85fortheDrive

What with gas prices being as high as they are, I've wondered about putting 87 in out 1984 S. The PO always put in 93 and I've been doing so as well. But I'd like to know who uses what.

Thanks

69gaugeman

plain ol regular for me. 3 years + and no knocking or pinging that I know of.

largecar379

if you have US spec (read: low CR), regular will do.

if you have a Euro/ROW (read: 10.5:1 CR), premium would be the norm.

my Euro runs premium, regardless of price.

----Russ

chrly924s

Porsche had a press release about 2 years ago when gas was hitting $3, that you could run regular in their cars as long as you didn't do any "competitive" driving.

G Man

I have read it is better as far as performance is concerned to use the lowest octane you can without detonation. Higher octane does not mean more power. 87 actually contains more energy than 93 does.

85fortheDrive

Hmm... How so?

Lizard928

the lower the octane rating the more explosive it is, meaning that the flame travels faster.

You use/have higher octane when you have boost, or want to run more spark etc.

but on a NA engine with conservative ign timing from the factory, you will get marginally more HP and TQ from a lower octane.

mark kibort

that would be an interesting dyno test. running regular at the race track. cool. more power and cheaper. (but i wonder how risky)
mk

V-Fib

+1

Lizard928

Mark, with the LH2.3 and the dual knock sensors you could probably do it, I doubt you would see much of performance gain or real loss.

On the track however I would run a higher grade as the engine runs hotter and therefor needs a greater detonation threshold.

Lizard928

I run my 86 32V engine on 87 octane and hear no complaints, pretty hard too. When I go to the US I run 90+ as you guys have a higher allowable water content in your 87 which I dont like.

PorKen

Did you mean to say 'lower octane', here?

I use 89 in the '81, only because I run a lot of cam advance (8° crank), which increases the compression. In stock trim, it runs fine on 87.

If you put in too much ignition advance, without good gas, you can see the dyno graph gets real squiggly at the top end from preignition, and there's no audible knock.

I don't see any US 16V in stock tune requiring more than Regular, Plus maybe in hot climates.

Lizard928

yup that is what I meant ken, I will go back and change that.

jpitman2

Why not make the options fit more of us? we have 91,95,98 here in Oz. In Russia I saw down to 76.....
Mine has never pinged or misbehaved on 91, cant notice any difference driving on it.
jp 83 Euro S AT 51k

marton

Here is what Porsche GB say about this topic; I understand this bulletin is in the public domain (no copyright)

Marton