Experts expect gas to top $4 a gallon shortly

[Bell]

Octane is a meausre of a fuel's resistance to pre-ignition. As fuel is compressed in a cylinder by the piston, the temperature of that fuel rises pretty much directly with pressure (thanks to the Ideal Gas Law). All fuels will ignite without need of a spark once they reach a certain temperature. Ignition of the fuel in a cylinder is a very controlled event, and pre-ignition, or ignition before the spark plug actually sparks, does all kinds of nasty things to the components in your engine, in addition to decreasing the power output of each combustion cycle.

Engine manufacturers design their engine duty cycles, spark plug ignition times, spark power, compression ratio, etc., based on an expected amount of octane. If you have fuel with too low an octane rating, it can pre-ignite. This pre-ignition is basically like having uncontrolled explosives going off in your combustion chambers, which puts enormous stress on engine components.

Conversely, putting in higher than required octane doesn't actually benefit you, nor will it increase your engine's power output (unless your car's ECM can electronically advance the spark timing and measure detonation events with knock sensors). In fact, it can cause damage, because higher octance fuel is actually harder to burn, leading to more unburned fuel in the exhaust, which raises emissions, actually robs power (less complete combustion in each power cycle), and shortens catalytic converter life, among other things.

Awesome. Thanks.

So is there an equivelant measurement of the octane of diesel since it dosn't normally need a spark to ignite?

[ccage]

Speaking of SUV hating -- consider this.

Based on a 40 mile round trip city commute 5 times a week (200 miles) with 87 octane at $2.699 and 93 octane at $2.899.

Cost to operate my '97 Jeep Grand Cherokee (318V8, Full-Time 4WD, 87 octane, 15 mpg Gas Hog): $35.99

Cost to operate an '04 MSM (Turbo 1.8, 93 octane, 20 mpg Performance Car): $28.99

Cost to operate my '93 Miata (1.6, 87 octane, 24 mpg Fun Car): $22.49

FWIW, when I bought the Jeep gas was at an all-time low of $0.78/gallon. It was also my only vehicle, so it had to haul people, band gear, more band gear, and tow a 10klb trailer -- which it did well. It's paid for, so I just haven't been able to bring myself to sell or trade it. I now also have an F150 -- which means I have no need to haul gear in the Jeep anymore -- and two Miatas. Guess which vehicles are getting driven the most? :)

I'll admit to joining in on the H2 hating. It's a massively huge vehicle that gets 10 mpg and has no real place on the road. But I think I'll stave off on the public bashing as if the general public goes after them the "performance crowd" is only a short distance behind. Driving a vehicle that's "bigger than you need" is wasteful, but so is driving a car modified for "performance beyond what you need for street driving."

And I sorta like the idea of "performance beyond what I need for street driving." Shame on me. :)

Chuck

[Bell]

Can I assume my 97 miata wants 87 to be happy? She dosn't knock.

[ccage]

Nice octane description, Iain!

Chuck

[Titus]

Both the Nissan Murano and the Super Charged Miata get 93.

[altiain]

Awesome. Thanks.

So is there an equivelant measurement of the octane of diesel since it dosn't normally need a spark to ignite?

You're welcome.

Honestly (and it shames me to admit this, since I work with large commercial diesel engines every day), I have no idea.

I think that diesel, by and of itself, is required to meet an applicable standard, and that all fuel labeled and sold as disel must meet that particular standard. Kind of like Jet A and Jet B kerosene.

[POS Racing]

So what can we do?

Not only is the price of gas going up, but pretty soon many of our favorite goods and services are also going to cost us more due the rising cost of energy.

[Billy Blaze]

Well its no laughing matter to me, but my 99 will not run worth a crap on anything but super.
I guess I will be paying $5.00 a gallon soon.

I dont know why it wont run on anything less without missing but it wont.
The only cure I have found is super unleaded, I am just thankful the Exterra runs on regular, and that the Miata will run my wife to work a whole week on a tank of gas.

I figure until Americans Unite and say we have had enough, and make the powers that be tap into our own oil then we will continue to stay under that heel.
Jack Boot to the Head.

[Dave04]

So is there an equivelant measurement of the octane of diesel since it dosn't normally need a spark to ignite?

Not a Diesel expert here (but I stayed at a Holiday Inn Express last night!)...

Basically, yes... it's called a cetane rating.

EDIT: after doing some reading on Google... I'm not really correct here, but... suffice it to say there is usually only one grade of diesel available in Texas (#2) and it's usually good.

[Bell]

This board is so learned.

So I wonder if one could formulate different chips for different cars that would adjust the timing and what not, making the engine run most efficiently at a lower octane. Sure there's a lot of other factors but in some cars it might get the job done.

I bet someone's already done that though. Seems someone has already taken all my good ideas. Damn that Steve Jobs. The J-Ped would have ruled the world!

[Treibenschnell]

$5.57 for regular unleaded in Atlanta.

[altiain]

$5.57 for regular unleaded in Atlanta.

Holy crap. Are you serious?

[sammm]

I paid $2.79 a gallon this morning

Same station is now at $2.89 a gallon this afternoon.

[Treibenschnell]

Holy crap. Are you serious?

Yup.

$3.14 for regular on Parker @ The Tollway in Plano.

[Titus]

So I wonder if one could formulate different chips for different cars that would adjust the timing and what not, making the engine run most efficiently at a lower octane. Sure there's a lot of other factors but in some cars it might get the job done.

That is how my 2005 Murano is. The Manual says you can use 87 octane but premium should be used for the best performance and gas milage.

NissanPerformanceMag.com says "The Murano can run cheaper low octane gas, but you will lose about 10-15 horsepower as the ECU controls the negligible pinging."

I read somewhere that running 97 will reduce your milage by about 1 MPG. At 20 mpg and $3.00 a gallon, a 1 mpg loss costs me 15 cents per gallon. The station down the street from me charges 15 cents more for premium. That makes the total cost of 87 and 93 the same for me. I will take the free bump in horsepower!

[altiain]

Here's a startling look at the trend in Dallas gas prices, from dallasgasprices.com:

Gas today: $2.77/gal
Gas yesterday: $2.65/gal
Gas 1 week ago: $2.60/gal
Gas 1 month ago: $2.21/gal
Gas 1 year ago: $1.76/gal

Up a dollar in the last year, and over 50 cents in the last month. Even before Katrina, the rate at which gas prices are spiarling upwards is increasing. This is ridiculous.

[onething]

From a friend . . .

A lot of folks can't understand how we came to have an oil shortage here in our country. Well, there's a very simple answer. Nobody bothered to check the oil. We just didn't know we were getting low. The reason for that is purely geographical.

Our OIL is located in Alaska, California, Coastal Florida, Coastal Louisiana, Kansas, Oklahoma, Pennsylvania and Texas.

Our DIPSTICKS are located in Washington DC

[srivendel]

This is from today...



S.

[Treibenschnell]

No suprise...

Some gas station owners are hiking the prices so as to turn away as many would be buyers as they can so as to hold on to as much overage as they can. They can then complain about unfair trade practices if someone else undercuts them by a large percentage. It's pure greed...

[sammm]

A lot of folks can't understand how we came to have an oil shortage here in our country. Well, there's a very simple answer. Nobody bothered to check the oil. We just didn't know we were getting low. The reason for that is purely geographical.

That part that pisses me off the most is this is all pure speculation. There are oil reserves in case of a shortage that they are just now 'talking' about releasing.