Ethanol-laced fuel bad for RX-8?

[labrat]

The federal government has a secret report detailing manufacturer's recommendations on which cars shouldn't use ethanol-laced fuel. The government won't release the report yet. Has Mazda OK'd the RX-8 for ethanol contaminated petrol? Ethanol is a lousy additive. With basic physical chemistry, you can calculate that the heat of combustion is 33% lower than iso-octane (33kJ/g compared with 44kJ/g). This relates directly to the energy you get from the fuel. This also explains why petrol companies argue that 10% ethanol addition reduces the effective power of the fuel by 3%. By direct proportion, 20% ethanol means a 6% power reduction. Incomplete combustion of ethanol (say on start up) results in acetic acid, which could slowly corrode your motor and exhaust system.

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[rex]

According to this article in today's "Mercury News", Mazda claims that the RX-8 can run safely on fuel containing up to 10% ethanol. I'd want to hear this from Mazda themselves though.

[Wing]

All fuel in Canada can contain up to a maximum of 10% ethanol. So the car better be able to handle it!

[timbo]

Ethanol is a lousy additive. With basic physical chemistry, you can calculate that the heat of combustion is 33% lower than iso-octane (33kJ/g compared with 44kJ/g). This relates directly to the energy you get from the fuel. This also explains why petrol companies argue that 10% ethanol addition reduces the effective power of the fuel by 3%. By direct proportion, 20% ethanol means a 6% power reduction. Incomplete combustion of ethanol (say on start up) results in acetic acid, which could slowly corrode your motor and exhaust system.

labrat

I think you answered your own question very accurately.

I would only use fuel containing ethanol, and as little as possible as a percentage, in an emergency situation.

Timbo

[DMRH]

I have read about this issue from the 1960's.

Curtis Wright bought a license for the rotary engine back in 1958 & started there own program.

One of the documented tests they did was octane testing Vs power.

I recall that testing was done from 100 Octane down to 87 Octane with less than a 3% difference in power. No ping or anything like that noted.

Not sure with the compression ratio as I'm struggling to recall what I just wrote. Plus being the 60's, it certainly wasn't turbocharged

Try doing that with a piston engine & watch it go pop!!!!!

So, whilst I will run Optimax in my twin-turbo 20B powered JC Cosmo, I'll use normal unleaded in all my "atmo" rotary vehicles as the only difference will be in the hip pocket.

[Hymee]

Originally posted by DMRH
20B powered JC Cosmo

Whoo-hoo! (Insert demi-god/bowing smilie here)