Andy Roe

Is it OK to use 98 Ron Super Unleaded fuel? Would this give a little more power if used?

Andy

Roygarth

I've been told that it makes no difference to performance. But when I had my performance chip fitted I was told to use 98 to gain full benefit.

Piers

Roly Baldwin

This topic came up a year or so ago.

I'm pretty sure the recommendation (from Adrian?) was that you shouldn't use higher octane fuels because the DMF is set up for 95 octane and will not function correctly if you put in 98.

Perhaps with a performance chip it's different ...

Roly
'90 C4

Adrian

Dear Roly,
You are correct. 95 RON is the recommended fuel for the standard 964. 98 RON is recommended only for Turbos and the RS. These aftermarket chips require higher octane fuel but overall engine life maybe reduced. My fuel cap label clearly states use 95 RON only. I personally tend to take some notice of these things,
Ciao,
Adrian
911C4

oscar965

Adrian,
I filled my last 4 tanks with 98 RON on my 1991 911 Turbo. I'm pretty sure it's only my imagination, but it feels like driving faster.
But my fuel cap label also states 95 RON, and I have a Turbo. In a recent magazine (I think GT Purely Porsche) I have read that 98 is recommended for the '91 turbo.
If it is only a tiny little bit better, this would be enough for me to feed my car with this 98-stuff. But is it ?

Riccardo

My fuel cap doesn't mention anything. Confusingly, its also red (which in Europe is normally the colour associated to leade fuel).

Christer

Riccardo

I am sure your handbook will confirm the correct fuel to use. <img border="0" alt="[cherrsagai]" title="" src="graemlins/drink.gif" />

Jeff Curtis

Let me shed some light on this issue...ANY octane rating for a given vehicle is MINIMAL octane rating advised.

You can certainly use higher octane fuel in most (any) vehicles, especially performance vehicles...such as the 964/965.

Think of it this way, all 3.6 engines have knock sensors, this is to adjust ignition timing when the sensors sense a "knock". SO, this suggests that our engines may "knock" every now and then??

...they do! <img border="0" title="" alt="[Eek!]" src="eek.gif" />

SO, the use of a higher octane fuel may make it so it NEVER knocks under load.

Here's my two cents on the use of higher octane fuels though...and I've worked with octane differences quite a bit as I grew up in the drag-racing community and went on to own TWO supercharged vehicles:

Outside temp. has a lot to do with whether one might want to use higher octane fuels in their vehicle. In other words, if it's Wintertime in the areas of the world where it tends to get cold/snowy/miserable, and you drive a 964, it's not likely you're going to experience much engine "knock" whatsoever...if using the minimum advised RON rating.

If you're in say, Australia, in the middle of the Summer where it gets blistering hot, it's surmisable to think that one may experience better performance by using a higher octane fuel, like 98RON.

...not a bad idea for ANY track events either.

I personally have not discovered any evidence of knock nor have I experienced any noticable power loss during an event, even in the 90+ deg. heat of Summer. I have recently had my engine ALL THE WAY apart as well...looks good.

As you may know, I have probably 40 events on my 964 since purchase 20 months ago.

I often witness 964 guys at the track putting the $4 a gallon 98 and higher octane "racing fuel" in their tanks...usually the RSA guys for some reason...and I kind of chuckle. If they have not performed some considerable upgrades to their engine like a radical chip and/or compression upgrades - then I tend to think they may be wasting their $$$$$$ a bit. But it is one HELL of an insurance policy. <img border="0" alt="[thumbsup]" title="" src="graemlins/bigok.gif" />

Here's what one MIGHT try, while at the track, go out on the morning session, when it's cool, with pump gas. Take another session, before lunch. NOW, you're down 1/2 a tank or so...top it off with your $4 a gallon fuel because the heat of the afternoon is presenting itself, and you're getting faster as well - at least I HOPE you are??

This would provide a reasonable "insurance policy".

Now you have 1/3 to 1/2 tank worth of "jet fuel" in there, you should be good to go as this should raise your octane up a couple points when mixed with your pump gas. If you stay for another day, and the previous day was hot as HELL, on the way to the track in the AM, top off with pump gas and go a few sessions, add some more $4 a gallon gas for the last few sessions.

Now that makes sense, but is still not necessary. I have NEVER used the expensive track gas and again, NO issues with engine internals are apparent...and I continue to get LOTS of passing signals. <img border="0" alt="[hiha]" title="" src="graemlins/roflmao.gif" />

SO, if you're street driving your 964, I would certainly say it's a waste of "bling-bling"...but it won't hurt a thing, as for a noticeable difference in performance...it's possible, but I'd better hear you claim that on a 98deg. day!

As a slight sidebar, I routinely use 89 octane fuel in my Chevy Silverado, but when towing, I always fill with Super Unleaded, which is about 92-93 octane in the U.S. - this I do because the truck is working harder to tow my trailer + 964 and my track gear ~ 5000lbs. Of course, it has a knock-sensor unit and I'm sure it's come into play every now and then...but I like to think that my routine is just added "insurance".