78-80SC Who is using 87 Octane

[dan79brooklyn]

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

[SilverPoly]

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.

[Tim Hancock]

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

[vesnyder]

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!

[Ytouf]

Originally posted by Steve79SC
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.

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.

[emcdan]

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

[Rick V]

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

[khamul02]

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".

[oneblueyedog]

87 for me.

[S2GART]

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.

[khamul02]

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.

[tonypeoni]

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.

[dan79brooklyn]

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?

[khamul02]

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

[kumma]

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

[stlrj]

Even my 86 3.2 Carrera runs fine on 87.