View Single Post
      05-07-2019, 07:00 PM   #210
Brigadier General

Drives: 17 M2 DCT LBB,11 e90 M3 ZCP IB
Join Date: Jan 2017
Location: Bay Area

iTrader: (1)

Originally Posted by Anthony1s View Post
All the research I've done indicates that ACN91 is still 91 octane, and that the difference is there are more detergents in ACN91 than other USA 91. Detergents to me mean something that will break down the oil as it lubricates the cylinder walls. So my inclination is to believe the ACN91 tune has a little less boost and/or timing than the regular 91 tunes, to prevent excess heat on the engine oil which is slowly degrading due to the fuel detergents.
It meets the requirements of being 91 octane (maybe) by combing RON and MON in a way that's inferior to other non ACN 91 fuels. The amount of knock Nezil was getting on the stock BMW M2 tune on ACN 91 was disturbing.