"Glen A. Renken" wrote:
What is the realistic horsepower of a 13B ? What about a 20B ( 3-rotor ??)
Will a Ross PSRU for a 13B fit a 20B ?
Anything from 160 HP to 270 HP.
For a normally aspirated 13B it is highly dependent on the intake manifold
design
and the gear ratio of the PSRU. The gear ratio limits the engine RPM and the
HP because
most props are limited to about 2700 RPM.
Side port engines are limited to about 200 HP except for the high power
version
of the RX8 engine and peripheral port engines are limited to about 270 HP.
Turbo charged engines can be anything up to about 400 HP.
Just be aware that the cooling system must be designed for the HP used.
That is probably a more practical limit on HP than anything else.
The engine itself is extremely robust and does not fail in the
hand grenade mode common with souped up piston engines.
In drag racing form turbo charged 13Bs generate up to 800 HP.
20B are 50% more for any given configuration.
In aircraft use nobody has worn one out yet.
Paul Lamar
Douglas Fir wrote:
Paul,
You mentioned before the Renesis turboed engine made in Australia blew up.
Obviously it had the high compression rotors and they were pushing it.
Correct me if I am wrong but didn't one of the later 13B have high
compression rotors, a turbo and a knock sensor to retard the timing if
detonation events were imminent? At least this is what the local mechanic
told me. Perhaps it was one of his racing cars.
I still haven't given up completely on using the Renesis and I keep coming
back to the fact that the side port configuration would be the best for
turbocompounding.
I would think with ethanol, and turbo compounding I would get my cruise
150hp fairly easily. Your thoughts.
For 300hp takeoff Hp. I do have the advantage of 10% increase in power from
ethanol and because of its cooling effect can safely boost a small ???
amount.
In the last 4 months I still can't confirm what the hp on the manual
Renesis engine is. Jim. M. told me 220hp was the most he could get out of
it. I don't know how it was configured though. If it is actually 250hp
(234hp) at 7700, normally aspirated then I'll go for it.
Doug in Japan
When I said "blew up" I did not mean in the hand grenade mode. What happens is
the resulting detonation fractures the 2 MM apex seals. I am not convinced the
detonation sensor always does the job. I think it only takes one detonation to
fracture a seal. When that happens it is too late to retard the ignition. If
I were you and I were going with a turbo I would use 3 mm apex seals and
low compression rotors.
I am attempting to get Mazda to make available through Mazda Speed thicker
wall
rotors for the RX8 engine so the after market guys can lower the compression
ratio
using NC mills. This will allow turbo or super charging the RX8 engine. The
thicker
wall rotors can go down the stock rotor machining line with no changes other
than
being identified. I think the cost of this program would soon pay for itself
through
the absence of this kind of negative publicity.
Mazda needs to focus on the rotary. They have announced a 3500 pound Mazda
Speed
"sport" version of the Mazda 6 with a turbo four cylinder engine that got a
less
than a favorably revue in Car & Driver. They need to get with an electric
assisted
turbo charged RX8 and a much lighter weight Mazda 3 with the rotary as soon as
possible.
Miata sales are in the cellar at 680 a month. A restyle will do nothing. The
Miata
needs a rotary as well to shed its chic car image. They also need to be
working hard on
a turbo compound version of the rotary to improve the MPG. Instead Mazda seems
to be going off in all directions at once.
You need to monitor the OBD II data output in real time when dynoing an
RX8 engine. You might think the throttle is wide open but the engine computer
may decide
otherwise. The throttle is fly by wire. Here is a "full throttle" pedal to the
metal acceleration run to 100 MPH in my RX8 monitoring the OBD II real time
data output. Note the throttle is only 77% open. Why did the engine computer
decide
not to open the throttle fully? Perhaps it was the 104 degree F temperature of
the air intake or perhaps it was because I had 87 octane fuel in there.
Paul Lamar
Paul
I just spoke with the racer/mechanic who sold me the turbo powered 13B. He
said its' stock hp was 260Hp though with a little fiddling he got a similar
engine up to 280Hp. I assume fiddling meant engine timing and a tuned
exhaust. I am well aware the engine can go way beyond that with bigger
turbochargers. In any case perhaps within two years someone will have low
comp. rotors for the RENESIS on the market. This would be my first engine
choice for the world trip on ethanol since turbocompounding is high on the
wish list. Taking off from water fully loaded was never in my mission plan
on this trip. SeaWinds will take off on water with 250hp (takes a while)
but the most important reason to have the SeaWind having a good chance for
pilot and plane to survive a ocean landing.
I will plan the cowling, engine mounts, radiator space, etc to take a 20B as
a back up plan, or for future use when I get the urge to go faster and
shorter distances.
So RENESIS rotors don't have enough meat on them to mill? Ah so.
Understanding takes place. I read that Mazda Aussie car was ONLY boosted
7.5psi. A good rammed air system can deliver 2psi. Perhaps somewhere between
these values.
Vance I believe mentioned that the best BSFC is achieved with a N/A engine.
I confess I don't completely understand that statement. A/F ratios should
remain constant in higher pressure situations as well as N/A conditions.
Perhaps it has to do with how complete the fuel is mixed or burned in high
pressure combustion chambers? Obviously the injectors are required to squirt
20% or more fuel into the chamber in the same amount of mixing time. The
mass of burnable material is more. Hence incomplete burning. Afterburner
chamber with attached sparkplug needed. Reasonably close?
I think spark-plugs attached to the end of tail pipes used to be a fad way
back when. Scare the horses and toast the tailgaters sort of thing:)
Doug in Japan
I suspect the reason turbo charged engines have lower BSFC is because of
the intercooler. The intercooler represents a loss of over all heat.
It takes HP to compress the air despite the fact most of it is coming
from the waste heat in the exhaust. There is some back pressure associated
with turbo chargers. Part of the energy stored in the compressed
air is in the form of heat. If you throw that away in an intercooler
you are losing some energy from the gallon of gas. The answer is to extract
as much energy out of the exhaust as possible in the form of turbo compounding.
Here is a heat balance chart for a RR Merlin aircraft engine. 2.5% is needed to
operate the supercharger.
Paul Lamar
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