[crummasel]

Hi there,

in an other thread the question came up if the CIS really needs the "bowled" piston shape. My understanding was that the turbulence induced by the special shape was used to create a reasonable mixture inside the cumbustion chamber since the CIS injects fuel partly onto the closed valve so a bad mixture occurs when the valve opens and fuel is aspirated together with air before the components are mixed and the fuel was carburetted.
Maybe i am wrong or there are contradicting theories?
Even if i did an uncounted number of carbed engines i did not excessively work on CIS engines especieally i did not experience CIS on domed pistons.
Only indirect experience by a customer who was reporting a very bad performance of a 2.4 CIS engine which another engine builder has equipped with domed pistons.

Can someone enlighten me on this question?

Or: why did Porsche change to bowled when introducing the 2.4 cis, back to domed on the 2.7 rs and back to bowled on the 2.7 cis?