vincheung

Took a trip up from NYC to Montreal & Quebec City recently and realized that outside of Montreal going north only 91 is available (my tank lasted with 93 in it for the round trip but it was getting low). In NYC and surrounding states 93 octane is readily available, i'm ecu tuned for 93 also. Just wondering what other 93 tuned guys do for longer distance drives where 91 octane is the max available at the pumps. Octane Booster? Run with 91 with more conservative driving? Knock sensors still compensate when 93 tuned?

I poked around online/reddit and didnt really walk away with any good information.

badq45t

I can only buy 91 in CA and I have added octane booster to see if the power and gas mileage was any different. I haven't done any tuning (not sure the 550e has available tune) but mileage and power seemed the same with and without the booster.

cfmistry

Who did your ECU tune? I think asking the tuner would be the most beneficial.

Donnymac

The compression ratio of your motor does not need 93. It will live just fine on 91.

Mitch Alsup

A lot of this octane stuff is dependent on how you use the car.

a) if you are always flooring the throttle--you best stick with as high an octane as you can get.
b) if you ease away from stops and ease up to cruising velocity--you need nothing more than mid-range gas.
c) live in mountains and use cruise control up and down hills--probably better to stick to higher octane
d) live near sea level and use throttle to keep distance from others--best to stick with higher octanes.

I use mid-grade gasoline with nary an issue in 7 years.

nybenzo

Whats mid grade? 89? We don't have 91 here in NYC. Its 93 or 89.

vincheung

Thanks for all of the comments, I know that 91 for stock mapping wont be an issue. Looking for input from what 93 tuned guys do when they have road trips into areas where pump premium is 91 only.

MBNUT1

As Mr Alsup suggested just keep your foot out of it when you are running the lower octane fuel.

will_atl

Mid grade is 89 here in GA, we have 87, 89 and premium, which don’t remember whether it’s 91 or 93! I’ve been using it for years, and it shows how little attention I show when I’m at the pump 🤦🏻‍♂️

I just filled up, we have 93 in GA!

SW20S

He's got a tune is the issue...stock 91 will be fine.

Bigg Willi

I have a handheld that lets me switch my tune from stock to moded (91) to race (93) since CA smog now can see a moded tune.

Donnymac

In what measurable ways can you tell the difference?

cfmistry

You can buy octane boosters from any auto parts store. That should work. But again, I would recommend asking your tuner.