Higher Octane Fuel for Speciale?

Absolutely: she will love it!!

 

Hi Murat!

Just try a tankful of 105 RON (aka 100 AKI): your 14:1 h.c. engine will never
sound, or feel, as good: trust your Italian friend

Hey you might even get a pop or two

xoxo

 

+105

 

The car will actually run it's very best on the lowest octane within it's optimized range. In other words, going above the recommended octane rating does't do the car any favors. Actually, the performance will decline.

 

Wrong imho: the total opposite; you are most likely basing your assumption
on theory and not actual, tangible experience.

I have tried 100aki octane in other cars (Huracan, R8) and it does indeed not make much difference but my 458, and for that
matter my 95 e36 bmw M3 coupe DD, respond to it dramatically: I feel increase in power, engine smoothness, throttle response and sound quality.

Mere placebo? Unlikely..

Last but not least there must be a reason why nearby Scuderia Corsa's challenge, GT2 and GT3 cars all run on 100aki.

best

 

I experimented with blending 10gal of 100oct and toped off the rest with 91oct. That's right around full tank of 95oct. Very noticeable increase above 6K rpm.
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First off, cars commonly do not have multiple maps. What happens is that sensors either detect knock or they don't. If the car is mapped for max power at X degrees of timing with X octane and there's no knock, it makes max power as it does not change timing. Nothing in the engine can detect octane, pure and simple. Our 458 Spider does not run faster on 99 RON than it does on 97 RON(Both Shell V-Power). Only difference is slightly better throttle response and a hair better fuel economy. Both run a bit better on 97 and 99 RON, than when running regular Shell 95 RON.

The C10 is not higher octane than the 100 AKI Carlo runs. The C10 IS 100 AKI fuel. AKI is the combined average between Motor Octane and Research Octane. The problem is that with the AKI and normal gas stations, you don't really know what you get unless it is specified. The most important number is the MON. A quality fuel has the RON and MON numbers as close as possible, i.e, 8-10 apart. There are limits as to how close they can be, as they are measured by different methods. If you have a fuel with say 95 RON, it will need a good MON number to work in a car made for 91 AKI. However, when you don't have to inform what the MON is, you can rely on a very high RON number and a low MON number, which will work as long as the engine is not loaded hard, e.g, when cruising etc. and the AFR stays between +15:1 and 14:1. This is also why the difference between US and European fuels sometimes are quite significant. You can have an e.g, 91 AKI fuel with 108 RON and 74 MON, which is not very good but will work in many everyday applications, and unfortunately not very uncommon for an AKI rated fuel purchased at the local gas station. This can also be due to the fact that the fuel nowadays are made a bit different than just 10 years ago, because of environmental issues associated with some octane increasing additives. This means that the fuel will go bad much sooner. If you want a fuel that is high octane and can sit in your car for months, get avgas. Just add a bit of oil to it, as avgas is usually a very dry fuel.

At the end of the day, what you want is a fuel that will not knock at any point and burn completely and cleanly in the combustion chamber.

Anyway.

If I were you, I'd run the C10 as it is not an oxyginated fuel. On a track, a higher octane can be good due to the fact that a hard driven car gets hot, and extra heat can cause detonation, which in turn will result in a power loss. It has a MON rating of 95 and an AKI rating of 100 octane which is more than plenty. It should burn cleanly and should not burn too hot. If you consider an oxyginated fuel, note that what some experience when putting high octane oxyginated race fuels into these cars like VP's VP100 street fuel, is that they run hotter, and the oxygination can cause a lean condition - which I'd do anything to avoid on a track. And what Challenge/GT3/GT2 cars do on a track, does not really have much to do with your Speciale - different setups.

I'd definitely give the VP C20 try as well. A very dense fuel for high compression N/A engines with slightly lower MON and slightly lower stoichiometric value. The latter should work well, considering most engines are mapped to rich up during hard loads.

Have you considered giving VP a call? They have a lot of different fuel and can give you the best guidance.

In any case, I'd not go with as high an octane as the Shell URT. A MON of 105 and a RON of 115 is way beyond what your engine can use. Also note that the really high octane fuels (110+ AKI) are usually very dry and thin. This can cause increased wear on engine parts etc.

 

Thank you very much for the information!
Def +1 in not going with anything higher than 100 or 101aki.

 

Forget about the compression ratio. There is no relation to what VP and Shell writes and your Speciale. When Shell recomends the URT for 9:1, it is simply because they developed that fuel for forced induction applications. In an N/A application, a 110 AKI fuel can run an extremely high CR. Also, VP has to rely on many types of engines and factors. like big block V8 race engines used in hot rods, drag cars, powerboats and what not. Those engines usually need race fuel when compression goes beyond 10:1, and some of the modern LS engines can go to about 11:1 before needing race fuels. What makes the 14:1 compression ratio work in the Speciale, has much more to do with combustion chamber design and direct injection than anything else. If you put heads on an LS7 engine that'll make the CR 14:1 and run 95RON in it as you can with the Speciale, you'll blow the engine apart before you leave your driveway - it will however work with C20. That is one of the things that makes these engines so incredibly advanced. Ferrari and others push the limits in terms of what attainable. If you had said to anyone 15 years ago, that in 2015, cars would have a compression ratio of 14:1 and run 95 RON fuel, they would have locked you up. Your engiine is so unique and built to run the lower octane with a high compression. That won't change just because you run higher octane. What VP and Shell say about octane in relation to the CR, is actually a little bit misleading, as it has much more to do with engine design and mapping, than anything else. The VP C10/C20 does not "just stop" working at 12:1, it depends on the engine.