McLaren Life banner

1 - 17 of 17 Posts

·
Registered
Joined
·
183 Posts
Discussion Starter #1
Last week I was lucky enough to be invited with the wife at the Toronto Pfaff day at the Mosport track. While there I was told by an engineer that the fuel required for the 12C is octane 95.

I was a bit surprised since the highest I can recall seeing at the pump here in Quebec City is 91. I've made quite a few phone calls at most major fuel stations around and nobody has it.

Petro-Canada told me that they have it in Trois-Rivieres which is 140km away! Great if I'm on my way to Montreal but not so great if I need to do a 280km return trip just to fill up the tank!

Anyone else has had this problem and know of a workaround like fuel additives?

Thanks for the help.
 

·
Registered
Joined
·
862 Posts
The 12C requirement is 95 RON, I suspect that your pump rating of 91 is (RON+MON)/2 which is the equivalent of about 96 RON.
 

·
Registered
Joined
·
183 Posts
Discussion Starter #3
The 12C requirement is 95 RON, I suspect that your pump rating of 91 is (RON+MON)/2 which is the equivalent of about 96 RON.
Hi Jerry. I've got an older Owner's manual (North America) for the 12C but I'm not sure how outdated it is. It states that the requirement is 94 AKI ((RON+MON)/2 ) which is what we read at the pump here in Canada. So it seems that I really need to look for 94, not 91.

Out of interest I've looked up what it would equate to in RON.

According to Wikipedia ( view the tables here), the conversion varies depending on country and fuel company.

According to Petro-Canada, their 91 AKI with no ethanol is equivalent to 97.2 RON, so your 96 RON figure is a good estimate for 91 AKI.

Cheers
 

·
Registered
Joined
·
1,925 Posts
According to Petro-Canada, their 91 AKI with no ethanol is equivalent to 97.2 RON, so your 96 RON figure is a good estimate for 91 AKI.

Cheers
I feel like we're going to solve for "a train leaves NYC going south at 42mph after accelerating 4mph...another train leaves from Chicago with a variable acceleration of..."

I was concerned about this too. The highest octane rating around NY is 93... I'm guessing this is good enough...
 

·
Registered
Joined
·
2,737 Posts
I'm pretty sure gas ratings are different in different countries, so I'm not sure what that is the equivalent to in the US, but I highly doubt they'd make it require an uncommon gas. If your gas station has three available types, I'm almost certain that the expensive one is the correct one. I've never seen gas stations that lack premium, as well call it.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
 

·
Registered
Joined
·
1,925 Posts
I'm pretty sure gas ratings are different in different countries, so I'm not sure what that is the equivalent to in the US, but I highly doubt they'd make it require an uncommon gas. If your gas station has three available types, I'm almost certain that the expensive one is the correct one. I've never seen gas stations that lack premium, as well call it.
I figure that too. Problem is we have only one company that makes 93 octane, the others "premium" is 91 or 92. My guess is the us 91 hopefully equates to the 95 in the manual.

The real question is dies the engine do better or worse when above it below the manufacturers recommendation. This varies widely from company to company and car to car. Some cars do better at
Their recommended octagon, and higher octane makes them run worse. Some just do better the higher the octane. Would be good to know what the case is with the Mac to fees it what it likes.
 

·
Registered
Joined
·
183 Posts
Discussion Starter #7
As I understand, the higher the octane content, the less chance of a self ignition of the fuel-air mixture before the piston is at the top of the stroke. The higher the compression and the hotter the air-fuel mix and the more chance that it can happen. This is very likely in the highly compressed fuel-air mixture of the dual turbo Mac. The danger of premature ignition is that it could damage the engine.

Hopefully on a normal drive on a public road, it wouldn't be an issue. This would only happen on the track where I assume you could easily get 94 AKI fuel anyway.
 

·
Registered
Joined
·
183 Posts
Discussion Starter #8
I'm pretty sure gas ratings are different in different countries, so I'm not sure what that is the equivalent to in the US.
Like Canada, the US uses AKI at the pump, look here for equivalent ratings in different countries.
 

·
Registered
Joined
·
862 Posts
Typically, octane in North America will be quoted as AKI or (RON+MON)/2 and in the rest of the world will be quoted as RON only (of course, there will be exceptions). A good rule of thumb is that the RON-MON spread is about 10 points for road use gasoline. Hence a European Super unleaded will be 98RON, 88MON and 93 AKI, I.e. similar to the American higher octane fuel.

The knock sensors in modern engines should easily adjust for minor variations in fuel quality so I'd not be overly concerned if the fuel was 96, 97 or 98 RON. There will be countries where McLaren are selling cars where the "best" quality fuel available will be no higher than 95 RON and McLaren are no doubt aware/have designed for this.
 

·
Registered
Joined
·
183 Posts
Discussion Starter #10
I was concerned about this too. The highest octane rating around NY is 93... I'm guessing this is good enough...
Yeah, I'd say so too. I'm just a little concerned that all we can get here is 91. I've written to McLaren and asked about fuel additives. Hopefully I'll get a reply next week.

Cheers
 

·
Registered
Joined
·
261 Posts
Typically, octane in North America will be quoted as AKI or (RON+MON)/2 and in the rest of the world will be quoted as RON only (of course, there will be exceptions). A good rule of thumb is that the RON-MON spread is about 10 points for road use gasoline. Hence a European Super unleaded will be 98RON, 88MON and 93 AKI, I.e. similar to the American higher octane fuel.

The knock sensors in modern engines should easily adjust for minor variations in fuel quality so I'd not be overly concerned if the fuel was 96, 97 or 98 RON. There will be countries where McLaren are selling cars where the "best" quality fuel available will be no higher than 95 RON and McLaren are no doubt aware/have designed for this.
Jerry, thanks for the info!
Would you happen to know what designations do we use here in the Gulf?
 

·
Registered
Joined
·
183 Posts
Discussion Starter #12
Jerry, thanks for the info!
Would you happen to know what designations do we use here in the Gulf?
My guess would be RON. Your owner's manual should be giving you the unit for your region

Cheers.
 

·
Registered
Joined
·
862 Posts
Jerry, thanks for the info!
Would you happen to know what designations do we use here in the Gulf?
Hey Ramy, RON is used in the Gulf.

In the Kingdom you'll have 2 grades ..... a 91R/82M regular grade and a 95R premium grade which, unusually, doesn't have a min MON spec.
 

·
Registered
Joined
·
1,925 Posts
Like Canada, the US uses AKI at the pump, look here for equivalent ratings in different countries.
Thanks for this, although it's still a tad confusing:

FUEL RON MON AKI
"EuroPremium" or "Regular unleaded" in Europe, "SP95" in France 95 85–86 90–91
Great Britain, Slovenia and Spain, "SP98" in France 98 89–90 93–94
"SuperPlus" in Germany 98 88
Shell V-Power in Italy and Germany 100 88
Eni(or Agip) Blu Super +(or Tech) in Italy 100 87 94

"Premium" or "Super unleaded" gas in US (10% ethanol blend) 97 87-88 92-93
"regular" gasoline in Australia, New Zealand, Canada and the US 91–92 82–83 87
Petro-Canada "Ultra 94" in Canada [10] 101.5 88 94


Hopefully the formatting doesnt go to hell. Anyway, it seems "likely" that US 91 should hit at 95RON... Clearly 92 or 93 will be at 97...
 

·
Registered
Joined
·
64 Posts
Just from some empirical observations from the current road trip. Putting about 3500 miles on the car in the last 10 day I have found:
Premium gas at the pump varies between 91 and 93. Most have max of 10% ethanol. ConocoPhillips brand is the one brand that has consistently had 0% ethanol. Not all stations have had Premium, especially in small mountain towns. Planning ahead on side trips can reduce the pucker factor as the range changes to "fill up soon". The car seems to like the 0% ethanol better, getting 1-2 mpg better than other mixes, but would have to have had better record keeping about highway/local driving to state definitively. Over all, I have averaged about 24.6 mpg. While these side trips along small mountain road are not helping my mileage, I am constantly reminded of my normal response to questions about mpg's ... "Do I look like I give a ____ about mileage?" The smiles per mile have been off the chart...
 

·
Registered
Joined
·
424 Posts
Ethanol has less energy content than straight gasoline, about 2/3, so a 10% ethanol mix will get about 96%-97% of the milage from 100% straight gas.

Engine compression ratio is fixed so the ECU will either retard timing or inject more gas per stroke to make up for the inferior fuel. That means worse gas milage.

Higher octane doesn't means higher horsepower. Always use the lowest octane gas the car will tolerate without knocking. It takes more energy to ignite a higher octane gas. If a car is designed with a 91 octane in mind, putting 94 octane gas in it is useless and in some cases the car will actually makes less power. Only benefit of the higher than factory spec octane rating gas is for those with a aftermarket tune. The tune will use timing advances to extract more power, that means higher combustion chamber temperature and that will need a higher octane rating to resist knocking. Or if the ambient air temperature is really hot so the intake mixture is hotter than normal, then a higher octane will help as it will prevent the ECU from retarding timing to keep the engine within spec.

I knew someone who was an engineer for Shell, he showed me some dyno data they did. They ran an engine spec-ed with 87 gas, when they ran it with 94 octane it actually made less HP. That was an eye opener.
 
1 - 17 of 17 Posts
Top