If memory serves me correctly, the ideal air/fuel mixture for alcohol is approximately 7:1, versus 12.7 or so to 1 for gasoline. This means that if two engines were both optimized for their perspective fuels, the alcohol fueled engine would use nearly double the fuel for equal distance travelled. This means that 'theoretically' a 10% blend would cost you at least 5% loss in fuel economy, more than likely more tho.
BTW: FYI, I have friends that 'blend' the fuel for the gas stations, and yes the additives are added to the base fuel according to who is selling the fuel. They put a different additive in the Shell than for PetroCan or Esso.

 

vp racing ms109 just about all the time. I keep a 20 liter container on hand at all times. I don't drive the ruf very much, so I probably go through 4 or 5 20 liter containers during the months of Apr to Aug. The gas sold at our local gas stations is complete garbage. If I do fill on techron 94, I will mix in 5 or 10 liters of the 109 just so I don't get the dreaded timing pull that is inevitable with the junk that is readily available at every intersection.

 

I use the Chevron 94 in both my Turbo and the 991. Absolutely no issues. If I use 91 in the Turbo I get "codes" thrown. Haven't had to try 91 in the 991 yet but will be driving to Los Angeles in the fall and know that at I'm going to find out.

 

Okay so try this on for size...gas does make a difference....I went on a small road trip recently and had to take a couple of tanks of non premium stuff....I started to get the cat rattle upon start up and shore 'nuff I got an incomplete combustion CEL... I cleared the code and have run a few tanks of PetroCanada Ultra 94 and the rattle has gone and the CEL has not reappeared.

Coincidence?

 

Nope.
I've been running PC 94 in my C2S for last 2 years or so.
No issues, engine runnig very smooth, quiet and powerful.
Keep in mind that these cars have been tuned to 93 octane gasolines straight from the factory.
If in doubt, check the under side of your gas filler lid next time you fill up.



=L=

 

Yeah, I've seen the octane recommendations but "the engine control system will manage that - right?"....

Like I said, aside from the cat rattle the car ran fine. But still, for me the lesson is very clear: my car needs the premium fuel!

Have a great weekend everyone!

 

Petrocan sponsored the Canadian Cup series this year and they all had to run the pump 94 fuel. The cars seem to be running fine although most of the teams would prefer to use 100 octane race fuel. If it works in a cup it should be plenty good for most street cars.....

 

Octane is good with PCan (Suncor), but lots of ethanol. That's partly how they get the octane rating up. It would be interesting to compare power output with the various fuels available.

 

Thanks for the update Ranchman.....I just became a V-Power buyer!

 

One thing that I believe is more important than the octane rating is that the older Porsches do not tolerate the ethanol content in many fuels. It will attack the seals and rubber fuel lines on the older cars ( pre-2001). I exclusively use Chevron Supreme Plus (94 octane) in B.C. It does not contain ethanol, all other Chevron fuels may contain up to 10% Ethanol.
This past summer I drove my 928 S4 to California and only used Shell V-power ( also no ethanol). The car ran flawlessly with no issues in using a slightly lower octane fuel.

 

Here is a nice write up… take a read.

http://www.searchautoparts.com/motor...tank?cid=95914