For what it's worth, I started using higher octane for about a 2 or 3 month period a couple years back. I stopped when my buddy who was driving behind me noticed puffs of black smoke coming out of the tailpipe everytime I wouls "get on it".
Sure enough I had someone else drive and I followed . . . yup, lots of black smoke. I assume it was from the higher octane and "build up".
I stopped using it and haven't noticed anything since . . . it only occured when i was using it. So for me it's good ole 87 until the Superchip shows up
p.s. I didn't notice any difference in mileage or performnace when using it either.
Higher octane fuel doesn't burn any hotter than lower octane. If that were the case it would cause detonation. Higher octane fuel has more resistance to break down into elements that can start the combustion process from the heat in the cylinder, and not a controlled spark.
Higher octane fuel has the same flame front speed as lower octane, there are slight differences, however they are too small to even be a factor.
Gasoline when vaporized/heated starts to degrade into seperate flammable elements, including free Hydrogen, and elements containing Hydrogen. These can burn with much less heat to start them off. What happens in the cylinder is as this uncontrolled flame front burns, it creates more heat in the cylinder, causing the remaing fuel to degrade and auto ignite, the gasses create more pressure as they expand,and are compressed by the piston. More pressure, makes more heat, and the visous cycle continues. Detonation.
High octane fuels have stronger(chemical) Hydrogen bonds, and don't give up free Hydrogen as easily. And they resist breaking down. Heat can come from compression, left over spent gasses, even a burr or piece of carbon on the head or on a piston.
A Ignition spark that comes too early in the cycle, causes the fuel to start it's burn, heat is released as the piston is still compressing the air/fuel mixture, it rapidly degrades from heat of the burn and compression(from the piston, and expanding gasses) , then auto ignites(explodes) and you hear a "knock". This is pre-ignition.
2001 F-150 XLT S-CAB 4.6
93 Kenne-Bell Supercharged Mustang
"Injection is nice, but I perfer being blown!"
When your engine detects knock, it retards the spark. Some engines retard 18 degrees or more.
By reducing the propensity to knock, you reduce the chances of ECM-issued spark retardation.
Where poor gas mileage is the result of retarded ignition spark timing, moving up to a grade of gasoline which eliminates the knock can result in seemingly-irrational improvements in gas mileage.
Spark knock also tends to wipe oil from the inside of the cylinder walls due to the multiple flame-fronts -- and the result is oil consumption. In such cases, elimination of spark knock causes an immediate reduction in oil consumption.
Try a tank of Gasohol Regular -- my non-scientific tests suggest that around here, it has greater knock-resistance than do other Regular gasolines.
Stepping up to a mid-grade octane level to eliminate spark-knock is good for your engine. You shouldn't see any ill-effects from a higher octane. Spark-knock over time will cause engine damage. Only thing bad about going to a higher octane is the higher price.
__________________ Welcome to the United Dependent States of America
Here's some good info on fuels although its not about cars it gives good info on what fuel does and doesn't do. I run 87 octane in my car and truck without problems but I run 108 octane race fuel in my bikes the higher octane makes a big difference in my modified bikes there's much less carbon buildup and my engine runs cooler but I don't see the need for higher octane fuels in a stock car, if your truck doesn't run properly under normal driving conditions with 87 octane I would have it ck'd out to find out why. assuming your truck is basically stock. ck it out http://www.motocrossactionmag.com/readtopten.asp?id=438
I don't care who tells me that I should use 87 octane, I'd never use it. It is cheaper for a reason and makes engines ping everytime. I use only 93, always have. It is not much more money and the engine will always run cleaner and never detonate. I think that the real reason Ford "recommends" 87 octane is so that they can justify selling you that ridiculous "INJECTOR CLEANING SERVICE" at 15,000 miles. With 87 octane, those injectors will be clogged up by 15k miles. Just my 2 cents.
As far as I know the only place higher octane hurts is in the billfold. Ignition knock will definitely hurt your engine. There are a lot of posts on persistent ignition knock in some engines. If you can eliminate it with 89 octane fuel then go for it.
Back in the 60's, SUNOCO gas had a variety of octanes available. You dialed your own at the pump. I ran the highest they had, burned two valves in short order. I believe the higher octane burned longer or something like that. Any way, use a quality 87(cheveron) and your engine will probably not ping, Just my .02
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company