Speciale and low octane gasoline

US 91 octane is 95+ in Europe - you are fine.

http://en.wikipedia.org/wiki/Octane_rating#Difference_between_RON_and_AKI

 

Don't put the crummy 91 octane in it! put in 100 octane if you can find it in your area,
I run my 458 on 100 and it's like it's a different car: much more power!
... can't imagine how the speciale would run on 100!!

 

A 458 runs just fine on 91 octane. If you track the car try a comparison of 91,98,100 octane, you will find little difference. Best

 

The speciale has very high compression, I'm amazed they allow anything under 93.

 

I put 100 octane in my 458 in warmer weather in So. California, and the catalytic converter alarm came on that was running too hot.

 

Interesting; thanks for the info. Some cars are more sensitive than others, mine has never
gotten too warm so far on 100..
best

 

High compression, high revving engines take advantage of the extra octanes.

 

Engines will only use the highest ignition advance they are mapped at. A 458 is only mapped for 95 (euro spec fuel) which is 91 US. Any higher is unlikely to damage but will produce no additional benefit. F12 is mapped for 98 (euro spec fuel) so 95 will slightly degrade performance. Unless you have the world's most sensitive butt accelerometer you won't notice any difference. It will get slightly better mileage from the 98.

 

I am under the impression that the 458 too is optimised for 98-100 octanes.

 

I don't know if this has to do with the US but in Europe is different.

 

458 is mapped for 95 RON (euro spec fuel) - well that's what it says in the owners manual and the tech manual. F12 is 98 RON (euro spec) - says the owner and tech manuals. I don't have the manuals for speciale and FF so can't check those. Page 31 of the EU manual and page 413 of the tech manual for 458.

 

Im in Europe but I was referencing the US 93, which I believe is 98 here.

 

You make less power with more octane on a stock car. The closer you are to detonation the more power you will make. Waste of money on a stock car. My twin turbo Gallardo makes more power on MS109 race fuel because timing is up and more boost 1000awhp to 1138 On race. Just stick with 91 or 93

 

Agree. I think you might get a little more power with 93 if you can find it but its not worth losing sleep over.

 

The Owner's Manual for my Speciale says 95RON
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An interesting thing to notice when running high octane in high performance cars, is whether or not it makes the exhaust pop and crackle. If so, that could mean that the engine can't burn all the fuel and thus possibly make less power. The energy in 91 and 100 oct. AKI is the same if the fuel density is the same, but high octane gas burns slower than low octane fuel, but have a higher flashpoint. If compression goes up or boost is increased in a turbo engine, yes then you can use high octane. But if the engine is not built for it, it usually just ends up burning less clean and might even make less power. Run what it was made to run. As was pointed out, if the engine is not mapped for it, it's of no use, there are no two ways about it.

 

My 2014 Italia manual says AKI 91-94. Interesting it's a range rather than just 91 or higher.

 

The problem with the Anti Knock Index rating is that you don't really know what you get, unless it is specified. If the fuel I'd have to use was AKI rated, I'd go with as high an octane as recommended, as you never know what the MON and RON actually is. Don't recall ever seeing a gas station in the US that specified this. In the worst case, the difference between the RON and MON number may be as high as 16+ and the MON is the one that really counts in a performance car, as that method of testing is far more demanding in terms of pre-detonation under high loads than the RON testing method. In Europe, the difference between RON and MON rarely goes beyond 8 as a fuel with a low RON needs a good MON to work. An AKI fuel might have a RON of 99 but a MON of 83, and could be sold as 91. This means that the fuel works ok under light loads cruising along with your low compression engine at 1/4 throttle, but not in a high compression car under heavy loads. For a 95 RON fuel to run as a 91 AKI fuel under light loads, it needs a higher MON of 87 to "help" prevent detonation. The positive here is that it runs well under both light and heavy loads. Not all fuels are created equal - far from it. And always refuel from a place that sells a lot of fuel, so you know you get fresh juice. Octane can drop rather significantly over time.

 

I ran and still run US 91 octane in the Speciale, Speciale A, Scud and the Itaila when I had her. It works just fine...when in doubt step harder on the gas

 

Thanks DK. Good to know.

 

I experimented with F&L 100 oct, blended 10gal of it in my 458SA.
I Figured 12.5 of 91 and 10 gal 100 oct would yield right around 95oct
I can confirm seat of pants difference above 6K rpm, pulls noticeably harder to the point where I hit the rev limiter on lower gears couple of times unexpectedly.
Below are the specs for the F&L which seems to be doing the trick.

Research Octane Number: 105
Motor Octane Number: 96
Anti-Knock Index, (R+M)/2: 100
Specific Gravity at 60/60 /F: 0.74
Reid Vapor Pressure at 100 /F, psia: 7.0
Distillation Range at 760mmHg, /F (Initial Boiling Point: 91) (End Point: 229)
Oxygen, Vol. %: 2.7
Color: Blue
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