deano

Reading the mazda site I noticed that the RX-8 is listed as being suitable for Ethanol blended fuels.

What does everyone think?

RXE16T

My cousin's first 13b turbo engine in his RX4 blew up because of poor fuel as a result of too much ethanol content.

Personally, it's only Optimax, BP Ultimate or Mobil Synergy 9000 going into my fuel tank.

No dodgy fuel from "Hassan's Discount Petrol" for me.

deano

I wouldn't mind supporting my local farmers. Mazda wouldn't have listed it as suitable if they thought it could damage the motor??

I'm not decided to run it though - bring on the feedback :-)

Kain

being from the midwest- ethanol here has the medium amount of octane (out of the usual three choices) at always the cheapest price. In my 8 I only use premium but would like to hear other's experiences

takahashi

I drove 6 km to find BP Ultimate... I am not using Craptimax anymore since i have since the impurity some reports stated...

I have not tried Mobil though

labrat

You can calculate with basic physical chemistry that ethanol delivers ~33kJ/g on complete combustion compared with ~44kJ/g for the hydrocarbon iso-octane, the industry standard for fuels (hence the term "octane"). You are getting one third less energy with ethanol than with iso-octane. This is why petrol companies claim a 3% loss with petrol with 10% ethanol. So that's the basic science.

There are environmental claims that burning ethanol lowers carbon monoxide levels, but there are emissions of acetaldehyde due to partially combusted ethanol at startup and during start-stop motoring are increased. Acetaldehyde is a suspected human carcinogen.

I have yet to see what I call a total energy balance for the production of ethanol from plant sources. Say you grow sugar cane for ethanol production. What does it cost in terms of ploughing the ground, planting the cane, fertilizing it (including the energy costs of producing the fertilizer), harvesting it, transporting it to the sugar mill, the cost of producing the sugar and then transporting it to the ethanol refinery, and then the net energy consumption in producing the ethanol? What is the total impact on greenhouse emissions through the entire production process. We also know that silt, pesticides and nutrients in runoff from cane farms have been blamed for damage to the Great Barrier Reef. In addition to the energy balance, we have the cost of labour to consider.

At the end of the day, you are left wih an argument about social engineering, and this becomes a matter of ideology and not of fact. Do we help the sugar farmers stay in an economically unviable industry by taxpayer subsidies? Why should farmers be subsidized when the rest of us aren't? Ask any of the hundreds of thousands of us (including me) who have been retrenched/downsized as a result of "restructuring". Did we get subsidized? Did we ever! Let's face it, along with the medicos, the farmers run the best lobby groups. If there is one thing that history has taught us, propping up unviable industries never works. They always go down the drain eventually, sucking our precious tax dollars with them.

timbo

… so don't bother with ethanol fuel blends, OK!

Gomez

It's only early in the day, but my vote for post of the day goes to the Rat.......

Well said.

Regards, Gomez.

deano

WOW - that was very technical.

Agreed, I'll go the rat and stick with premium.

Everyone you talk to tells you something different as to which premium is best.

Labrat? Maybe we should ship you some fuel to analise :-)

labrat

Sorry about the techy stuff. Unfortunately, we don't do fuel analyses. I'd stick with the premium. Like the others, I either use Optimax or Ultimate, but since my wife shops at Coles, I snaffle the docket and head for the Optimax pump these days. I don't know enough to know which brand is best, or indeed whether there is any real difference between brands. I just don't believe in ethanol in fuel. The right place for ethanol is in beer or wine, IMO.

There seems to be a general consensus growing that most cars, regardless of whether they are "prestige" or "performance" are better off running on premium

RXE16T

On a somewhat related topic, I've heard that Australia has one of the most crappiest fuel octane contents in the developed world.
Can anyone verify this?

Apparently in Japan, their minimum octane in their lowest grade of fuel is 100RON compared to our premium brews of 98RON.

Does this mean that Japanese refineries use a lower or zero mixture of ethanol in their fuel?

Can this somehow relate to our lower power rating and rotten fuel consumption?

takahashi

...ehhh I think high octane is 100 RON nojooc... I will check with my friend in Japan

Hymee

iTrader: (1)

Don't let octane rating confuse potential power. There are different additives that are used to increase the "Octane Rating" (which is really an anti-knock rating). Some additives to can lower the energy content of the fuel, others can enhance it.

There is a pretty good thread in the tech garage about this, although I recall it got a bit off track at some point.

I'll give an example - LPG has a higher equivalent Octane Rating than petrol (~110 from memory), but has less energy content.

A higher octane fuel allows you to run higher compression, which means the engine has a higher efficiency.

I second Gomez's nomination for Post of the Day award to Labrat!

Cheers,
Hymee.

RXE16T

Higher compression = higher efficiency = higher power output, no?

labrat

Hymee's right. One of the arguments for ethanol in fuel is that it boosts the octane (anti-knock) rating, however, as I've said, it produces less heat on combustion (read energy) than the iso-octane component of fuel. I'm prepared to be shot down here, but high octane fuels are also high in "aromatics" like toluene and xylene, which are very energy dense. Getting the right blend of anti-knock properties and energy content takes a lot of skill in the refineries, particularly as the feedstock is a natural product, and subject to variation dependeing on where it comes from. Oils ain't oils.

I don't think you can blame the refineries for crud in fuel. If there's dirt or water or fungus in fuel, that's almost certainly coming from the service station's tanks.

Hymee

iTrader: (1)

Higher output yes, but with caveats. If you went too high for the octane rating of the fuel, you would be going backwards.

You can run an LPG powered engine at higher compression than petrol, but you will get more power out of the petrol engine.

So it is not a simple argument.

I suppose what is important is, that you need to have a fuel with the correct anti-knock rating for the compression ratio of you engine. That would narrow the fuel choice down. Then you would ant to pick the one that has the highest energy content - such as more xylenes and toluenes rather than ethanol. Then you would also want to weigh up the price... Like Labby said, it is a complicated balancing act at the refinary. Then sometimes you get water in it!

Diesels have a higher compression than pertol engines, but are they more powerful? I don't want to get into that for now.
That is a whole other debate on torque v's power

Cheers,
Hymee.

timbo

…but it is an incredibly interesting experience to compare driving -- indeed, the necessary driving style -- of a high hp vehicle vs a high torque vehicle.