VVG

So is there any real benefit to using 93 octane in our cars or is performance really maxed out with 91 on the stock ECU? Can your performance actually be hurt by using 93, as it may lead to incomplete combustion?

Xxyion

I believe these cars are meant to run on 93 if you can get it as that's the standard Premium gas in most places. They are technically detuned a bit to run on 91 is my understanding so running it on 93 should yield closer to reported HP and TQ numbers.

But I'm just a keyboard mechanic so take what I say with a healthy lick of the salt block.

c1pher

I think most modern ECUs can detect the full range of regularly available fuel (87-93 octane) and adjust accordingly. I doubt you'll see much power increase, maybe 5 hp. I believe the reported HP is reported based on 91 octane since that's what they claim is the minimum. However, I'm just a keyboard mechanic too.

MaddMike

I had a CX-9 and they had different HP quotes based on what gas you put in it. Bottom line is that most modern engines have knock sensors that will adjust the tune based on gas quality.

ExMB

List of U.S. states by standard octane ratings

beez

The ECU in you car is optimized for 93 octane, but it will adjust easily to 91. It will adjust to 89 or 87 octane, but it will retard the timing a lot, and not run very well. It will not hurt your engine to run on 93 octane... to the contrary, it will like 93 better than 91. Putting higher octane than 93 in it, is a waste of money unless it's a turbo car. If you're going to run it on the track, but you live in a state that has 91 octane as standard, you can put a couple of gallons of unleaded race gas (usually 100 or 101 octane) usually sold at the track, then fill the rest with 91, and you'll get to about 93 octane. The HP and TQ figures from the factory are tested on the European equivalent of US 93 octane.

dnimi123

Or E85 or Im going to try Boostane as it seems to work for some. Only going to put in 2 - 3 OZ to go from 91 to 93. Way cheaper than race fuel. I already checked with my tuner who said it should work.

Prime

Damn I feel sorry for you Americans.
we have 98 at pretty much every fuel station here in Australia.
Not sure what Porsche does to your market configuration to allow such rubbish fuel. Our manuals say only use 98, not even 95 let alone 91!

ExMB

Yep, a totally different rating scale. Maybe you should come up some from down under.

beez

Like Europe, your 98 is the equivalent of between 93 and 94 as measured by the US standard.

Prime

I now understand but it doesn’t make any sense.

MaddMike

Nor does the standard system and yet here we are.

MrFunk

My buddy says it's noticeable between 91 and 93 in his GT4.

Lucifer

Your 98 is 93 here, and at least in California I have that in basically every single gas station

TRZ06

My g/f has a CX-5 and it does the same thing. In fact, when you run 87, it won't let you get to redline, it will short shift by about 500-700 RPM short of redline.