DUR0N

After an unfortunate mishap with my refreshed S2 engine (the camshaft seal popped out, oil pressure gone and the bores/pistons were toast), I'm now looking into rebuilding this engine...again.
Block will come back from the machine shop any day now, they said it would be bored/honed at first oversize:104,50mm. They couldn't believe it themselves that it didn't do more damage.
The valvetrain had some leakage on the exhaust side, but that should be cleared up with removing carbon deposits. Pretty good for a 280k km engine.

I've already looked around here, as the most knowledgeable people seem to be on this board, but couldn't find any thing interesting that matches my scenario.

I'm going to order a set of wossner pistons, seems to be the cheapest option but I'm wondering how far i can go with those. Soon, around here only 98 RON fuel will be sold (premium) so can retune for that. Pistons could have a bowl, upping the cc's (will the stock injectors hold up?) How much could I increase the compression, without changing cams? Will the conrods be strong enough?

I'm not looking to go into the standalone ECU - MAF - cams route unless the power gain is significant, but I do an EEPROM writer.

924srr27l

Contact Mike @ Lindsey Racing, he'll be able to assist and supply you with a set of Wossner pistons and the spec required from the machine shops honed measurements.

www.lindseyracing.com

He sorted and supplied a 2.7 N/A for me, see the website build for details

www.924srr27l.co.uk



R

H.F.B.

Recently there was this thread posted:
F/S 944S2/968 105MM Wossner Pistons

As far as I know, they are still for sale on Ebay. $830 OBO

PaulD_944S2

Was the block honed or made oversized and then given the Alusil treatment?

V2Rocket

I would just get stock-CR, oversize pistons.
The machine shop working on the cylinder head will cut the deck a little which will slightly raise the compression ratio...maybe from 10.9 to 11.0:1 or so.

98 RON is what, 93 AKI? Wouldn't push much past that for a mild-mannered street engine.

DUR0N

The machine shop called, they discovered a crack in one of the bores while machining.
My guess is selling everything I still have and buying a used engine will be a better way to go. Machining for steel liners+pistons or finding a good short block+pistons will both be more expensive.

DUR0N

Arominus

Don't discount a 968 engine if you find one, its an easy swap. One bore in my original S2 motor went south and we just ended up buying a 968 engine instead. Well worth the little bit of extra wiring required to make it work.

rosse

DUR0N, I think its good there is a crack in this block, because this would be a disaster. It looks like they machined + honed the alu, like it was a steel block? Alusil does not work like that.

Or is this before they installed liners and the crosshatch is a coincidence?

jhowell371

Good spotting rosse. Sure looks like they cross hatched the cylinders like it was an iron block. One of the guys on an other board had a block cross hatched too by a uninformed machine shop.

DUR0N

They said these pictures were taken after boring to 104.50mm, before honing. Does that make sense?

rosse

doublepost

rosse

It depends. It does not really look freshly bored with the correct tooling, but I'll give it the benefit of the doubt. After boring it should be honed, but not in the same way a steel block is honed. It needs either the 'old' way with the felt hone and the correct silica paste, or the 'new' way with special alusil hones. An alusil bore should never ever have a crosshatch pattern when finished.

So my guess is they would have honed it with a hone for steel blocks, you would have built it with fresh pistons, put a lot of effort and money in it, and it would have lived for a few hours before eating itself (again).