voiceprint1

In CA where we have 91 octane as our premium, do you guys add octane boosters to a full tank? If not does 91 octane cut some power out?

I put a small octane booster in over the weekend, and it seemed smoother overall, but it could just be my imagination.

Blu311

I copied this from another thread after searching...

From the manual:

Fuel Recommendations
Your Porsche is equipped with catalytic converters and must use UNLEADED FUEL ONLY.
Your engine is designed to provide optimum performance and fuel economy using unleaded premium fuel with an octane rating of 98 RON (93 CLC or AKI). Porsche therefore recommends the use of these fuels in your vehicle.
Porsche also recognizes that these fuels may
not always be available. Be assured that your vehicle will operate properly on unleaded premium fuels with octane numbers of at least 95 RON (90 CLC or AKI), since the engine’s “Electronic OctaneTM knock control” will adapt the ignition timing, if necessary.

Blu311

And was recently discussed here:

https://rennlist.com/forums/997-foru...carrera-s.html

voiceprint1

Does the 91 lower the overall power of the car or does the knock sensor compensate for that difference (however small) it may be?

Blu311

Read the thread I posted above, it should answer that.

stronbl

Since I reside in CA and track in CA, I was interested in this issue too. I've done many, many track days using standard CA premium unleaded fuel and many (but not as many) track days by buying unleaded race gasoline at the track (usually 95 - 98 octane (R+M)/2. )

I couldn't really tell any significant performance upgrade with the race gasoline (i.e. improved times or engine/car performance) as I burn through a lot of gasoline during each session. In the end I stopped buying race gasoline and just buy Chevron (first choice), Exxon, or Shell (second choice) premium unleaded and save a few bucks.

The car/engine/fuel system seems to adapt well to fuel octane differences is my conclusion.

GrantG

I think the car will make slightly more power with 93 (using both less or more, surprisingly, can cause a decrease). People often assume that really high octane fuel is more volatile, but actually it's the opposite (the reason it doesn't detonate with high compression). So, for best performance at the track I wouldn't run pure race fuel, but I would run a gallon or two mixed with the 91 if I had a choice.

voiceprint1

Thanks stronbl, did you notice a difference in "feel" with higher octane, I may be overly sensitive but I swear the car felt smoother after putting in the additive. I had filled up at Chevron beforehand.

Blu311 thanks for that link, I know that gas additives are highly debated, whether they are beneficial ect.

stronbl

I did not notice any meaningful differences. But to be honest, on the track there are more things I'm doing and contemplating than thinking about the "feel" of the engine due to fuel differences. As I said, my only real data point was lap on lap performance. I record a lot of ecu & engine data, and I never really saw much of anything that I could point to suggesting any difference was solely due to fuel variations. And given the price point of almost triple the cost for the race fuel, the benefit / cost ratio was heavily in favor of "standard" CA premium fuel.

But don't get me wrong, if you feel a difference by using an additive, go for it.

Lahainabry

I have done a few gallons of the 101 from the 76 dealer here in NB.
I don't think I notice any real difference.

Edgy01

In Europe they offer a significantly higher octane fuel than the 93 that Porsche AG recommends. The guys at the factory told me to not bother putting in the expensive fuel. It simply gives very little back. In California we are plagued with the crappy 91 octane, but you can augment it with either an octane additive or mix in AVGAS to get it up to the point that the octane knock sensors don't have to retard your ignition to prevent premature detonation. You may hear a difference but it is likely that you won't feel a difference.