tigerhonaker

Guys,

Does Europe Have Higher Octane Than America?

Terry

user 68932563

93 at every gas station in cali? I only see 91

Xxyion

where? The only place ive seen 93 is the race gas station on Sunol down in Fremont. Ive never seen 93 anywhere else.

Alpha Ice

I would recommend not running lower than 91 octane, and it would be ideal to run on 93 whenever possible. The vehicle is built with a certain compression ratio, and the higher compression ratios do require a higher octane to make sure you get a full spark. While I do think the engine would be able to mitigate any knocking or possibly limit timing, it is written in the manual that if you go with 91, it is not recommended to run the engine wide open throttle. I do my best to travel the extra few miles to get 93 anytime I can for this car. I would strongly not recommend running 87 or 89 with the compression of this engine, as it will not always properly ignite the fuel (from my understanding of how these reactions take place). I'm not a mechanic, but I am a nerd in some of these things, and I know everyone's knowledge is going to be subjective.

TXshaggy

The OM for my 2021 Spyder says 93 Octane is recommended.

Lists alternate fuel minimum octane rating of 90.

There is an information note stating that in an emergency, refueling with octane as low as 86 is permissible. However it says not to floor the accelerator pedal with octane levels at 86.

Octane numbers above pertain to US octane measurement, other locations will have different numbers based on RON/MON measurement.

VVG

I don't think there is any question about 87 or 89. It is really about 91 , 93 or higher. How much power can the stock ECU allow for with higher octane fuels.

TRZ06

Union 76 at Foxworthy in San Jose also has 100 race gas, just FYI

VVG

So does 100 octane feel faster than 93 on a stock ECU? Has anyone dyno'd on 100 with a stock ECU?

TRZ06

I don't know, I haven't tried it yet. I plan to this spring though. I used to do a half 100, half 91 on my SS 1LE on occasion and I did notice it had a little more pep, better throttle response and the exhaust note had a cleaner/crisper sound to it.

I think the GT4 motor has a little higher compression ratio than the LT1 6.2L , so it definitely should be able to be felt. HOWEVER, GM is notorious for using very conservative timing maps on their tunes. I am not sure where Porsche lands in that regard.

colnagoG60

Per M-Engineering, Porsche lets the cars run ***** out until knock starts to occur, then dials it back just enough to stop knock, and always riding that line.

85Gold

And if that is the case then running 100 should add power.

Peter

beez

Running higher than 93 - 100/101, etc) is wasting your money... the stock ECU sees any octane above 93, as 93. You can tune for it though.

TRZ06

Actually what that means, if true, is that unless the temps are hot, you might not notice too much of a difference from 91 to 93. What I meant was that GM tunes their performance cars to pull timing VERY early, so there is a bigger benefit to running a higher octane.

If Porsche rides that line and pushes things further out, then timing is pulled less often and only when knock is detected. So, as long as there is no knock, you are getting more on 91 than say what GM would give you.

VVG

Okay...these two statements contradict each other. So which is it?

Jim Rockford

Would love to know realities around 91 vs 93, temperature factoring in etc. in terms of capping power.

Here where I am (Toronto) we have Shell 91 but that has zero ethanol, which I like. We have 94 available but it’s 10% ethanol which is what gets the octane count up.

Typically I have run 94 during the depressingly short 6 month driving season, then 91 no ethanol when storing the car over winter but I’d rather run 91 with no ethanol all the time if no power impact… unless it’s under extreme conditions and power is affected which I understand, but I would like to know under what parameters that comes into play.