If you have a truck, does 93 run it any better than 87? In a 2 stroke outboard?

It all depends on the how the computer is tuned. My Ram says to run 91 but I run 87 and can't notice a difference. My Harley says to run 93 and I do. The one time I ran 87 because thats all they had and I NEEDED it I could definitely tell a difference. Running higher than recommended is basically throwing money away in my opinion.

X1

Run whatever the manufacturer recommends for your vehicle... running higher octane does nothing to help anything.

From someone who works in the fuel business,,,,, No. Octane is an anti ping rating. Put the 87 in with the proper two cycle mix, and motor on.

Only truck I've had that it mattered is my 98 Chevy 3/4 ton with a 350 in it. I run 87 in it except when pulling a goose neck then high test, and yes there is a difference.

I run high test non-ethanol in all my small engines. Don't own a boat though.

You might want to take a step back before issuing a blanket statement like that. Octane is a performance rating for all engines, not simply an anti-ping rating. Two strokes don't "ping"...they burn pistons and sleeves with improper octane. Octane required by a 2 stroke outboard (or any other 2 stroke, for that matter) depends on cylinder compression. I have some heads that I run that require 110 octane race gas...some with a little lower compression that requires 100LL...and some that live just fine on 93, but would blow the engine on 87.

In a 2 stroke, one should run what the manufacturer recommends in a non-modified engine. In a 4 stroke, it won't hurt a thing to try a one-step lower octane in a tank to see if it causes your engine to ping. If it does, go back to what's recommended. If it doesn't, run it. If your vehicle is still under warranty, run what is recommended by the manufacturer and don't take chances in voiding your warranty.

Contrary to popular belief, 87 octane produces more horsepower than 89, 93, or any higher octane gasoline...even race gas. It burns hotter, producing more btu's. Problem is, its rate of detonation is much less controlled than higher octane fuels. The higher the octane, the cooler the fuel burns and the more controlled the detonation. Higher compression is required to "use" the higher octanes.

Using a higher octane gasoline than is needed (required) can result in unburned fuel simply exiting the engine through the exhaust...a complete waste. Using a lower octane gasoline than needed can be catastrophic...especially in a 2 stroke.

EDIT: My response wasn't necessarily aimed at you, quailman. I realize you were probably assuming that he meant is it better to run 93 in an outboard that you already run 87 in (and already determined that it's ok to do so). I'm simply trying to get everyone to not assume that all outboards are designed to run on 87 octane gasoline.

The higher the octane the cooler it burns

The octane number of a gasoline is a measure of its resistance to detonation. Usually using a higher octane than the engine is rated for reduces performance & increases emissions. In an old, carbon deposit filled engine, a higher octane gasoline may make it run better by reducing the pre-ignition caused by the carbon deposits.

Higher octane fuel burns cooler. This also helps with detonation. This is how it was explained to me when I sold fuel.

I have always wondered just how accurate the octane is at the fuel pump. Especially since most fuels are delivered via pipeline to tank farms. There has to be some mixing going on.

My FIL had a tank farm and all fuel came by barge and left in tanker trucks. He sold to mostly independent service stations. The fuel was the same. The additives were added to the tanker when it was loaded to make it different.

This is true. Shell, Chevron, and the others add their own additives to make it better than the next guys. Or so they say.