polecat702

You are in Canada. Different requirements for gasoline additives, or oxygenation.

Doug_B_928

Forgive my ignorance, if ethanol is used to increase the octane in the U.S., how does Shell increase the octane for their VP gas in markets where they say it's ethanol free? Just curious as I have not looked into this and so have no understanding of it. I guess what spawned my query was how one can be sure that the V Power Shell sells here really does not have any ethanol. I've asked at service stations and the only answer I've received is that the pumps themselves say "contains no ethanol" beside V Power.

Big Easy Sharkster

I believe MTBE (Methyl tert-butyl ether) is an octane enhancer. It's not allowed in the US anymore, not sure abt Canada. Ethanol replaced MTBE here in the US

mark kibort

ive been using 91 octane for 15 years of racing now with the holbert and stroker holbert car. up to 11:1 compression, and no knock issues.

polecat702

I'm not familiar with Canada's standards with regard to ethanol. I do know that strait gas has a higher octane rating than blended gasoline. Non-ethanol (100%) is available but is getting harder to find.

gasoline (base) 1 US gallon= 114,000 btu/gal
gasoline ( reformulated, ETBE)= 111,811 btu/gal
gasoline ( reformulated, MTBE)= 111,745 btu/gal

gasoline ( regular unleaded)= 114,100 btu/gal

Ethanol is the type of alcohol found in beverages. It takes one and a half gallons of ethanol to equal the energy found in a US gallon of gasoline; the reason is because ethanol only has 76,100 btu's of energy. Less energy means less miles per gallon. Blended gas burns cleaner than strait gas, at least that's the rumor, but I don't believe it. Basic physics. A lot of states no longer sell non-blended gasoline, this was done to meet the standards of the " Clean Air Act. "

Gasoline is created at the refinery, and it's octane rating is controlled during the refining process.

FWIW, back when I was a teenager we bought Chevron Custom Supreme in the white pump at 105 octane. It was the juice for street racing, and I always ran it in my Harleys. It looked like grape juice, and we all filled up on Friday night, and it smelled like pure power going into the tank. I think it had twice the Ethyl levels as other gasoline.

The Forgotten On

At a 76 station near my house they sell 110 octane. But at ~$6 per gallon, it can be a bit expensive to fill the car up with. Great it you run a car with a turbo larger than the engine like a lot of supra owners do

But for 80-84 US 87 is fine. All other years should use 91+ or adjust your timing accordingly.

WallyP

Might be worth answering one of the questions in the first post...

Octane boosters are worthless. They do exactly what they say they will - they increase the octane rating by up to "ten points". A "point" is 0.01 octane numbers, so used as directed, the crap will increase your fuel's octane rating from 87 (R+M)/2 all the way up to 87.1 (R+M)/2...

R.Pires

Thank you Wally!
So I guess my only option is to start using 95 and "hear" what my engine says about it....
If it's not happy I'll have to retard timing a little.
i could follow my owners manual instructions about driving it slower than usual, but that's not an option

By the way, my ignition timing is set as per users manual, 26º before TDC at 3000rpm with distributor vacuum disconnected.
In case I have to retard it what will be a safe adjustment?

Regards

FredR

You are spot on with that one- The OP has a 83 Euro S based in Portugal and his car will not run on low octane "witch ****" without causing serious damage [I rather suspect] and he is quite right to be concerned however as long as Portugal stays in the EEC [???] I suspect he will be able to purchase "the good stuff" albeit he may have to look around a bit more to find it.

As a general note for those that may be interested, gasoline is a blend of various hydrocarbons streams produced from various process units that refine various crudes that themselves vary quite dramatically depending on where the crude comes from. Refiners can vary the crude source to some degree but every change has some impact.

Gasoline is and remains the fuel of choice because nothing compares in terms of energy liberated relative to the cost to deliver to the end user. Thus we need to be able to liberate the maximum energy output. Ethanol is an alternative blending stock produced external to an oil refinery. Its advantage is its octane rating - its downside is its poor heat liberation not to mention its impact on some materials that older cars like ours were simply not designed for. MTBE is an alternative blending stock with good octane rating but it is environmentally disastrous if it leaks into the groundwater. That plants were built to market this before the environmental repercussions were understood tells you something- to my knowledge no country running them has dismantled their MTBE plants and they simply dump it on less regulated markets.

Even in oil refineries there was a rush to find alternative processing units to compensate for the loss of TEL and in the early 80's refiners jumped through hoops to install Isomerisation units that basically join two different types of C4 [LPG] molecules to form a version of iso-octane [the benchmark of 100 RON]. They subsequently discovered that this also increased the benzene content - the most carcinogenic hydrocarbon known to mankind that is easily absorbed through the skin. Heavens only knows what this lot does to those handling petrol pumps who breath in fugitive emissions from gas tanks when being filled.

Aviation gasoline still uses lead to this day but the relatively low volumes in play has taken the environmental lobby to the point where they are no longer interested. AVGAS has special requirements to meet the 100 plus octane rating and to stop it from boiling at the service ceiling such planes operate at. This means that LPG components cannot be used in the blend and therefore they contain a lot of Platformate. A tankful of purely Platformate would be very nice.

Running AVGAS in a 928 will cause no problems whatsoever on non CAT 928 models like the OP owns. The models imported into the Middle East had no CATS-even the GTS's. If it is used on a CAT model it will kill the platinum catalyst immediately. I suspect that even if one can get some of this leaded fuel using it in cars on European roads is probably illegal now.

A tank full of this stuff would probably solve my current sharktuning problems on No 6 cylinder!

Regards

Fred

R.Pires

Hi Fred,

Thanks for the clarification
For now Portugal is still part of the EEC, but as things are today we never know in the future...
For many years all major suppliers had 4 types of fuel, diesel, diesel Premium, 95 and 98 with prices increasing in the same order.
The 98 was the most expensive one, about €1,70 per litre.
A few years ago some "marginal" suppliers appeared, with what they call low cost fuel that, according to them, doesn't arm the engines the only difference is that they have less additives and that's why they can sell them sometimes 25 cts cheaper per litre!
So, some "illuminated mind" made a law that those low cost should be available in the major selling points, BP, Repsol, Shell, etc.
And those big companies, to avoid building new tanks and all the expenses involved in an operation like that, thought it was easy to replace the two types of fuels with lower sales, diesel premium and 98 with those low cost diesel and low cost 95!
I hope that at least some petrol stations keep the 98, the bigger ones with more tanks, I really don't know and at this time it's difficult to guess, but, as you say I'm concerned with having to use 95, retarding timing, or whatever and mess with my engine that is running great!
However, I don't know if it's comparable, but there is a post on this thread by Mark Kilbort that says is been running 91 octane fuel in his race car for 15 years, with up to 11:1 compression, and no knock issues, so if my car as a 10:1 compression I should be more than ok with 95!
But I know things are not that simple, that's why I'm really concerned about this matter!

Thanks all for the opinions!

Regards