Sorry for the long post.
RB26dett:
Sand cast iron, closed deck engine block
As already stated inline 6 (&V12) engine layout has perfect balance, and is even firing.
Some inline 6 engines do have torsional vibration problems due to length of the crankshaft, but this can be overcome with good design.
VQ35de
High presure die cast alloy, open deck engine block with cast iron cyclinder liners.
60 degree V angle. A 60 degree V6 in even firing (unlike a 90 degree V6 which needs splayed crankshaft journals in order to be even firing)
But a 60 degree V6 still has end to end vibration.
for more info on this try http://www.autozine.org/technical_school/engine/smooth1.htm
The open deck engine block is weaker than a closed deck engine block. However VQ's have been reliably boosted, proving how strong this design can be if designed and manufactured properly.
High pressure die cast engine blocks can also sometimes have problems with porosity.
VR38dett
What we know:
alloy block, plasma coated alloy cyclinder liners
95.5mm bore, 88.4 mm stroke
The engine could be a VQ35hr (or VQ40de) engine block with different liners and rotating assembley.
Or
As stated the engine is said to be based on the racing engines.
Modern racing engines tend to use the lost foam casting method. This method is very accurate with complicated shapes, is consistant and parts tend to have better finish than sand casting (also no chance of a stray sand particle going though your oil system) Lost foam also has the advantage of lower tooling investment, allowing production to be more flexible.
So if the engine really is based of a racing we are talking about a very very VERY serious piece of kit.
BRING IT ON
Cheers
P.S. I do also mourn the end of the inline 6. L28 with twin SU's and extractors sounds soooooo horny