Ask the Editors: Do Twisty Pipes Rob Power?
Wouldn’t flipping the cylinder around and running a straight pipe be best?
This is actually a very good question with an answer that can get complicated. We’ll try and break it down to keep it nice and manageable. You aren’t incorrect in assuming too much exhaust restriction can rob an engine of power in the same (but opposite) way that too restrictive an air intake can. So then the ultimate performance boost would be running straight pipes or better still no exhaust at all? Not quite.
The reason taking off your pipe isn’t an automatic performance boost is that back pressure plays an important role in tuning the performance of an engine as well. The expansion chamber portion of an exhaust pipe is literally catching and containing a combination of exhaust gas, sound and pressure. As crazy as it seems, sound waves can actually disrupt an engine’s ability to time properly – this is especially true with 2-strokes where an expansion chamber is literally crucial.
A good performance pipe maker will test countless bend configurations to determine which offers the best combination of performance while achieving sound output goals.
Also do keep in mind that our ATVs have an additional factor to consider – very limited space. There are certainly instances where a good length of straight flowing pipe would offer a boost in performance but the realities of properly routing it around the machine’s frame spars, air box and plastic make that impossible.
