So here's what I did:

Start with a slightly dirty A4 1.8TQ (or your favourite turbo Audi). Put a couple of wooden blocks around the rear wheel on the opposite side to what you're working on and jack up the front wheel where the SMIC is (passenger side on mine).

http://img138.imageshack.us/img138/757/img7825s.jpg

Then remove the wheel and put an axle stand under there for extra safety:

http://img85.imageshack.us/img85/4122/img7826s.jpg

Pull out all the screws (beware of the one on the bottom, outside, near the edge of the bumper, it's a 1/4 turn anticlockwise to unlock, otherwise, you'll snap the plastic nut that it locks into......... like I did :roll: ). All the screws are Torx T25 bits which are real easy to work with.

Once you've undone ALL the screws, the guard liner will simply pull out. It doesn't take too much wiggling to set it free. And be aware that it will be FILTHY! It's hard to believe the amount of dirt on and around it. It shows just how uncontrolled airflow is from the front of the car!

http://img138.imageshack.us/img138/4788/img7830s.jpg

Now that the liner's off, you can see just why the SMIC is such a cr@p setup for airflow:

http://img685.imageshack.us/img685/1376/img7833s.jpg

How can you think that putting the washer bottle behind the intercooler is going to assist with getting heat away from it?? :beat:

[cpitts]

ANYWAY, so from the picture above, you can see the silver SMIC in the background behind the washer bottle. There's a rectangle on the bumper side that could be used for ducting, as is a gap under the washer bottle and a small triangle to the right of the washer bottle (which is the only area with line of sight airflow to the IC itself!! OH for a better washer bottle design!!!

So, you take your guard off and take to it with a Stanley knife. I decided to use the 3 airflow areas as well as I could so I cut out a full triangle for the best airflow area and marked up vents for the other 2 off-side areas to allow for pressure relief and heat removal.

http://img41.imageshack.us/img41/9657/img7835s.jpg

The vents are just lines with about 1cm edges cut in it and then bent up with a set of flat nose pliers. The plastic is so hard it keeps it's shape once bent! :-)

One thing I didn't get a pic of is a sheet of adhesive foam (~10mm thick) I put on the metal beam beside the water bottle (on the wheel arch side) to seal the air and force it out the air holes rather than around the rest of the wheel arch.

Then fit the liner back to the car and it now looks like this:

http://img20.imageshack.us/img20/8035/img7838s.jpg

As you can see, the holes line up with the appropriate gaps and the job's complete.

Took the car for a test drive on a 29' NIGHT (39' day) and the power delivery was VERY consistent. Certainly a lot better than I expected. Car also seemed to want to pull more consitently to higher revs and the turbo seemed to be more consistently audible, so it was most likely boosting more consistently (hence the extra whistling).

Even parked the car for a bit to let it heat soak and it didn't seem to be any different upon takeoff! So either it's always crap or consistently able to remove heat better.

Happy to field questions on this so fire away.

To add to this, I've updated my personal blog/website with this the content of this thread and some additional discussion/explanation of the physics behind the changes, etc.
Click here to have a more detailed read: http://www.corptech.no-ip.org/doodads/htdocs/cars/MY05A4_mod_SMIC_vent.asp

CP

[kermac]

Good write-up, CP! I put in an S4 wheel liner on my b5 early in the piece - have never found out whether it makes any difference, but Audi must have felt it improved things on the S4/RS4, so by extension it ought to work in a turbo A4.

It's perhaps not such a difficult mod to do back-to-back comparisons on - if you were logging Intake Air Temps, you could tape over the slits, do a couple of runs, then whip off the tape and do a couple more?

[cpitts]

That's the plan. I can slide in a backing plate behind the liner and do the tests then pull it off and re-do the logs. I've had an offer for a VAGCOM so in the new year some time, I'll give it a go.

As stated above though, the idea here is not to increase power, just to make it's delivery more consistent in hot and cold temps. If you can make the guide sufficiently better to get the air away and keep the overall temps down during the rev range then you'll create higher power levels in your power curve which will feel like more power overall, but in reality, it's just fattening up the torque curve in different parts of the rev range. You're not going to increase your peake power output, just make that power level across a wider band.

The nett effect is you get more of the peak power and torque across the rev range. . . . if that makes sense. . . . . . . kind of why I like to do these little tests on a dyno, you can actually see the change in how the power is delivered.

[Rock]

ood write up. i did the same thing a few months ago , i already posted the pics on another thread but just in case you missed it....
http://photos-e.ak.fbcdn.net/hphotos-ak-snc3/hs211.snc3/21836_222271486555_606111555_3534350_7272040_n.jpg

http://photos-c.ak.fbcdn.net/hphotos-ak-snc3/hs211.snc3/21836_222271496555_606111555_3534351_3342508_n.jpg

[cpitts]

I would have gone down that path Rock if the water bottle wasn't in the way (B6 is different to the B5). In fact, I would have just cut a huge square out of the liner and put in wire fly screen mesh and squared off the edge with a frame and pop rivets.

[Rock]

I would have gone down that path Rock if the water bottle wasn't in the way (B6 is different to the B5). In fact, I would have just cut a huge square out of the liner and put in wire fly screen mesh and squared off the edge with a frame and pop rivets.
yeah i suppose im lucky, my water bottle doesnt sit as low as the b6 does, so it was easier to fit, i just did it this way to prevent dust and mud splashing back into the engine bay and to make it look as stock as possible. i was actually thinking about doing the same to the airbox, but decided against it.

[cpitts]

To add to this thread, I've updated my personal blog/website with this the content of this thread and some additional discussion/explanation of the physics behind the changes, etc.
Click here to have a more detailed read: http://www.corptech.no-ip.org/doodad..._SMIC_vent.asp (http://www.corptech.no-ip.org/doodads/htdocs/cars/MY05A4_mod_SMIC_vent.asp)

Also have some other info in there about silicon intake pipe work that's been performed and will also be performed in the coming months.