It
might be OK since its NA, the ECU will react to the knock and retard the timing. Or you will break a ring land or spin a bearing pre-maturely, especially with those tight bearings for that thin expensive oil. The worst thing to do is switch back and fourth.
Would you run 87 in any other 11:1 engine? I wouldn't, and I wouldn't run 87 in the Scatty Pack (wish I had one).
Shoulda just bought the V6 Doc, then you could run spin tech oil and 87, but I know you wanted to look cool
gM..... that ECU .... what’s the timing retard range ? .... and ORE blow a hole in the piston ! Switching back and forth ??!!
87 in an 11 to one motor ? ... there’s a famous OEM motor that was I think 11.2 and the OEM almost directed it to be 87.
QUITE HONESTLY... when I found out SOME PARTICULARS about the SP ... I almost kicked myself for buying it because the SP you cant put any type of trailer hitch on it. Like for hauling a small boat or utility trailer.
The LOOK ? .... how about that Charger GT ??!!
Doc, I probably shouldn't have commented because I really don't know what the ECM/map for the Scat Pack has in it, or even really if the logic has changed from the older stuff. And I've never even actually tuned a Gen III hemi car or truck (I will when I buy one). But I have tuned other EFI applications. I'm really speaking in generalities of the knock logic for most engine management systems (exactly what you're not supposed to do, logic can vary a ton and is important0 and what I saw when I explored the maps in some of the the older G3 stuff. What I looked at had max retard of 5-15 degrees total, varied by RPM, I.E. up to 10 degrees at peak torque, 5 degrees at redline, and as much as 15 degrees at super low RPM.
The comment on switching back and fourth is based on the fact that the ECU will generally realize that it has to keep pulling timing and store it as a semi-permanent adjustment (will check periodically to see if it can add it back). But if you fill it back up with 93 its going to realize it can add it back, and when it doesn't knock it will un-learn the long term correction. When you fill it up with 87 again its going to knock and pull timing until it learns to store it as a long term correction again. But in the mean time it does get subjected to the knock. You will not hear the knock, the ECU is pulling the timing before you hear it.
The rule of thumb used to be 6 points in octane decrease needed 8 degrees of timing pulled, the new stuff probably doesn't require as much to be pulled.
Being NA can you get away with it? Probably, but the question is for how long? Lots of people run 87 in their cars that are supposed to get 91 or 93. Some people drive old carbed stuff detonating like crazy. Boosted stuff will absolutely break quickly if its detonated excessively, rings, ring lands, or bearings. The more power you make, the more you pack that combustion chamber, the more damage knock can cause. The 392 is making some pretty healthy NA power for 392 cubes.
It won't break immediately because even if it pulled no timing it should last for a little while. The engineers know a tank of bad gas at some point is a good probability, and they do know people will try to run 87, so there are going to be safeguards. Also they are actually set up to run on 91. It's not a guarantee but I can say for sure, subjecting the engine to more detonation will increase the likelihood of a detonation related failure.
me for even THINKING about running 87 octane fuel ? 
... BANJOnes ! ....well then someone must have actually TINKLED IN YOUR TANK for regular not to work FINE in a 5.7 !
