difference between r302 and a4
 

just wondering what the difference is, i found a fully machined a4 block for 1800, and im thinking i can get a dart block for that much.

what are the differences between the a4 and r 302 blocks

The biggest difference between the two blocks is that the R302 block has siamese bores, and the A4 doesn't... the cylinders in the R-block are connected internally, in that the coolant doesn't circulate between the bores vs. the A4 bores, that allow coolant to circulate between them, like the factory block.

The R302 block can be bored .125 over, and the A4 can be bored .090 over.

Also, the R-block is factory rated to handle more HP than the A4, mainly due to the siamese bores connecting the cylinders together.

-Ryan

which would be your choice

r302
a4
dart

i can get a new dart block for 1850

Although I currently have an R-block, if I were to do it again, I'd go with the Dart block. They come fully machined from Dart, and have a true 4-bolt main system (1-5) vs. the SVO blocks (2-4)