2019 Canadian Truck King Challenge

ShinerBock wrote:

Lessmore wrote:

ShinerBock wrote:

ksss wrote:
I have never owned a 6.2L in a pickup, I have several friends that have them. They run midgrade, which here is 87 they have never had issue. I have an LSA in my Camaro. I run 91 in that only, we don't have 93 octane here. I don't know what the fall off in mpg is, but unless the pickup can sense the octane level and detunes itself, there is no more energy in a gallon of 91-93 than there is in a gallon of lessor octane. The knocking, that is addressed by the higher octane. I don't know anyone here that has that issue but not to say someone hasn't.

Are they the new L86 6.2L engines? The L86 is direct injected and have a much higher compression ratio of 11.5:1 than the older LSA 6.2L that was 9.1:1.

My 2015 Impala has the DOHC V6, 4 valves per cylinder, 305 hp engine with a compression ratio somewhere in the 11 to 1 area. The manual says regular gas is fine and out here that is 87 Octane. I think I have used 85 octane regular gas...in some areas of the states...with no issues.

I stated compression ratio and direct injection because that is the major difference between the old 6.2L and new one. However, it is not just about compression ratio that determines the octane requirement.

Combustion chamber size(the bigger the chamber the more timing is needed), RPM, emission controls, and other variables also plays a big role in engine timing/tuning. Your small chamber 3.6L may be tuned to achieve that 305 hp with regular fuel and can adjust timing(to an extent) for more power with premium fuel. The large chambered 6.2L on the other hand may be tuned for higher octane to achieve its 420 hp power levels, but reduces power on lower octanes

Wide band knock sensor will allow for some timing adjustment, but conditions can exceed the amount that can be adjusted.

Yeah, knocking is frequently caused by spontaneous combustion from heat of combustion just like in a diesel. If that is going on you can take the spark plugs out and throw them away and you will still have knock. Backing off the throttle and keeping the revs up will help some but the control systems will fight you on that in an attempt to keep up fuel economy.

I am trying to avoid taking a side on whether 93 octane is required but the wording in the manual is very suggestive that it is. I wonder what happens to your warrantee if you use 87 octane? That may be the most important consideration. Either way, the wording is strong enough that I consider that engine not suitable for my use and will stick with my EcoBoost that delivers similar results with regular fuel.