Gang,

Prior to the unleaded fuels that we have now the octane levels of gasoline was a lot higher. Preceding the early 70's, Regular was something below 93 to 95 octane and Premium or (Ethyl as it was called then) was at least 100 octane. Super Premium was well over that. Sun Oil Company had what was called "Sunoco 260" and that stuff was the only thing to run it you had any type of muscle car of that era. It was "said to be" almost 120 octane. Now whether that was the true or not I don't know. What I do know is that it made a major difference in the performance of our (13 to 1 compression small block Chevy) Drag car at the time. Before the early 1970’s and low compression motors and “knock Sensors” we ran Regular in almost everything that was 10.5 and below. In the mid 70's when the EPA made the oil companies remove their "Leaded" fuels from the market (because they found that lead screwed up the “Cat’s”), they in turn gave us this junk that we now call "Unleaded Gas". From that we ended up with about four levels of octane. 87, 89, 91 and 93 octane, a spread of only 6 octane from low to high. This stuff today wouldn't even make the high end level of the "Regular" of the 60's and to think that we call 93 octane "Premium" today<LOL>. If you feel that you need to run High Octane gas in your “High Compression Z” try “Turbo Blue”. Now that’s true “Premium” fuel and it will really give your “Z” some zip. Now guys it your turn to blast me with how incorrect I am and that the octane rating is different now than it was then and so on. So go for it, I’ve got my flame suit on.

Mspeasl
Central Illinois - Form member since 2/02

"Growing old may be mandatory, but growing up is optional"

03 Redline Touring 6sp "350Z" (Pre-Ordered 02/02) - Delivered 29 August 02
05 Satin Jade Pearl Chrysler 300C 6/04



Hey Mspeasl,

I was around in the 70's running high compression motors with horsepower of 400+ and what i can remember your facts are correct.The only pump fuel we would run is the Sunoco "260".It had a handle you would turn to select the Grade desired from low 100 to 260.
I'm sure there is someone out there to find something to flame on you about though.LOL





I, too, remember those days (we're dating ourselves guys!) but I don't think todays engines need that kind of octane. With all of the emissions and fuel mileage requirements today, engines have changed dramatically; don't think I would want to run racing fuel or its equivalent in my Z for long, if at all. Any thoughts on what that stuff would do to a VQ35? From what I have read, not much, and nothing good.



>oil companies remove their "Leaded" fuels from the market (because
> they found that lead screwed up the “Cat’s”),

And the lead was horrible for humans and the environment....



I was just in Italy and what I found interesting was the octane ratings. I was filling up my scooter...yes a scooter, at a Shell station and made note of the grades of gas. The have 2 grades, premium and super premium.
They were 95 and 100 octane. So when in Italy you run high octane or you run HIGHER octane....lol.

Also gas was about 1.30 euros for a litre. There are 3.8 litres in a gallon. It will cost you $1.30 USD to buy 1 Euro. Who wants to do the math. Ok I'll do it.

One gallon costs 4.94 Euros or $6.42 USD per gallon.

2005 350Z Touring Roadster - Super Black - 6speed
Borla Exhaust and K&N drop-in.

Other toys include:
2006 Subaru WRX Wagon
2002 Isuzu Axiom SUV
2002 H-D Electra Glide Ultra Classic
2002 H-D custom Fat Boy
2001 Kawasaki Drifter 1500



European fuels are rated higher because they only use the "research" octane number, where we use (R+M)/2, average of the "research" number and the "motor" number. The motor number is lower, and more relevant, it's based on the CR at which a variable compression ratio motor starts to ping.

Or something like that!

Long/short: They don't REALLY have higher-octane fuel over there.



That's not what my father-in-law and brother-in-law told me and they live there. They said their regular unleaded is basically the same as our super unleaded. I just assumed it was higher from the number on the pump.

2005 350Z Touring Roadster - Super Black - 6speed
Borla Exhaust and K&N drop-in.

Other toys include:
2006 Subaru WRX Wagon
2002 Isuzu Axiom SUV
2002 H-D Electra Glide Ultra Classic
2002 H-D custom Fat Boy
2001 Kawasaki Drifter 1500



LIVING in a place doesn't mean you KNOW what the actual real-world octane of the fuel there is, does it?!

From the Wikipedia (not that it's 100% reliable either, but I'll take this over youre father- and brother-in-law's word!):

>>>In most countries (including all of Europe and Australia) the "headline" octane that would be shown on the pump is the RON, but in the United States and some other countries the headline number is the average of the RON and the MON, sometimes called the Anti-Knock Index (AKI), Road Octane Number (RdON), Pump Octane Number (PON), or (R+M)/2. Because of the 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-95 (regular) in Europe.
<<<

Also, I screwed the pooch on research vs. motor octane:

>>>The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel through a specific test engine with a variable compression ratio under controlled conditions, and comparing these results with those for mixtures of isooctane and n-heptane.

There is another type of octane rating, called Motor Octane Number (MON) or the aviation lean octane rating, which is a better measure of how the fuel behaves when under load. MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, a higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON. Normally fuel specifications require both a minimum RON and a minimum MON.
<<<



But they do have 100 octane and if its actually lower then and really more like 95 it is still higher than ours.

2005 350Z Touring Roadster - Super Black - 6speed
Borla Exhaust and K&N drop-in.

Other toys include:
2006 Subaru WRX Wagon
2002 Isuzu Axiom SUV
2002 H-D Electra Glide Ultra Classic
2002 H-D custom Fat Boy
2001 Kawasaki Drifter 1500



Sunoco and others still make 100 unleaded if you can find it and it's legal to use in all street cars. But it over $7.50 a gallon.

FWIW, you want to run the lowest octane your engine was designed for. The lower the octane the higher energy per gallon, yes higher. Additives are added to gas to raise the octane to SLOW the burn rate down but it also lowers the energy output as well. It's a myth the higher the octane the more performance. It's only more performance if the engine managment system can advance timing based on octane. Do some research and you will find out. BTW, this is based on my own research and the racing engines I build and race, from med to high compression.

--
Derek Smith

2003 350Z LS Enthusiast
1972 240Z L28 w/ Tripples


Post Edited (Jul 21, 2:50pm)



i wasnt born till 78 so i dont know what yall old farts are talking about :-)


------------------

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'01 Yamaha R6



Just to throw this into the pot. I have had a few kids from the local high school and the junior college come up to the airport and purchase aircraft fuel. we carry 80 and 100 octane low lead, they claim that the 100 octane steps up performance in their older mustangs, firebirds and chev. Have no real knowlege as to what effect it has on the performance, but I know what happens if you put car gas in an airplane, there is very little performance.



Bristol,

That's an old Hot Rodder (Dragracer) trick that we used to do back in the 50's when we couldn't get real good high octane gas (pre Sunoco 260). The one thing that you couldn't do was run straight "Avi gas" or you could burn pistons and such.

Mspeasl
Central Illinois - Form member since 2/02

"Growing old may be mandatory, but growing up is optional"

03 Redline Touring 6sp "350Z" (Pre-Ordered 02/02) - Delivered 29 August 02
05 Satin Jade Pearl Chrysler 300C 6/04



You should use the octane rating your engine is designed for, yes.

>The lower the octane the higher energy per gallon, yes higher.

No, octane and energy per gallon are mostly unrelated. You can alter the ratio of pentane, heptane, alcohols, etc to change this and still maintain the same octane rating.

>Additives are added to gas to raise the octane to SLOW the burn rate

Octane is not the burn rate, this is a common misconception. It is a measure the tendency of the fuel to pre-ignite in a hot cylinder.

> down but it also lowers the energy output as well.

No, depends on what you use to alter the octane. This could be true depending on your fuel mix, but it is not a foregone conclusion.

> It's a myth the higher the octane the more performance.

Finally, some truth. The octane is only useful if you have an engine that can adjust to make use of it.



cmcniel,

You're correct "There has never been, and never will be a fuel with an octane rating of 260 or 280".

"Sunoco 260" and "280" were Marketing names of their Gas.

Mspeasl
Central Illinois - Form member since 2/02

"Growing old may be mandatory, but growing up is optional"

03 Redline Touring 6sp "350Z" (Pre-Ordered 02/02) - Delivered 29 August 02
05 Satin Jade Pearl Chrysler 300C 6/04



Zoldman,

As I said ""Sunoco 260" and "280" were just Marketing names of their Gas." A lot of brands used whatever means they could trying to get you and I into their stations to buy their goods. I'll bet you even remember when they handed out "Pink Ware" as a give away to get you in<G>. I know I do.

Mspeasl
Central Illinois - Form member since 2/02

"Growing old may be mandatory, but growing up is optional"

03 Redline Touring 6sp "350Z" (Pre-Ordered 02/02) - Delivered 29 August 02
05 Satin Jade Pearl Chrysler 300C 6/04



I do remember them giving away glassware.