Hi everyone,

So it came time for me to fill up for the first time last night. I had just assumed that premium gas from one of the four major brands here in California would be sufficient. But as I was about to fill up, I noticed that AM recommends 93 Octane gas and here in Cali that stuff is hard to find, if at all.

So, I quickly did some searching and found a 76 station that sells 100 Octane gas. Not knowing anything, I filled up half my tank with 100 Octane and the other half with 91 Octane, assuming that would net me around 95.5 Octane. Does that sound right to everyone? Does gas work that way (i.e., mixing different Octanes to acheive the desired Octane level).

Also, later that night I ran across the following post: http://www.pistonheads.com/gassing/t...1424.67158&nmt=

It was interesting to see that our cars were mapped using 97 Octane and so in order to get the 380 BHP or 420 BHP, 97 Octane needs to be used.

But even more interesting was the fact that the V12 Vantage has no knock control and so ifyou use anything less than 95 Octane you run the risk of damaging your car. Why the heck would the V12 Vantage not have knock control? I've seen plenty of them here in California, and I doubt all of their owners are out there looking for 95 Octane or higher when it is such a pain to find.

 

I normally use 91 but sometimes I buy VP ms109 and mix it ( I have AM power upgrade for higher octane fuels )

 

The V12 probably doesn't have knock control because it's a pretty old design, but that's just a guess. As for the 97 Octane thing, I'm a little confused/surprised by that, and though I've never spoken to Mike I'm assuming that he means 97 RON (Research Octane Number.) In Europe the Octane number shown on the pump is RON.

A different testing methodology called MON produces an Octane number usually 8 points lower than RON testing. In North America the number shown on the pump is an average of the two (you've probably seen the formula R+M/2 written on the pump.

Because it is averaged, the difference is reduced to 4, so when he refers (on a UK forum) to the cars being mapped to run on 97 Octane I'm 99% certain he's referring to what us North Americans would call 93 Octane on our pumps.


Edit to Add: That's also a reason (based on having lived both in Europe and North America) that the Brits think US gas poor quality - they just see a lower number on the pump and don't realize the system of measurement is different.

 

Thanks for clarifying that Stuart.

Makes me feel better to know that when it is time to upgrade to the V12, I won't have to worry about possible engine damage from the use of 91 Octane here in Cali for the V12 engine mapped to 95 RON without knock control.

 

No sweat. And just to confirm I'm just inferring that this is the case, but given that most UK pumps only go up to 98, sometimes 99 RON (94-95 on American Pumps) if they were mapped for 97 R+M/2 you'd be looking at 102 RON which, in my 6 years there I never even saw available at the pumps. Tescos and a couple of others sell 100RON but that was the highest I've ever seen. They wouldn't have mapped it to suit something that's not even commercially available in Europe, let alone North America.

 

I hadn't noticed the quality, but couldn't miss the price! Your gas is amazingly cheap, I'd like to be able to buy it over here instead of petrol, which has now just gone over $10 per gallon

 

I know a guy who can convert your petrol-burning car to a gas-burning one for cheap!

 

If he can include a years supply of gas at US prices I'd be interested