E92 Octane Rating

[burtonsbs5114]

Around me I have 91 ethanol free and 93 with ethanol. I go with the 91 ethanol free gas from BP.

[Helmsman]

Originally Posted by m3m3mr

There's a thread somewhere here with guy had fouled up orange colored spark plugs from octane boost. The plugs on our cars serve as knock sensors.

Cheers mate. Yep aware of the plugs part of the knock sensor but didn't quite get why increasing octane would foul them. Or is it the boost itself that would be harmful in any way?

[BimmerRookie]

Originally Posted by BuffSlut916

Yeah had to pay over a grand for convertible roof parts, paint, cabin sensors, little shit like that. Diagnostics ran me $200, sensors themselves ran me $400, roof parts $200, paint $200, labor $200 at BMW Mountain View.

But point taken regarding octane rating. The guy at the dealership told me it was chill for a little bit but not to make it a habit.


Out of curiosity, is there a limit for octane ratings for the S65 when filling it with 100+ race gas?

Lol at the dealership guy, what a fool. They hardly ever know what they're talking about anyways!

I think it would do you some good to find a nice independent workshop to handle your service needs. Parts are parts and there's hardly a discount to be found (in most cases), but independent shop labor and expertise will in most cases be better than the dealership. I would strongly suggest you take some time to do you research so you don't get wrecked again and put in tanks of 87 octane

[dparm]

Originally Posted by Helmsman

Cheers mate. Yep aware of the plugs part of the knock sensor but didn't quite get why increasing octane would foul them. Or is it the boost itself that would be harmful in any way?

There are many different chemicals used to boost the octane rating. It's possible some of them are not intended for "street driven" vehicles and are targeted a race cars where plugs are changed very often.

[dparm]

Originally Posted by BuffSlut916

Out of curiosity, is there a limit for octane ratings for the S65 when filling it with 100+ race gas?

The anecdotal evidence on here seems to indicate that the gains from anything above 93 are minimal. Beyond 95 or 96 octane it's actually going to start causing problems since you won't get a complete burn.

The easiest way to tell is to watch the timing advance. If the car continues advancing the timing as you increase the octane, it's technically taking advantage of it. Whether or not that translates into a noticeable power increase is another story. Altitude plays into it as well (higher altitude shouldn't require as high of an octane, but this is also negligible until you talk about living in the mountains).


Short answer: the car makes its rated 414hp on 91 octane. If you can get 93, great. If not, just run 91 and call it a day.

[STC]

Originally Posted by BuffSlut916

Yeah had to pay over a grand for convertible roof parts, paint, cabin sensors, little shit like that. Diagnostics ran me $200, sensors themselves ran me $400, roof parts $200, paint $200, labor $200 at BMW Mountain View.

But point taken regarding octane rating. The guy at the dealership told me it was chill for a little bit but not to make it a habit.


Out of curiosity, is there a limit for octane ratings for the S65 when filling it with 100+ race gas?

I was wondering what happened to your roof. Oh and the "guy at the dealership" - pls don't listen to him.

[Helmsman]

Originally Posted by dparm

There are many different chemicals used to boost the octane rating. It's possible some of them are not intended for "street driven" vehicles and are targeted a race cars where plugs are changed very often.

Always a proper answer - pls make sure you don't leave us completely for the Vette club man.

[burtonsbs5114]

What's better 91 w/out ethanol or 93 with ethanol?

[Shredicus]

Originally Posted by BuffSlut916

Lmao not at all

Aight, just checkin fam

[SDPLV]

What the...owns E92 M3 but can't throw in $5 more for 91 octane. C'mon man. Is this foreals?

Nothing's gonna happen anyways.
My guess is they know people will run 87 no matter what they write on there.

A lot of owners tune to 91 Octane maps, even though stock "requires" 91 anyways.

[Captain Apex]

Originally Posted by dparm

The anecdotal evidence on here seems to indicate that the gains from anything above 93 are minimal. Beyond 95 or 96 octane it's actually going to start causing problems since you won't get a complete burn.

The easiest way to tell is to watch the timing advance. If the car continues advancing the timing as you increase the octane, it's technically taking advantage of it. Whether or not that translates into a noticeable power increase is another story. Altitude plays into it as well (higher altitude shouldn't require as high of an octane, but this is also negligible until you talk about living in the mountains).


Short answer: the car makes its rated 414hp on 91 octane. If you can get 93, great. If not, just run 91 and call it a day.

Your last line, are you implying on 93 it makes 414+?

[MachinesWithSouls]

The very first time I went to the track I was...unprepared...for how fast this thing eats fuel at high speeds. I ended up putting 100 octane in it at the track for half the day and the car ran just fine, though only as a last resort.

I wouldn't put 87 in it. Skip the Starbucks run for a few days instead.

[Fix-It-Finicus]

Keep it to 91+ only mate

[deseroner]

Stop taking it to dealer , no wonder you are using 87 ha. But for sure use 91 plus on cars . High performance motor .

[Dave07997S]

Originally Posted by Helmsman

Cheers mate. Yep aware of the plugs part of the knock sensor but didn't quite get why increasing octane would foul them. Or is it the boost itself that would be harmful in any way?

Its the octane boost formula not the actual boost of the octane. However, if you are running 1 litre of octane boost such as Torco Race Fuel Concentrate in 16 gallons of 91 it won't harm anything to do it every once in awhile. I found that its just as inexpensive to blend unleaded race gas as running the Race Fuel Concentrate.

Dave

[Spoolin1]

Originally Posted by BuffSlut916

Hm ok. This may be a dumb question, but what is engine knock?

I usually cruise around in my car on the highway and rarely punch it until I get my pockets back up next week.

If you can't afford the little bit of added cost in premium fuel that this car requires, you might want to think about getting another cheap on gas car. God forbid something needs repaired on the car.

[Helmsman]

Originally Posted by Dave07997S

Its the octane boost formula not the actual boost of the octane. However, if you are running 1 litre of octane boost such as Torco Race Fuel Concentrate in 16 gallons of 91 it won't harm anything to do it every once in awhile. I found that its just as inexpensive to blend unleaded race gas as running the Race Fuel Concentrate.

Dave

Thanks Dave, I was for fun trying a bottle of injector cleaner that apparently also had some octane boost. As I run 99 (RON) in the first place I got curious if that was a bad move.

[roastbeef]

Like you ran out of money, or the gas station ran out of 91?

[HomoPirate]

Originally Posted by BuffSlut916

Yeah had to pay over a grand for convertible roof parts, paint, cabin sensors, little shit like that. Diagnostics ran me $200, sensors themselves ran me $400, roof parts $200, paint $200, labor $200 at BMW Mountain View.

But point taken regarding octane rating. The guy at the dealership told me it was chill for a little bit but not to make it a habit.


Out of curiosity, is there a limit for octane ratings for the S65 when filling it with 100+ race gas?

Don't go Bmw Mountain View for any services. They have the worst service department in bay area. Just look at the Yelp reviews or ask your friend who had business with their service department. Go Stevens Creek Bmw next time. That will save you some hassle and money.

For the question you are asking, putting 87 gas will save you few dollars on a full tank fillup. But you are creating other problems that might get you headache. For the peace of mind, go for 91 all the way with top tier gas station. I can save money from eating but not from driving.

[pbonsalb]

Higher octane will allow you to hit the timing targets in your tune, but it won't increase those programmed targets. Many cars do not seem to be hitting their factory targets all of the time. Higher octane will help. But if you can do it on 93 or 94, then 100 won't add anything.

You can mix on some unleaded race gas with no ill effects.

Some octane boosters like Torco reportedly turn your plugs orange. If this affects the knock sensing, which is done through the plugs, that would not be good. Don't know.

I use water/meth with a tune for it. Since it flows only when needed, I am not wasting expensive fuel all the time the car is running.

E85 is the cheapest way to go apart from possible parts costs depending on your needs (pump, injectors, flex fuel sysyem, tune) but the gains are limited without an E85 tune. I would consider E85 but none in my area.

[dparm]

Originally Posted by Captain Apex

Your last line, are you implying on 93 it makes 414+?

Possibly. It will vary for every motor and the specific conditions. If you can get 93, you might get a few HP over 91. But if you really think you can feel a few horsepower when you have 414...well, then your butt dyno is better than mine.

[pbonsalb]

Maybe on 91 there is less chance of hitting 414 crank hp. These cars tend to range from 330 to 360 rwhp SAE on a Dynojet in stock form. There is a dyno database somewhere with results that can be organized based on mods, octane, etc. Seems like the 93 results average out a little better than the 91 but I did not actually add and average. The record for a stock car is 361 and I think it was on 91, so anything can happen.