Can octane be to high?

If it's leaded fuel, you don't want to run too much of it.

Like Steve says, in a stock Mark VIII you would not see any benefit. In a heavily modified vehicle, it allows more advanced timing and higher compression without knock.
 
Thanks,
yes it is expensive $8.00/gal. I am not planning on using it I was just curious. I wonder why they are selling it here. There are no tracks near by, but I guess there must be enough modified cars around to create a demand.
 
Thanks,
yes it is expensive $8.00/gal. I am not planning on using it I was just curious. I wonder why they are selling it here. There are no tracks near by, but I guess there must be enough modified cars around to create a demand.

I'd love to find that around here. :D I can get 105 unleaded only @ the track.

I believe that high octane fuel actually burns a bit slower, so if you don't need it, it would actually hurt power (but not the engine).
 
Higher octane fuels actually contain marginally less energy. They also burn slower.

Octane is a measure of resistance to knock. That is all it is. More octane does not equal more power or more energy. Engines that are more likely to knock - high compression, high boost, and so forth - can benefit from higher octane fuels.

In an engine that would otherwise knock with more advanced timing, higher octane allows more advanced timing without knock. This generally applies to Mark VIII engines - but only up to a point. These engines were designed for premium fuel, and can benefit from those fuels by advancing timing, or rather, not retarding timing. If you want to know if your car could use higher octane, run an autotap or similar and look at what the knock sensors are saying.

As a general rule, the car will make the most power with the lowest octane fuel it can safely run.

If you want to run higher octane, look into E85. It's about 105 octane and a lot cheaper than race gas. Everything in the fuel system has to be safe for alcohol, though, and you'll burn about 30% more fuel because ethanol contains less energy than gasoline.

Too high an octane can cause damage to an engine, because the fuel is not done burning when the exhaust valves open. You lose power and put your engine at risk.

Lead probably won't hurt your engine but will kill your cats and your o2 sensors probably won't like it.
 
Higher octane fuels actually contain marginally less energy. They also burn slower.

Octane is a measure of resistance to knock. That is all it is. More octane does not equal more power or more energy. Engines that are more likely to knock - high compression, high boost, and so forth - can benefit from higher octane fuels.

In an engine that would otherwise knock with more advanced timing, higher octane allows more advanced timing without knock. This generally applies to Mark VIII engines - but only up to a point. These engines were designed for premium fuel, and can benefit from those fuels by advancing timing, or rather, not retarding timing. If you want to know if your car could use higher octane, run an autotap or similar and look at what the knock sensors are saying.

As a general rule, the car will make the most power with the lowest octane fuel it can safely run.

If you want to run higher octane, look into E85. It's about 105 octane and a lot cheaper than race gas. Everything in the fuel system has to be safe for alcohol, though, and you'll burn about 30% more fuel because ethanol contains less energy than gasoline.

Too high an octane can cause damage to an engine, because the fuel is not done burning when the exhaust valves open. You lose power and put your engine at risk.

Lead probably won't hurt your engine but will kill your cats and your o2 sensors probably won't like it.

Good explanation. Should we make this a 'sticky'?
 
if you run E85 you will be way to lean without a computer program.

But the car will run on it without a program just not well and its not good for anything in the car.
 
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