2JZ is a deep skirt block design that IS inherently stiffer than the VG block. Also, block concrete stiffens the cylinder bores that are connected to the main webbing. It is very frequently used in Chevy and Ford V8 designs to prevent the blocks from splitting. They don't have so much issue with the cylinder walls themselves breaking so it IS very much used to stiffen the block itself in all of the applications that I have seen. Also, if you look at the design Brett intends to use larger fasteners than the original oil pan bolts. I am assuming the original holes will be drilled and tapped. Finally, if it isn't necessary why did Nissan run them on the GTP and IMSA cars? Think about it for a second. They put tens, maybe even hundreds of thousands of $ to develop the engines for their race series. Do you think they would go to that amount of trouble if billet caps would have the same effect?
