>>>>>WOT 5500 RPM at 4500' manifold pressure is 26.5 in. hg.
>>>>>5200 RPM at 4500' manifold pressure is 23.5 in. hg.
>>>>>5200 RPM at 6500' manifold pressure is 22.0 in. hg.
>>>>>
>>>>>I don't know what the white exhaust means but it is not lean. Maybe
>>>>>in a car with a catalytic
>>>>>converter and muffler white means lean. My O2 sensor is working
>>>>>perfectly as far as I can tell. It reads 0.8 average anytime
>>>>>in flight with RPM over 4000. That is when the ECU is
>>>>>operating on internal maps. It read 0.45 when I was at 3000 RPM on
>>>>>base leg. That is when it is closed loop using the O2 sensor.
>>>>>
>>>>>--
>>>>>Perry Mick
>>>>>
>>>>Make a low pass and tell me what it is nearer sea level,
>>>>Sounds a bit low at 4500'
>>>>Or just during takeoff. What is the field elevation there?
>>>>
>>>>Paul Lamar
>>>MMV is only 160 MSL. If I climb out full throttle at 80 knots RPM is
>>>5150, if I climb at 90 knots it is 5200, manifold will read 30.0
>>>near the ground. I will have to fly again to see what the manifold
>>>pressure is 5200 RPM level flight near SL.
>>>
>>>I'm guessing Mazda purposely runs the engine at 0.8V O2 sensor
>>>best power mixture when the engine is at high RPM and high load,
>>>because in the car you are generally only operating there when
>>>you are accelerating and want the power. But like Tracy says,
>>>for airplanes you want to lean it back in cruise. I just need
>>>to see if I can trick the ECU somehow to do that.
>>>
>>>--
>>>Perry
>Things are not adding up Perry. You are burning 100 HP worth of fuel
>max (7 GPH) and your RPM is 5200 at 30" Hg manifold pressure you should
>be developing about 140 HP.
>
>Paul Lamar
5200 RPM and 30" Hg is climbing out. I may be burning 10 or 12 gph
during climb out, I just don't know. My gross weight would be
approximately 1400 lbs. and climb rate is maybe 800 fpm. The only
fuel burn numbers I have are from long trips. I used to burn 6.5 gph
cruising at 4800 RPM, now I burn 7 to 8 gph cruising at 5200 RPM.
I guess I could cruise around WOT for awhile and try to determine what
my fuel burn is, probably over 10 gph and closer to 140 HP like you say.
BTW, what is the source of that chart? It has plots for "old" and
"improved" manifolds. I'm guessing the "old" manifold is the 1986
and the "improved" is 1989. In that case you will get results comparable
to mine by using the "old" curve, which does show a peak close to
146 HP at 6500 RPM. I think the 1989 engine was rated more like
160 HP at 6000 or 7000 RPM.
--
Perry
8 GPH is 96 HP at BSFC of 0.5 and 80 HP at a BSFC of 0.6.
10 GPH is 120 HP at BSFC of 0.5 and 100 HP at BSFC of 0.6.
12 GPH is 144 HP at BSFC of 0.5 and 120 HP at BSFC of 0.6.
That dyno curve is from a Mazda SAE 841017 technical paper published
in 1984. The old is the non dynamic chamber version pre about
1985-1986. Note the lack of the torque peak at 2000 to 3000 RPM in the old
140 HP chart. The dynamic chamber was developed and used post 1986
to enhance the torque at 2000 to 3000 at the expense of peak power.
The 160 HP engine shows that torque hump at 2000 to 4000 RPM.
You are using the stock dynamic chamber and EFI so your engine is 160 HP
at 6500 RPM or so. BTW took me a long time to convince Ed of this fact:)
The 140 HP comparison engine was probably the early 4 barrel, 4 port
short intake manifold, carb version of the 13B used from 1974 in the
RX4 and 13B Cosmo. This is the engine I had in my Cosmo. All EFI systems
have been dynamic chambers from about 1985-1986 through 1991. In 1992 the
dynamic chamber was refined and improved and used only with the
turbo RX7 in the states.
BTW Tracy built a flow meter using the injector pulse width.
Tracy what is the status of that device? Can you loan it to Perry?
Paul Lamar
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