Regular fuel vs. Premium Fuel

[hj60]

All gas (& oil) comes from the same pipe, but it's separated in a refracting tower into an unimaginable number of products before it ends up at your filling station.

What I mean is the finished product arrives in Phoenix from the same pipe. Then the companies add their additive packages at the transfer station before trucking it off to filling stations.

 

[paultaegel]

Octane Ratings

Unless some of you guys are running high compression motors, nobody should see better performance with high octane. An easy way to put it is, the resistance to knock is related to how fast the fuel burns. The higher octanes burn slower than low octane. That is why if you run forced induction or have a high compression, you run the higher octane for the slower burn, more resistant to knock properties. Because high compression and forced induction create greater heat in the combustion chamber, the low octane fuel tends to pre-ignite, which is, of course, knock. With our low compression motors from the factory, theoretically we should see better performance with lower octane because it is burning faster. To each his own.

Excellent point. You're absolutely correct -- an FJ is not a racecar: the lower octane fuel will deliver better performance in the lower compression 2F engine. A lot of people have the impression that more octane equals more punch. Lots of additive makers contribute to this misconception by naming octane boosters "The Outlaw" and suggesting that there are octane levels that aren't "street legal." This is pure bullsh*t. The additive makes the fuel a higher octane and therefore LESS volatile.

 

[hank14]

I'm pinging some right now with regular 87 Octane, and I think everything's tuned to factory specs (I'll check the timing again now that I've got all the smog stuff working). Does the wonderful- earth, ozone layer, and farmer's pocketbook saving 10% ethanol added have anything to do with pinging?

 

[ad20k]

I'm pinging some right now with regular 87 Octane, and I think everything's tuned to factory specs (I'll check the timing again now that I've got all the smog stuff working). Does the wonderful- earth, ozone layer, and farmer's pocketbook saving 10% ethanol added have anything to do with pinging?

Not an answer to your question, but I had a long standing pinging problem with my 62 running 87. I agonized over getting the timing set to factory spec for some time, then tossed the timing light in the tool chest and started adjusting by ear. I put a 12mm wrench in my center consol and pulled over every time I heard it ping and nudged the distributor clockwise (less advance) bit by bit until it went away. Now it runs great without any noticable loss in performance, no pinging on 87 octane. This is after a recent rebuild with 165-170 psi on all cylinders, getting 15-17mpg. I never tried higher octane gas but don't feel there is much to gain at this point.

 

[DirtyLittleSecret]

Excellent point. You're absolutely correct -- an FJ is not a racecar: the lower octane fuel will deliver better performance in the lower compression 2F engine. A lot of people have the impression that more octane equals more punch. Lots of additive makers contribute to this misconception by naming octane boosters "The Outlaw" and suggesting that there are octane levels that aren't "street legal." This is pure bullsh*t. The additive makes the fuel a higher octane and therefore LESS volatile.

Nice to see this thread since I've been touting it for years with my greasemonkey buddies...

 

[deaddrift]

Is a three-year-plus thread resurrection the record here on Mud?

ha ha

 

[DirtyLittleSecret]

Is a three-year-plus thread resurrection the record here on Mud?

ha ha

By no means...just means we're a little slow (I know I am).

 

[hank14]

Not an answer to your question, but I had a long standing pinging problem with my 62 running 87. I agonized over getting the timing set to factory spec for some time, then tossed the timing light in the tool chest and started adjusting by ear. I put a 12mm wrench in my center consol and pulled over every time I heard it ping and nudged the distributor clockwise (less advance) bit by bit until it went away. Now it runs great without any noticable loss in performance, no pinging on 87 octane. This is after a recent rebuild with 165-170 psi on all cylinders, getting 15-17mpg. I never tried higher octane gas but don't feel there is much to gain at this point.

That's what I'm planning next- I've had it about a year, been working on it slowly, and am planning on pulling the valve cover, adjusting the valves, and replacing the spark plugs again to see if it will pass smog in TX. I'm not in a smog area, but I want it right since it's almost 100% stock and I'm picky. If it's still pinging, I'll do what you suggest with the timing. Thanks!

 

[stinkyfj60]

With the low compression of the 2F there is no real need for higher octane.

Even my 390 in my wood truck runs fine on lower premium.

I had a '68GTO with a 400 that had 10.75:1 compression, it liked a higher octane fuel...

 

[red_dirt_okie]

If your timing is overly advanced you WILL run better on higher octane fuel. I guess the real question is "Do you gain noticeable performance from a 2f by advancing the timing?"

 

[rover67]

i like the post about $3.00 gas..

 

[Skilter]

Summertime I run a blend of 3/4 regular and 1/4 mid grade due to the additives they put in the summertime formula for emissions. In winter, I run all regular 87 grade.