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.

According to this article (http://www.themercury.news.com.au/common/story_page/0,5936,7231189%255E421,00.html) 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.

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

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

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.

Originally posted by DMRH
20B powered JC Cosmo

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