Auto Racing: High performance engines, high performance engines, exhaust gases

Question
Steve, how do headers increase horsepower? Thanks, KP

Answer
Ken-

  The idea with headers is to let the engine breathe better.  Since the tubing is usually less angular and not as restrictive as stock manifolds, it allows air to pass more freely out of the engine.  The ends of the headers, or the "collectors" also usually scavange gases better and increase the flow rate of exhaust gases.  While there are lots of different types of headers, it's always best to find one that fits your engine best.  If they're too big then your engine will lose backpressure which, while backpressure is usually a bad thing, is still necessary in small amounts to keep the engine running properly.  Of course, if they're too small you're obviously missing out on some power.  It's also important to upgrade your exhaust system from headers-back to really take full advantage of them.  Hope this helps.

Steve