98 vs 91 Fuel

hooksey said:
Go to a different servo, if they are not turning over a lot of fuel litreage,  it will be stale  :'(

Always found 98 excellent in the Jota and if 91 used, runs outta puff and pinks.

Yet the 750 will run fine on 91 = lower comp engine  ;)
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The two servos I use are high turnover. I'm not convinced this is the problem but as with everything you have to eliminate things.
 
cbertozz said:
The two servos I use are high turnover. I'm not convinced this is the problem but as with everything you have to eliminate things.
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Maybe they do turn it over.........  but what do they water it down with under the cover of darkness?  :-X

Shiftee pricks !
 
Laverdalothar said:
May I add that compression makes a big difference and also ignition timing? Also, a higher octane fuel tends to burn faster, but ignites "harder".
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Are you sure Lothar?
I thought higher octane fuels burnt smoother and slower.

In the old days high octane had Cyclo Hexanes (from the benzine ring family) - smooooooth burning but worries over cancer.
 
SimonR501 said:
Are you sure Lothar?
I thought higher octane fuels burnt smoother and slower.

In the old days high octane had Cyclo Hexanes (from the benzine ring family) - smooooooth burning but worries over cancer.
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pretty sure... The Octane grade depends on the mixture of volume percentages of Isooctane and n-Heptane. 95 has 95 volume% Isooctane and 5volume % n-Heptane.

n-Heptane burns easier and earlier (around 200?C), that's why a high compression engine would self-ignite earlier with this stuff. the less n-Heptane is in the mix, the higher the octance grade and the less quick the mixture ignites => it is harder to ignite => hence the plug fouling with bad ignition systems and weak sparks.

more n-Heptane in the fuel means, that the n-Heptane - as it self-ignites already at 200?C - makes the flame-front distribution harder to controle. Depending on where the heat is in the combustion chamber (edges of the valve seat f.e., edges of the valve itself that get hot), the n-Heptane starts potentially - at an uncontroled timing - to burn itself - means: to early. Effect is pinging/ringing.

With higher octane fuel, you are less prone to this happening. The Fuel ignits harder/later, but more controlled.

Tests however have proven, that even with modern engines, this does not show any difference in torque or power - unless you adjust ignition timing to it... You can use more pre-ignition and get the timing closer to the ideal point with higher octane fuel.

That is at least how I learned it, but I am not a technichian, so someone with a better background may correct me at any time, please!!
 
When I bought my Duc's a bevel and a belt, the mechanic recommended 95 and stated the 98 is too dense for them.
Which I found was pretty much on the money. 

I run 98 in my Jota and it goes like stink on it. Not quite as well on lower octane.
The plugs show good colour, I know you can't read them like in the old days but you still get an indication.

I prefer BP, but am happy with Caltex.
 
Tippie said:
Does the "golden rule" of anything over 10:1 compression requiring 98 still apply? Fuels aint fuels no more, what with mixes of ethanol and whatever. My street bike has my ex racing pistons and so is set up at 10.5:1, and here in Norway 98 is readily available for the moment, but I have occasionally filled 93 (the low octane alternative) and not noticed any difference, however I don?t get to use it in anger as both the speeding fines and tight roads work against it. My bucket list has the bike touring down to southern Europe, where from experience there isn?t 98 readily available. Should I reduce it back to under 10:1?
To my knowledge using a higher octane does neither damage nor cause plug fouling, the only effect is on your wallet. People used to use very high octane avgas back in the day in standard street bikes with no ill affect.
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Lee,

I think Austria is the southern-most frontier in regard to 95+ octane rating.  98 and 100 readily available in Germany, 100 generally only from Shell, BP and Aral, and expensive.  91 octane was phased out several years ago.

A mate formerly involved in engine management and mixing fuels for a major WRC contender reported the hotshots are now using a mix of 90% E85(85% ethanol) and 10% 98 octane... ends up at 102 octane rating, burns extremely well in hi-comp engines, doesn't eat rubber fuel lines and complies to "pump fuel" rules.

Never had any issues using "too high" octane fuel, other than the waste of money.  ::)

piet
 
Back until the early 90's, I use to mix my fuel for a 2 stroke Kawaski twin 36mm Mikuni dual carburater 440 Intruder mill in my Sportfire John Deer Snow Machine with Sunoco 240 (110 Octane) with an Octane Booster named "Redex" and a cup of Methyl Hydrate into 5 gallons.

She started with a BANG of Ether when it was -40C and the smell of the fuel stand off was intoxicating.
 
Vince said:
Dont know what they put in the original Shell Optimax in Sydney about 15 years ago but my bike didnt like it at all. As I said 98 Shell now is fine.
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Ethanol  Vince

Use 98 you idiots
 
Something out a layer of yellow gunk on the inside of this hose in days..

wdnEMKIz2aSIKbYD02ZcvI6brQ_w08SsSauIBv_loBfDAnpNZHsWahbUSvQwlwCPmtWXtZ9I9r6CEvCt9X63RIh-T66-_Zz_jzV3hnZNf0YRY3RvKsz0eDc3BSmpTnd04emlVDo=w1081-h1444-no
 
Paul Marx said:
Piet, are you sure E85 is Vodka?

Paul
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No, fuel for combustion engines, 85% ethanol, 15% other shit, probably to prevent it from evaporating... don't think I would take a sip, not with Martini, orange juice or whatever.  ::)

Reckon comp. ratio would need to go through the ceiling to get a Lav running on vodka.

piet
 
Use 95 its was introduced to be used in older engines 98 is only for modern engines with advanced engine management systems along with VVT, Hi relative compression ratio's, in a lot of cases turd blowers and so on with controlled cooling systems that are designed for rapid warm up and a higher operating temp than older engines. ..interesting one of the main bug bears with an air cooled engine is getting it to run at operating temp...sure at idle in traffic it still takes a long while for the oil temp to see 100 degrees.. where as a modern engine will be there in a very short time.

Oh did I mention it has more ethanol in it also... which is just great for old steel fuel tanks.
Therefore not only are you wasting your money using it in your Lav you are also asking for poor running not to mention the crud that the ethanol leaves in its wake.


Oh and just so I understand  Who says you cant read plugs with modern fuels.....just got to know what you are looking at as it aint as simple as twas back in the day but can be done and can tell ya a lot about your engines. If they are black sooty esp around the nose of the insulator then the combustion temp is too low for the plugs, which then is the main cause of cold fouling as the modern fuels burn cooler and our engines take longer to get to operating temp.
( but what would I know as deal with this type of shit every day just about ) 

Interestingly we were talking about this last night at the club meet ...... back in the day we used to use B7ES for city riding and bung in B8ES when we were going on a trip. 

I do wonder what the future holds for our old engines though as the governments push harder for higher ethanol contents in the fuels... if there is petrol to be had in another 10 years or so... perhaps now with the demise of the diesel in passengers vehicles around the corner that petrol may get a reprieve for a while.
 
hooksey said:
Good luck finding 95 in the near future ! On the way out the door as sale volume is low.  :o
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And here lies the problem for a lot of the current auto manufacturers esp a lot of the imports.. as quite a number of modern vehicle's are designed to run on a minimum 94 RON.. but a lot of el cheapo owners decide to run 91 which then causes issues down the track with their engines then they want to cry warranty when in fact of case they have caused the issue... now with the current consumer laws its a bloody mine field.

Here's what I reckon will happen... as the oil companies can gouge on an average another 10 to 12 cents out of a litre of 95... they will phase out the 91 as the more import vehicles we get coming in here now that most of our own manufactures have jumped ship ( though I work for now the 3rd largest vehicle manufacturer here in Aus ) it will be the 91 which gets phased out. They they will only have E10, ( which currently is 94 RON, 95 and 98 is my guess oh and the E85 for those who own such pieces of crap which run that type of water ooops fuel.  Now if some Gov have their way as they are trying to push the sugar cane industry they might just make E10 95 RON and tell the owners of older vehicles to sod off.

Now Red your just showing off now
 
I was shocked to see a 95 browser with a small sign saying contains 10% ethinol, it was a shell station. Seen 1 only so far.
 
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