Fuel for Gassers

rk911 wrote:

enblethen wrote:
Waste of money!
Run 87 octane.

waste of $. run whatever octane grade your owner’s manual calls for.

Which is 87 octane.

Octane ratings are, at least in most areas, posted on the pumps. 87 octane is regular gas, 89 is mid range and 91 is premium.
Some areas in the plains states there is 85 octane. My 7.4 TBI doesn't like it.

bukhrn wrote:

rk911 wrote:

enblethen wrote:
Waste of money!
Run 87 octane.

waste of $. run whatever octane grade your owner’s manual calls for.

Which is 87 octane.

i try to not assume.

It’s hard for me to find 91 or 93 non ethanol. But when I had my V-10 Excursion I used 93 non ethanol when I could. Big difference in power and mileage. Having double the fuel capacity at 80 gallons the hit will be harder on the wallet. And while the savings will be small the improved performance will be worth every penny.

Here is a quote from the Ford owners manual for a 2021 F-53 motorhome chassis for the fuel requirements. (which is essentially the same thing it says for my 2013 Ecoboost engine BTW..)

Look it up for yourself at https://owner.ford.com/tools/account/how-tos/owner-manuals.html?year=2021&make=Ford&model=F-53%20Motorhome%20Chassis

Some fuel stations, particularly those in
high altitude areas, offer fuels posted as
regular unleaded gasoline with an octane
rating below 87. The use of these fuels
could result in engine damage that will not
be covered by the vehicle warranty.
For best overall vehicle and engine
performance, premium fuel with an octane
rating of 91 or higher is recommended. The
performance gained by using premium fuel
is most noticeable in hot weather as well
as other conditions, for example when
towing a trailer. See Towing (page 83).
Do not be concerned if the engine
sometimes knocks lightly. However, if the
engine knocks heavily while using fuel with
the recommended octane rating, contact
an authorized dealer to prevent any engine
damage.
We recommend Top Tier detergent
gasolines, where available to help minimize
engine deposits and maintain optimal
vehicle and engine performance.

So yes, 87 is said that it'll work.... But using premium is better when the conditions are more extreme... Take it or leave it. Waste of money or not. In the end, do what works best for your situation.

Good luck! Mitch

Why does premium fuel give more mileage and power?

Richard

RLS7201 wrote:
Why does premium fuel give more mileage and power?

Richard

Richard,

This is a very good question, and I will try to answer it without getting too "engineer" for you.

In times past, engines did not have a computer to control fuel mixture and ignition timing. Now many do.

They listen intently for any knock that is the result of wrong conditions including spark timing. When they hear a knock, the box will start a bunch of corrections that some engineer has tested and advised. Usually the cure is to back off the spark timing. While this will cost some mileage, because the ECU (Engine Control Unit)never gets tired of listening and gets board at sitting still, when it hasn't hear a knock in a while, it will dial in more timing advance. It may also lean out the mixture a little (he can also use fuel to quell a knock). Another correction that many ECU have is to lower the engine temperature. There is not a great deal he can do here, but it is again involved with fuel mixture and sometimes the engine fan speed control.

When you have your very own computer and a raft of sensors, you can pull off all manner of nifty things.

If I lost anybody in here, come back and I will try again.

Matt

We pretty much use the cheapest unleaded fuel available at the pump wherever we happen to be, sometimes 85 octane at high elevations, mostly 86 is what we normally pump in our neck of the woods. We do occasionally add octane booster to a tankful, and it sure does have a positive influence on the miles to empty info from dash display, although from our experience it is wishful thinking on the ECUs part, just a minimal power boost noted.

We have plenty of power and we do traverse many inclines to get to where we are going, which is routinely at high elevations where gassers lose significant power. Now, if we had any performance issues we would get premium, thus far our 40' Monaco gasser is taking the hills using plain ole regular. For our sports cars we use premium as they just flat out perform better, our SUVs, full-size vans, and HD trucks all get regular unleaded.

The only real "octane" issue is if filling up at high elevation where they are allowed to sell lower octane fuel and driving on it to lower elevations/mountains.

When filling in places in the mountains, we always read pump octane rating and put in the octane called for by our vehicle. It may NOT be their regular.

I always ran premium when towing through the Smokies. No knocking !