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The smaller the diameter pipe the higher the velocity of air in the pipe (assuming that the charging pressure remains constant) Likewise as you increase the dimaeter of the pipe the flow velocity will reduce. It is a bit like connecting a small hose to a water tap as opposed to a large hose. The small hose will squirt the water much further while the large hose will have the water dribbling out at the same pressure.
The problem with lower velocities in turbo engines is that with large diameter pipes the velocity becomes so slow that lag becomes apparent. Large diamter pipes also increase the tendancy of the engine to be laggy because the turbo has a larger volume of air to compress. To take it to extremes imagine haveing a turbo blowing into a sealed room (intercooler) with a small exit at the other end(outlet). Air will not flow out the other end of the room untill a few seconds after the turbo blows the air in. Where as if you use a small diameter pipe instead, the boost is almost instananeously transmitted to the other end (= less lag). But there is only so much air you can force through a small pipe at a given pressure, thus lowere efficency.
Hence larger pipes are not always better, but as with everything in cars the dimater you choose to use will always be a comprimise.
ie use a small pipe for maximum responsiveness, but lower efficeincy. Use a larger pipe for higher efficiency but lower responsiveness. The same is true for exhaust systems but it is even more complicated.
Hope this helps
, Fri, 1 Dec 2000 12:09:51
, Fri, 1 Dec 2000 01:05:19, Fri, 1 Dec 2000 14:50:53, Sun, 3 Dec 2000 22:55:01, Sat, 2 Dec 2000 15:29:14
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