Let’s Get Technical with Powerzone by Sirazul Izlam
Extractors – Size matters?


In the previous issue we’ve discussed about the importance of choosing the ‘right’ length extractor and some tips about the how the finishing of an extractor should be as it does affect its flow capability.

Now we continue with the pipe internal diameter, which is also very important. Most of us think that the bigger it is the better because there is less “back pressure.” However, gas flow dynamics does not simply follow this logic.

Remember, we have to induce siphoning, to create a self-extracting effect. So, what size or diameter is correct? This, again, should be calculated from formula. As a rough guide, for engines of less than 1.6 liters capacity, the diameter is around 1.5 inches for the primaries, and 1.75 inches for ....

(Get the full story in Extremekars September 2007 issue)