Fuel

[maxman]

Hello guys,

So the 911 is put back together and back out on the road for spring. I'm in love.

Anyway, what type of fuel would you recommend for an SC? Here are my choices:

91 Octane Non-Oxy
92 Octane Premium
93 Octane Premium

Thanks!

~Max

[javadog]

91 ought to be plenty. It depends upon the year of the car. Some ran fairly low compression and can live on 87. I'd suggest trying to find a station that sells 100% gas, with no alcohol.

JR

[psalt]

Which SC ?

The factory fuel spec for the 80+ high compression SC was 87 octane.

The engine was detune to 25 degrees BTDC to accomodate this. Depending on the condition of your engine and its running temps, if you have 93 octane fuel, you can advance the timing a few degree and get a small benefit.

[maxman]

It' an 82 Euro Spec.

I like the idea of the 91 Non-Oxy because it won't have alcohol.

[Steve@Rennsport]

Originally Posted by maxman

It' an 82 Euro Spec.

I like the idea of the 91 Non-Oxy because it won't have alcohol.

You can use that as long as you remain conservative with ignition timing.

[maxman]

Originally Posted by Steve@Rennsport

You can use that as long as you remain conservative with ignition timing.

I'm a bit of a novice. Can you explain?

I hav not adjusted the timing at all, but I don't know what the pervious owner my have done.

I just ran a tank of 92 premium through, and it seemed to like it.

~Max

[javadog]

Originally Posted by maxman

It' an 82 Euro Spec.

Well, that changes things. In 1981, Porsche raised the compression on the Euro SC and changed the octane requirement to 98 RON, so you may need 93 or 94. I'd have the ignition timing checked and probably the CO, as well.

I used to have a Euro car that could tolerate 93, if I was careful, but it wouldn't run on 91 without backing off the timing.

JR

[maxman]

After stumbling through the german manual, it calls out 98 RON, that seems to be about 91 octane?

Any euro SC guys out there? What are you running?

[Oh Haha]

I run 93 or 94(when I can find it) octane only in my SC. It's available at most fueling stations around my area. I don't worry about what brand it is, though I do tend to fill up at Sunoco most times.

[javadog]

In Europe, fuel octane is measured with a test called the research octane (RON) method. There is a different way of testing, called the motor octane (MOT) method. The same fuel sample will measure differently using each test. Over here, what you see on the pump is the average of the two methods, thus the R+M/2 that is posted on the pump. There isn't a direct correlation bewtween RON and R+M/2, but you can generalize that 98 RON is probably close to 94 over here.

JR

[psalt]

The 82 Euro has 9.8:1 compression and a 98 RON fuel spec, which is around 93-94 CLC octane. So you should use the highest octane on your list.

[Gunter]

+1

We get Chevron 94 here.

As a side note: If your distributor was never serviced or the curve checked, how would you know if it performs correctly?

IMHO, along with deciding on the right octane, making sure the distributor works as it should is as important.