Needed some technical advice regarding 91 octane fuel. Currently own a 2007 997 Turbo with about 26,000 miles (Upsolute ECU mod and NHP exhaust) that was purchased and used in Southeast Michigan where 93 octane is plentiful, and only fuel used in my car. Currently using my car in Sacramento for business. Is it harmful to the engine to be running 91 octane now ? MY concern is that the Upsolute ECU is not programmed to handle the lower octane fuel. Currently have had no problems in normal driving, however have avoided WOT so far (but would love to open it up!) Also, would it be better to add those "Octane Boosters" (eg 104+ or NOS brand) to the fuel tank to correct the issue ?

Thanks in advance for your help guys !

 

http://volvospeed.com/Reviews/octane_boosters.html

 

To be safe, you would be better off blending in 100 oct which you should be able find pretty easily in the Sacramento area. To get 5 gal of 93 oct, you would need to mix 3.9 gal of 93 and 1.1 gal of 100.

 

I believe that the ECU should adapt to the gas you are using (within reason) and it shouldn't be a problem to use 91 octane, you'll just experience a bit of pulled timing.

How do you like the Upsolute tune? I had considered it when I was first looking at getting a tune but there was no feedback available at that time.

 

Upsolute tune has been great ! I purchased the car at 12,000 miles and was already installed along with exhaust. No issues at all, just had spark plugs changed at 25,000 miles again with no issues. Too bad your not in the Northern California area, otherwise would let you drive my car to see the difference. Perhaps the next step for me is a dyno....