Non-tuned 4.0 Mustang runs better on 89 octane vs 87?
10-04-2011, 04:29 AM
#11
3rd Gear Member
Join Date: Mar 2010
Location: Clinton, Tennessee
Posts: 761
On my stock 4.0 in my 2000 Explorer it pinged pretty bad on 87 so I always ran 89 in it, it also got about 2 miles more per gallon on the 89. I ran 89 in my Mustang when the station was out of regular and I was out of gas and put 89 in it, no change in the Seat of the pants HP but mileage did go down.
10-13-2011, 10:26 AM
#12
Join Date: Oct 2011
Location: AZ
Posts: 40
BETTER GAS IS ALWAYS BETTER
I FOUND OUT PUTTING A HIGHER OCTANE FUEL IN THE CAR YOU GET BETTER GAS MILAGE AND PERFORMANCE NOT A HUGE DIFFRENCE .BUT THINK OF THIS THIS WAY WOULD YOU PUT CRAPY OIL IN YOUR CAR .SAME THING GOES FOR GAS THE HIGHER OCTANE THE LESS ADDATIVES YOU HAVE TO PUT IN IT .
10-15-2011, 12:02 PM
#13
2nd Gear Member
Join Date: Mar 2010
Location: Toronto, Ontario
Posts: 417
On another note, I think I'll try running 89 for a couple of weeks, see if it makes a difference.
10-15-2011, 01:57 PM
#14
Cut & Paste Expert
Join Date: May 2007
Location: NW Arkansas
Posts: 13,322
The 89 might have been 'Ethanol free'.
Octane ratings do not add any BTUs to the petrol.
Higher octane ratings make the petrol less susceptible
to pre-ignition or detonation allowing for higher compression
ratios and more timing that equals more HP out of any given
displacement engine.
Without a tune 89 is a waste unless your 87 is really 87 + 10% ethanol.
Adding 10% Ethanol reduces the BTU content of the petrol by 10%.
Find some Ethanol free fuel thats 87 and try that on the ol butt dyno.
I did and yikes, its gravitating.
11-04-2011, 07:39 PM
#15
Join Date: Nov 2011
Location: Virginia
Posts: 8
I have an 07 4.0L and it runs great on 87. You just got cheap gas.
If you are getting better gas mileage it is because your foot is feeling a little liter on this tank as opposed to the last tank. The owners manual says 87. No need to spend the extra money.
If you are getting better gas mileage it is because your foot is feeling a little liter on this tank as opposed to the last tank. The owners manual says 87. No need to spend the extra money.
11-17-2011, 10:20 AM
#17
Moderator
Join Date: May 2006
Location: Michigan again!
Posts: 8,579
No, higher octane gas isn't "better" than lower octane. Putting 87 octane in a car tuned for 87 doesn't mean you are running crappy gas - your car is tuned for that octane and can't take advantage of the different octane burning pattern.
Octane has nothing to do with the amount of energy in the fuel. High octane fuel will not give any significant increase in performance in a low compression engine. You do not see any benefit from high octane fuel unless you have a high compression engine.
The octane rating is the fuel's resistance to spontaneous combustion under compression. The higher the octane rating, the more compression it takes to make the fuel spontaneously ignite.
The octane rating is the fuel's resistance to spontaneous combustion under compression. The higher the octane rating, the more compression it takes to make the fuel spontaneously ignite.
You might want to read this: http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm
The Low-Down on High Octane Gasoline
Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner's manual.
The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.
Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.
Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner's manual.
The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.
Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.
Will higher octane gasoline clean your engine better?
As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car's engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.
As a rule, high octane gasoline does not outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car's engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.
11-30-2011, 08:20 PM
#18
I started using 91 gas over a month ago in my stock v6 mustang, to prepare for my CAI and tune i just ordered (still waiting...
)
I noticed a slight difference. Not a major one- but i noticed my car had a little more response to the throttle, and my engine ran MUCHH smoother. It used to act up with boggs in the engine with 87. I get smoother results with 91 stock.
)I noticed a slight difference. Not a major one- but i noticed my car had a little more response to the throttle, and my engine ran MUCHH smoother. It used to act up with boggs in the engine with 87. I get smoother results with 91 stock.
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