Tom W

FWIW, I did the experiment that confirms Viken's statement that the ECU doesn't compensate for higher octane gas. I made over 10 runs over 3 days with a G-Tech for each type of gas using CA 91 and about 98 octane (mixed 91 and 104.5). There was no significant difference in the results (weather was in the mid-60's to low 70's and the engine was warmed to normal operating temp prior to testing).

I did see a slight improvement when I changed my cars chip.

I am not quite convinced that there will be no performance difference between 96-100 octane and 91 octane gas on a hot day (100+ °F) at Thunderhill. Under those conditions I would think that our less-than-specified octane gas in CA could lead to the ECU retarding the timing (and lower performance).

Viken

You are quite correct. My 993, always pinged in hot weather (90 degrees +) running 91 octane. This means that the ECU was not quite capable of retarding the timing. During those hot days, I always used a mix of 91 and 100 and the car ran perfectly.

Dirt Track Racer

Why is it that anytime a question of fuel comes up, everyone thinks or expects to go faster with higher octane fuel? Is it marketing by the fast and the furious crowd? Is it the NOS generation? I just don't get it.

The one and only purpose of higher octane fuel is to resist knock in the engine. On hot summer days at high rpms, your motor will knock more, so you need more octane. Won't help you go faster, just help you to not blow up your motor.

This idea of octane making your car faster makes me think of the numerous posts proclaiming cars are faster after PSS9 installs? Come on. The suspension doesn't make the car faster. The driver that can take better advantage of a better suspension does.

DTR

PS - my race cars take 120 octane leaded. Does that make me faster than my rivals at the dirt track? No. It just keeps me from blowing up my expensive race motors.

rcwelch

Dirt Track Racer...This is giving me a RON headache MON.

Ray Calvo

Sunoco 94; don't live in liberal greenie-weenie La-La Land and can get it, so I use it.

RE Dirt Track Racer: I would agree so long as the car doesn't have an electronic igniton system that will adjust the ignition timing on the detection of knock. If such adjustment does exist, higher octane fuel that will prevent this ignition timing adjsutment will give some added "punhc"> Going to even higher octane fuel where the timing isn't adjusted then will do nothing.

Howdy993

Last year I recall reading an article on "Why buy premium gas?"

The Porsche official was quoted as saying (paraphrased) That they have to sell their cars all over the world where the latitude of octane quality can be quite wide. He went on to say that Porsche cars are built to perform within this wide octane range.

I personally would NOT recommend or use anything but premium as specified in the owners manual.

You can bet the farm that the factory would not step up and offer a free rebuild if you ran Plus or gasp Regular grade fuel in the car.

Howard
98 C2 cab tip

leeham

Now I'm interested. I drive the 993 every workday on a 20 mile trip through the country with only two traffic lights between my driveway and the office parking lot. It's a very crowded drive with thousands of vehicles going to the same place, kinda like being part of a train. These conditions are ideal for economical driving, and the "train" averages about 60 mph. I could save a lot of money by substituting 87 or 91 octane fuel for this commute. My question - If 91 is good enough for CA, why not also for me? I've been running 93 since I bought my first Porsche 8 years ago. If I try 91 and it doesn't knock, is everything else OK? Would knocking be obvious enough to hear over the exhaust and road noise, or would it be nearly undetectable?

Viken

For that kind of driving, you can use any gas.

24FPS

chevron supreme w/ techron. nothing else... no pings either.