2.7 block material
 

I understand that there are some 2.7 911 engines that were not the dreaded magnesium ones that had so many problems.

Can anyone give me a couple of quick ways to tell what the block is made of?

All 2.7 engines had '7R' Mg cases. Some 2.8 RSR engines were retrofitted with aluminum cases from a factory 'update' kit via the racing dept ...

well.....this sounds stupid......but aluminum looks like aluminum,,and magnisum looks like "it",, mabe hold a pc of aluminum next to it?? To the half way exp. eye one can recognize aluminum ez.
If it is a 2.7 chances are termendous thats its a "mag" case...and there is nothing wrong with them if the updates have been done.

There was a short run of 2.7 RS engines with a aluminium (silumin) crankcase. From chassisnr 9113601490 an aluminium crankcase was fitted for homologation purposes.

Aluminum will look "silverish". Magnesium is more of a darker grey...

Also, the alu case that was used on the 2.7 had cooling ribs on the bottom.