Ethanol or Non Ethanol

[CatScan]

Originally Posted by Tcoat

The manual says a "minimum of 91". That to me means exactly that. Now having said that there is no risk to throwing something less in in a pinch. The car is probably not going to have issues but will pull so much timing that you will notice the power drop. Power drops with these are not cool.

Again, you translate what I am trying to say into something understandable, thanks.

Let me try: To think that Toyota/Subaru designed this car WITHOUT considering that at some point some of them will HAVE to run on low-octane gas "every now and then" is idiotic. That's what the ECU is for.

Then again, I'm ASSuming that the typical owner of a car will read the manual and understand what's going on.

[billwot]

Originally Posted by CatScan

No shit on the tune, that's fairly obvious. And a tank of something less than 91 octane won't kill your car. Got any proof of how bad that is? List of dead cars? Class-action suit?

Don't ever go to Colorado, I guess, where up in the hills you might find yourself stuck with 85 octane gas. The horror!

No amount of "tuning" can alter the 12.5: CR.

[CatScan]

Originally Posted by billwot

No amount of "tuning" can alter the 12.5: CR.

Perhaps I am not speaking English. Are you saying the ECU can not (or was not) programmed to handle sub-optimal fuel?

[FRSBRZGT86FAN]

Originally Posted by CatScan

I'm still waiting for reports of an FR-S/BRZ damaged by using lower octane "every now and then". Are these cars only sold in areas that have 91 or better? Or is it that the possibility of running lower octane if needed was taken into account when they built the thing.

Whatever, I guess.

Originally Posted by CatScan

Ahh. Perhaps number-one son could find a YouTube video or someone could text him. No doubt the owners manual is waaaaay too big with too many words to even open.

I forget that people take advice from the www instead of an actual, factual source.

My car runs great on Alphadelic IPA. You guys should try it.

Originally Posted by CatScan

RTFM must be an age thing at well. It would never occur to me to not read the owners manual. Regardless, putting anything less than unicorn pee in your car every now and then if you have to will not cause you any problems.

Originally Posted by CatScan

No shit on the tune, that's fairly obvious. And a tank of something less than 91 octane won't kill your car. Got any proof of how bad that is? List of dead cars? Class-action suit?

Don't ever go to Colorado, I guess, where up in the hills you might find yourself stuck with 85 octane gas. The horror!

Originally Posted by CatScan

Or 87 if you have to. You wont hurt the car. E85 is the best solution though.

Originally Posted by CatScan

Perhaps I am not speaking English. Are you saying the ECU can not (or was not) programmed to handle sub-optimal fuel?

Originally Posted by CatScan

Again, you translate what I am trying to say into something understandable, thanks.

Let me try: To think that Toyota/Subaru designed this car WITHOUT considering that at some point some of them will HAVE to run on low-octane gas "every now and then" is idiotic. That's what the ECU is for.

Then again, I'm ASSuming that the typical owner of a car will read the manual and understand what's going on.

Dude you're attacking everyone with fallacies This is what the manual says for posterity as these type of threads continually keep popping up and no one bothers to either do a search before posting or simply look at the quick start up guide or manual of the car and it's quite sad.



In layman terms use 93 AKI/98 RON or higher, if you don't have that available you may use 91 but only if the higher grades are unavailable


It does not mention 87 however, the assumption can be made the highest available average octane is 91 (U.S. and candian AKI I think canada uses it not sure) or 95 RON in other places.

If you do put 87 you have to understand you're taking a longevity risk, why? Every time the car has to alter it's IAM (Ignition Advance Modifier) below 1 or that means knock is being detected and it is having to adjust to try and prevent another "knock event" (not sure if that's the right term @steve99 knows his stuff about this ), once the IAM reaches 0 you're out of luck the ecu can no longer adjust timing to counter the lower octane fuel and knock will happen consistently. Every time this pre-detonation knock occurs you put a lot of stress on parts specifically the valves, piston head, and rods, ESPECIALLY in an engine with as high compression as this where they have a tendency to knock on lower fuel like 87 because with lower octanes it is more likely to ignite. Now putting 87 in a full tank once or twice is no big deal but if you keep doing it to save a few bucks or because you think you know what your doing you're creating unnecessary wear long term to the engine.

This isn't a new concept to engines or sports car, in fact a Shelby GT500 from 2007-2010 didn't even come with a knock sensor and doing something irresponsible like putting fuel under 91 would probably kill the car in a few highway runs. I don't understand why you're making a big deal when everyone is telling you you're wrong, including the manual and science. Find something of hard tangible evidence to prove us wrong.

[billwot]

Originally Posted by CatScan

Perhaps I am not speaking English. Are you saying the ECU can not (or was not) programmed to handle sub-optimal fuel?

Not at all.

What I'm saying is a 12.5 CR dramatically increases the potential for detonation, and no amount of tuning can change that.

Yes, the ECU can adjust timing, A/F, etc, to tolerate the lower octane, but there will be definite compromises in performance, efficiency, and longevity.

[Tcoat]

Originally Posted by FRSBRZGT86FAN

a lot of stress on parts specifically the valves, piston head, and rods, ESPECIALLY in an engine with as high compression as this where they have a tendency to knock on crappy fuel like 87. .

Point of clarification. The octane level of fuel has nothing at all to do with it's quality. A fuel at 87 is every bit as good as a fuel at 100 in the engine it was intended for. Octane is strictly the knock resistance level not the fuel quality indicator.
So yes 87 would be crappy fuel for our cars but that does not make it crappy fuel in general.

[FRSBRZGT86FAN]

Originally Posted by Tcoat

Point of clarification. The octane level of fuel has nothing at all to do with it's quality. A fuel at 87 is every bit as good as a fuel at 100 in the engine it was intended for. Octane is strictly the knock resistance level not the fuel quality indicator.
So yes 87 would be crappy fuel for our cars but that does not make it crappy fuel in general.

My bad I say crappy relative to what this car normally is supposed to use octane wise, I'll fix it

[Tcoat]

Originally Posted by FRSBRZGT86FAN

My bad I say crappy relative to what this car normally is supposed to use octane wise, I'll fix it

Figured that may be the case that was why I added that last line.

[steve99]

Here is a real world log taken from a stock car (stock tune) in South Africa.

They only have 95 RON fuel about same as USA 91 fuel.

note the IAM is 0.2, for best performance and economy it should be 1.

Their are still knock corrections of 3 degrees (FLKC) even though the eCU has reduced timing substantially by lowering the IAM to 0.2.

Once the ECU reduces IAM to 0 then that,s the limit of its ability to correct for knock.

No all the south African cars are not blown up on side of road, but 95 ron fuel is about the limit of what the ecu can safely cope with. note this log was on street not track.
The south africian car were one of the first to get the DI seal failure due knock, on the early roms when the transient ignition retard was not enabled. This log is from a car on A01G rom which has the DI seal fix/retard changes.

All the tune in all stock ecu's is same throught the world, the differnt id are just to cope with metric/imperial or other differences in car lie tire pressure monitoring ect.




http://datazap.me/u/steve99/south-af...=2-27&mark=280

[Chanpion]

The owner's manual actually says 93 octane and do not exceed 10% ethanol I believe. You can read it yourself.

EDIT: Thanks for the clarification, I knew it was low ethanol but couldn't remember how low. I don't carry my manual around.

[steve99]

Originally Posted by Chanpion

The owner's manual actually says 93 octane and do not exceed 30% ethanol I believe. You can read it yourself.

Correct 93 is prefered fuel for max power and economy.

ethanol content limit is likely due to the ecu limits on correcting for fuel density changes due ethanol content by using fuel trims LTFT.

ethanol burns very clean and has a higher octane rating than most pump fuels.

as long as your fuel has an octane rating recomended by manufacturer and ethaol content recomended by manufacturer you will be fine

[CatScan]

I use E85. I have also had to use several tanks of 87 when that was all that was available "every now and then". The horror.

[mdm]

Originally Posted by Chanpion

The owner's manual actually says 93 octane and do not exceed 30% ethanol I believe. You can read it yourself.

Let me help:

[CatScan]

Originally Posted by mdm

Let me help:

That's in that book-thing in the glove box, right? Strange how well the car runs on E85. And for 87, I just back the plugs out a few turns to lower the compression. Problem solved.

Here, I shall also respond with a picture:



You do your thing, I'll do mine. You panic if you have to over having to use "crap" gas "every now and then".