randallb wrote:
Rag,
Probe sells all styles of pistons including hypereutetic. I have also ben involved with many types of high performance engines from NA to Nitrous to Nitro and have talked to a lot of the old timers like Tom Prock at JE about the hypereutectics. I once saw a guy break a hyper piston free reving his engine, about 4500 rpm, showing off. Do what you like I am just trying to give advice based on 40+ years working on everything from stock, at the dealership level, to 8,000 HP Nitro Coupes. I must ask one question. Did you understand the part of the article about taking the silicone content to a percentage higher than the aluminum and silcone's ability to meld? 12% silicone has always been the maximum amount of silicone you can add to an aluminum alloy and have it fully integrate. Above 12 % is where the brittleness comes from in a hypereutectic piston. If you are interested in why manufacturers are using these pistons I will be willing to point you to more articles having to do with piston rock cold, etc.
I hope you never have an upper ring land break but if one does you will now know why.
Randy
p.s. I also looked long and hard at a new Monaco 30 SFS on a Workhorse chassis and being a hot rodder at heart looked at all of the "tuners" in the market at that time. My studies convinced me that I would be perfectly happy with the stock tune up. Also, one of the original complaints that most of the "tuners" were attempting to fix was the sooty exhaust pipes on the 8.1 powered RVs. The only way to clean up a tail pipe on an exhaust system that long is to take fuel away. Opps, detonation.
Randy,
I read what the article said and that they build pistons with an 11% mixture of silicone. They did not give the percentage of silicone in the GM 8.1L pistons. Don't the pistons follow the same engineering logic about leaving HP on the table. Why would that same engineer spec a poor piston that would fail?
I was not making a change to hot rod my 8.1L but I did want to increase the low end torque and power available for mountain climbing while towing. They also reprogrammed my Allison to allow the overdrive to come on a few MPH quicker and shift a little sooner to take advantage of the increase in engine performance. This made a big improvement with my hill climbing ability but had an immeasurable affect on fuel mileage. I was not looking to accomplish what a full Banks system may provide.
I've actually never noticed my exhaust to be sooty but I do monitor my AF ratio. If my pipe gets sooty, so be it and like you say, leaning it out is the only cure it and that can lead to detonation.
