I searched, and coudln't find any pictures on how bad a forged piston screws up stock h22/h23 frm sleeves. does anyone have any pictures or more detailed information besides "frm and forged piston don't work together"

 

PrecisionH23 has seen this personally. He has posted pics in the past.

 

To my understanding, due to the manufacturing proccess, forging has a dissadvantage in that the component itself develops denser areas. I believe this makes them "unbalanced" relatively speaking when commpared to a cast object. Casting sets material in a more controlled proccess.

Anyway, I think the the unbalanced nature of forged pistons, make them too rough and rowdy for the FRM sleeves.

I read a little of everything so this means I'm also not accurate on everything. So if I'm totally off, I'm open to correction.

 

what iss frm? is it just the stock sleeves? ive seen the pics precision posted. what causes that? i was thinking of running forged pistons, but wasnt sure if I needed to sleeve or not, I am going to do the f22 crank and rod install in the h22 block...

 

Forged typically = getting your block sleeved. As for the mahle FRM compatible forged pistons I've heard mixed comments.

FRM = Fiber Reenforced Metal (terminology?). They're supposed to be lighter and cooler than Iron sleeves.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Televator &raquo;</TD></TR><TR><TD CLASS="quote">Forged typically = getting your block sleeved. As for the mahle FRM compatible forged pistons I've heard mixed comments.

FRM = Fiber Reenforced Metal (terminology?). They're supposed to be lighter and cooler than Iron sleeves.</TD></TR></TABLE>

but what causes forged pistons to do this scarring to the sleeves?

 

That I don't know for sure, but like I stated earlier, maybe it has something to do with the properties inherited in the manufacturing proccess. The more erratic density changes might have something to do with it.

I also read that they initially only come out in a rough shape and any finner details have to be added in a later proccess.

 

 

that makes me sad

 

http://www.saffil.com/pdfs/aut...p.pdf

Information about FRM.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">
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i heard if you use engine oil that.., that wouldnt happen

 

what it all comes down to is thermal expansion. forged pistons expand just like any other material and depending on the amount of heat that and the material type determines how much expansion. ideally you want the piston and cylidner to expand together or atleast enough so there is no piston to wall contact. frm probably has a low thermal expansion rate. so as the forged pistons heat they expand and the cylinders don't or atleast not enough

now this is not the only thing happening but im not an expert, nor do i claim to be, but without a different than normal material and a coating on the skirts forged and frm don't mix.

now i know they use the different material to help side step the thermal expansion bit, but the coating on the skirts probably has to do with the hardness of the frm and the fact that it chews up the pistons and rings before the cylinders wear.


edit: mahle has the forged pistons witha coating, they work with frm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by prelittlelude &raquo;</TD></TR><TR><TD CLASS="quote">what it all comes down to is thermal expansion.</TD></TR></TABLE>

That was my thought

 

I guess nobody is using the FAQ or search engine today.