Piston question

[QUICKSILVER]

I haven't seen any listings for these pistons on S&F. Has anyone ever used any GLM, or Redline pistons. They are made by the same company. They are fully machined hypereutectic pistons with a hard anodizing coating on top resisting temperatures up to 1560 F. They have a hardness of HV280-400, and are T-6 heat-treated. Sounds like they should be almost as good as forged. I have used the hypereutectic pistons in car motors with good luck. I was just wondering if anyone here has used them. I can buy them for a very fair price. Less than $75 each for a Merc 2.5.

[capnzee]

This sounds very interesting! It seems like the tops of the pistons are the weak link on modern, high performance outboard motors. I have heard that the pistons on aircraft engines are often coated with cilicone to resist high temperatures. Why not 2 cycle outboard motors? capnzee

[Propelled Marine]

Quicksilver,

Both Pro and SeaCross pistons, are hyperutectic cast pistons.


The hi-silicone content cast piston allows for tighter clearances. The hyperutectic casting process also makes for a cooler running piston.

[capnzee]

But Nick, are they any good? and if they are, why isn't everybody using them? Is it cost preventative? I remember a bout 20 years ago, Ford made an entire engine of silicone. That engine was supposed to be the final answer. When something goes wrong, it seems like the top of the piston is the first to let go. Look at the OMC engines with the ring grooves at the top of the skirt, they were good for one "hot run". It seems like a silicone dome might have helped. Something that close to the fire ought to be able to take 1200 degrees or so without coming unglued! Do you have any knowledge as to price etc. on the type piston we are discussing on this thread? capnzee

[Rickracer]

And the savvy builder will cryo treat them too. There are probably some benefits to thermal and/or antifriction coatings as well, but I suspect that would be trial and error unless one already knows of a coating or system that will definitely work and stay on the piston. :cool:

[Propelled Marine]

capnzee,

Yes, the pistons are good but the pistons aren't designed to go to 10,000rpm's. The hyperutectic cast pistons make great replacements for stock motors. Guys have run pro pistons 7000-8000 without problems. People have had a lot of success running them hard, but if your serious get the wiseco's (forged pistons) and have John Marles modify them.

[capnzee]

Hey Nick, been there, done that! Hope they are as good as you say. Capnzee

[Propelled Marine]

capnzee, pro pistons got a good reputation.

Gee, it looks like rain today:( :(