SCCA Production Car specifications state that .0475 is the max over
allowed for any engine regarless of size available. These pistons can be
of any manufacturer but must be made of metal. Cosworth JE and weisco
pistons are all available in .040 over bore. I don't know if i'd venture
into territory over .060 since the wall between 1&2, 3&4 and 5&6 would be
very very thin.
aaron
On Wed, 25 Nov 1998, Egil Kvaleberg wrote:
>
> On 25 Nov 1998, Aaron Johnson wrote:
>
> > since .0475 is the max over bore
>
> FWIW, it seems .060 overbore pistons was available from ST once upon a
> time, making .060 the max allowable overbore in many racing classes. That
> is the reason that forged pistons are usually available in +.060 only.
> Additionally, the standard gasket will fit.
>
> 2.7 litre territory can be reached by boring to 77 or even 78mm, in which
> case you'll need a purpose made copper gasket (no problem). Mazda 1300cc
> pistons is a popular choice here, although you can also have pistons built
> to order.
>
> Further increase is possible by increasing the stroke, but that is a very
> costly exercise since it requires a special crankshaft as well as special
> conrods.
>
> See http://www.kvaleberg.com/t_tune.html for more information.
>
> Egil
>
>
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