MAX. effort pistons--Forged vs. Billet

[swampbuggy]

First off let me say that i am sure this has already been discussed before. Due to two factors 1. I am not very good at searching, and 2. things change with time. My engine builder has said that CP piston manuf. has told him that a FORGED piston is stronger than a BILLET piston ?? Would like you folks in the small group who REALLY know the tested facts on this subject to please comment. Mark H.


TRUTH WILL ALWAYS BE TRUTH WHETHER ONE BELIEVES IT OR NOT

[KnightEngines]

Forged is stronger due to grain structure.

BUT - billet gives far more freedom of design, it doesn't need to be able to be squeezed into shape, so the design itself can be stronger/lighter.

In other words it depends........

[Mark O'Neal]

In other words...if they don't want to (or cannot, due to limitation in technology (or reality)) make a forging, they'll make them out of billet.

[Morgo]

Yeah,some oddball engine no one wantto produce the forgin moulds;the billet one from some general forging is just so much cost sensitive.
Or real oddball one just take the bar of aluminium and machine it from that.Than make moulds and forge the piston to maybe onetime customer.

[Mark O'Neal]

If that were the case, we'd just use a forging that would fit. Some of these high end forgings have specifications that can't be done on a forging press.

So, you mill them from a blob.

[swampbuggy]

Mr. O'Neal........are the expansion rates the same on forged and billet pistons ??? Mark H.

[pamotorman]

some NASCAR engine builders used billet as a bud sold them the tooling to do it

[Mark O'Neal]

Mr. O'Neal........are the expansion rates the same on forged and billet pistons ??? Mark H.

The most common answer in engine building is "it depends". The material being equivalent would dictate that it remains the same rate, the rest is the design of the parts.

So....it depends. I most cases I don't think it would be much different, if at all. But I've never made billet pistons. They wouldn't exactly fit the production model I used. Diamond is probably the most experienced.

[Mark O'Neal]

Mr. O'Neal........are the expansion rates the same on forged and billet pistons ??? Mark H.

The most common answer in engine building is "it depends". The material being equivalent would dictate that it remains the same rate, the rest is the design of the parts.

So....it depends. I most cases I don't think it would be much different, if at all, but I've never made billet pistons. They wouldn't exactly fit the production model I used. Diamond is probably the most experienced.

[user-23911]

Maybe a discussion first about how and why pistons fail?

I've yet to see a cast piston fail that wasn't due to detonation or some other outside influence.

[MELWAY]

It’s probably not about a failure mode

More about what will make more HP due to keeping a better ring seal due to distortion under running conditions

[swampbuggy]

Thanks for all the reply's everyone, Mark H.

[Scotthatch]

What the alloy is matters .....
NA HP is nicer then nos or boost HP

I have pushed even cast steel strut OE pistons hard but it's like running a 20 amp fuse on a 20 amp draw any mistakes and it burns ....

Then there is coatings

There is a lot to pistons when you look at all that and weight ..skirt....pin...lock...quench...clearance...valve relief...ring size and placement.... gas ports ...pin location

[DCal]

It's interesting to me that you said that about steel strut cast pistons ....indicating that they are weaker than non-steel strutted. And you are right, they are weaker, but it's been misunderstood for a long time. I learned from Nick Arias, Frank Pisano and others that the steel strut is there to keep the piston clearance to a minimum when they're used in situations such as door-to-door salesmen. Because the aluminum cools quicker than the hot cast iron block it would create piston slap when started back up and the struts fixed all that