what octain do you use

[alan6272]

Was wondering what oct. you use I read the 944 takes min.91 I use the cheap stuff and it works just fine for me.

[jcommin]

I live in Chicago. Gas isn't cheap here.

[mikepellegrini]

I use regular (87 octane) for my NA and premium (92 octane) for my 951.

I always buy "good" gas (e.g., Union 76, Shell, Texaco), as opposed to el cheapo stuff - like Arco, for instance, or off brands. There's a reason it's so cheap, after all.

[ronster]

My '99 Boxster calls for 92 but we only get 91 in CA. After a visit to The Racing Group a few months ago the Porsche trained engineers there convinced me I could use 89 with no problem. Tried it saw no difference in mileage and performance and have used 89 since. I also only use Chevron and Shell gas.

[VirginiaF1]

Shell 93 at $4/ gal. As of last fueling...

[egil]

98 octane (RON) at a price equivalent to US$10 per US gallon

[Guest765]

Originally Posted by egil

98 octane (RON) at a price equivalent to US$10 per US gallon

i sure hope you're running the boost to justify that.

[egil]

Originally Posted by fwayfarer

i sure hope you're running the boost to justify that.

Octane in Europe is displayed as the RON number only, whereas the US uses the average of the RON and MON numbers. So 98 RON is comparable to 93 octane in the US.

Gas prices on the two sides of the pond are not particularly comparable, though

[flash968]

it's all about the compression ratio, the ignition controls and the load

i have only ever run the best fuel possible in anything out of which i wanted performance - engine output specifications are rated at the upper range of the octane required - anything less than the upper range specified causes the ignition control systems to retard timing and cost me power - if it says, for example in the case of the 968, 90 minimum to 93, then at even 91 i am losing 4.8hp (the rule of thumb is 1 point in octane represents 1% of power available) - you may not feel it, as it is only a few horsepower, but i feel that anything less than what i can have is cheating me out of some fun

further, even on the denali, which can easily run on 87, if i plan to tow, given that i have reprogrammed it for 89, i bump up the octane to 89 to keep the knock sensors from engaging, which not only makes for more power, but also runs cooler and gets better fuel economy (about 1mpg on that car) - 91 seems to make no difference on that one, and might actually run hotter

[Guest765]

Originally Posted by egil

Octane in Europe is displayed as the RON number only, whereas the US uses the average of the RON and MON numbers. So 98 RON is comparable to 93 octane in the US.

Gas prices on the two sides of the pond are not particularly comparable, though

makes sense.

[gmorken]

Originally Posted by alan6272

Was wondering what oct. you use I read the 944 takes min.91 I use the cheap stuff and it works just fine for me.

Have never used anything other than 93 octane and its running 24mpg in the city. Sunoco offers 100 octane at their regular gas stations around the drag race track at Gainesville, FL... it would be fun to give that a try but not at $9.25/gal.

[alan6272]

I know gas prices are out of this world in most places, here in NC it is now at $3.59 for 87 oct. 2 weeks ago it was $3.98 go figure.

[J1NX3D]

Originally Posted by egil

98 octane (RON) at a price equivalent to US$10 per US gallon

I use 98 ron also. 98 has become more common in NZ over the last 5 yrs. I use 95 in a pinch though.

[Jrboulder]

We have 85 octane here in Colorado. I use 87 in the winter and 85 in the summer. Today the density altitude is 7600. I see no problem using 85 octane.

Jackson

[Aufgeladen944]

I use 93 in the 951.

[nynor]

91

[ERAU944]

the 951S gets 93

the 944 gets 87

as mentioned, octane ratings are anti-knock indexes, not ratings for the performance of fuel.

the higher compression the engine, the higher octane you will need to prevent detonation.

while turbocharged engines typically have lower compressions, the much higher manifold pressures means that the combustion chambers in turn see much higher pressures, and therefore higher octane fuels are required.

to get the best performance, always use the LOWEST octane that you can WITHOUT any kind of detonation/pinging.

on my old miata, that was mid-grade (89) even though the book called for 87. i blame combustion deposits.

[James Chimney]

If I use Shell the 87 I get a little "run on" when I shut the car off and it is hard to start the next time, 89 works better and 93 I see no difference, 89 for me all the time

[J1NX3D]

i should have added, all the 944 n/a's i've seen, sold new in NZ, all have a sticker on the instrument cluster saying 'use 98 octane only'

[CatsEyes]

Originally Posted by mAd924

i should have added, all the 944 n/a's i've seen, sold new in NZ, all have a sticker on the instrument cluster saying 'use 98 octane only'

Same in Australia. Except my sticker's inside the fuel cap.

Aside from the different ratings described above, I believe the US-destination models were re-tuned for lower-octane US fuel.

944s down here will be Euro-spec.