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MAR34807@aol.com wrote:
Felix Miata <bogus.due2UCE@gate.net> wrote in article
<377CCF25.3ACF@gate.net>...
John G wrote:
Carl H wrote:
There is some debate as to the correct volume to use to describe the volume
of a rotary engine.
for comparison purposes.
generally many racing classes impose a factor of about 1.4 - 1.5.
As technology has changed with piston engines this factor has changed in
real terms.
In 1973 it was very rare to find a 1146cc piston engine putting out 135 HP.
The free-er airflow through the rotary makes it more equivilant to a quad
cam big valve piston engine.
Mazda published a book back in 1984 which had comparitive calculations on
the efficiency of a rotary versus a piston engine. Rotary = 12% piston =
14%. (Nuclear power =22%)
Since then advances in seal technology have reduced this gap.
The main reason for the lower value for the rotary is caused mainly by the
overlap between exhaust and intake.
If you put a lot of overlap in a camshaft this also drops efficiency.
The new side exhaust port rotary significantly reduces overlap, as the
charge is now more fully expanding prior to discharge the engine is now
more efficient.
The inlet port can be slightly smaller than on the 13BREW and still develop
similar horsepower.
The production model will probably be detuned to 200HP NA.
As for economy most people have heavy feet. The secret to economy from a
turbo car is to keep the turbo off boost. I have been able to achieve
economy figures at least 20-30% better than most of the road tests I have
seen.
1997 RX-7 5 speed manual. 21.5 MPG town 29.4 MPG Highway Dyno
248HP
(Right hand drive)
Booting It of course sees these figures drop but very comparable to a
porsche.
1973 RX3 4 speed manual 12A 22.8 MPG 33.6 MPG Highway. Dyno 149HP
small
s-port
(for comparision 2.0 litre ford cortina 20.2 MPG & 26.7 MPG 68 HP if lucky
)
Note also that both of these vehicles had the emission controls removed.
And mixture recalibrated.
especially in the case of the RX-3 this added around 15% economy.
We havent yet seen anyone turbo this side exhaust engine should be great.
F1 piston engines run big cam overlap and use LOTS of fuel. At the RPM they
race at the gas flow is acting as a dynamic seal. (volumetric efficiency
also increases with RPM) .
Tip: You can do this with a rotary by turboing a bridge port or small
peripheral port. Use a really big turbo so you can overcome the charge blow
through and reach a point where the gas acts as a dynamic seal.
If the mixture is tuned right to compensate for charge dilution large
horsepower is possible.
12A with D4 Turbo Bridgeport 4 inch wastegate 568HP @ 9500 RPM. 18psi
boost.
(8 dowels in rotor housings)
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