I am afraid I will have to agree to disagree on that.
Boost is a major player in damaged pistons. The more boost you run in a car, the more heat it generates. The more heat that is made, the hotter a piston gets and the closer it gets to melting point. This goes for exhaust valves and turbine blades too. If turbine wheels get too hot, they can get to the point of disintergrating. Hence the reason why people are using inconel shafts. They are much lighter and tolerate more heat. Even when you dump fuel into a cast piston motor, you are just delaying the inevitable.
How does WRXHOON have melted pistons from detonation???
Ok, if latent heat was not a problem, why would people change to forged pistons?
Detonation is something you can easliy aviod with reduced ignition timming or water injection to name a few. They run the forged pistons so they can run MORE boost on pistons that are designed to take MORE heat as the melting point is much higher.
You don't hear of people saying "ohh, yeah I have decided on putting forgies in my car because it detonates" as he would kindly get flamed on any forum/pub/track/auto salon? well maybe not the last one...they would be a "ohh and ahh" coming from teh audiance
I have been playing around with forged pistons with a mate of mine for about 2 weeks. We had a set of pistons that his customer distroyed and decided to play experiment with them. These were not the factory forged pistons in an RB26 (already done that one) , these were ROSS forged pistons.
We (well, I did anyway) put one in the press, smashed one around with a hammer and put one in the lath to see how it machined up. I cant think of anything to do with the last one... On that note, you would be surprised how much load a gudgeon pin will take before it is deemed useless.
Brittle can be taken in a few ways on a forged piston. Run lean mixtures and death spiral the engine and they will be "brittle" in a sence and almost flake away instead of melt. Death spiral only happens on race engines running race gas. VP, ELF, METHANOL, AVGAS etc. What happens is the mixture is too lean and too much timming, however you can not tell that it is pinging due to the race fuel. After a hard dyno run then engine idles funny. Then a comp test shows that they are all different. A leak down test shows that the rings are still sealing.
This must be what they mean...Why would anyone run a piston that is more suseptable to shattering, breaking ring land and generally being "brittle" etc as a performance upgrade? The engine would shlt itself!
So, what WRHOON might want to do is bore the damaged cylinder until it cleans up then see if you can get pistons in the required oversize then bore the rest. Obvoiusly if it is excessive he will need a new block.
Getting back to the Stock = forged piston debate, how many RB26DETT engines have you seen running 1.5 -1.7 Bar with stock internals? I have seen many and when done properly they are fine. Keep it away from detonation and lean mixtures and you won't bend rods, you won't break rings and ring lands, and you won't melt the pistons or pop the head gasket.
Heck, my car was running 1.6 bar with Nismo N1 turbos (now for sale) 700 cc injectors, nismo fuel pump and Motec M8 and it has done so for the past 3 years without a problem.
What cast piston can do this? none, they will melt even with a good tunner keeping it away from det!!!