Colorado Mountain Driving Question

[Ford_6L_E350]

Originally Posted by BajaSportsmobile

There is the chance that if there is something wrong with your engine and it is experiencing Pre-Ignition and/or Detonation, that the Knock Sensor on the side of the block will detect this problem and tell the computer to retard the ignition timing. Retarding the timing will result in lower performance and less fuel economy. In this case higher octane will mask the problem, not tell the computer to retard the timing and you will get better performance and economy, in line with what you would have gotten if nothing were wrong with the engine.

http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm

While all that is true, running premium will often increase fuel economy. It has on most every newer, computer controlled engine that I have owned. And the reason has to do with marketing more than anything.

Since the engines have knock sensors and can safely run any grade of gas, the marketing guys insist on saying they use regular. But, because of the higher compression (old engines had 7.5 or 8:1 compression for use with regular, 9 or higher to 1 needed premium. Now, some engines with 10:1 compression spec out regular) the knock sensor will detect some ping and reduce the ignition advance to get rid of the the knock. The reduced ignition advance also reduces power and fuel economy. Hence, premium can increase mileage in some vehicles - not all. My Chevy PU gets
~10% better mileage with premium, and premium costs ~5% more than regular. Guess which grade of fuel I use in it. Same story with the pickup I sold last year. My VW Jetta gets the same mileage on either, so it gets regular.

Mike

[BajaSportsmobile]

Not to dispute anyone's personal experience, but many controlled experiments have proven otherwise.

As hard as the manufacturers struggle to produce higher fuel efficiency averages across their full line of passenger and light duty vehicles to satisfy Government Regulations - if it was true, they would be spec'ing Premium in any vehicle that would get better mpg by using it.

There is plenty of research out there.

Kinda like the P/U owners you see driving around with the Tailgate down, thinking it will improve mileage when exactly the opposite is true.

[Ford_6L_E350]

Baja,

Clearly you mind is made up and nothing will change it.

I've tracked every tank of fuel I've put in my vehicles, and at least my PU's get better mileage with premium than they do with regular. I don't really care if you believe it or not.

Mike

[BajaSportsmobile]

I said I was not going to dispute personal experience - if it works for you, it works for you, I'm good with it.

[BIGVANS]

Just remember, everything BajaSportsmobile said is true according to lengthy test results under controlled circumstances. Just about everyone out there has their own test with their own setup and that explains why “results may vary”.

[BroncoHauler]

Yet it is very true that higher HP, if driven the same as lower HP, will result in better mileage (the premise behind tuners geared for better MPG). The problem being "...driven the same as lower HP...". So if higher octane provides higher HP (don't know if that's true or not), it stands to reason that higher mileage can result.


Herb

[BIGVANS]

Very true! I saw that first hand over the years I worked for an automotive manufacturer. We drove Ford E150 XLT vans all over the US to visit dealerships. The vans with the V6’s consistently had higher overall fuel bills than the V8’s did. After awhile of that they only ordered the V8’s for us.

[regist1]

We just made the trip to Moab, UT and back from Missouri, Took I-70 through Denver. We have a EB, 2WD, loaded and pulling our Jeep CJ8 on a trailer with lots of spare parts. The 5.4L handled the whole trip very well, we did top the pass at the tunnel doing 45mph however we passed several slower moving vehicles on the climb. Best tank of fuel was 12.8mpg and worst 8.4 mpg, average just under 10mpg. We made the trip to Colorado every summer, never had a worry about the 5.4L. The photo was taken from our campsite 2-1/2 hours west of Crested Butte.[photo][/photo]