high or low octane gas?

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justscooten

high or low octane gas?

Post by justscooten »

ok i dont know if this as been talked about if so im sorry but i was out messing around it the garage to day was looking over my blur for the millonth time and the tag under the set states that to us gas of 92 octain or higher so not reguler but premium. so i was wondering is what octain dos eveyone use and have you seen any differents in high and low octain.
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afriendofcheese
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Post by afriendofcheese »

I always use premium as advised by the dealer. I probably would do it anyway since we're only talking and exrta 10-15 cents a fillup!
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illnoise
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Post by illnoise »

huh, I never noticed that, I've always used regular. Maybe that's my problem.

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Post by jfrost2 »

Dave at metro scooter told me to use regular/unleaded no matter what...

"It's the extra pollution that gives the bike some power!"
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nissanman
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Post by nissanman »

Wether or not you need 87 or 91 depends on two things. Was is set with timing for 91 and what compression ratio you are running. High compression (usually high RPM and heavily modified) will probably need the high test stuff... most scooters run low compression so that they'll run on some of the crappy gas found elsewhere in the world making 87 fine for most. If you're not getting a "knock" or "pinging" you don't need any higher octane gas.
justscooten

Post by justscooten »

im just going from what it says under the seat of the blur ... it says fuel 92 or higher
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shark
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Post by shark »

justscooten wrote:im just going from what it says under the seat of the blur ... it says fuel 92 or higher
Ditto on my Buddy!!
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Post by Corsair »

viewtopic.php?t=1015
pocphil wrote:I am offically charging 1 Beer for every time I post this to some scooter forum. So, because I love the Modern Buddy forum so much I will consolidate it and we'll call it a freebie.

Laymans Guide to Octane

1 - OCTANE is the resistance to detonation. High compression engines cause fuel to pre-detonate - this is called KNOCK. It is dangerous to your motor.

2 - Scooters (all that I'm aware of) use notoriously LOW compression engines. 87 Octane has been shown to be fine. In high altitude areas I've even run 85 Octane in my race scooter and it did not knock one bit.

3 - HIGH OCTANE does not equal "Clean" or "Power" - Running a motor designed for 87 Octane fuel on 92 will actually make it run poorly, less power and worse mileage. The detergent additives are specified by the company selling the fuel and they are consistent from 86 - 94 octane.

4 - If your Jaguar, Snowblower, JetSki, Scooter, weedwacker etc. runs fine on 87 Octane without knocking or running on after you turn off the key, keep using it. Keep in mind modern vehicles are designed to run on a WORLD of different fuel qualities. The worst fuel you can pull from a pump in the US is going to be much better than the best fuel you can pull from a pump in India etc.

5 - Octane is not Octane. The numbers we use in the US are based on an average of 2 different testing methods. The number found In most countries (including all of Europe and Australia) the octane that would be shown on the pump is the Research Octane Number but in the United States and some other countries the headline number is the average of the RON and the Motor Octane Number. So, the gas we call 87 Octane R/M is actually written in most owners manuals as 92 or 93 Octane (RON).

If not specified assume the Octane number in the manual is a RON number. As most vehicles (scooters) are not manufactured in the US.

Here is our "real world" application data:

In 1999 the Ohio Department of Agriculture conducted a test of 1000 gas stations. 85% Of these stations were pumping non-premium octane fuel from their premium pumps. Audits of these stations were conducted and it was seen as a regular practice for stations to have "Regular" account for approximately 82% of their monthly sales. Yet it accounted for over 95% of the fuel they ordered from their supplier. Unless they were giving away thousands of gallons of 87 Octane fuel, it was quite obvious they were selling the 87 out of the higher octane pumps.
justscooten

Post by justscooten »

ok good to know thanks corsair i was just alittle worried scoot around town didnt but much gas in the tank and i filled it up with regular (shell) from what i thought i read it needed primeum. so all is good . thanks for the info
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Post by blurblaine »

Interesting octane discussion... :lol:

Hmmm, I've always used 'super' in my Blur as I figured it would just be better.

I do remember 'back in the day' when close to out of gas in a small town in MO in my new 1985 Dodge Shelby Charger and having to pump regular since it was all they had that my car didn't knock or 'diesel' but would stall at low RPM with that lower octane fuel.

I would be highly hacked off to learn that the 'super' pump was the same lower octane fuel and I was getting ripped off ... so don't make me mad! :shock:
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Post by nissanman »

Most likely not ripped off... But the Shelby was a higher compression engine and needed 91 octane gas. If it was really cheap gas excess moisture in the tank could've been the real problem. Engine can't burn water :lol:
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Post by lobsterman »

As this topic has been beat to death on Modern Buddy before (and part of that thread is quoted above), let me just say this.

Most octane labels on our scooters and in the manuals are almost certainly quoting the non-US octane calculation methods. Those calculation methods result in higher octane numbers than the ones we're used to in the States. Look closely at the pump where the octane number is some time, you'll see (R+M)/2, which refers to two octane calculation methods divided by two to get an average.

To put it simply, our scoots don't need hi-octane US gas. The equivalent is usually much closer to mid grade (89) US gas, and you could probably do just fine on 87 US octane as many scooter owners can tell you from personal experience.

There's also a lot of disgreement about whether higher octane than you need is harmful or even gives lower performance. I can't say for sure, though an engineering source I trust says it won't really hurt anything to put in higher octane than you need. I do know this: 92 octane costs more than 89, and why pay more than you need to, even in small quantities?
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octane

Post by itcardoc »

If you look closely at the label under the seat it says "RO 92 or above". This is the research octane # which is usually 4-5 points higher than the pump octane #. So this would put the pump octane# at about 87. The only octane rating you will see on pumps in the US is "pump octane" which is research octane# + motor octane # divided by 2. So as an example a gasoline could have 3 ratings: motor octane 82, pump octane 87, and research octane 92. So our Blurs would take 87 and above. Also stated in POCPHIL's post above.
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Post by showtime2100 »

I use 93 in my Blur. The dealer advised and it just make sense...Like someone said its just 10-15 cents more to fill up our tank with premium. If someone is getting me....so be it...Every gas station isn't doing it so...87 instead of 93 every now in then by accident....no problem..(in my scooter)
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Post by BlueMark »

Use regular. The 92 octane in Taiwan is 87 octane in the USA.

Running higher octane than your engine is designed for will not improve performance, will not run cleaner, and will not improve mileage. But it WILL cost more.

-Mark
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Post by GY6Stroker »

High octane fuel has more detonation resistance compared to lower octane fuel.

High Compression Ratio + Lower octane = Faster Combustion = Preignition

The Blur 150cc (Gmax) has a Compression ratio of 9.5:1 which performs best with 92 Octane fuel.

DCR between 7.5 and 8.5 runs best on 91 or better octane fuel.
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Post by babblefish »

BlueMark wrote:Use regular. The 92 octane in Taiwan is 87 octane in the USA.

Running higher octane than your engine is designed for will not improve performance, will not run cleaner, and will not improve mileage. But it WILL cost more.

-Mark
Especially since some gas stations around here are charging $4.50 a gallon for premium! :shock: :cry:
Last edited by babblefish on Fri Apr 25, 2008 5:44 am, edited 1 time in total.
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Post by jim_0068 »

GY6Stroker wrote:High octane fuel has more detonation resistance compared to lower octane fuel.

High Compression Ratio + Lower octane = Faster Combustion = Preignition

The Blur 150cc (Gmax) has a Compression ratio of 9.5:1 which performs best with 92 Octane fuel.

DCR between 7.5 and 8.5 runs best on 91 or better octane fuel.
For those wondering what DCR is, it stands for dynamic compression ratios and isn't the stated compression of the motor. Also, not only does compression have a lot to with octane but IGNITION advance (both how much and how soon) have a lot to do with what octane works the best.

The reality is, that sometimes you can't even hear knock if it's present. That's why they started equiping EFI cars in the mid to late 80s with knock sensors. For the amount of gas a scooter uses, the extra 10-20 cents is worth the safety; not only that but especially because gas is different depending on where you buy it. Some are dirtier and doesn't burn as well and contains more ethanol that others.
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Post by NathanielSalzman »

Wow, I can't believe this is such an issue. How cheap are you people? Seriously. I put premium in my car (supercharged MINI Cooper S) because that's what it requires. I've done the math and I'm paying $50 extra per YEAR in the car over the price of regular. So that's all of buying an extra tank of gas and then some over the course of a year. Chill out folks. That people are looking for excuses to save at most $0.25 on a tank of scooter gas is just confounding.

And yeah, as jim_0068 has pointed out, octane requirements are not tied directly to compression ratio, but have just as much to do with ignition timing. In the MINI, for example, it's not a high compression ratio engine either, but it gets premium because that's what the timing is set for. Sure it's got fancy knock sensors and there are penny-pinching MINI owners who put regular gas in their cars. And what happens? They lose a lot of pick up and they get poorer gas mileage. So what was gained? They felt clever at the gas pump? "I'll show those engineers at BMW! They don't know what they're talking about!"

Only premium in my Blur. You do what you like. Spend that quarter on somethin' nice.
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illnoise
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Post by illnoise »

It's not a matter of being cheap, it's just been discussed to death on a thousand forums, and all the experts that I trust (read phil's post) have determined that US 87 octane is the best choice for most scooters.

Anyway, high octane gas isn't BETTER, it won't make you go faster and it's not even necessarily "better for your engine", it just has different qualities that make it ignite better in high-compression engines. I know lots of people that use high-octane just assuming it's better just because it's more expensive, and it's not. Coleman Fuel, Diesel, Jet Fuel, and Milk are even more expensive than premium, but they're not designed for your engine. It just so happens that it works fine in scooters, but as far as I or other people (who are much smarter and ride much more than I do) can tell, it doesn't work any better than regular gas, so why bother?
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Post by jim_0068 »

illnoise wrote:It's not a matter of being cheap, it's just been discussed to death on a thousand forums, and all the experts that I trust (read phil's post) have determined that US 87 octane is the best choice for most scooters.
Which may be very true and to be honest, at 9.5:1 with very little timing advance 87 octane would probably work fine and i bet in a controlled real world testing anything higher than 87 (if it is optimal) would actually create lower hp and mpg.
Anyway, high octane gas isn't BETTER, it won't make you go faster and it's not even necessarily "better for your engine", it just has different qualities that make it ignite better in high-compression engines.
Not quite, the only thing that higher octance gasoline does is BURN SLOWER, that's it. The higher the octane the slower the burn; thus you need a higher compression ratio to ignite the fuel efficiently.
I know lots of people that use high-octane just assuming it's better just because it's more expensive, and it's not. Coleman Fuel, Diesel, Jet Fuel, and Milk are even more expensive than premium, but they're not designed for your engine. It just so happens that it works fine in scooters, but as far as I or other people (who are much smarter and ride much more than I do) can tell, it doesn't work any better than regular gas, so why bother?
Like i said above, most likely there isn't enough timing advance to create a high enough DCR to warrant really high octane.

Also for those who are curious i have built numerous motors (mostly supercharged and turbocharge) and also tuned them. I was big into drag racing a while back so i have some pretty good knowledge on this subject. However it would hard to find out what these GY6 motors really need unless i knew how much timing they had and how fast it was advanced.
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Post by nissanman »

I'd assume there's little to no advance modifications done by the owners. Just what's stock for the Blur's setup from the factory. So if 87 works from the factory...
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