Am I missing out running 91 octane?

[Newb17]

Not sure how much better these cars run on 93?

[pbonsalb]

Probably a few rwhp. The dyno database can be searched by octane. The 93 cars are a little ahead, on average. Might be 2-3% but I have not done the math in a few years.

http://www.bmwdynodatabase.com/

[dparm]

Originally Posted by pbonsalb

Probably a few rwhp. The dyno database can be searched by octane. The 93 cars are a little ahead, on average. Might be 2-3% but I have not done the math in a few years.

http://www.bmwdynodatabase.com/

Based on the stock cars listed there, and with a Dynapack, it looks like a few percent indeed. Again, every car is going to be a little bit different. There are freak cars that will put out a bit more than the average.

Best way to test this is to get your exact car dynoed with 91, then refill with 93 and return to the same dyno (ideally on the same day or a day with nearly identical conditions).

So to answer your question...yes, you are missing out on a bit of power, but for driving around town at partial throttle, you aren't going to notice.

[Longboarder]

Look like the highest dyno stock car in the database was mine. Done on 91 octane with 300 miles on the ODO.

[Beemdog]

I had a vision where the future gas stations sold 95 octane pure gas (no ethanol) at a premium price, since all the cars used for regular transportation had gone electric and most gas powered vehicles remaining were hotrods, vintage cars, motorcycles, and spendy exotics. I know a lot of guys would gladly pay 50+ cents a gallon more for something like that right now (even for a 93 octane in CA), whether they needed it or not. On a weekend fun car, what the heck? Problem is, distribution and storage (extra tanks at the station) make this impractical despite the apparent market.

[1MOREMOD]

I use 92 e0.

[Newb17]

Looking into boostane. Any good?

[buffstocover]

Originally Posted by 1MOREMOD

I use 92 e0.

Where do you get that?? There's an independent Spirit station near my house that sells 90 e0, but I don't run that because it's not the 91 min required. Never seen higher than 90e0 around here.

[AMG_LAWL]

Ive noticed that when I put 91 in my car (all the time) that I get a better throttle response. On 89 (very rare occasion) ill feel that the throttle response is a bit sluggish.

[wanesso]

Originally Posted by buffstocover

Where do you get that?? There's an independent Spirit station near my house that sells 90 e0, but I don't run that because it's not the 91 min required. Never seen higher than 90e0 around here.

I always use 93....usually Sunoco.....and readily found around here in upstate NY. It makes a difference I can feel.

[Flying Ace]

no, I came from a 93 state to the 91 state. No difference in terms of butt dyno

[cenix]

i'd have to say that knock control is more relevant than any added power you will perceive running on a higher octane. the motor was designed to run a minimum octane. keep it there or above to keep the motor happy.

[buffstocover]

Originally Posted by wanesso

I always use 93....usually Sunoco.....and readily found around here in upstate NY. It makes a difference I can feel.

good to know. Thanks for the reply, but I was specifically asking 1MOREMOD because I think we're in the same neck of the woods! Cheers. I love drivign up to Vancouber and hitting up that bright red nozzle of jet fuel or whatever it is for like $15 a quart (metric) or something.

[Flying Ace]

Originally Posted by buffstocover

good to know. Thanks for the reply, but I was specifically asking 1MOREMOD because I think we're in the same neck of the woods! Cheers. I love drivign up to Vancouber and hitting up that bright red nozzle of jet fuel or whatever it is for like $15 a quart (metric) or something.

wut?

[1MOREMOD]

Originally Posted by buffstocover

Where do you get that?? There's an independent Spirit station near my house that sells 90 e0, but I don't run that because it's not the 91 min required. Never seen higher than 90e0 around here.

Where do you live? I just type in ethanol free gas washington and there is a whole list. Organized by city and gives address and phone as well as which varients they sell. I use this in my e46 m3 track car and have found it to work well.

[JoePcone]

I came from CAlifornia back to Chicago, 91 to 93 octane. I feel like I felt a difference but its nothing big at all. The cold weather night here made way more of a difference than the octane, I believe.

[1MOREMOD]

Right cold weather does make more of a difference. I find that on track my car behaves more like a cooler day on hot days and on cool days I set lap records.

[dparm]

Altitude will also affect the octane requirements. In theory, higher altitudes don't need higher octane.

[Beemdog]

Originally Posted by dparm

Altitude will also affect the octane requirements. In theory, higher altitudes don't need higher octane.

Good point-- on an naturally aspirated engine, thinner air means less cylinder "packing" and therefore lower cylinder pressure with a corresponding decline in the tendency to knock as altitude decreases. With a turbocharger, you would still want high octane at high altitude since the turbo wastegate controls boost pressure, keeping the cylinders packed with air and making up for the increase in altitude (turbos are great on airplanes).

[Newb17]

Originally Posted by Flying Ace

no, I came from a 93 state to the 91 state. No difference in terms of butt dyno

[OzCraig]

98RON downunder

[pbonsalb]

Originally Posted by dparm

Altitude will also affect the octane requirements. In theory, higher altitudes don't need higher octane.

But altitude also means less power. About 3% loss per 1000 feet.