I was down at the shop this weekend doing some cleaning and happened upon a box from Nebraska. Inside was a couple pistons I have abused over the years with nitrous.
Pic 1:
Piston on the left was my first kill. Piston on the right was #2. Both renditions of the motor had been 12.00@108+.
Both failures were caused by a tune-up that was fuel rich. It is a popular misconception that fuel rich will not hurt anything. That is only partially true. Too much fuel will collect in the top ring land and when it ignites it will push the top of the land up. This is one area where forged pistons do make a little difference. Forged will take longer for the piece to break off, but it will break off eventually. These pistons are the KB hyper 2.2 turbo slugs. Cast and hyper pistons will break the land off faster than a forged will. Make no mistake, even a forged piston with the land pushed up is junk.
Closer view of the land broken off.
Piston #1 also had this damage from making a pass with the nitrous on after breaking the land off. Piston #2 did not have this because it broke after I crossed the finish line and was coasting. Yes, the damage occurred AFTER the throttle was closed. That is a mark of a way fuel rich tune-up.
Piston #1 again. Myth: Nitrous will cause hyper pistons to shatter. No, but they will split in half if you spray a damaged piston. Mike found this when he took the rings off. Piston fell apart off the wrist pin.
There is a groove burnt in where the spray was on after the initial damage. Nitrous will act like an acetylene torch if given a chance.
Final myth: Forged pistons will hold up better than cast of hyper. Maybe, IF you are breaking stuff from sheer horsepower overload, but forged pistons will not hold up to a poor tune-up any better than cast or hyper.
When nitrous (or any boost) is good, it's great. When it's bad, it's real bad in a hurry.
