Can I Run Race Gas In My Street Car?

Race gas is for race cars, period! Street cars usually have static compression ratios of between 8:1 and upwards of 11:1, but it's usually in the 9:1 and 10:1 area on most performance "street" engines.

The problem with running race gas is that if you don't have the compression to compress the fuel and air enough, you'll actually run SLOWER! I see this happen all of the time at the race track where during the Wednesday night drags, people with bone stock cars will go fuel-up with 110 or 114 octane race gas and wonder why they aren't running as quick, or as fast as usual.

Contrary to popular belief, the more octane in gas, the COOLER and SLOWER the burn is, and more importantly, the more compression is required to get that fuel to release its energy. Higher octane (in layman's terms) simply means that it's a more controlled burn under higher pressure conditions, such as high compression or high boost / nitrous engines, etc. What happens to regular gas if you have too much compression or too much timing? You ping (detonate). Detonation literally destroys engines. It breaks piston tops, rings, blows head gaskets, etc. It's not good. So how do you remedy that? You use fuel with a higher octane rating to get that uncontrolled burn back under control. The more compression you have, or the more boost you're running, the more octane you need (in general terms) to keep it under control and to keep detonation away.

When gas becomes unstable in a burn, it goes from a "push" on the piston top, to a slam, like hitting it with a sledge hammer! Go push a car 10 feet. It isn't that hard if you just lean into it and give it a nice, steady (controlled) push. Now stand behind it and hit it with a sledge hammer. You hit it really hard. In fact much harder than you did by just pushing on it, and MUCH harder than you could with just your hand, but did it move? Nope, but you sure as hell just destroyed the trunk! That is the difference between a controlled "push" and an out of control "slam" or "detonation". It breaks pistons, blows head gaskets, cracks rings, hammers bearings, stipples the piston top and combustion chamber surfaces, and a few other undesirable things as well.

To keep higher compression race engines under control, a higher octane fuel is used to keep that "push" from becoming an out of control sledgehammer hit. Without the higher compression, race fuel doesn't burn real well. Alcohol is no different. If you light a teaspoon full of gas, it flashes up into a pretty big, bright yellow flame. If you do the same with alcohol, it barely lights, has a clear / bluish flame and doesn't throw much heat. It takes more alcohol "volume" to make power in an engine to the tune of about 2.7 times more liquid volume compared to gas, but with that 2.7 times more fluid, it brings more power with it than gas does when compressed, and alcohol, much like race gas, likes higher compression ratios to release that energy. Typically, alcohol engines start at about 12:1 compression and go up from there to upwards of 16:1. Do that with pump gas and it will knock itself apart, literally.

I guess a good analogy would be how people refer to "jet fuel" as if it is somehow super hot and volatile, almost explosive, when in fact, all jet fuel is, is just clean Kerosene. Not so scary sounding now, is it? High octane race fuel is sort of the same way. Nitro won't even burn unless it's compressed. You can literally put a match out in it, but under compression, well.... it's a whole other story!

So, the moral of the story is; unless you have at least 12:1 compression (of more), do not run any 110 octane or higher race gas in it or you'll go slower. If you have 10:1 - 11:1, you can run up to about 100 octane and be fine, but if you have in the 9:1 area, don't even bother.

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