Gas Octane (...should probably save this for February)

[DucDave]

So...Manny's thread about running out of gas is drifting off topic. But, I'm interested so thought I'd take it here...!

I am pretty much of the school that most modern vehicles...motorcycles included...pretty much have no issue running 87 or 89 Octane gas. I run both and can tell no difference what so ever.

When I put 93 in my bike it's a bit of an anthropomorthic thing...like, "Hey baby. A little something 'special' for you. I hope you like it!"

Can anyone convince me that there is any real benefit for street bikes or cars?

[beet]

I'm with ya on this one Dave, if it don't ping yer wasting yer $. Even my air cooled runs better on reg. I do run 93 when it's hot out, but the only thing I notice is it back fires more on the let off.

[obsolete]

So...Manny's thread about running out of gas is drifting off topic. But, I'm interested so thought I'd take it here...!

I am pretty much of the school that most modern vehicles...motorcycles included...pretty much have no issue running 87 or 89 Octane gas. I run both and can tell no difference what so ever.

When I put 93 in my bike it's a bit of an anthropomorthic thing...like, "Hey baby. A little something 'special' for you. I hope you like it!"

Can anyone convince me that there is any real benefit for street bikes or cars?

Most modern cars "can" run lower octane but you may lose power due to the knock sensors picking up some pinging. My Trans Am would pull timing with a bad tank of 93, visible on data logging.

Even if it still gave full timing I'm sure there wouldn't have been catastrophic failure, but it would be undue stress probably shortening engine life. By how much, who the fuck knows.

The best octane is the lowest octane that doesn't knock. How can you tell with no knock sensor and data logger, I dunno but I'm sure the manufacturer will tell you.

[e30addict]

What Alex said. There are so many variables.....

Drive like grandma and in cool temps, prpbably won't notice a difference. The more you flog it and the hotter it is, the more you'll notice a difference.

Oh, and the BMW's get premium, truck and bike run on 87. I'll run 89 in the street car during the winter though.

[obsolete]

What Alex said. There are so many variables.....

Drive like grandma and in cool temps, prpbably won't notice a difference. The more you flog it and the hotter it is, the more you'll notice a difference.

Word. If you go to high altitude cities, Denver and Albuquerque I've seen, the pumps usually don't even carry 93. 91 is the highest.

[Wishbone]

Its worth it for me to run 93 in my Acura. I can run 87 but the CPU retards my timing and I loose MPG. My holeshot jet kit had big bold print saying 87 was the best octane. I will use higher If I ever bump up the compression.

[The Snowman]

I'm with Alex on this one. (I can't believe I just typed that.) My car's manual requires a minimum of 91 octane due to higher compression. I have accidentally selected 87 and it ran less than stellar.

The street bikes are a different story. They both run on 87 just fine. One is carburated and the other fuel injected.

[obsolete]

If your motor runs great on lower octane it can actually lose performance/mileage on a higher octane due to an incomplete burn. I don't however think this is as much of a problem now a days as newer cars have much better ignition systems.

[obsolete]

(I can't believe I just typed that.)

If you typed it more often you'd probably suck less.

[jwm2k3]

I've never put anything but 93 in my bikes, but in my F150 pickup i can totally feel a difference between the normal 87 i use and when i put in 93.

[FirstDuc-1098]

I notice a slight mpg advantage with 93 on both my carb and injected bikes

[TTD]

Prior to my current bike...always went with 87.

But my 08 CBR600 "pings" down the straight on 87. Might have been bad gas, but now I run 91+.

[e30addict]

Word. If you go to high altitude cities, Denver and Albuquerque I've seen, the pumps usually don't even carry 93. 91 is the highest.

That flipped me out the first time I saw 85 octane

For those wondering why.... less atmospheric pressure means you can't develop as high a cylinder pressure, so you don't need the extra knock protection.

I remember having a top speed of 60 at 9,000' in a car. 2nd gear was the highest gear it could pull

[markbvt]

It really depends not only on the engine itself, but on the fueling. I run 87 octane without issue in all my vehicles except my Triumph, which calls for 89 according to the owner's manual. When I got it, it was jetted a little on the lean side, and I found that I actually had to run premium in it or I'd get some pinging under heavy acceleration. Later I deleted the airbox in favor of pod filters on the carbs and installed more open exhausts, and rejetted accordingly (slightly on the rich side), so now I can run 89 without issue and have even run 87 from time to time without noticing any pinging -- but since it's an air-cooled bike, as a rule I try to stick with 89, just in case.

--mark

[Stoneman]

Regular octane in my truck, mid in the Caddy & TL-R...

My truck runs fine on the lower-grade stuff, but the Caddy surges a bit and takes longer to warm up on it. The TL-R sputters sometimes on the low-grade stuff and hiccups on the high-grade at about 4000RPMS's under light load but runs perfect on the mid-grade stuff...

No matter what anybody tells you, if you're vehicle's engine wasn't designed or modded to run on higher octane fuel, you're wasting your money and any gains are imagined or perceived...

[obsolete]

It really depends not only on the engine itself, but on the fueling. I run 87 octane without issue in all my vehicles except my Triumph, which calls for 89 according to the owner's manual. When I got it, it was jetted a little on the lean side, and I found that I actually had to run premium in it or I'd get some pinging under heavy acceleration. Later I deleted the airbox in favor of pod filters on the carbs and installed more open exhausts, and rejetted accordingly (slightly on the rich side), so now I can run 89 without issue and have even run 87 from time to time without noticing any pinging -- but since it's an air-cooled bike, as a rule I try to stick with 89, just in case.

--mark

When I say engine, I was referring to the complete system. Sorry, for the confusion. But I very much agree. My bike runs lean on the lean side so I use 93 just as some added protection. It's not an actual solution to the problem and leaves power on the table, but it keeps things a little safer.

That flipped me out the first time I saw 85 octane

For those wondering why.... less atmospheric pressure means you can't develop as high a cylinder pressure, so you don't need the extra knock protection.

I remember having a top speed of 60 at 9,000' in a car. 2nd gear was the highest gear it could pull

Living in Abq sucked for that. 1/4 miles times where, on average, a second slower.

[SSearchVT]

Another thing to take into consideration is how long the gas has been sitting in the tank at the station, especially with the ethanol content. At a busy station it's probably not a concern - but, some of the stations in the backwoods of VT, Ill grab the 87 nozzle before anything else...

[beet]

I get better milage from 87 then 93, in the big twin!!!!!!! 2 or 3 MPGs. Never pinged...

[Awesome]

No.

[Kurlon]

Also note most European brands don't adjust their octane suggestion for the US rating system, European octanes tend to be higher than the equivalent gas over here.

[RandyO]

Also note most European brands don't adjust their octane suggestion for the US rating system, European octanes tend to be higher than the equivalent gas over here.

they run the same octane we do, they just use a different octane measurment, Research Octane Number (RON) rather than the (R+M)/2 method we use (average of the Research Octane Number and the Motor Octane Number )

91RON = 87(R+M)/2

[e30addict]

91RON = 87(R+M)/2

It continually surprises me how few people realize this.

They just focus on the 91 and assume they need to run premium.

[obsolete]

It continually surprises me how few people realize this.

They just focus on the 91 and assume they need to run premium.

It costs more and has a higher number... It has to be better.

[Jim]

Wirelessly posted (BlackBerry Giggity: BlackBerry8330/5.0.0.438 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/104)

My bike is mapped for 93. Doesn't matter if it needs it or not, it's my preference and I'll continue to use 93.

[obsolete]

Wirelessly posted (BlackBerry Giggity: BlackBerry8330/5.0.0.438 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/104)

My bike is mapped for 93. Doesn't matter if it needs it or not, it's my preference and I'll continue to use 93.

Use 93 cause it's mapped for it, not because you're a dingleberry.