CSL Pistons - oversize- help

Marc-M

Marc-M

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This has probably been asked..... but.....

I need new pistons for my CSL – the ones that are in are .25 oversize and we think this was done by the last owner – but I seem to remember that they may have been build by the factory with .25??? but who knows.

However, my engine builder says I need +0 .75 or 1mm oversize ...

Trying to find these sizes for the CSL is a bit hard

Does anyone know a stockist??

The ones I have seen (+0.25) and are crazy prices and I am wondering if its cheaper to get forged set made up.

Any help would be appreciated



Marc
 
.25 is first oversize and wouldn’t have been in there from the factory. .25 is hardest to find though, check with Walloth, and .75 and 1.0 which is the max you can go are easier to find.

Correction: .25 over was used in the CSLs with 3003 motors.
 
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What's the useful OD limit for knurling a piston?

Custom pistons have been used by members of this forum - use the Search function and they may turn up. Some conversation with various BMW specialist engine rebuilders could be useful.
 
Well it is quite apparent that getting oversize pistons for the CSci Csl are not available – I can only get .25 oversize and I need .75 or even 1mm oversize.

So, my only option is to get some made, and after talking to a few folk – it’s not a big deal.

To get JE forged pistons made is much cheaper than buying off the shelf old stock---So, a result…

However, talking to one of the specialists he says that they need to be made of 40/32 alloy and not the standard 26/18 alloy – as the 26/18 specification is for racing – and has bigger clearance and expansion – or something like that – does that sound plausible??



Does anyone out there have forged pistons and do they know what they are made of??



Thanks



Marc
 
Ps - I will have a set of .25 pistons for sale
The engine guy says they are ok - one has slight scratching on the skirt but are quite usable....
 
Not sure, but maybe ask @eriknetherlands, i think some time ago he was considering purchase of the set oversized pistons +0,50 as a spare from @Stevehose. Maybe Erik (if he purchased them) will not need them & will re-sell them to you.
 
It was always my understanding, faint though it may be, that forged pistons expanded more than cast ones, and thus needed to be fit a little looser in the bores. This may be strongly alloy-dependent, best to check with your chosen professional. The guys at JE Pistons should be able to tell you right away.

Search function would also likely turn up whomever has done this before. I know I've seen it mentioned previously.
 
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