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Re: AIR BOXing
Let me clarify my position on the air box mods. And also. let me state
for the recored, that i have not done very many mods on audis, i only
repair them. The art of 'tuning' something is two fold. #1 tuning is done
to a certain item to provide the best service to other items with the
intent of making the engine more efficient. #2 Actual tuning of the
intake manifold and exhaust manifold requires the use of a flowbench in
order to ensure that each runner is flowing the exact CFM. The manifolds
are what really should be called 'tuned'.
Allow me to take a point in your post. I dont know for sure why Audi did
what they did inside the airboxes. First, All F.I. rabbits and Sciroccos
of the early years had horns, or at least directional scoops. Many times,
these were taken off due to being to restrictive. And yes, the early CIS
is antiquated even though they are used very late. The mechanicals of the
system, with out the benefit of electricity, although very reliable, are
frowned upon by EPA.
I dont mean to come across as wanting an argument, I just want to bring
up some ideas. I have spoken to factory reps and other people in the
automotive repair business including racers, and although a racer
himself, I don't normally give up allot of my secrets.
Scott, perhaps the fins inside of the airbox are for structural strength.
OK, I'm sure to some extent, perhaps the airbox is 'tuned'. Audi wouldnt
just make a box for the filter and leave it at that. With the interest of
low noise and good cold weather starting, they had to design it with the
known features such as a warm air valve. Again, I haven't done it on my
audi yet, but on older VW, a few extra holes in the right places didnt hurt.
One last thing on your comment about tuned exhaust. You are right, the
cat and muffs. are similar to an airfilter in the fact that "how can you
tune through ...." It the purest form of the word 'tuned'. After the
cat, the exhaust is not tuned. Even though manufacturers say they are,
they are not tuned in the way the word was originally designed. An
exhaust manifold, or better yet, and exhaust header is tuned by ensureing
no only equal flow per runner, but also for pulse direction/resonance,
which is probably more important than flow. 95% of the exhaust tuning is
done in the header. After that, one can aid the tuning by ensuring the
exhaust diameter is not too larger or small, that the bends are smooth
and not kinked (mandrel bent) and that the mufflers are not too
restrictive. Backpressure is possibly the biggest concern here, as it
can be affected by mufflers, small pipe and lots of bends
Yes, essentially everything before the air filter and after the cat is
tuned to an extent, just not in the true sense of the word and also not
in the greatest of precentage of the overall picture.