Is this correct?

[intergalactica]

The following was posted on http://www.earlyabodyforum.com:

"Well, the only experience I've had with forged pistons is that they make the engine sound like a diesel when its cold. They rattle around in the bore 'til they expand out as they warm up. Unless you race, or generally "beat-the-snot" out of the engine all the time, I think forged pistons are a waste of money. Hyperuetectic's are a great compromise of strength and economy. Assembled correctly ,for regular driving, and the occasional "Chevy-destroyer" blast, cast pistons are just fine."

I have three questions:
**Are forged pistons noisy?
**Are forged pistons worth it?
**Do 273 Commando motors have forged or cast pistons?

 

[toolmanmike]

Forged pistons if fit properly don't rattle much when cold. My HP273 with
100,000 miles and factory forged pistons doesn't rattle when cold. If they do rattle excessively when cold the piston to cylinder wall clearance is too loose.
Cast pistons work great for most street engines and with the HP-273 there isn't much available for forged pistons. Egge has cast pistons listed and Flatlander Racing lists forged pistons in any bore size and compression ratio although I have never contacted either place to confirm that info. The factory 273 pistons were forged with the 2 barrell motors having flat tops with 4 valve reliefs and the HP motors had a slightly domed piston to raise the compression. toolmanmike

 

[ramcharger]

Forged pistons can be noisy and the engine should be warmed up before beating on it. The noise goes away by the time the engine hits 150 F or so. I've ran forged pistons before and it's really not that bad and I hardly noticed it.

Are they worth it? Only if you're running forced induction or lots of nitrous.

Sorry, can't help with the 273 commando question.

 

[1968FormulaS340]

I run forged pistons and they can (but mine don't) rattle around in the bore or sound like a diesel. Forged have a diferent thermal expansion rate... A bit looser when cold but correct when warm.

But....

Forged pistons are not needed for most street/moderate track builds and they will not make your car faster.

Forged piston can take a higher level of detonation before failing. This is not such a huge bonus as you engine should be tuned not to detonate in the first place.

As far as a 273 having forged pistons.... I don't know...... Most factory engines (except some high compression or force inducted engines) had/have cast pistons.

So unless you are running on the edge of the compression for pump gas they would be a waste of money.