Poll for Octane Used in SVX on Highway

[oab_au]

Hi Octane does not burn slower. If it did, the engine could not run at a higher speed!

It only allows the engine to run higher compression pressures and temps without detonation. It does not produce more torque or HP. It allows the engine to produce more torque because of the higher compression ratio that can be used.

Search the thread 'performance fuels except nitrous'. It went through the subject.

Harvey.
p.s. I use 96,

Hi Harvey - since you're in OZ what specific fuel 'brand' would you recommend - if any? I guess that an octane level of 96 implies you run Shell Optimax??

Thanks,
Pete.

[CDG]

Oh, I forgot to mention, everything worths the opposite in the other Hemisphere, so Harveys also right.


Hey does anybody get the "Petroleum Bypass Engineer" thing?

[oab_au]

Originally posted by amuse
Hi Harvey - since you're in OZ what specific fuel 'brand' would you recommend - if any? I guess that an octane level of 96 implies you run Shell Optimax??

Thanks,
Pete.

I just use 96 premium. I have used 98 Optimax down in Vic. did not notice any difference. I also got some Energex 10% ethanol premium out at Lighting Ridge that seemed ok, is that you get in Q. land.

Harvey.

http://theserviceadvisor.com/octane.htm

CJ

[oab_au]

Originally posted by cjoffe
http://theserviceadvisor.com/octane.htm

CJ

That report is vague, simplistic and makes incorrect statements.
I would not be guided by it!

Harvey.

[Uncamitzi]

Originally posted by oab_au


That report is vague, simplistic and makes incorrect statements.
I would not be guided by it!

Harvey.

Harvey,

I'm not an expert either (as the author of the site states), but it would seem that his information, while simplistic, was correct.

What are his incorrect statements...?

[oab_au]

Originally posted by Uncamitzi


Harvey,

I'm not an expert either (as the author of the site states), but it would seem that his information, while simplistic, was correct.

What are his incorrect statements...?

I don't think the author has a good grasp of Automotive engineering.

He states: "Octane, by definition, is the resistance to burn or detonation. The higher the rating, the slower the burn when ignited during the compression burn cycle of the piston. The higher octane allows for better control of burning for high compression engines. So we want to match the correct octane rating of the gasoline to the engine design to ensure complete burning of the gasoline by the engine for maximum fuel economy and clean emissions."

The burn rate does not depend on octane rating, it depends on the fuel type itself.
The octane rating does not control whether the fuel is completely combusted or not, this depends on the air fuel ratio.

He states: "It did in older engines using carburetors to regulate air/gas mix They cannot as accurately regulate the air/fuel mix going into the engine as a computerized fuel injector. Carburetors need adjustment, as a part of regular maintenance, to keep the air/fuel mix as accurate as possible. So many times, these adjustments were not made regularly causing too much fuel to be mixed with the air. When this happened the gasoline would not burn completely soaking into carbon deposits. This would cause a premature ignition of the gasoline due to the intense heat in the engine cylinder creating "engine knock." When this happened, people would change to the higher octane/slower burning gasoline to resist the premature burn, thus minimising the knocking problem. And it worked. Good solution"

He now is stating that a rich mixture would cause premature ignition of the gas due to the intense heat causing knocking.
Rich mixtures don't cause excess heat, lean mixtures cause excess heat.

He states: "When you use a fuel with a higher octane rating than your vehicle requires, you can send this unburned fuel into the emissions system. It can also collect in the catalytic converter."

He is still confusing a rich mixture with the octane rating, excess fuel mixture will affect the catalytic converter. Octane has nothing to do with emissions.

He states: ". In the early 90's, an early warning symptom was a rotten egg smell from the tailpipe. Easy fix, go back to using regular 87 octane gasoline. The rude odor usually disappears after several tanks of gasoline. "

The smell was from too much Sulphur in the fuel.

He states: "All gasoline burns at the same rate, it is the additives that create the different octane ratings for the different types of engines."

This is the first time he is right.

Harvey.

This is a far better explaination
http://www.geocities.com/motorcity/l.../octane1./html

That link is not working. Go to the bottom of his site, click "Gasoline and Your Engine" in other references.

[CDG]

I read through some of the contents and it appears that the individual has some good points, under specific circumstances, but there are plenty of holes in his logic.
His point is to make it simple, and that he did.
Use what your car's manufacturer recommends, increase if it knocks, try lower if it doesn't.

What we need is some raw readings from the Oxygen sensors to really test it out.

Who's got some equipment hooked up to their Oxygen sensors?

[CDG]

Hey, Harvey is right, read the other link, way better than the root site.See repeat url from Harvey's post, cause its that good: http://www.geocities.com/motorcity/l...0/octane1.html

[oab_au]

Originally posted by CDG
Hey, Harvey is right, read the other link, way better than the root site.See repeat url from Harvey's post, cause its that good: http://www.geocities.com/motorcity/l...0/octane1.html

Yes Chris, an old one but the theory is still the same. Written by another Aussie,!
Harvey.

[CDG]

Not bad for some-one who's toilet water swirls the other way.

[oab_au]

Originally posted by CDG
Not bad for some-one who's toilet water swirls the other way.

No Chris!,,,,, ours goes the right way, Clockwise. You blokes are on the wrong side

Harvey.

[CDG]

Right. you just keep thinking that.... from a guy who doesn't get snow on their christmas tree's