While we are on the topic of alcohol and higher compression. Can

anyone out

there who races tell me if the rotary apex seals will hold up in

higher

compression ratios of 11:1 for a thousand hours or so?  I believe the
standard high compression rotors are around 9.5:1.

Doug in Japan

You will not get a significant amount of additional power at 11:1

because

the rotary combustion chamber deteriorates quickly as the compression

ratio

rises above 10:1. Too much surface area so the fire goes out. IMHO
alcohol is probably more affected by a combustion chamber with a high
surface to volume ratio. Just a wild ass guess on my part. If higher
CR's  worked Mazda would have used them years ago on the NA engines.
I know they spent millions researching this.

The rapid increase in Hc emissions as the compression ratio is

increased

is indicative of the combustion chamber's problem with compression

ratio.

Another reason why the Wankel is better suited to turbo charging.

Paul Lamar

Paul

Thanks for the graphs.  Pollution does seem to go up with compression
ratios. Of course the data is for low RPM ... 2000  with low octane

fuels.

Ethanol is high, around 110 octane.  I think I understand where you are
going with this line of thinking though. See if I got this right? With

the

rotary it is more efficient to use the turbo charger to increase the air
density within the combustion chamber by boosting the volume of air (and
consequently increasing the pressure) to get it to burn more fuel and

hence

produce more horsepower rather than by trying to use  engine power to
compress more air by lessening the depression in the rotor hence

increasing

the compression ratio.

 Question??  With the low vapor pressure fuel, ethanol, should I use the
9.7:1 rotors or the 9.0:1 rotors to get the best fuel burn?  I

understand by

using gasoline Mazda requires the low compression ratio rotors with a
turbocharger. Detonation issues no doubt.

Doug in Japan

Yes on the first part.

I have no idea on the second part.

Yes on the Detonation issues. That is mainly a question of seal fracture.

3 mm steel

seals are much more resistant to fracture than stock cast iron 2 mm seals.

Paul Lamar

Vance W Jaqua wrote:

Doug - If my memory serves me, long duration flights were part of your plan.
If so,
what is driving you to high alcohol fuels with notably poorer sfc? also
while
turbo charging provides higher "comprssion ratio", it does not provide the
improvement in sfc of  NA higher compression ratio . Vance

 
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