[KingLT1]

The LT4 fuel system high to low with a JMS booster will handle E60 on about 8psi or E80 on 6psi. Most pump E85 is actually between E65-E80.

Adm performance was able to run full pump E85 with the LT4 supercharger pullied up to 6 psi combined with LT4 fueling on a SS. The car made 600whp with that setup on their dyno. I believe that was a M6 car, so expect a little less with a A8.

Heat isn't as big of a issue with the LT4 supercharger on a LT1 because you can make similar power to a ZL1 with less boost due to the LT1 having 1.5 point higher compression. The heat issues you are reading of are with ZL1/Zo6's when guys try to pulley them down and spin them past their efficiency range. 9-10psi is about max for a stock LT4 without porting before it starts becoming a heat pump.

The LT4 setup on a LT1 with E85 @ 6psi would make a very efficient, fun, and reliable combo. Again if you don't mind mixing, then you could run a little more boost on E60.