P1-EH

I've had my 997 since December, and am finding it hard to locate enough stations with the recommended grade of gas. The minimum (RON+MON)/2 aka AKI is 93. I have been filling up at a Sunoco station nearby with their 94.

Are there any other stations that have 93+? I sometimes get stuck with 91 and only put in enough to get me to a Sunoco station.

Cheers,
Mark

Dale Gribble

mark,
that 93 number is derrived from the european way of rating gas. 91 octane is its North American Equivalent and is perfectly acceptable.

Example: In japan, you get 100 octane at the pump, but it is calculate differently (roughly the equivalent of US 93-95). Don't fret, just load up with 91, use the pennies saved for a coffee, and drop the hammer!

jumper5836

+1

pongobaz

Mark,
there's been lots of discussions on this and as Omar pointed out, 91 here is the equivalent. I personally don't use Sunoco 94 since it contains ethanol which I found created a lot more black soot on my tailpipes and has been mentioned as a potential (unverified) culprit in cats going bad. FWIW, I've been running Shell V-power 91 which is completely ethanol free for the last 3 years without problems.

Jaak Lepson

In my research I have found this to be true ... also use Shell 91 in all your outdoor tools such as outboards, skiidoos etc ...

Ethanol makes these toys run leaner causing premature failure. Some in threads in other fourums have brought this problem out. I found using Shell 91 makes these toys very happy!!!

P1-EH

Thanks, gents for this info. Strange that the 93 is actually 91, because the label inside my gas cap says minimum 93 (RON+MON)/2 which is the formula Sunoco (and I believe all North American gas stations) use for their fuel grading.

The ethanol causing the carbon deposits on my pipe tips is interesting.

But since you guys obviously know what works, I'll stick with Shell 91 V-Power. I use that exclusively on my other toy.

Thanks,
Mark

old man neri

What does the manual say? If you bought the car used I wouldn't trust the sticker on the gas cap.

There is a good story on Pelican about a guy complaining that he was finding it hard to find 100LL (aviation fuel) to fill up his car. He was doing there because some previous owner had stuck in a sticker as a joke. Ya.....

topspd

I use Shell Vpower w/ my 997S and haven't had any problems. And mine has the same sticker.. I actually get better mileage using VPower as opposed to Ultra94.

b5audia4

Is Sunoco 91 also with ethanol? or is it just the 94?

Jaak Lepson

IIRC 5% Ethanol. Look on the pumps, they give the Ethanol levels as per their sticker.

JDSStudios

+1 on Shell 91 NO ETHANOL.

Someone here, a while back sent me a link with a long detailed document
explaining the harm Ethanol causes in several components, and specially
when it separates from gasoline after 90 days or so.

Ethanol causes far more harm in early engines, but why risk?

Jaak Lepson

From PZULL post on 03-22-2007 ...

"I did quite a bit of research on gasohol (benzene/ethanol blends) when doing an EFI project for my 965. Synopsis of my findings:

1) Ethanol has about 2/3 the BTU (energy) per volume compared to gasoline

2) Ethanol can be detrimental to certain car parts (usually older cars) not resistant to it. eg. rubber parts harden and crack, uncoated steel fuel tanks may rust, slightly more wear in fuel pump, faster deterioration of cat

3) Ethanol and Gasoline does not remain homogenous indefinitely ie. they start to separate if left sitting for too long

4) Gasohol has a faster combustion rate than plain gasoline

5) Ethanol has a higher latent heat of evaporation meaning it will create a cooler charge for the engine (good for power)

Most modern cars will run on gasohol without much drama but would not be optimised for it for the following reasons:

1) As gasohol has faster combustion rate, ignition timing needs to be changed. Cars with knock sensors may compensate for this a bit but depends on range of adjustments made by factory ECU

2) If a car is not running cliosed loop, engine will run leaner and hotter with gasohol. Few cars have ability to compensate for this and you will need a programmable ECU installed to tune the car eg. Motec, Autronic (which I used)

However if you have a programmable ECU and tune for it you can expect more power but higher consumption. The cooler charge due to more fuel being injected and the better cooling effects of the ethanol will increase charge density and increase power (drag racers use 100% alcohol)

Breakeven point in cost terms for higher fuel consumption in a tuned car is reached when gasohol prices are 4-5% cheaper than gasoline. Anything cheaper and you save costs.

In an untuned car, breakeven point is worse because consumption is much hiogher due to fact that car is not optimally tuned for characteristics of gasohol.

Anyway I'm no PhD physicist but this is what I learnt from research and implemented in my project and it worked really well. For many other reasons my 965 now has 420bhp (at 34 degrees C) compared to factory 320bhp. In lower temperature and humidity like in Canada (ie. 20C) I should get above 450bhp. No issues with pinging as car is optimised for fuel in where I live "

MichelleJD

Does anyone know about BP in Canada? I use that here in the States and am wondering if I need to switch when I get there.

Jaak Lepson

Long gone .... Stick with Shell 91 ...100% gasoline ...

Mark Lue

Normally I would agree but I believe Michelle's 951 is modified. In that case maybe the Sunoco 94 would be a better alternative... better safe than sorry.

Maybe someone with a built 951 could chime in... .