Bathtub Piston

[jherko]

Looking for a single mahle bathtub piston, standard bore 88.97mm, weight group +. I have a set but my number 2 cylinder is showing some wear while the others are in good shape. Would prefer to find a mate rather than replace them all, but will consider sets as well.

herkojhATgmailDOTcom

[Guest]

Well, if you want a "bathtub" piston, I presume you want Tii, 9:1 c/r. (Maybe Ti 9.3, but you'll never find those.) Otherwise, isn't a 'flat-top' for the 121 head the goal?

mac.

[jherko]

Some say 9:1, some say 10:1, I guess the best is to give the measurements...

Top of pin to top of piston (excluding raised bathtub portion): 31.10mm

Piston length (excluding raised bathtub portion): 80.08mm

Overall length (including raised portion): 85.45mm

Height of bathtub: 5.37

Inside casting marks: 89V3V1+ and CO21

[Guest]

Mysteries suck!

I can't match your measurements to anything in the MAHLE catalog.

How 'bout a pic of the dome on the top of the piston.

The crosshatching on the side of the piston has me wondering too. Neither the MAHLEs nor the K&S I have on the shelf have that feature.

Let's keep looking.

mac.

[jherko]

The top

[kcdonahue]

Those pistons have been knurled... That is what creates the crosshatch pattern on the sides. Quiets piston slap down quite well...

Damn I really need to read more slowly... "that piston has been knurled" Are all of your pistons knurled like that?

Regardless.... Measure you cylinders carefully.

KC

[jherko]

Yep, All knurled, I'm using a different block for rebuild, the one these came out of had some serious pitting from a cracked head that sat for some time.

[kcdonahue]

You definitely need to measure each piston and see how the skirts measure up compared to each other and while your are at it measure the ring gap too. The reason the pistons were knurled in the first place was that there was likely too much piston to cylinder wall clearance.

KC

[Guest]

Definitely NOT 9.0:1.

Looks like you have some original bore, 10.0:1, MAHLEs that have been cut for a non-stock cam of higher lift (pistons have been cut for valve clearance).

Now, what's with the brown colored "box" around and above the pin?

Let's keep looking.

mac.

[jherko]

Definitely NOT 9.0:1.

Looks like you have some original bore, 10.0:1, MAHLEs that have been cut for a non-stock cam of higher lift (pistons have been cut for valve clearance).

Now, what's with the brown colored "box" around and above the pin?

Let's keep looking.

mac.

Thanks for all the help Mac (and KC). These came out of an engine running a 301 cam, so that explains the clearance cut. Given that they are knurled and some what of a rarity, I think I'm gonna post them for sale (rather than find a mate) and replace the set with some new ones from Ireland, rebore, etc...

[Guest]

NO, NO, NO!

Before you go off and order some cheap shit pistons from some California poser/manufacturer, consider spending a few more bucks and phone Rob Torres at 2002 Haus and tell him you want that set of second oversize MAHLE 10:1 121 head pistons he has on the shelf (I know he's got 'em! Don't accept "No." for an answer). They might be one of the very last sets of 10:1s in existance.

mac.

OK, now you can thank me.

".......... do it right or don't do it at all................."

[jherko]

Oh Boy, here we go. I hope your going to bail me out of the poorhouse after I make this call...

[jherko]

Arrived today

[scestes]

So you just ordered a new set? What did you order and what did it set you back?

[jherko]

They're MAHLE 10:1, 1.0 over. Set me back $900.