Paul,

With all the recent discussion about P-ports and intake manifolds, I
thought I would ask some basic questions about the various engine
versions and how they stack up for different aircraft requirements.

I’m not sure I understand things correctly, but it seems some engines
have four intake ports and others six. Do the turbo versions use the
four ports? I assume the six ports are for better driveability and
torque at lower rpm?

What about the Renesis, how many ports do these have? I understand the
Renesis also has switched to exhaust ports on the side castings, instead
of P-port exhaust as on the 13B?

If so, it would seem that the 13B engine would be a better starting
point for a turbocharged or turbocompound engine, since the P-port
exhaust would be more energetic?

However, if one wanted a normally aspirated engine of up to say 180
horsepower, perhaps the Renesis would give better fuel specifics, and
maybe a little quieter exhaust? If you need 200hp or more, you would
probably want to go for P-port, whether Renesis or 13B.

It seems that making a manifold is pretty much required as the stock
manifold, besides being a heavy casting, will not easily fit under a
cowl? So if you are making a manifold, it would seem that making a
P-port with only two tubes would be the easiest from a fabrication
perspective. Making a six-port manifold would be the most work, it would
seem.

Regards,

Gordon.


Yes all Mazda turbo engines use the four ports.
Correct on the six ports. The RX8 engine is six ports.
True on the work involved. A six runner low profile manifold long
enough to work at 6500 to 7500 RPM is not easy to make.
The stock RX8 manifold is not that heavy but it is way too
tall to fit under a cowl. I thing the fuel specifics would
be about the same. After all Mazda won Lemans with the same fuel
allocation as the piston engines and used p-ports.

Mazda is always trying
to squeeze a quart of low RPM torque out of a rotary pint pot.
The 2.6 L 13B engine has not been increased in displacement
since 1973 while the power has gone from 120 HP to 240 HP.
Mazda is now forced to compete with 240 HP 3.5 L all aluminum V6
engines from Honda and Toyota. However the RX8 still has a 500 pound
lower weight advantage despite the cast iron end housings.
Car empty weight closely tracks engine weight.

Hopefully the 16B is real.

Paul Lamar ...No rotor no motor.

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