Gasoline Choices

[humfrz]

Originally Posted by dssence

So you're saying that the octane rating here it's lower than in the US ? like 91 from the US would be equivalent to 98 ?

Octane is measured differently in some countries. The mon/ron ratio is different.

Someone who isn't lazy may want to explain ....

[TM]

Originally Posted by dssence

So you're saying that the octane rating here it's lower than in the US ? like 91 from the US would be equivalent to 98 ?

Something along those lines.

Here's a simple explanation from wikipedia:

In most countries, including Australia and all of those in Europe, the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI, and often written on pumps as (R+M)/2). It may also sometimes be called the Pump Octane Number (PON)


To get back on topic. I'm sure it'll be fine sticking to 91 even after going FI.

[chrisl]

Originally Posted by dssence

So you're saying that the octane rating here it's lower than in the US ? like 91 from the US would be equivalent to 98 ?

I think it's 93 (R+M)/2 (US) = 98 RON (Euro), if I remember right, but I could be wrong...

[dssence]

Ok so now I think I got it in my country it's stated as RON+MON/2 and in the US it's not that nomenclature right? so US 91 would equal a 95 octane in my coutnry?

[Coreyviper]

Not sure how true this is, but a buddy of mine drives truck, and said that the Techron they use at Chevron is just one bottle that they dump into the tank of a whole truck full. Maybe it's super concentrated? I know it's off topic, i've just always wondered.

[j34r86]

Can u use e85 ...


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[smg1138]

I only use Shell V-Power 93 here in TN. If only they didn't use any ethanol, it would be perfect. If all you've got is 91 though, go with that. That's the very minimum you want to use in this boxer engine.

[Clembo]

Mine (and all my four-cylinder cars) run best on unbranded 93 octane Stop & Shop grocery store gas. Their additive pack seems to be well suited for smaller high performance engines. I started out using Shell V-Power but the FR-S and the MX-5 both run much better on the grocery store gas.


My V-8 Mustang runs terrible on the grocery store gas and I have to use Shell V-Power 93 for that. BP Ultimate 93 works well in the Mustang also but it's hard to find in my area.

[Asinar]

Originally Posted by dssence

Ok so now I think I got it in my country it's stated as RON+MON/2 and in the US it's not that nomenclature right? so US 91 would equal a 95 octane in my coutnry?

Basically, there is more than one way to actually measure the octane of a fuel (as in, laboratory methods). The two methods commonly used with automotive fuel are RON and MON. Most of the world only lists RON as it gives them a bigger number. MON mixes up the RON test a bit to better simulate how an engine actually behaves. (Just consider their first letters: RON=Research, MON=Motor) The United States (and presumably, those countries dependent on US refining capability) average the two together, giving our comparatively lower rating.

Aviation fuels use yet more mechanisms to measure the octane, so 100 Low Lead (current standard for AVgas) cannot be directly extrapolated to 100 octane as it would be rated on automotive fuels. Aircraft engines operate at significantly higher altitudes than automotive engines and are run at 80% power continuously during cruise. As you'd expect, that requires different testing conditions for the rating system.

Also, the lead content is AVgas is super high. Despite being called "Low Lead" (or even "Very Low Lead"), it's lead content is significantly higher than automotive fuels ever were. And the danger from lead poisoning (of the engine) is far from theoretical. It attacks the cat, O2 sensors, and the sparkplug gap (especially at lower power outputs). You'd probably end up with a CEL before finishing the first tank. Oh, and the fuel is dyed blue, so it would be pretty trivial for anyone to see you were doing something wrong.