Well this morning I had to go on about a 300 mile trip, about 20 miles in I noticed I was on about an eighth of a tank so at 4:00 this morning I pulled into a Exxon and filled it up, about half full I noticed I was putting Premium on accident, well other then the 20 cent price gouge I didnt care at the point in time. Well to get to the point of the story, this trip envloves alot of passing, the kind where you pop out floor it go aroud three cars and realise you are going over 90 by the time you get there, well I have made this trip alot in the Explorer, but this time it really felt alot peppier. I went around 2 cars once and by the time I got around I was going 105 ! (From 55, and they were close together) it also had a harder kick down, like when I first bought it, the wiplash hard kind ! My question is could the premium gas of done this, becuse if it did I don't mind the 20 cents extra!

P.S. 2000 EB 52000 miles V8

 

Mostly what premium does is allow the engine to run a more advanced timing (more power) without pinging and detonation. It's difficult to feel actual gains by seat of the pants....it's easy to be fooled. The only real way is to do it on a dyno.

 

Unless you go from 87 octane to race fuel, but that's a REAL price gouge; $4+ a gallon.

 

It is my understanding that higher octane gas simply burns slower than regular gas. The result of the slower burning is the reduction of “knocking” which is the gas/air mixture igniting too violently. The benefit from higher octane is the ability to run higher compression and therefore getting more power out of the gas/air mixture. I’m of the understanding that simply using high octane gas does not produce more power in a low compression engine. Perhaps some of the more educated/experienced users can address this issue. I’d like to know how it all actually works.

 

Computer controlled engines may allow a little extra timing with premium fuel, but like said, it would be unnoticable.

I'm running 87 in my Audi this time to see if there is a diff from the recommended 91. Owner's manual says you can run either, but recommends 91.

So far I can't tell any diff.

 

The chemistry of it is that higher octane fuel actually has slightly LESS energy content per gallon. The only way it is an advantage is if the engine pings on lower grades. Some engines do have knock sensors that will retard the timing, reducing power and mileage, if ping is detected. You might try a dose of Chevron Techron if carbon has built up and you are pinging on 87. That worked for my 2.9L Ranger.

Jim

 

I have always found premium fuels to make my vehicles perform better. They allow for better throttle response, and actually better mileage. The local Sunoco station to me runs 10 cents off 93 octane on Thursdays (brings the price to a few cents above mid grade). Can you figure out which day I strategically fill my trucks up??


Rich

 

Most of the time on the newer computer controlled vehicles, if you are pinging on the reccomended grade, you have other problems and not bad gas.

In cases like this going to a higher grade is merely a expensive band-aid in the long run.

 

Just because it has a higher resistance to detonation does NOT mean it burns slower. In fact usually it will burn faster (higher octane), I just recently learned this myself. Leaded race gas does burn slower, but thats another story. Some engines do make better TQ w/ higher octane (and better MPG), even those w/ no knock sensors or det. problems, some don't change at all, some (very rarely) lose power. I used to be on the other side of the fence (low of octane as possible), because of some incorrect things I had read, but experience has changed my mind. It also varies between brands, epecially as you get to higher (100-105) race fuels. Some of them have shown to make consistent 4% power increases, all else equal, some just allow more comp/timing. VERY complicated subject, engine size, state of tune, mechanical condition, types of metals used (piston, cyl, head etc.),comp ratio, fuel temp, air temp, engine temp and many other variables all affect this. And it only takes one thing being differnet between engines to potentially change the outcome. If you guys disagree I'll be happy to pull up some documents w/ proof, just don't have them handy at the moment

Also from what I understand (meaning this could be hogwash) Gas companies don't advertise premium as more powerful since in some cases it won't be and they'll be sued. Personal experience has shown V8's tend to benefit more from the bump-up than say, a Honda Civic. Again higher octane does not neccessarily mean slower burning.

Superranger: Pinging isn't neccessarily and indication of anything other than needing a different flash on newer cars. Not saying your wrong, it can be the sign of a more serious issue, but usually (almost always on newer cars) it's not and you will be fine sticking w/ a grade higher, and keeping the power that would (usually) be taken when they re-flash it (retard timing). I definatly understand the mentality of "it says 87, it should use 87" though. I just don't consider more power a problem

 

Well, a higher octane fuel doesn't burn slower, it just doesn't ignite as quickly when compressed (as in a gas engine). The higher octane works in a high compression motor not by burning more slowly, but by igniting at a higher pressure and therefore preventing knocking. About the "slower burning" idea. Take 2 identical amounts of 87 and 93 octane and ignite them at the same time. Now, I have never done this, but I would guess that they would both burn at the same rate and extinguish at the same time.