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Report Your Local Gas Prices Here (retired discussion, please see the new one)
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Rocky
gas at the local exxon is still 309x x=9.
The oil companies have done their best over the decades to imply (if not outrightly state) that higher octane gas is "better." It's not, just different. Please read the following -- I know it's lengthy.
I think that it is highly unlikely that your car (or any car for that matter) will get better mileage with a grade of fuel that is higher than what the manufacturer calls for in the manual.
Why? Simple, if an engine is designed to operate at peak efficiency, said efficiency will degrade to a certain degree as you move away from the recommended fuel grade.
The whole thing is that the different grades of fuel take different lengths of time between the spark event and when the flame front is fully organized. The lower the grade of fuel, the quicker the flame front is developed.
Engines are designed with certain combustion chamber configurations and compression ratios so that when fed the proper grade of fuel, the Peak Pressure Point (PPP), which should theoretically happen at about 15 degrees after TDC [top dead center]. If you use a lower grade of fuel than what is called for, your PPP occurs sooner at say 10 degrees after TDC, and that is where "Pinging" or "Detonation" (sorry Shifty, "Pre-ignition" is where the fuel combusts on its own before the spark event, hence the name "Pre-ignition", this condition WILL destroy an engine very quickly) occurs.
Detonation is in essence the flash combustion (instead of the flame front smoothly burning all of the fuel in the combustion chamber) of some amount of end gas due to the higher pressures associated with the early PPP. The issue here is the degree of detonation, a very little is considered harmless by some and beneficial by others, personally, I'll refrain from comment. Moderate detonation, where you can hear light "Pinging", is where the problems can start.
A brief Pinging event when you first press the throttle is most likely harmless, however, if said Pinging continues, engine damage (in the form of burned valves, burned pistons and broken rings) can result. Severe detonation, a condition which is extremely rare in modern engines, can destroy an engine in a matter of moments.
The flip side of using too low of a grade of fuel is using too high of a grade of fuel. Now the flame front takes too long to get fully organized, resulting a late PPP of say 18-20 degrees. Now what happens is that your fuel is far from being fully burned before the exhaust valve opens, and as such, the flame front continues burning fuel right past the valve and into the exhaust manifold. Basically harmless, but since it doesn't convert the resultant heat into mechanical energy, it is also highly inefficient.
Now let us add modern electronics into the equation. My BMW, which carries a "Premium" fuel recommendation from the manufacturer, can run safely on lower grade fuels, however, the computer senses that detonation is occurring and retards the spark event. The delayed spark keeps the PPP at that engines' designed in optimum point. Unfortunately, since the ignition has been retarded (resulting in cooler temperatures in the chamber), the engine is not running at peak thermal efficiency, hence lower mileage and power.
Regarding cars that carry a "Regular" fuel recommendation, it is unlikely that the engine in said cars was really designed for "Premium" fuel, and as such, said engines will not benefit from higher grades of fuel. Using higher grades of fuel in such a car will most likely result in LOWER mileage per gallon of fuel, and possibly INCREASE combustion chamber deposits, which is never a good thing.
Rule of thumb. Use the fuel that your manufacturer recommends.
Best Regards,
Shipo
It used to not be worth it - 15% more cost for 5-10% more power, but with gas at $3.45, paying 20 cents more just about breaks even.
Lastly, this is only really true if you have a modern car. My 67 Mercedes, which has carbs, runs like I dropped a load of manure in it on 87. Truly diesel-like results. Of course, the car was designed with leaded fuel in mind, so 91 unleaded IS about 87 then.
Local gas in delaware is 87 $2.94, 89 $3.04, 93 $3.14.
Is that like those "high-tech" mattress ads that tout 65% less back pain? :P
For instance - a GM with the 4 speed automatic - maximum torque and HP is developed at about 80-90mph in third gear the gearing is so silly high. Honda and Toyota's 5-speed automatics are simmilar, though third gear for them is actually useable to pass on the highway. (Can't do that with a Buick - 2nd gear tops out at 60mph.)
But in older cars, the difference is apparent within a few blocks. That's how we know - that and the official HP tests. Toyota and Honda - notice how the HP ratings dropped from a few years ago by 15-20HP or so? Nothing changed - just the test has to now be run in running form, with A/C installed, the lowest rated fuel it can use, regular oil, and so on. Of course, it's not hard to figure out what gimmicks they must have been resorting to over the last two decades by turning that around.
*Note - if your compression is a bit low from age, higher octane tends to help as well, since the car will tend to detonate the fuel later than it should on 87. - which is another reason most classic cars do better on the premium stuff.
Last week's report
kcram - Pickups Host
It's not like you're trying to pass on a 2-lane road where the last sign you saw said "next passing zone 20 miles."
Here in central VA today, 3 stations in a row had $2.74 for 87: BP, Kangaroo, and Chevron. So, why buy Kangaroo when you can get Chevron (with Techron, and a "Top Tier Gasoline") for the same price?
When I drive on I-95 in Delaware, I'm usually going from VA to NYC, so most of that is 8 lanes, including the bridge to NJ.
Your silly state charges $3.00 to cross the bridge southbound and another $3.00 a few miles later, with no discount for EZ Pass, for a total of 20 or so miles at most within Delaware. Meanwhile on the NJ Turnpike, my last trip cost $3.20 northbound and $4.95 southbound, and that was for nearly the entire length to NYC!
Speaking of silly, the speed limit in DE is 55 mph; I go between 60-65 in the far right lane, and it's like being in the Indy 500.
Back to gas prices in central VA, Hess is still holding at $2.75 for 87, 1 cent above the 3 stations I mentioned yesterday.
Flash your lights at them - one or the other will move or adjust their speed a bit in reaction.
i believe that left-turn-signal is a legal-in-50-states way to try to rent a clue to left-lane-bandits. legal but not necessarily effective, of course.
hey, this is supposed to be about gas prices:
3.15 -> 3.21 range for 91+ octane in southern NH.
The part of I95 you out of state vehicles use is only 1/3 of the whole I95 which has mostly three lanes not four lanes each direction.
Delaware only charge a toll when you entering the southern state line or exiting out. which is very fair considering you guys create so much pressure/conjestion on the road especially during the summer season.
The Del Memorial Bridge you are crossing is connecting Delaware to New Jersy and the toll collected mostly will go to NJ. You can avoid paying this toll by passing through the northern part of DE and entering PA and charge by New Jersey through Comm Barry Bridge. I is at least fifteen miles from the toll at De state line to Del Memorial bridge, and not a few miles.
I agree that 55mph is silly thats why no DE vehicles will obey this limit. For you guys driving at 60mph even at the right lane will always be tailgated by De instate vehicles.
Maybe it is because the Power Tour is in town today...
Down in the Lancaster, PA area I'm seeing $2.59
Let the Gouge Begin!
Rocky
You know, a shot of penicillen would take care of that burning sensation when you urinate. Besides, how much beer would you have to consume to fill the tank on your Buick?
:P
You're right, if it were that simple, the automakers would have nailed it years ago. They struggle right now for every tenth of an mpg for CAFE purposes.
I can't believe the snake-oil peddlers are still trying to palm off those stick-on magnets for your fuel line that are supposed to "polarize" the fuel molecules, claiming more efficient combustion. Motor Trend was advertising them back in 1974!
Rocky
Could be...or could be the urea injection that was going to save the diesels from the 2207 emissions standards. :surprise:
Rocky
Rocky
as a green measure i have been trying to drive closer to 70 than to 80 and have set my vehicle's "overspeed indicator" to 85 mph.
I heard that the price of crude fell with the death of that Al Qaeda guy. I have yet to see any effect. I hope that guy is in the Muslim version of hell where he gets his 72 virgins and they're all Rosie O'Donnell!
When something good happens, crude goes down, but the gas prices are held up and week later the average pricing is down $.03.
2014 Malibu 2LT, 2015 Cruze 2LT,
87 - $2.599
89 - $2.999
91 - $3.059
93 - $3.099
diesel - $2.799
25 gallons of D, another 70 bucks...
kcram - Pickups Host
Still hanging steady at $2.75 here
Rocky