Power & Fuel consuption 95/97/98 Ron

[stewart999]

I am soon to be the proud owner of a new 997s and was wondering what peoples views were of different fuel types in the porsche engine. This will be my first porsche so I have no previous experience of the benefits of different fuels in the tank!

In my audi TT I used to observe swifter performance and better fuel economy (approx 2-4 mpg)using optimax than standard unleaded.

Any views on performance and fuel economy would be much appreciated!

[turbobloke]

stewart999 said:

Any views on performance and fuel economy would be much appreciated!

Well as youn asked...

Like YGS I've always found better performance and fuel economy from fuels like Optimax in performance cars. Your 997s engine sensors and ecu will make the most of the fuel so I can't see why your past experiences will change.

[GreigM]

Don't know if I feel much difference in power, but find I get better mpg with Optimax, so the cost tends to be eliminated with that alone.

[verysideways]

Ditto - it some of my cars i've had to use "super" so i use optimax anyway. In those cars where i've had a choice, i usually find better throttle response if not outright power on optimax, and always better mpg (which negates the extra cost).

HTH

VS

[diver944]

Check the manual when it arrives as to what is the recommended fuel. If it is 97 RON then that is what it will run best with. It will still run with 95, but the knock sensor will retard the ignition to protect the engine and you will get slightly less power.

Do the Boxster and 996 have 97 RON as the recommended level? I know 993 and 968 did, but I'm not sure about the current models. I am guessing they do.

[polar993]

verysideways said:

....and always better mpg (which negates the extra cost).

Is this really the case? If so, I will start shoving in the Optimax, however I am naturally sceptical of such claims. Can anyone reassure me??

[turbobloke]

polar993 said:

...I will start shoving in the Optimax, however I am naturally sceptical of such claims. Can anyone reassure me??

I've had significantly better mileage out of Optimax on every performance car I've driven, nobody could say for sure you'll get the same result but I suspect it would be well worth a try, see two or three tankfuls through and see what goes.

[stewart999]

Thanks for your words of wisdom. Have just had a call from the dealer to say the car will be with them next week. Doubt they'll even fill it up with anything!Anyone had any gifts off their dealer when they've bought a new car?

[softinthehead]

i put a post up about optimax a while back - it made no difference to my 944 but then the engine was old and without the necessary ECU to take advantage of it. My 968 specifically says 98ron but of course it had 95ron sloshing about in the tank on delivery. changing to optimax brought really quite obvious benefits - engine seemed smoother, power delivery was better, fuel economy improved slightly, allowing for the fact that I was driving more aggressively with the better response to the fuel. Given the relative dearth of high octane fuels until recently, most cars are now optimised for 95ron, but your 997 manual should say if it will work better with 97-98. On balance I thought optimax well worth the benefits and I'm naturally both stingy and skeptical about these sorts of things

[GreigM]

polar993 - its worth a try, both my boxster and now the GT3 (moreso with the GT3) definitely gave better consumption with optimax. However, don't expect miracles on the first tankful - it will take a few tanks for the ignition timing to adjust properly - whatever you do don't see-saw between optimax and regular, as you then get the worst of both worlds. For example, in the GT3 I get about 197 miles to a full tank with regular, and about 220/230 with optimax - although I have to experiment more to confirm this.

And whoever asked - yes, the 996 and boxster are recommended to run on either 97 or 98 (can't remember which).

[glpinxit]

Check out the current 'Ride' magazine in which they tested Optimax against bog standard unleaded and someone else's premium stuff (sorry I'm sounding vague- I'm at work and the mag is in the loo at home). Helpfully they also used two bikes, one running carburettors and the other sophisticated modern fuel injection and ran them on a dyno. Their conclusion is that the premium stuff is better and (iirc) Optimax the better of the two. Somewhere between one and two % improvement in power and mpg.
I also recall that they were rather dismissive of the cost/benefit ratio. I thought this rather mean when a performance exhaust for the bikes would probably only have produced much the same result for quite a lot more outlay.
Guy.
Edit to say that I'll try and remember to post the results this evening.

>> Edited by glpinxit on Thursday 6th January 11:00

[glpinxit]

I've checked the article. Ride's results from dyno testing Shell Optimax, BP Ultimate and basic unleaded in a 2003 Suzuki GSXR600 (fuel injected) and a 2002 Kawasaki ZX6R (carburettor)as follows :
fuel UL Optimax Ultimate
Kwak 101.8 bhp 102.7 102.9
Suz 98.5 100.4 100.0

Rather than the improvement in power from these fuels I'd like some of what they use to get 600cc bikes to produce over 100bhp in such a cheap package. Would Reddex achieve this?
Guy.

[cyrus1971]

off topic a bit but on the continent one can get Shell VPOWER fuel. Lousy name but damn that stuff really is rocket fuel 100+ ron … got at least 20 bhp more in my 996TT from it.

[Dr Strangelove]

polar993 said:

verysideways said: ....and always better mpg (which negates the extra cost). Is this really the case? If so, I will start shoving in the Optimax, however I am naturally sceptical of such claims. Can anyone reassure me??

I always put it in the Mrs' Scenic (she doesn't) and always get a better MPG, also it pulls smoother at Motorway speeds, and has more punch. The difference (in this car) between the two fuels is tangible, to the point where it transforms the cars character. Quite amazing really. (what are they putting in the standard stuff?)

Also, my porkie doesn't really like anything other than Shell's finest. It just feels less responsive with standard liquid gold.

[tony.t]

diver944 said:

Check the manual when it arrives as to what is the recommended fuel. If it is 97 RON then that is what it will run best with. It will still run with 95, but the knock sensor will retard the ignition to protect the engine and you will get slightly less power. Do the Boxster and 996 have 97 RON as the recommended level? I know 993 and 968 did, but I'm not sure about the current models. I am guessing they do.

The knock sensors retard the ignition when knock ocurrs. Higher octane fuels are actually less likely to cause knock - that's their point really. Higher octane allows higher compresion or turbo boost which is why race fuel is 100+.
If the cars' ECU is designed to run on 95 octane fuel then using higher octane fuel ought to be a waste of money since the chip is running full ignition advance and no knock should ocurr on an engine designed to run @ 95 RON. However the engine will not retard the ignition if higher octane fuel is used.
Vice versa if the ECU chip is running max ignition advance @ 98 RON then using 95 RON will cause knock and ignition to be retarded and power loss.
By removing the ignition timing ceiling for 95 octane a re-chip can liberate a few more bhp by setting the ceiling higher, say 98 RON. The car will run the same power with 95 RON and the knock sensors still protect the engine from damage as before.