audi_since_90

never heard a knock, less performance but still adequate.

But I'll stick to 93 anyway.

MisterJJ

Supposed to take 2-3 tankfuls for computer to adjust.

danham

Octane is often misunderstood.

In very simple terms, it can be defined as resistance to detonation. Additives and the refining process, IOW, make high octane fuel burn "slower" than low octane. This does nothing to directly affect mileage, unless of course you use fuel so low in octane that it hampers engine performance.

In the real world, it would take you many months of keeping very precise data to detect a measurable mileage difference between 87 and 93 octane fuel.

-dan

audi_since_90

Seems that way for the 2.0t - not so for the 302 in my '72 Bronco

danham

I had a '70 Econoline van fitted out as a camper, with the 302 "boat anchor" engine.

The single biggest factor in its (lousy) mileage was a malfunctioning automatic choke. I put a manual cable on it and the mileage leaped well up into the lofty realm of 15 or so [g].

Of course I had a bumpy cam and solid lifters and rumbly exhaust too.

So are you saying that you can measure mileage differences between octane grades in the Bronco? I would think that with a nasty old carb and the infamous wobbly static timing on that engine, you'd have enough variables right there to mask any such difference, but I never tried it myself and would be interested to hear your experiences.

-dan

audi_since_90

4bbl Carter AFB w/ man choke+ Elec.Ign. ~12mpg w/93 < 9-10mpg w/87

danham

Guess I shoulda tried rocket fuel, which was CHEAP back then [g].