QUIKDECISION

I just got off the phone with an engine Co. They were recommending Hypereutectic over the forged pistons. This is for the application of rebuilding a mercruiser magnum 454. These are twin engines that are for a formula F311. The block will be bored .030 and I am going with roller a hp-500 cam roller lifters and rockers. The heads are the Gen VI rectangular port 454... Max rpm will likely be 5200 RPM. Thanks very much for your thoughts.

Badtoon

""forged""

dyno

done it both ways....this time I opted for forged...If you can afford them use them.

Whiteknuckle

A good hypernutectic is far superior to a stardard cast piston, but is very brittle. Oil control is much better with the hyper's than forged pistons. Howerver in the end, the forged are stronger. I guess you need to decide whether the power output of your engine pushes you into an area that forged is required. You can purchase a set of forged pistons made in the USA for a price not much higher than the hyper's. Check Speed Pro's if money is an issue.

CC247

Ditto on the Speed-Pros, they don't cost that much more.

1BIGJIM

iTrader: (1)

I just got done rebuilding an engine that had Kieth Black hypernutectic pistions in it. Long story short, spun a rod bearing , and debris got into the pistons skirts. Replaced with Speedpro Forged for additional $150.

Hydrocruiser

I hope you find this helpful...I think it's a nice summary that I enjoyed reading:

http://www.hoon.tk/tech_tips/pistons.html

Summary:

"In the instance if building a mildly supercharged 5 litre V8, or pushing for 450hp out of a normally aspirated engine, there is probable little advantage in investing large sums of money in forged pistons, when a correctly-tuned engine with either standard Eutectic items or modern design Hypereutectic (ACL Race Series or similar) pistons will give the same power output and reliability levels".

My mechanic agrees anything over 475-500 HP and forged is the way you NEED to go according to these guys and others.

...interesting that GM's HO's are limited to 425 HP.... coincidence? I think not....in the developmental stage they were "talking" about 475-500 HP ya know...GM said no after testing and reviewing the results I read....if GM could have made the 425 HP HO a 500 HP HO look at the business they would have retained when they replaced the 502's with 496's...and it all boiled down to pistons, rods and the crank used I understand....agreed??

Every Mercury 525 is technically a loss of revenue that could have gone to GM. The 502's were bullet proof....I read an interview that Reggie gave a long while back and he thought the GM/Merc 502's "walked on water"...

...also the GM 502's had lots of "room" for hopping up and tons of aftermarket stuff that was around....and they were priced very nicely as well. The Merc 525's of course have more of the good parts...don't get me wrong..but the GM 502's were icons in thier own way.

Raylar has great aftermarket parts for the 496's and it looks like without changing pistons etc. 475-500 HP is "easilly" attainable... probably intake, heads and exhaust and you should be there....or a blower with just enough psi to get you to 500 HP as well....just thought I would throw that in.

The information on the "hyper" pistons is bearing out they can take it up to 500 HP if the engine is well tuned... spark detonation would be a problem of course...

Wobble

Jegs and Summit both have good deals on forged pistons from JE and SRP

tomcat

As I understand it the advantage of the hypereutectic piston is its lower expansion rate which allows tighter piston to wall clearances. How does this work in a marine engine where clearances are generally larger?

articfriends

iTrader: (1)

Forget the hyperteuctic pistons,there is much greater chance for detonation and extreme circumstances that hyper pistons just won't stand up to on a marine engine,plus personally i have cracked skirts on them before on a gm zz4ho motor. Hyper pistons quite often have no good support to skirt behind oil ring land and break there,haven't heard about any forged pistons with cracked skirts!! Smitty