new IB owner

[Fishcop]

Reasonably common thing.

I lived with this issue for a few years before fighting my natural lazyness and installing a couple of in line fine filters just before the fuel bars.

Later I fully cleaned and resealed the tank as part of the overall restoration and I have had no issues since.

Do check your tank to make sure it's not rusting and also swap fuel vendors if you have any doubt about the quality they are providing.

[Motolita]

Hi John
In line filter are the next job.
I will check Chris's blog but I think he refurbed the tank.
The fuel I have put in is BP Ultimate Unleaded from a fairly busy servo.
Out of interest what fuel do you guys use?
Ian

[Fishcop]

Hi Ian, the gunk could just be one of those once in a blue moon things, you know what to do now

I actually buy my fuel from a little independent station a few hundred meters from me. The owner is an American Muscle Car guy (I think he bought the station just to write off his car stuff ). He assures me he keeps the latests testing gear and renews pump filters regularly. He loves his cars...

Octane wise - standard old Porsche engines don't need 'premium' at all - you're wasting money on the high octane stuff if you have standard compression. I just go with the regular stuff and steer well away from ethanol on principle. I have no real experience with any of the aftermarket additives people like to put in fuel.

[SM911]

Octane wise - standard old Porsche engines don't need 'premium' at all - you're wasting money on the high octane stuff if you have standard compression.

Wow Fishy, that's a big call.

I'm the first to say that I know very little about fuel, but those with a lot of experience in this game say we should -wherever possible - use BP 98 octane.

How have you come to this position? And don't get me wrong - we all need guys like you who ask 'WHY do we do that?'

[Motolita]

Hey John
Yes, every blue moon would be nice, filters being done over the weekend to be safe.
My engine is higher comp than std. I asked Don Munro about fuel for mine & he said use the BP Ultimate 98 octane.
Ian

[Fishcop]

How have you come to this position? And don't get me wrong - we all need guys like you who ask 'WHY do we do that?'

Ping/knock... If your engine doesn't, and everything is tuned well, then your fuel is doing its job. Higher octane does not mean 'more power'. Higher RON/octane (a measure of compressibility before detonation) fuel prevents knock in higher compression engines, so if I was running an 11.5:1+ CR performance motor, sure I'd be running the 98. My RS spec engine is the factory 8.5:1 CR and simply doesn't need premium for either knock prevention or 'fuel efficiency'. It will still push out its 190Hp

Don't get me wrong, you can't harm your engine using premium. But like everything else in this modern world, products are "value added" and I don't buy the hype. Certainly not the extra 15 cents a litre premium (pun intended).

Buying the 'best fuel I can' for me means clean, water-free (hence hate of ethanol), and a good price.

As always, listen to your mechanic and treat everything you read on the internet with suspicion...

I literally sign this post off with YMMV

http://www.motoring.com.au/advice/2008/myth-busting-high-octane-fuel-will-make-a-car-faster-7513

http://www.early911sregistry.org/forums/showthread.php?111077-what-octane-do-you-use-on-your-stock-2-4-engine-(and-ethanol-)&highlight=fuel+octane

https://en.wikipedia.org/wiki/Octane_rating

[Merv]

I was told to use 98 but my comp ratio is now 9.8. Otherwise many of the US experts seem to agree with John

[mario lanza]

I agree with john and that's without my physics and chemistry training. However with my Morris cooper s at 10.5 compression you need more than 95 octane ideally. My 2.7 carrera like John says is fine without. But I buy it because they say it is cleaner burning and has cleaning agents. But John is right that is value add nonsense I suspect.

However, ignition timing and temperatures also affect pinging. Really hot weather or advanced timing or a run down cooling system then you might want the added insurance. On really hot Melbourne days it can make a noticeable difference to knocking - but I have not noticed in the 2.7 carrera low compression and all.

A 2.0 or 2.2 S might be different....

[mrar]

I am with you John.
Currently run standard fuel on low compression engine cars (it's in the manual),ones that state 96 and high compression use 98.

[Fishcop]

Thanks Mario (and Sean). I was going to mention hot weather - and up here in Qld we do get some. But I choose not to drive an old 911 without A/C when it's hotter than 30șC

FWIW I've got a well mapped distributor set up especially for my engine and modern fuel, and MSD. It was $$ well spent.