Originally Posted by 08Hemi
can someone tell me why our engine is recommended to run on 89?? (I am referring to a 5.7 HEMI wth mds)...and with the new diablo tune are we running any risk of hurting the engine ie using 91 octane and tune?? I know it has something to do with engine temps but would love some more info...
When you run the 91 or 93 tune, it pretty much adjusts your timing to compensate for the higher octane fuel and get you more power.
They recommend running 89 stock because that is what stock timing will benefit the most from. You CAN run 87 or 91/93 stock, but for the best performance, Mopar says to use 89.