here what
www.n2o.org got to say
"Will nitrous hurt my engine?
First, realize that nitrous oxide does not damage parts. Detonation and extreme lean conditions are what cause parts to fail while nitrous is being used.
Second, start with a sound engine. If you have bad rings or valve seats and are already experiencing detonation, no matter how minor, then you will most certainly find yourself buying some new engine parts down the road because of the damage which may occur when you use your nitrous kit.
Third, check the engine to make sure that it is remaining healthy while the nitrous is flowing. Checking the plugs after nitrous passes is a good idea for all power levels. If you notice that part of the electrode is partially missing or complete gone then you need to check your combination and correct whatever problem exists. Also look for Dis-coloration and aluminum deposits (or ``purple boogers'' as they are more frequently called in racing circles).
As with any other performance enhancing product, damage may occur. The most common part failures when using nitrous oxide are broken ring lands and ``windowed pistons'' (those with holes in them), and the possibility of a backfire through the intake. Follow the basic rules and your engine happily coexist with your nitrous system."