Which fuel to use???

[Digga]

I am sure there are many different views on this but was curious to get opinions on which fuel to use with a focus on E85.

I used BP100 octane (leaded) when I was a kid but now I just buy 98 octane ULP with a good quality 2T oil. I hear people talk about using AvGas & Methanol etc no doubt chasing that extra 1% but also hear about the downsides with these as well.

I cant be bothered with anything complicated so its straight out of the pump for me. However, I was curious to know if anyone has had a crack at E85? Octane ratings vary somewhat depending on the source refinery but typically are as follows:

Reg ULP = 91RON
Reg + ULP = 95RON
E10 = 94 - 100RON (90% Reg ULP + 10% ethanol)
98ULP = 98RON
E85 = 102- 105RON (85% ethanol + 15%ULP)
100% ethanol = 108RON
100% methanol = 108RON

So, interested to hear views & experiences from the forum specifically around the use of E85 as a renewable fuel 

[80-85 husky]

possible issues with rubber parts with ethanol. I know it destroys common rail diesel injector parts to the point of just throw it out. swells all the rubber.

[Digga]

Right, well methanol & ethanol are chemically almost the same so for all those using methanol, they would experience the same problems.

Lets see if anyone out there has tried or is using E85 then.

[sleepy]

It is a bit different to methanol.
Stoichiometric ratio for E85 is around 9.7. Meth is 6.4 and normal petrol is 14.7.
That is the amount of air to fuel mix for chemicaly correct burning, normaly richer for best power.
The E85 will give up to 10% more power than petrol with comp ratio increase and the obvious jetting change. Internal corrosion is not as bad as methanol but still would require some attention in 2 strokes.
Other difference is in the cooling efffect, methanol air mix latent heat is 78.4 btu/lb (figures from an old book in imperial) pure ethanol air mix 44 and petrol 10. E85 wouldn't be as ggod as pure ethanol though.
Other thing to look out for is the mixing with 2 stroke oils, most don't mix or stayed mixed.
I do know someone that was using E85 in racing 80cc MX bikes with good success but I don't recal what oil he was using. I would guess the castor based oils should be ok.
 

[oldyzman]

I wonder about E85, is it true that sometimes methanol cannot get enough heat into the engine, therefore the E85 might put a bit more heat.... plausible?

[Lozza]

The best fuel is the one your engine is tuned to. After much experimenting and brewing of pump fuels we found a mix that gave a nice increase in power without any jetting or ignition changes. The now discontinued United 100 fuel was pour in the tank hp. A few of the Aussie made race fuels work really well.

[skypig]

I had no corrosion or plastic/ rubber issues running Methonol ("Shell A") "back in the day". The biggest issue was the castor oil. ("Shell M") Can turn to jelly in carbs if left. Not the cleanest burning stuff in the engine either.
Both no issue for heavily maintained race engines.

Personally I'd steer clear of fuels with Ethonol in them for vintage engines.
The stuff can swell road bike plastic tanks. (Heaps of warranty issues in the U.S.) Eats some rubber/plastic too I'm led to believe.

Modern engines are designed to use it. Vintage not.
I'd be worried about every rubber/plastic part between the fuel cap and the exhaust pipe. (Main seals even?)

[pokey]

Dammed if you do dammed if you dont. Ethanol while potentially a good source if power and greeny friendly has its downsides and they are many.
Ethanol (metho) is hydroscopic thus absorbs water. In this state it is extremely acidic and attacks all it comes in to contact with. Place this mixture with oxygen and put it under pressure and you have an empty wallet as its effects are quintupled.
The ability to combine oxygen readily is also how it has the ability to make power.
If your going to pull your engine down and replace everything then run ethanol.
i dont use it as you may have gathered.  Ever clean an ally case with an acidic or alkilli  fluid? Not pretty. Now imagine that bubbling under pressure and thats what you get.If your running an engine at a high tune consider the effects if the fuel and the alternatives.

[pancho]

I am sure there are many different views on this but was curious to get opinions on which fuel to use with a focus on E85.

I used BP100 octane (leaded) when I was a kid but now I just buy 98 octane ULP with a good quality 2T oil. I hear people talk about using AvGas & Methanol etc no doubt chasing that extra 1% but also hear about the downsides with these as well.

I cant be bothered with anything complicated so its straight out of the pump for me. However, I was curious to know if anyone has had a crack at E85? Octane ratings vary somewhat depending on the source refinery but typically are as follows:

Reg ULP = 91RON
Reg + ULP = 95RON
E10 = 94 - 100RON (90% Reg ULP + 10% ethanol)
98ULP = 98RON
E85 = 102- 105RON (85% ethanol + 15%ULP)
100% ethanol = 108RON
100% methanol = 108RON

So, interested to hear views & experiences from the forum specifically around the use of E85 as a renewable fuel 

Whats the relationship RON /Octane Rating?

pancho.

[skypig]

Research Octane Number - RON
Is one way of measuring/ expressing Octane rating.

My understanding is that "Octane rating" is the fuels resistance to detonation.
Higher ratings do not in themselves produce more power, but allow higher compressions and mor ignition advance (without detonation) which can contribute to extra performance.

Far from an authority

[N22]

Fresh is best as far as unleaded goes.So using fuel that has been sitting in the shed for a while,in an unsealed plastic drum is asking for trouble.I have been using av gas in our bikes for years,as we keep some on hand for the chopper,it has a use by date for aerial use,so we always have some out of date,but it is stable and lasts for ever.You can't use it on the road,because of the lead content.It is the best fuel in chainsaws etc,because it maintains its octane rating.
As for modern 4 strokes,both carb and injected engines run very well on av gas 100/130,and time between rebuilds is greatly extended,other people will disagree,but anyone who has ridden my 06, stock standard CRF 450(stainless steel valves) comments on the power and smooth running of the engine.It will stay with most 450 motocrossers,at least to the end of the starting straight!
As for fouling plugs,and gumming,I have never had a problem.The sweet exhaust smell gives away that you are using av gas,so you would want to check up the legalities if you are racing.

[Lozza]

Avgas isn't made to make HP it's made to stop little Robbo's falling out of the sky. It's is made to a higher and more consistent standard than pump fuel that's why engines run better on it, the lead definitely extends service life. The 450 would run much better on proper 100 ULP race fuel. You can still actually use leaded fuel on the road just it's not sold any where. ULP has light "front ends" that escape as soon  as the lid comes off. 

[skypig]

I'm tempted to use 50/50 PULP/AVGAS (100LL) (and oil at 25:1)
That's where my OCD brain is at, today.

[80-85 husky]

there is a servo 500metres from my place that's the fuel I use! usually ultimate BP...I use plain garden variety ULP  if im broke!

[Tim754]

'The best fuel is the one your engine is tuned to' Thanks Lozza for the precise be all and end all statement on this subject.    again......