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I had a supercharged Regal GS, other than performance and MPG there was no noticeable difference with 87. It ran just as well however because of the loss of MPG it was pointless.
I've got a related question for someone who knows.... I drive at a higher elevation -- 4,000 feet asl and above (generally 4-5,000) -- so never get the sea level h.p. ratings. With older cars I'd often run a lower octane rated gas because of this and never had a problem. My new Prius calls for 87 octane but can use E85 (which I don't), but would it be safe to run regular 85 octane at these higher elevations?
I still refer to it as regular, mid grade, and high test. My daily runs on high test only, and I am not even tempted once to cheap out, engine repairs are more expensive than the few cents I would save. (Ever seen pistons from a pinging engine ? )
There is also a difference between brands of gas. My ex had a Buick that would ping on anything but Chevron Supreme. One day I borrowed her car and it was pinging and I asked if she bought some other brand and she admitted she was too busy to drive across town so she bought high test at another station.
I have also filled up my one car at non ethanol stations and not only did the car pull better, but I got substantially better fuel mileage.
Premium is certainly better because it burns a lot cleaner leaving your engine cleaner inside and less emissions. Also you get better mpg's with higher grade fuel.
That is a blanket statement that isn't entirely true and helps continue the myths that "premium" fuel is "better" and 87 octane is cheap crap.
A manufacturer puts the same detergents in each grade of fuel. The only difference is octane rating which is resistance of fuel to burning.
An engine is designed to use a specific fuel octane to make power, and not the other way around. There is no benefit to running higher octane fuel if your car requires 87 octane and is not knocking. You aren't going to make more power or better fuel economy. In fact, it's quite the opposite. Lower octane gas burns more easily and readily and completely.
In cars with high compression, or forced induction, knock can be deadly, so manufacturers typical spec higher octane fuel which has better resistance to preignition. Manufacturers also try to wring every bit of HP out of an engine because Horsepower sells cars. The added timing leads to detonation as well, so the added fuel octane gives a little bit of a buffer to prevent this.
Again, there is no performance gain due to octane levels in fuel. The performance gain is from the ENGINE running the fuel it was designed to work on so the power and fuel economy your car is indirectly related to the octane you run. It's the engine design that makes the power and fuel economy. If the manual says 87...run 87 **. If you think running 87 is being cheap, then you have clearly fallen for the marketing hype pushing people towards higher octanes.
** I put an asterix here because there are exceptions. Often, as cars age the cylinders can become caked in carbon increasing combustion chamber temps and lowering CR slightly. In this situation, even when running the required 87 octane the engine will experience detonation. In this case, the owner should consider running 89 octane or higher to prevent this.
Last edited by BostonMike7; 09-25-2015 at 07:54 AM..
That is a blanket statement that isn't entirely true and helps continue the myths that "premium" fuel is "better" and 87 octane is cheap crap.
A manufacturer puts the same detergents in each grade of fuel. The only difference is octane rating which is resistance of fuel to burning.
An engine is designed to use a specific fuel octane to make power, and not the other way around. There is no benefit to running higher octane fuel if your car requires 87 octane and is not knocking. You aren't going to make more power or better fuel economy. In fact, it's quite the opposite. Lower octane gas burns more easily and readily and completely.
In cars with high compression, or forced induction, knock can be deadly, so manufacturers typical spec higher octane fuel which has better resistance to preignition. Manufacturers also try to wring every bit of HP out of an engine because Horsepower sells cars. The added timing leads to detonation as well, so the added fuel octane gives a little bit of a buffer to prevent this.
Again, there is no performance gain due to octane levels in fuel. The performance gain is from the ENGINE running the fuel it was designed to work on so the power and fuel economy your car is indirectly related to the octane you run. It's the engine design that makes the power and fuel economy. If the manual says 87...run 87 **. If you think running 87 is being cheap, then you have clearly fallen for the marketing hype pushing people towards higher octanes.
** I put an asterix here because there are exceptions. Often, as cars age the cylinders can become caked in carbon increasing combustion chamber temps and lowering CR slightly. In this situation, even when running the required 87 octane the engine will experience detonation. In this case, the owner should consider running 89 octane or higher to prevent this.
If your car is designed for regular unleaded gas running premium will not do any good, you will be wasting your money.
My 91 F250 takes 87 octane Regular unleaded but can carry a cord of wood to heat my home in the Woodstove/Fireplace and also sometimes carries two 20 Gallon propane tank(s) for camping trips or for the Grill/BBQ all are great forms of fuel and get the job done
That car is designed for premium, the one I have now with same engine sans the supercharger could care less....
That makes complete sense. Without the supercharger the effective compression ratio is lower which means you can use a lower grade fuel as knock is less of an issue with lower compression engines.
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