Mixing 89 octane with 100 question

Unleaded to unleaded is linear and an easy calc. Mixing leaded and unleaded would have to be calculated by a lab. https://www.google.com/search?q=octane+mix+chart&tbm=isch&tbo=u&source=univ&sa=X&ved=0CDAQsARqFQoTCOvi0N7zhskCFUGplAodeLUGKg

 

A 50/50 mix would give you 94.5 octane.

10 gallons of 89 plus 5 gallons of 100 would give you a little more than 93 octane.

 

I think if you did 60% 89 RON and 40% 100 RON you're pretty close. At 2:1 you'd be slightly less and that is probably fine.

 

Why are you using such a high octane-rated fuel? Have you raised the compression ratio or have a pressurized intake system?

The Ferrari octane spec is usually given in RON units while the markings on the US fuel station pumps are in AKI units -- a 93 AKI US fuel is about a 98 RON euro fuel. On a stock US 3.2, I believe 89 AKI fuel would be fine (it's just barely under the 95 RON spec and unless you are flogging it on a hot summer day I doubt you'd have any trouble), and 91 AKI would be a little over spec.

 

It's a free country, but not sure why you'd not consider the direct F specification as adequate - happy motoring...

 

its linear so blending is easy.

just make sure your car can adapt to the higher octane.

 

the math is simple btw,
((n gallons x octane 1) + (y gallons x octane 2)) / (n+y)

i.e.

5 gallons of 89 + 10 gallons of 103
(5x89)+(10x103) / (15)
1475/15 = 98.33 octane

 

In case anyone is wondering, the static CR is 9.2, dynamic CR which is what is applicable here is 8.15:1 , yeah that low. Cranking PSI is ~160. Which is one reason why these engines respond well to forced induction. Also the cylinder heads flow numbers are poor, very poor. The VE (volumetric efficiency) does not hit 100% so DCR will not match CR at any point in the RPM range. The target DCR for best power and efficiency is 8.1:1 on regular pump gas, and look at that! it's what Ferrari did. I'll skip effective CR or what the engine really runs at, but figure it's ~90% of the DCR.

 

I think somebody already did that for you?

 

I would caution the OP to read the label(s) carefully on the pumps / fuel sources for whichever he decides to use. The "RON" method for octane calculation is most commonly given, at least as an alternative, on US pumps / specs. In most states, it is the primary method used.

 

Its pretty clear you don't know why your running it, you only know that someone "told" you to..When asking a question you don't know anything about, you should take the advise when give, not just the advise you are looking for.. i run 87 in mine.... why?? because i understand why and when its needed for higher octane..as does the other guy.. oh well, burn them dollars..ill save mine!!!

 

Can't agree with you here. AFAIK, it's a legal requirement to have the AKI rating shown on the pump in the US. Maybe the RON equivalent is allowed to also be shown, but it's not in the legal requirement.

 

In the US I've never seen anything but the AKI shown on the pump. RON = Research Octane Number, which is one way of measuring gasoline octane content and is what is used around most of the world. MON = Motor Octane Number and is another way of measuring octane content. RON is typically a higher number than MON.

AKI = (RON + MON)/2 That's why you see (R+M)/2 on the octane label on every pump in the US.
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The yellow sticker and AKI calculation was by FTC regulation in the later 1970s. In the early 1970s and prior US gasoline octane was measured by RON.

 

Ahhh.... That was the source of my confusion on the issue. Thanks for clarifying, guys..... I stand corrected.

 

Typical response form your kind.. never wrong , always right, never knowing anything and only accepting statement in which support your views..

 

Alden:

Harris Oil in Mt Dora on US HWY 441, just south of SR 46, has 93 octane non-ethanol priced at $3.219 per gallon. Open until 5 p.m. weekdays, Saturday until noon. Other option is to buy the 89 octane non-ethanol at some WaWa gas stations and then add an octane booster that you would find at most auto parts stores. Either option works out to just about the same money spent for 16 gallons.

Now the fun time:

Alden, you did say in your first post that the gas is for your Mondial. Most of the people responding were addressing the octane needs of a Mondial.

Josh: ADVISE is a verb. ADVICE is a noun. They are pronounced differently: "I advise you to heed the advice Tom gave you." If English is a second language to you, I would give you a pass. However, that is likely not the case.

Secondly, what exactly did you mean by "form [sic] your kind" in your last response to Alden? People that own a Ferrari? People with an Anglo-Saxon first name? Please elaborate, so others here can determine just what kind of a person you are.

 

Holy cow!
We're usually more civil to each other in even motor oil and timing belt discussions!

It's like an FChat P&R takeover in here!

All this in response to a trivial problem, easily googled and understood by most persons that would have the technical basis for being anal about the precise octane number they're running in their car.......

 

You guys are way smarter then I am! i hate to think the damage I did running Avgas through my vehicles over the years in my younger days...great data...

 

"Octane booster" from the auto parts store at best raises your AKI rating by one point. Meaning 0.1 octane. It says so right on the can. Multiple cans max out at about 0.3 AKI number increase. Hot Rod magazine tested this out a few years ago. Don't waste your money. Unless you want to pay race gas prices for 89.3 AKI gas.