Jim bailey - 928 International

The Porsche tech spec book for 78-79 states regular grade fuel of at least 98 octane (Ron) ,the 1980 S gets premium of at least 98 (RON) . So the old very brown 1980 runs regular !!

Bret928

Never really looked into it but the PO told me he ran the highest octane avalible - so I run 91 octane. Besides that what I normally run in my Truck because I've programed it for the higher octane (knocks with regular 87).

BTW is 93 not sold here in Kalifornia? Can't seem to find it anywhere.

85fortheDrive

Marton:

Me, ever-the-neophyte, now wonders the following:

1. Does 95 RON correspond to 87 octane?
2. The change from 95 to 98 actually occurs before the S models were produced, with no change thereafter. So perhaps the 16V descriptor is not particularly relevant in this context...?

Thanks, folks.

hacker-pschorr

Tim - stop worring about it until spring. After the next dyno weekend you will not want to run regular anymore

JHowell37

With gas prices as high as they are, the difference from regular to premium remains at around $.20-$.30. As the gas prices continue to rise and that difference remains the same, the difference as a percentage actually goes down. When I lived in SC about 7-8 years ago I remember having a VW and running it on 87. Those were the days. You could get regular gas for about $.80/gallon. So it only cost me about $11 to fill up. To make my point, back then 87 cost $.80. Middle grade was $.90. Premium cost about $1.00. So premium was 20% higher then regular. Now gas costs a lot more. In this area 87 costs about $2.85. Mid grade costs about $3.00 and premium is around $3.15. Even though the difference between grades is greater in terms of dollars out of your pocket, as a percentage, premium is now only about 10% higher then regular. So for me, I'll use premium. It doesn't cost much more. But I also have to say that I've never been one to shop gas prices either. I don't know who has the cheapest stuff in town because I use the same 2 or 3 gas stations and that's it.

As for the energy output, I too have heard that 87 produces more then premium because (I'm no engineer, chemist, or physicist so forgive my poor description) 87 is more volatile and unstable then premium. It's like "Pride of Baltimore" vodka, versus Grey Goose. Both will get you drunk, but which one will you be feeling in the morning?

marton

In the USA, the octane ratingi s quoted as (R+M)/2. If, for example, a gasoline has an RON of 98 and a MON of 90, then the posted octane number would be the average of the two values or 94.

European vehicles specify only the RON number, which is a higher value, and makes it appear that the vehicle needs a higher octane fuel.

Marton

Tampa 928s

I have a 86 with a chip and was advised to run 93!

justin

My 80 model runs regular 87, no problems, I run the 93 octane once in a while ,but I dont notice any change.

FlyingDog

You'd have performance loss and worse mileage due to the knock sensors retarding ignition. The retard loop on LH 2.2 cars does the same thing.

6mil928

I run 89 here because our 87 is junk sometimes. Jason

FlyingDog

89 is 1/2 or 2/3 "junk" 87 depending on whether your local gas station has 91/92 or 93/94 for premium.

ShawnSmith

Yep. Mid-grade isn't shipped to gas stations - they make it on site as a blend of the cheap and the expensive stuff.

SharkSkin

I can use low or mid-grade but if I'm driving hard it will ping occasionally. I just use 91 since I never know when I'll be driving hard... oh wait, yes I do...

6mil928

Not sure if that's true but all I know is my dodge truck will ping with the 87 here but not the 89. Believe it or not we have no name brand gas stations here like exxon or cheveron. We only have Love's or Circle K. Ah the joys of small town living. Jason

robot808

I have been using the 93 in my 82US 16V, but after reading this I think I'm gonna switch the old 87.