Rick's Free Auto Repair Advice

Does premium gas increase power

Will premium gas increase power

Every day people ask “Will premium gas increase power?” And I’m always amazed by the answers they get. So I’d like to straighten this out. If your vehicle requires 87 octane and you use a higher octane gas, you’re wasting your money. You will NOT get more power. Octane has NOTHING to do with power.

Premium gas will provide more power in these conditions

If your engine was designed for premium gas, but you fill it with lower octane regular gas, you will lose some power. The engine computer will detect knock and retard ignition timing. If you then refill with premium gas, the engine computer will eventually move timing back to the optimal setting and you will regain power.

But putting premium gas in an engine designed for regular gas will not give you any more power.

What is premium gas?

Premium gas has a higher octane rating. But octane refers only to the gasoline’s ability to resist igniting from the heat of compression. Octane does NOT add any ENERGY to the gasoline. Instead, think of octane as a FLAME RETARDANT.

One of the laws of physics is that gasses heat up when they’re compressed. So in a high compression engine, that heat can ignite the gasoline before the spark plug fires. That causes a flame front to start pushing back against the piston before its reached the peak of its upward travel. That pushback damages the piston and crankshaft bearings.

To get more power out of gasoline, some engines are designed to compress the air/fuel mixture more. Those engines require more octane to prevent detonation. So a 91 octane is more resistant to detonation than 87 octane. And, on really high compression engines or older engines with turbos, some car makers require 93 octane.

If you put 87 octane in an engine that requires 93, the engine computer will retard timing to compensate. But there are limits to how much it can alter the timing. See this post for more information.

In the meantime, don’t let ANYONE tell you that higher octane provides more power.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat

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