engine and drivetrain Piston ID?

[boxy02]

Anyone recognize these pistons? Opened up a 76 long block tonight with an E12 head on it...

Is 88.97 the first over bore? Thx,

[AceAndrew]

Stock bore (89mm) piano tops.  Based on the height of the pop-up I'm going to estimate the US 9.0:1 comp. version (given it's a bit less than 3mm).

[boxy02]

Thx Andrew! Picked this up from a fellow FAQer... I'm researching M10 turbo motors......uh oh.... ?

Ill be looking for 8:1 flat tops eventually. 

[TobyB]

Agreed with Andrew that they're in the 8.8-9 range.

 

I will hazard a guess they're aftermarket- the KS and Mahle pistons are

both usually stamped with size on the smooth, machined surface, and none of the ones I've seen have the

cast- in letters on them.  Plus, unless you've wire- brushed them or something, that marking on the crowns would make me think

the engine's been apart a time or 2.

 

But that's just a guess- I've only seen a dozen or 2 engines apart...

 

t

 

[stephers]

Hi boxy02      sent you a pm about some NOS flat top Mahle pistons 89.47mm 

 

Thanks, Rick

[boxy02]

Got it, thx Rick.  I need to do a lot more research and make some decisions about how I'd like to go about this build before I can commit to buying parts. 

[boxy02]

19 hours ago, TobyB said:

Agreed with Andrew that they're in the 8.8-9 range.

 

I will hazard a guess they're aftermarket- the KS and Mahle pistons are

both usually stamped with size on the smooth, machined surface, and none of the ones I've seen have the

cast- in letters on them.  Plus, unless you've wire- brushed them or something, that marking on the crowns would make me think

the engine's been apart a time or 2.

 

But that's just a guess- I've only seen a dozen or 2 engines apart...

 

t

 

Yeah Toby, I think your spot on, it looks like someone wire-wheeled the piston tops. There are pits in #4 and there's no lip at the top of the bore for all cylinders, making me think someone dingleberry-honed them and re-ringed the pistons and stuck them back in? I don't know....eventually I'll disassemble and get it inspected before committing to machine work. It's definitely been apart.

[boxy02]

Turns out, they are mahle pistons...but they're hammered. There's evidence of piston slap...

 

Rick, can you send me a few pictures of your flat tops please?

thx, 

[mac]

.....sent ya a PM.

 

mac.

[boxy02]

Mac, sent ya one back...

[TobyB]

How did you figure out they were Mahle?

 

curious,

t

[boxy02]

8 hours ago, TobyB said:

How did you figure out they were Mahle?

 

curious,

t

"MAHLE" was cast in the piston skirt inside...

Sending you a PM.

[TobyB]

Well, I'll be- that's pretty conclusive, huh?

reading your PM now,

 

t