Picked up some used Forged Mahles... Question (pics fixed)

[TedzBug]

So... I picked up these 90.5 forged mahles with the impression they were in "good" condition...

I'm wanting to build a mild turbo, also got a hold of a used forged CW 69mm crank.

What do you think of these? Was this a bum deal, or are they worthy of running? Cylinders have been honed, told they were round...

[Stray Catalyst]

I've re-used worse... but I'm not using a turbo. How thick are the walls on those cylinders? The piston that's got valve scars on the top would worry me. And the first picture - I've never seen marks like that before, did it break a piston ring? I'd expect that cylinder to be all torn up - I've re-honed a cylinder that had a wrist pin clip break, it wasn't pretty.

Stray

[TedzBug]

they are the machine in 90.5 cyls. dont know the wall thk till I am home to check...

I guess $150 wasted now is better than trashing a built engine...

lesson learned maybe. trust no-one.

[Marc]

There are actually two diameters of "machine-in" 90.5 barrel, the original ones were 97mm on top and 94.4mm at the case (they're too thin for turbo use IMO, at least without powersleeving) - the modern ones, which I believe these to be, are 98/96mm, same as "classic" 92s. The early pistons used a thicker ring package (2.0/2.0/4.75) than the late (1.5/2.0/4.0).
That one piston started to melt down, probably from a too-lean mixture, and I wouldn't trust it for a high-performance application. I've run worse in low-compression motors. The one that was kissed by a valve looks fine from here, that's a pretty light smack. Looks like it hit once, bending the valve, and then a few more times pounding it into the guide...

[TedzBug]

at this point, I've emailed the seller from thesamba.com and let him know that this was completely misrepresented...

damnit...

[Marc]

I think I'd rather run a new set of Chinese ("AA") than these, for the same money.
IMO the used set you've got is overpriced by ~50%, even though new Cima/Mahles are going for $390 they aren't worth that much (to me). Ask for $50 back and see what happens. Nobody besides UPS or USPS makes any money shipping these things back & forth, and any time they make the trip with no broken fins it's a near-miracle.
I've got more good-used 90.5 pistons sitting around than I have cylinders for (my son's left his baja out in the rain and let the jugs fill up & rust out several times)...I could probably come up with a decent set of pistons, given some time. Do you have access to a gram scale? Get me an accurate weight and maybe I can find a single to replace the scorched one...juggling wristpin weights opens up possibilities too, best if you can weigh all your pistons and pins separately.


http://www.thesamba.com/vw/classifieds/ ... id=1514324

[TedzBug]

Response from the seller this morning:

"If you want to send me the two pistons that are questionable I will be happy to send you two that are good.  I have several spares and am getting rid of all of my 90.5 stuff. I have used several sets of these used pistons and cylinders with no problems.  The cylinders have been honed and are straight.
Thanks,"

I may sent the whole pile to him...

I want to build a reliable engine... this direction wont get me there.

[TedzBug]

He has called me to try to resolve... says he'll send me 3 pistons and a set of rings....

hmm...

[Marc]

That should give you enough to work with. I've got dozens of wristpins if you need any to balance out the pistons.

[TedzBug]

Sending them back... Getting most of my money refunded.

Going to spend my money on proper parts so i can build a reliable engine....

Thanks for taking a look for me guys.


And while i'm at it... Whats a good P&C choice for a 1776 turbo?

[Marc]

Did you see that set of new Mahles for $300 at theSamba? If you go for them be sure that they're the later size with thicker cylinderwalls.