Gas octane

TahoeBound · May 21, 2008

Some of you guys have some funny math. 87 vs 91 here in SD (at least my local Chevron) is about .45/gallon. So for the 25000 mile example that difference is about $300/year. Lets say average ownership is 5 years - that's $1500. Not chump change IMO.

Now for me its 10000/yr @ 45 mpg's so I'm looking at closer to $100/year. That's a lot more do-able IMO.

Now, whether 87 or 91 should be run - if it runs fine on 87 why spend more $$. Of course you could ride an FJR and then its a no-brainer, the manufacturer recommends 87 (or higher).

PilotDave · May 21, 2008

From what I've heard, I think that I will stick with 93 octane particularly when you also get some 87 octane when you first begin to fill if the hose is shared for all gas grades. Thanks. Cordially, Dave

Gti20vturbo · May 21, 2008

Randy Bowers said:
And cooler weather is not as bad as hot when using reg.. M2C

Yeap the hotter the intake charge and the more load you have on the bike the more octane you should have. Having said that in cooler temps with a light load and regular commuting duty you can easily get away with less octane. I have not run 87 yet (not sure I will) but I have run 89 and get 45 to 50 mpg commuting. Next few tanks I will run 91 and see how that goes.

Texas_ST · May 21, 2008

The main reason for requiring 91 octane for the ST1300 is the overall increase in the compression ratio over the ST1100. The ST1100 had a 10:1 raation and the ST1300 has a 10.8:1. The higher octane fuel is to prevent detonation at the higher compression ratio levels.

The higher compression is needed to increase the hp output to the advertised 125hp at the crank as opposed to the 100hp of the ST1100. A 200cc displacement increase alone would not necessarily provide a 25hp increase.

mitch96 · May 21, 2008

What I don't get is the FJR and the ST have close to the same compression ratio and the ST needs premium..........

Hummmmmmmmmmm

mitch

Pete in PA · May 21, 2008

Texas_ST said:
The main reason for requiring 91 octane for the ST1300 is the overall increase in the compression ratio over the ST1100. The ST1100 had a 10:1 raation and the ST1300 has a 10.8:1. The higher octane fuel is to prevent detonation at the higher compression ratio levels.

The higher compression is needed to increase the hp output to the advertised 125hp at the crank as opposed to the 100hp of the ST1100. A 200cc displacement increase alone would not necessarily provide a 25hp increase.

Nope. Not the compression ratio, XX was 11 to 1. I even installed a 4 degree ignition advancer and still ran fine on 87.

st1300r · May 21, 2008

Octane discussion here

firemanlt · May 21, 2008

I have always put 91 in my "07" since I bought it. This week I filled up before a ride and around 100 miles later I noticed it pinging when I pulled away from a stop. This never happened before. How do you know you are getting what you pay for at the pump? I obviously got some bad gas or less octane. Should I put in some additives in to get me through the rest of this tank?

mikew1231 · May 21, 2008

IMHO yes, if it pings you're getting pre-ignition. Didn't read the attached link about octane ratings, but it's pretty simple. The higher the compression the more likely the gas will explode before the piston reaches the top, the higher octane gas has more additives that keep the gas from pre-maturely igniting. The ping and knock you hear is the piston trying to go down from the explosion before it's at the top of it's cycle.

Seems like this would be a very bad thing. I use octane booster in every tank on my boat, it needs the octane boost as it pings if I don't.

Fireball · May 22, 2008

I've been playing this game for years with many vehicles. I don't own anything with a modern "knock sensor" system that adjust timing when it pings. I find when the weather is cooler, or I am going to stay at higher altitudes I can get away with regular in high compression engines under 10:1, Unless i am in Utah.

Pete in PA · Jun 29, 2008

Well I've now had my ST a few months and over 2k miles and have settled on mid grade 89 octane.

No pinging, no loss of power, 45 mpg for the entire tank full, instant reads 50-55 on the hiway.

After the problems I've read of water in gas I think this solves that problem also since mid grade pulls from both tanks at a station.

chokozip · Jun 29, 2008

In oregon we max out at 91 octane.I wish we could get 93.
Idaho has 92 octane.

You may not see a diffrence right away on 87 or 89 but give it time.let your injectors crud up a bit them run a tank of 91 through.You will see a diffrence.And More so on slab riding than in town.

I run 91.If I could get 93 I would run that.

Have I tried this test?Yes.
In the ST?NO I always run super.
Ran the test in chev full size pickup.We seen a gain of 3mpg.

Sean:biker:

Drew · Jun 29, 2008

Pete in PA said:
....
After the problems I've read of water in gas I think this solves that problem also since mid grade pulls from both tanks at a station.

Almost all stations with 3 grades run seperate tanks of product, the gas is not "mixed" at the pump.

The mid-grade is probably the slowest moving product and the oldest gas. Most cars that need higher octane run premium and most folks that are willing to shell out above and beyond regular choose premium.

Youc can look at the ground fills to see the three gas grade product tanks...(from the Petroleum Marketers Assn.)

White lid: 87 Octane (regular unleaded)
Blue lid: 89 Octane (Plus formula)
Red lid: 93 Octane (Super)
Orange lid: Vapor recovery line

Drew

Pete in PA · Jun 30, 2008

Drew said:
Almost all stations with 3 grades run seperate tanks of product, the gas is not "mixed" at the pump.

The mid-grade is probably the slowest moving product and the oldest gas. Most cars that need higher octane run premium and most folks that are willing to shell out above and beyond regular choose premium.

Youc can look at the ground fills to see the three gas grade product tanks...(from the Petroleum Marketers Assn.)

White lid: 87 Octane (regular unleaded)
Blue lid: 89 Octane (Plus formula)
Red lid: 93 Octane (Super)
Orange lid: Vapor recovery line

Drew

Hmmm...Everything I've EVER read/heard is they deliver 2 grades of gas. Thanks for the lid color thing I'll have to check now.

RibsST1300 · Jun 30, 2008

I've found a great benefit to running 89 rather than 91/92.
Reduced throtlle snatch...a slightly weaker motor is less throttle sensative.
I still get mid 40's or better mpg.

Drew · Jun 30, 2008

Pete in PA said:
Hmmm...Everything I've EVER read/heard is they deliver 2 grades of gas. Thanks for the lid color thing I'll have to check now.

It really depends on the brand/station. The newer stations can blend reg/prem. in a 60/40 ratio. Older Sunoco pumps blended regular/ultra94 to deliver up to 4 octanes of gas.

But then again, there's a brand new Mobil near me that definitely has 3 product tanks. Some brands, the plus is blended by the tanker driver at the fill, others at the teminal, others at the pump.

Drew

Pete in PA · Jul 1, 2008

Checked 2 stations so far and running 50%.

Shell only 2 tanks even labeled, 1 super, 1 unleaded.

Sheetz 3 tanks, I was surprised.

Since Sunoco has 86, 87, 89, and 93, they MUST be blending but I haven't checked.

At least with ethanol the water should be more mixed with the gas and unless there is a LOT of water there shouldn't be a problem.

RobsTV · Jul 1, 2008

The major downside to E10 gas is that the alcohol content attracts moisture. The alcohol attracts and joins with the moisture in the air to create larger amounts of water in the fuel tank than had occurred with MTBE blends. Ethanol bonds to water and the mixture falls to the bottom of the tank.

E10 can only handle about a max of 3 teaspoons of water per gallon. Higher concentrations of ethanol can handle much more.

If you use the vehicle all the time, then it's not an issue, but as many bikes have such low miles, and are rarely used, this should be a major concern. (for example, the '93 I purchased in Feb 2008 had 13,000 miles on it).

EASt · Jul 1, 2008

Personally, I'm going to run 91+ in the ST unless there's just nothing else available and I'm in the middle of nowhere. I like to 'baby' my ST, and accordingly will give it the best gas I can find. I'll even go out of my way to run oxy-free 92 if I can find it.

That said, if it's about saving money, I'd rather kill my morning cup of designer coffee if I have to balance a gas budget (and I do).

$2 for coffee every morning x 5 days a week = $10 a week in coffee.

$10 a week = $40 a month = $520 a year = $2600 every 5 years on coffee.

91 octane gas is cheaper than designer coffee. Whoulda thought? :coffee1:

Don B · Jul 1, 2008

OK, I've always filled 'er up with premium unleaded. The label on the 1300's tank clearly states: "Utiliser une essence SUPER sans plumb d' un indice d' octane (PON) de min. 92." The English translation says to use PREMIUM unleaded gasoline with octane rating (PON) of 92 or greater. Owner's manual also recommends unleaded 92 (or higher) pump octane number.

My question for the gas experts is, does PON = (r+m)/2, as displayed on the gas pumps?

Gas octane

TahoeBound

PilotDave

Dave Wilson

Gti20vturbo

Texas_ST

Born to ride.

mitch96

Pete in PA

st1300r

firemanlt

mikew1231

Mike W.

Fireball

Pete in PA

chokozip

Drew

Pete in PA

RibsST1300

Drew

Pete in PA

RobsTV

EASt

Streuselkuchen

Don B