Up the river with no 91 octane
 

If a motor is built to run on 91 octane and only 87 is available, what are the best options? Add octane booster, and/or change carb jets, and/or set timing back, ..... ?

Re: Up the river with no 91 octane
 

What is the motor? Blower or NA? I would think that if you have a blower you can just stay off the boost?

Jon

Re: Up the river with no 91 octane
 

If the motor is built to run 91, then I wouldn't run 87. I could maybe see 91 to 90 or 89, but not 4 points less.

Option- Pull boat to gas station... Pain in the a$$, but better than engine probs.

Re: Up the river with no 91 octane
 

Add some 114 octane race fuel. Figure out what you need to get the octane. 50 gallons of 87 and 10 gallons of 114 will get you 91.5 octane fuel.

Re: Up the river with no 91 octane
 

I Would Add Booster. Why Take The Chance. Buy A Case And Keep It In The Boat.

Re: Up the river with no 91 octane
 

I also carry booster for "those occasions" and never had a prob. Retarding the timing 2 to 5 deg.will also insure against detonation but who wants to mess with that? And performance suffers. Do NOT mess with your carbs! --- JP

Re: Up the river with no 91 octane
 

There was a a thread recently about boosters. From that, it seemed that "boosters" would actualy boost octane a few points, points as in to the right of the decimal point, not the left. ;)

Other than mixing in super high octane, what can you do to boost say, 50 gallons of 87 octane to 91+ without using racing fuel like Griff mentioned?

Re: Up the river with no 91 octane
 

I've read that you can add toulene to the gas to bump the octane. I don't know the ratio, but I bet MCollinstn does. :)

Re: Up the river with no 91 octane
 

Cuda: :evilb: Ready for the Fun Run?

Re: Up the river with no 91 octane
 

Toluene "is" 114 octane.

50 gal 87 + 10 gal 114/toluene DOES give 60 gal of 91.5

50 gal 87 + 6.5 gal 118 Leaded GIVES 56.5 gal of 91.3

Torco Accelerator Leaded Race Fuel Concentrate is the best bang for the SIZE. Not necessarily the best bang for the buck, but as far as hauling around with you, it takes less room than anything else that delivers the same boost.

Cost assumptions:
87 unleaded: $2.00/gallon
114 toluene: $2.85/gallon
118 leaded race gas: $7.50/gallon
Torco accel: $17.00 per qt.

50 gal 87 + 3 quarts of Torco = 50.75 gallons of 91
Cost: $2.72/gallon

50 gal 87 + 10 gal toluene
Cost: $2.13/gallon

50 gal 87 + 6.5 gal 118 Leaded
Cost: $2.63/gallon

mc