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Actually, these ls motors run better on super. They have a higher compression ratio and the “premium” super, higher octane, whatever you want to call it, gives it a better combustion which we all know.. a better, more complete, clean burn equals more horses and better mileage
) does not suddenly make your car a high-performance machine. It also does not mean your engine is burning cleaner or more complete. In fact, it could be the opposite. If the engine can't benefit from higher octane by it's mechanical design or tuning, then it won't. A fuel's octane rating is basically how much that fuel can be compressed before it spontaneously ignites. Lower octane ignites more easily, higher octane takes more pressure to make it ignite. Another way to word it is that higher octane is less "flammable" than lower octane.
Not talking about ‘cleaning the engine with premium’ a higher compression engine, like the ls, benefits from higher octane. Because higher octane gas burns slower, it is more resistant to knock when subjected to higher RPM and cylinder pressures. Compression ratios also factor into cylinder pressures. Higher ratios cause highercylinder pressures and therefore cause the engine to be more susceptible to pre-detonation or knock."Premium" has nothing to do with the cleanliness of the fuel in regards to what it's supposed to reference, which is the higher octane level. Yes, some brands may mix in extra detergents or whatever to their premium and not in their regular, but I doubt they go through the trouble. It's really all about octane and to sell it, they call it all of these names that make you feel like you're doing your engine and fuel system a favor. Pouring a fuel into your tank labeled "Premium" or "Super" or "Ultra" or "V-Power" (V-Taaaaaaaaaaack!!!
So, how can a fuel that's MORE resistant to burning burn more completely and cleaner? It doesn't. In general, the LS engine platform, although rated for 87 octane, is mechanically designed to run more optimally on 89 or higher. I experience noticeable differences in performance when running 89 and there may be even more when on 91-93. This doesn't mean the fuel is making more power. It's because the compression ratio (dynamic more so than static) and stock tuning maps are a hair too aggressive for 87. On hot days or with crappy gas or when under elevated loads or even with just more spirited driving, the low octane gas that ignites so easily, well, it ignites TOO easily. This is what leads to detonation ("pinging", "spark knock", etc.). The PCM detects this via the knock sensors and retards the timing, which reduces engine power. For someone that drives it forever on 87 may be pleasantly surprised if they tried 89 or higher. To them, it would be like they just filled up with a tank of "supercharged gasoline" when all they did was allow the engine to operate optimally and produce the power it was always meant to produce in the first place. In an engine that is NOT as "high-strung" (lower compression, less aggressive timing, etc.), running a fuel that is more reluctant to burn (high octane) at least means reduced power and likely unburnt fuel, which means dirtier combustion chambers and eventually clogged cats. A fuel-injected engine constantly monitors and adjusts the fueling so the unburnt fuel problem is mildly mitigated, but it still occurs, especially under WOT.
Personally, I'd rather let the engine run how it should and not be hindered by the PCM reacting in efforts to keep the engine from self-destructing.
