Aftermarket cast pistons? Hypers or not?

[iTurbo]

Are aftermarket cast pistons such as the Clevite 533P (for swirl head) or 532P (for G-head) regular cast aluminum or are they hypereutectic? Is there a way to tell by the part number if they are hypers or not?

[roachjuice]

I think they are all hyper. Except the mahles.

[iTurbo]

Damn. I thought it was only the Keith Black brand or something that were hypereutectic. I just bought a set of Clevite 532P pistons for an '85 Turbo I on eBay from mpcentral for $77 and it just said they were cast; no other info. Oh well, not like I'm going to be making any more than ~180 WHP with this motor anyway.

[Force Fed Mopar]

http://www.turbo-mopar.com/forums/showthread.php?63521-Some-real-world-cast-pistons&highlight=real+world+cast+pistons

[iTurbo]

Reading that it seems they are just regular cast pistons. I'll post again when I receive them. Hopefully it says something in the documentation that comes with them.

[cordes]

I know I posted in the referenced thread, but the 533P is not a hyper and it is a great piston. The problem I had when getting mine is that they were not being made for the floating pin at the time. I'm not sure if that has changed at all or not.

[Force Fed Mopar]

I know I posted in the referenced thread, but the 533P is not a hyper and it is a great piston. The problem I had when getting mine is that they were not being made for the floating pin at the time. I'm not sure if that has changed at all or not.

Mine are floating pin T2 pistons.

[cordes]

Mine are floating pin T2 pistons.

That's very good to hear. I know I picked up the last four floating pin pistons Sealed Power had at the time. That was about 4 years ago now though.

[Force Fed Mopar]

Well, my are like 7 years old :)

[cordes]

Well, my are like 7 years old :)

I see. So that is a real concern then.

[iTurbo]

Isn't the only difference the pin bushing though? So if you wanted floating pins you could just buy the bushings and have a machine shop hone them out and press them in? Or is there something else about the casting that is different?

Been looking all over the net for a pistons that are clearly marked/advertised as being hypereutectic and so far the only ones I'm finding are the Keith Black Silv-o-lites. At any rate I suppose I wouldn't mind too much if the 532P set I bought did turn out to by hypers. I'm mostly buidling this motor for the experience before building up some motors that I actually have a lot of money into and won't be pushing it above stock except for opened exhaust. Just a simple G-head log TI really.

[Directconnection]

Damn. I thought it was only the Keith Black brand or something that were hypereutectic. I just bought a set of Clevite 532P pistons for an '85 Turbo I on eBay from mpcentral for $77 and it just said they were cast; no other info. Oh well, not like I'm going to be making any more than ~180 WHP with this motor anyway.

If hypers, they will have the abbreviation in the part # before the actual digits. Like 532 you have, it may be HE 532. Mahle was bought out... and I now see two kinds of Mahle pistons at work (of the cast type that is) poor quality hypers and the quality cast pistons we are used to seeing on our factory turbo motors. Both have been coming in with the red Mahle box.... so buyer beware.

[Directconnection]

Isn't the only difference the pin bushing though? So if you wanted floating pins you could just buy the bushings and have a machine shop hone them out and press them in? Or is there something else about the casting that is different?

Not sure if I'm following. But in order to have a full floating setup, you need two things: #1) a clearance between the piston pin and the small end of the rod (preferably .0006 on the street) #2) a set of locks and the pistons machined to accept the locks....

Normal press fit setups, the press fit of the small end of the rod and the pin (preferably .0015 press) is what keeps it from sliding out.

So, to make a press fit setup into a full floating, you bore out the small end of the rod (hoping there's a good amount of material afterwards) for a .002-.004 press fit of the pin bushing, then *BORE* the pin bushing so it's totally parallel to the housing bore (ie: totally square) *then* you hone the pin bushing for a .0007" street clearance (race motors typically have .0010 to .0015) As for the piston, you check/hone it for a .0005" street clearance (.0007 to .0012 race) To hold it together, now you need pin locks. Some cast pistons (about 50% of them) give you these locks and have the pistons machined for locks for both setups.

Now, in the old days: race shop hone away the .0015" press fit in the rod, and made it into a .001" clearance so now the pin was floating and metal on metal! You'd be surprised... I've seen some of these old school race motors/parts come in like this a usually were ok (parts swap meet finds) Chevy had their L88 or LS7 (I forget the designation) 454 from I think the '68 or '69 era and it had something like a .600" lift factory solid lifter cam, forged 12:1 (or higher... I forget) compression, nitrided forged crank, nice ports on those heads btw.... and full floating pins that were *steel on steel* They did do a factory hardness treatment to the small ends, though...as evident by the weird color difference of that small end of the rod like it was dipped into something. My boss tells me all this stuff.... but being Chevrolet, it kinda goes in one ear and out the other. It all started with an argument of BB Chevy supremacy vs Hemi. Their L-whatever "500 hp bone stock" Yeah, I find out through the years huge mechanical cam (for a factory cam) huge compression, big port heads, etc.... more like a Max Wedge spec sheet.

[83rampage]

If hypers, they will have the abbreviation in the part # before the actual digits. Like 532 you have, it may be HE 532. Mahle was bought out... and I now see two kinds of Mahle pistons at work (of the cast type that is) poor quality hypers and the quality cast pistons we are used to seeing on our factory turbo motors. Both have been coming in with the red Mahle box.... so buyer beware.

This makes sense...If you go to Rockauto.com and look up pistons for a 2.2L turbo it has Sealed Power #533 and in the description it is a cast piston.

Look up a 2.5L turbo piston, and it has an "H" in front of the PN (Sealed Power pistons as well). In the description it is called cast piston, but hypereutetic is also mentioned.

Learn something new everyday.:thumb:

[iTurbo]

Thanks for the info and clearing that up for me Steve!

[Directconnection]

Thanks for the info and clearing that up for me Steve!

No problemo dewd!

[BlueShadow]

FWIW, ive got the 2.5 Clevite pistons (from mpcentral too) and Im thrilled with them. Stand up to some (just audible) detonation seemingly well actually. Run 25psi on them.
That said, I was being an idiot while racing last year and it was pinging heavily (quite loudly), didnt let off, and I broke a ringland. Replaced the one, and its been great since. Love the price too.

[iTurbo]

Got the pistons from mpcentral yesterday. They didn't really come with any documentation/info other than the label on the box. The tops of the pistons just have, "75mm" stamped on them as they are +.030".

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