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How far can we go with high octane fuel? Can ECU do anything with octane above 100? Curious if anyone has done dyno on 100+ octane or compared 1/4 times when running 100 octane compared to 93 or 91 octane.
 

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two points. 1. lots of ppl think that 100 is only good if detonation is being caused by lesser octane fuel. so, 100 would counteract problems already existent. (i personally loved using 100 this summer)
2. with anything much over 100, youre going to be looking at too much ethanol in the gas, and maybe messing up some sensors along your fuel lines and exhaust tract
 

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two points. 1. lots of ppl think that 100 is only good if detonation is being caused by lesser octane fuel. so, 100 would counteract problems already existent. (i personally loved using 100 this summer)
2. with anything much over 100, youre going to be looking at too much ethanol in the gas, and maybe messing up some sensors along your fuel lines and exhaust tract
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ethanol is not really the problem. There is 100 octane unleaded, and 104 octane unleaded. Maybe it is just where I am, but I have never seen anything above 104 octane that is unleaded. 110 and 116 are leaded fuels, which while they will burn fine in our car at first, the lead will kill your O2 sensors and cat converters eventually. Albiet this will happen only if you use it more than occasionaly and over time. The car will probably run great on it at first.
 

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yeah, im just rolling off the top of my head. im planning on putting some 104 in the tank for the drags on sunday...but only after checking out how leaded it is.
 

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One of the tracks here, Rockingham Dragway, has carried as high as 114 unleaded. Not sure if they still do or not. I will find out some time.
As for any benefit over 100... not sure. Not sure how our ECU monotors timing and boost as engine load changes.


Thanks,
Jason
 

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HiBoost runs C16 in his car all the time, running in the 11's on several occasions now. so leaded fuel won't hurt the engine or anything, it's just the O2's and cat that will have the issue over time, as stated.

i might be wrong here, but does the speed scale timing up and then back off with knock? i know the atenza did this to some extent, so added octane would show on the dyno. but at a certain point, it's just safety, not performance. if the car isn't pinging on 100 octane, and the ecu won't add any more timing, there's no point in adding octane.
 

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2 things, you can obviously get a test pipe and run without a cat, and second, they actually make o2 sensors you can buy that will not be affected by leaded fuels. they had them for my audi a few years ago.
 

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ethanol is not really the problem. There is 100 octane unleaded, and 104 octane unleaded. Maybe it is just where I am, but I have never seen anything above 104 octane that is unleaded. 110 and 116 are leaded fuels, which while they will burn fine in our car at first, the lead will kill your O2 sensors and cat converters eventually. Albiet this will happen only if you use it more than occasionaly and over time. The car will probably run great on it at first. [/b]

not quite. using leaded fuel in your car will spell quick and painful death for the cats, foul up the O2 sensors, and really not provide you with any other benefits save having to spend a whole boatload of money to replace the emission stuff you ruined. "eventually" is not a good time frame to describe it, more like "immediately".

The older cats could stand a *little* bit of leaded but even then it was playing russian roulette but the modern ones are much more fragile in regards to being ruined almost instantly by lead.

you do NOT need any higher octane than 104, you dont even need that in a stock Speed6 engine. The 93 octane premium that comes out of the pump at the corner gas station should be just fine, for that matter.

burning a higher octane gasoline than the motor **needs** only accomplishes one thing, spends your money faster.




two points. 1. lots of ppl think that 100 is only good if detonation is being caused by lesser octane fuel. so, 100 would counteract problems already existent. (i personally loved using 100 this summer)
2. with anything much over 100, youre going to be looking at too much ethanol in the gas, and maybe messing up some sensors along your fuel lines and exhaust tract [/b]
actually gasoline blends over 100 octane, either leaded or unleaded, are not ethanol blends, they're straight gasoline. and the ethanol blends available in regular pump gas will not do any damage to your fuel, emission, or exhaust systems......if that were the case there would be millions of cars back at the dealer for repairs, as most pump blends these days contain at least a small percentage of ethanol. E85 is a whole different story, and unless you car is specifically designed to burn this fuel it will cause you problems.
 

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....

you do NOT need any higher octane than 104, you dont even need that in a stock Speed6 engine. The 93 octane premium that comes out of the pump at the corner gas station should be just fine, for that matter.

burning a higher octane gasoline than the motor **needs** only accomplishes one thing, spends your money faster.
....
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From what I've read, while this is true for N/A engines since they cannot efficiently compress high octane fuel, it is not true for an FI engine with an ECU capable of advancing timing. The question is at what octane will the ECU no longer advance timing. At that point there is no advantage to going higher. Backup on this from someone knows this for a fact and isn't just regurgitating like me?
 

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the question is will the speed motor actually advance timing at all...
dont bother with gas your car isnt designed for its just a waste of money....

and please tell me that someone on here isnt getting knock and thinks they are fixing the problem with better gas...yes it is a temp fix but please fix the problem the real way first.

and for the record if you have a high compression engine FI or not they can run higher octane but you need to have the computer tuned for it.
 

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This is speed6 forum right?

"HiBoost runs C16 in his car all the time, running in the 11's on several occasions now. so leaded fuel won't hurt the engine or anything, it's just the O2's and cat that will have the issue over time, as stated."

A MazdaSpeed6 runs 11's?
 

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This is speed6 forum right?

"HiBoost runs C16 in his car all the time, running in the 11's on several occasions now. so leaded fuel won't hurt the engine or anything, it's just the O2's and cat that will have the issue over time, as stated."

A MazdaSpeed6 runs 11's?
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HIBoost is running a turbo 6i IIRC. The effects of leaded gas should be the same though.
 

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the question is will the speed motor actually advance timing at all...
dont bother with gas your car isnt designed for its just a waste of money....

and please tell me that someone on here isnt getting knock and thinks they are fixing the problem with better gas...yes it is a temp fix but please fix the problem the real way first.

and for the record if you have a high compression engine FI or not they can run higher octane but you need to have the computer tuned for it.
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Of course, but I think that the average turbo combined with an ECU that advance timing can probably run higher octane than the average high compression NA engine. I haven't seen anything concrete on the ability of the MS6 to advance timing, but a fair number of people have said they use 100 octane and can feel the difference strongly.
 

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Personally if i was looking for a temp boost I would use toloune or some other industrial additive that has been proven... I beleive straight toloune is 116 octane? 112 maybe? Either way on a factory ECU going to a 96-98 octane mix is going to give you the same benifits of a 99+ octane... so spend some money on something cheap and easily bought at any paint supply store...
 

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Of course, but I think that the average turbo combined with an ECU that advance timing can probably run higher octane than the average high compression NA engine. I haven't seen anything concrete on the ability of the MS6 to advance timing, but a fair number of people have said they use 100 octane and can feel the difference strongly.
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the higher octane fuel burns longer right.... everyone knows that so you def are right that a turbo car will run better with fuel burning longer.... but only if your car needed it. not many people are running more than stock boost. no one can change there timing, and there needs to be tuning for it to be good for the car. im sorry im not trying to be a dick i just dont want people running around trying to stuff jet fuel in there speed 6's and thinking its gonna solve there problems especially without the computer knowing whats going on.
ha ha
to play devils advocate with myself maybe the speed6 computer can tell what kind of fuel you are putting into the car and adjust to that, no one knows

sotp is great but hopefully its not doing anything bad
 

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How far can we go with high octane fuel? Can ECU do anything with octane above 100? Curious if anyone has done dyno on 100+ octane or compared 1/4 times when running 100 octane compared to 93 or 91 octane.
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I have run everything in my car from CA 91 to straight 101. While I have never dynoed the car on either, I can say the only noticeable difference (butt dyno) is from 93 to 95. After roughly 95 octane the car feels the same regardless of octane. Of course this is not an exact science as I simply blend the gas in the tank, but by my calculations I haven't felt any noticeable difference above 95 octane. Given a margin of error I doubt factory tuning would take advantage of anything over 100 octane. I personally run between 93 and 95 90% of the time and the car runs great.
 

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I have run everything in my car from CA 91 to straight 101. While I have never dynoed the car on either, I can say the only noticeable difference (butt dyno) is from 93 to 95. After roughly 95 octane the car feels the same regardless of octane. Of course this is not an exact science as I simply blend the gas in the tank, but by my calculations I haven't felt any noticeable difference above 95 octane. Given a margin of error I doubt factory tuning would take advantage of anything over 100 octane. I personally run between 93 and 95 90% of the time and the car runs great.
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I will mirror everything you said. Here in Cali I haven't come across anything other 91 r+m/2 and 100 motor octane from the pumps and I have run more than a few tanks of each. Judging only by throttle response and sotp feel anything over 94-95 octane blend of the two seems to be a waste of money.
 
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