91 Octane Detonation?

[93gtmustang]

I can get ethanol free 91 octane in New Lebanon NY.
I have my timing at 15 degrees advanced running 93 octane with ethanol in it.
Do you think I'm good with the 91 or do I have to back the timing down a couple degrees to be safe from detonation?

 

[AeroCoupe]

Typically and I stress typically with pure 93 octane gasoline and E-85 you can add a couple of degrees of timing. Where the E-85 shines is high compression and/or boost.

None of that applies directly to your question but in a way it does. My Coupe is dyno tuned and the tuner let me know that ethanol or not he wanted 93 octane. I asked if running 91 would hurt anything and he said no but that 91 should be the minimum I put in the car. I do not change the timing.

 

[93gtmustang]

Thanks!
So what do you usually run. 91 or 93?
What does he have the timing at?

 

[93gtmustang]

Or how about using an octane booster to raise it to 93?
Do these products really perform? If so, which is the one to use without damaging O2 sensors etc...

 

[Mustang5L5]

It’s hard to really say if it will be fine. Too many variables. Yes, 93 should be slightly more resistant to detonation than 91. Whether or not you will be fine on 91 depends on things like carbon deposits on valves/heads, compression, actual timing, etc. What one person gets away with may not work for another.

For instance, I could not run 87 octane on my bone stock engine. For some reason it would always detonate. I needed 89+. Other folks run 87 perfectly fine. When I pulled my heads off down the road….carbon.

 

[AeroCoupe]

10 degrees of base timing and the tune takes care of the rest on my setup.

Run the 91 and back the timing down a couple degrees. Run it and if you want to bump the timing check the plugs. It’s what we all do if we are trying to squeeze all the power we can out of a motor. Like Mustang5L5 said each motor can be different.

Tip to keep the tops of the pistons and combustion chambers clean. Put a 150 shot on it and nitrous will keep it nice and sparkly in there…or all over the street. Either way carbon won’t build up.

 

[93gtmustang]

I had sold my car back in 2016 for my child's college tuition. When I bought it back, I checked the timing. The bolt on the distributor wasn't tightened all the way down. The timing between 22 and 23 advanced with the spout out! The car wreaked of gas. He said he ran 110 race fuel mixed with 93 octane. I don't know why? It cooked O2 sensors.
I always ran 15 advanced with 93 octane. Never had a problem. I want to run the ethanol free 91 octane to make the new fuel lines I just put on last longer.

So what's the deal on octane boosters. Anyone have experience with them? I read on some forum that the Lucas Oil Octane booster made their plugs turn orange lol! I don't know?

 

[93gtmustang]

10 degrees of base timing and the tune takes care of the rest on my setup.

Run the 91 and back the timing down a couple degrees. Run it and if you want to bump the timing check the plugs. It’s what we all do if we are trying to squeeze all the power we can out of a motor. Like Mustang5L5 said each motor can be different.

Tip to keep the tops of the pistons and combustion chambers clean. Put a 150 shot on it and nitrous will keep it nice and sparkly in there…or all over the street. Either way carbon won’t build up.

Where you serious on the nitrous lol!?

 

[AeroCoupe]

No way man. You run the fun juice lean enough to clean combustion chambers and you are going to see the inside of it the hard way.

 

[Noobz347]

I remember having this conversation [years] ago and I thought this might help as General Heads Up. Note that other octane boosters will have different mix rates:

So for 91 to 93 Octane you would need 2.7 oz for 15 gallons.

For 87 to 93 octane you would need 8.85 oz for 15 gallons.

BOOSTane Mixing Chart

The BOOSTane Mixing Chart helps you blend to the exact octane you need. Pick your starting octane and desired octane to determine how much BOOSTane is needed.

boostane.com

I've never used this product. It's what showed up in my search results.