93 Octane and Higher Engine Temps????

[winnie32v]

I got into some bad gas in the spring and filled my tank with 93 Octane gas. Runs OK now.
BUT, a friend with the same V-10 engine told me that the 93 Octane would burn hotter and that I should watch my heads so I didn't overheat.....etc, etc.............

I have driven my unit about 50 miles and didn't see the temp gauge move above where it always is.

So, any comments or input would be appreciated.

I also wanted to go from Pa. to Fla. in the fall and try to use only 93 octane as a test for performance and gas mileage but am not sure this would be a good idea now.

Please advise.
Thanks for the time.

[Winepress]

It doesn't burn hotter than lower octane it just has more additives to prevent pre ignition in the combustion chamber. With modern engine controls, you should not see any difference.
Wish we could get 93 here in California, but the wise ones have determined that 91 is all we need.


Try and live up to your dogs opinion of you.

[C-Leigh Racing]

Lower the octane rating, faster the burn rate, meaning in the cylinder when the piston is at top dead center & the spark plug sparks & ignites the gas vapor, that flame front expands from the spark plug outward until it burns up all of the gas vapor at the cylinder wall.
When that happens, all the vapor being burnt up, you'll get detonation or spark knock some say, but if you use a higher octane rated gas, which will burn slower, that flame front will not move as fast & will stop the spark knock from not burning up all the vapor completely out to the cylinder wall.
Cylinder compression amount & the gas octane rating have to match each other or you'll start melting those aluminum pistons.
Neil

[John Hilley]

The engine tune is optimized for 87 octane, but the 93 octane shouldn't hurt any thing. You won't get more performance or better mileage.

[House Husband]

Originally Posted by C-Leigh Racing

Lower the octane rating, faster the burn rate, meaning in the cylinder when the piston is at top dead center & the spark plug sparks & ignites the gas vapor, that flame front expands from the spark plug outward until it burns up all of the gas vapor at the cylinder wall.
When that happens, all the vapor being burnt up, you'll get detonation or spark knock some say, but if you use a higher octane rated gas, which will burn slower, that flame front will not move as fast & will stop the spark knock from not burning up all the vapor completely out to the cylinder wall.
Cylinder compression amount & the gas octane rating have to match each other or you'll start melting those aluminum pistons.
Neil

I don't think so. The burn rate should stay the same no mater what octane. Unless you want to throw in some formula for adding alcohol, which might change burn rate.
As already noted, Higher octane fuel reduces pre ignition.
You could change my mind if you can provide documentation from an undisputable source.

Richard

[Winepress]

Agree. You could also add more air to change the burn rate, but you are correct that today's fuels have the same burn rate. Octane rating does not relate to the energy content of the fuel. It doesn't burn any hotter. The numbers, 87, 89, etc. are just ratings for the level of resistance to detonation,it is not an indicator of "performance"




Try and live up to your dogs opinion of you.

[aauummm]

Originally Posted by winnie32v

I got into some bad gas in the spring and filled my tank with 93 Octane gas. Runs OK now.
BUT, a friend with the same V-10 engine told me that the 93 Octane would burn hotter and that I should watch my heads so I didn't overheat.....etc, etc.............

I have driven my unit about 50 miles and didn't see the temp gauge move above where it always is.

So, any comments or input would be appreciated.

I also wanted to go from Pa. to Fla. in the fall and try to use only 93 octane as a test for performance and gas mileage but am not sure this would be a good idea now.

Please advise.
Thanks for the time.

Paying a Premium for High Octane Gasoline? | Consumer Information

[NeilV]

Some may actually see a decrease in fuel economy with the premium gas in a low compression engine as it really is meant for high compression engines. At a compression ration of 8:1/9:1 you should use regular while at 10:1 mid grade is a good choice and at 11:1 and above you should be using premium.

The V10 comes in around 9:1 so it is designed for regular gas.

One benefit to premium can be that they typically have three times the minimum amount of detergents required by the EPA to keep your engine running clean and that they usually have some form of pressure additive to protect the valves as a replacement to the lead and other metals that were used in the past. On a low compression engine like the V10 though you really don't need the extra pressure additives and you can every few fill-ups just throw in a can of fuel system cleaner.

We can get isolated from this due to the computer controls on the engines and the automatic valve adjusters. A few years back I had a carbureted motorcycle with manual valve adjusters and no computer so I found out very quickly what effect using regular gas had on the valves in an engine with a 10:1 compression ratio as I was having to adjust the valves every month due to the valve seats sinking into the aluminum head from lack of a pressure additive however going to mid grade or premium made it so I had to adjust the valves much less often. I tried using regular in the winter months to see if it was just in the Heat of Summer that I had to use a premium grade to extend the time frame between valve adjustments on the motorcycle and found I was back to adjusting them monthly on regular gas.

[94-Newmar]

Originally Posted by RLS7201

I don't think so. The burn rate should stay the same no mater what octane. Unless you want to throw in some formula for adding alcohol, which might change burn rate.
As already noted, Higher octane fuel reduces pre ignition.
You could change my mind if you can provide documentation from an undisputable source.

Richard

Here's an article from Sunoco's racing fuel division that should clear up just about everything: Sunoco Race Fuels | Beyond Octane

[Murf2u]

Originally Posted by Winepress

With modern engine controls, you should not see any difference.

Wish we could get 93 here in California, but the wise ones have determined that 91 is all we need.

Do you have an old high compression engine or something that requires more than 87 octane fuel?

It'll never pass muster on the road, but 100LL sure wakes up a performance motor.

[Winepress]

Yes, I have a car with a turbo. It would run stronger with a higher octane. Manual states 91 octane as the lowest recommended.


Try and live up to your dogs opinion of you.

[Murf2u]

If it's an import check the manual to see 'which' 91 octane it needs.

The European (and most of the rest of the world) method is different than the method we use here to determine octane rating. They use the RON system, in North America we use an average of the RON and MON system.