78-80SC Who is using 87 Octane
 

The 78, 79 (and 80?) SC's are 8.5/1 compression.
The previous owner/dealer said 87 octane is sufficient.
However I have only ever used 89 in my '79.
But rising gas costs and curiosity got me thinking maybe 89 really isn't necessary.
I don't have the factory manual, anyone know what Porsche reccomended?
What are your thoughts?
Thanks

I've heard it said that 89 octane is the least used fuel at the pumps and thus sits there longer. I'd go with 87.

I run 91 since my rebuilt engine is using euro p&c's.

I run 87 octane in my '79 SC and that is all that is required.

I've used 87 in my 911 and cannot tell the difference from the 93 I normally run - and with the price of gas I suspect I will be using it more often!

Just FYI...gasoline only comes in two octanes to the station: 87 and 93. 89 octane is just a mixture of the two drawing from the 87 and 93 octane tanks in the correct proportions.

I can't tell any difference with higher octanes but mine runs better with 87 Chevron (tecron) than the others.

If I run 87 in mine (82) I get alot of predetionation under hard throttle. 89 is a little better but still not too quiet. We don't have 91 where I live so I feed my SC93. With $.10 diff. per grade it only costs me $4.00 exrta to use the good stuff if I let it get that low. Just go with the higher grade and drive hard&happy

Just noticed you have an 82sc. Didn't the compression rate go up for the 81SC? Not 100% sure. but if it did that would explain the "predetionation under hard throttle".

87 for me.

The owner's manual for my '83 says the min. oct to use is 87. Here in CT, that is averaging $3.05 a gallon right now. Also, here in CT "super unleaded" is 93 octane, whereas some parts of the country the highest you can get is 91.

Must be the Carreras that got the higher compression ratio. Well, those guys have plenty of money so that higher octane should be a problem.

This is news to me. I had a 78 and a 82 sc and both would knock badly with anything lower than 90 although it mostly happened when in 5th gear at lower speeds.

Right on..so I will be running 87 from here on.

Let you know if any issues...

The Venezuelan gas is good : CITGO?

Which Co. should I give my $$ to?

All I know is my owners manual says 87 so that is what I use with no issues.

use the lowest octane rating that doesnt cause pinging and definitly not detonation. anything else is just money out the exhaust pipe.

Even my 86 3.2 Carrera runs fine on 87.