Bill, At 43 psi it would flow approx 14%
less fuel than at 56 psi. New Flow = old Flow * Sqrt(New
Pressure/old Pressure) for a rough estimation.
In any case, if you take the set of
4 injectors as 295 and 500 cc/min. Together they (at 56 psi) would
presumably give you 2*295 + 2 * 500 = 1590 cc/min at WOT (all 4 injectors
pumping). Even if you derate them to 85% of that flow - it comes out to 1315
cc/min.
To find a rough estimate of power from
that flow, I convert to gallon/hr 1315 * 60 = 81090 cc/hr = 21.42
Gallon/hr.
So HP = 21.42*6/0.55 = 233 HP
approx. So in short, unless you are running forced induction, you
are going to have fuel for your engine’s likely power even at 43
psi. A bit less at 39 psi, but still not likely to put a hold on your
power production – unless as I said you are running a turbo or
supercharger.
Personally, I would simply make my primary
injectors the same size as my secondary and know I would have sufficient power
on either pair to produce nearly full power. Nice insurance in case you
ever have to turn off a pair due to a bad injector (its happened) and you don’t
have to mess with mode 6 to try and balance the EC2’s operation of two
largely different injector sizes.
At least that’s the way I see it.
Ed
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bill Bradburry
Sent: Friday, June 19, 2009 4:27
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Perhaps
it is 56 psi was [FlyRotary] Re: 295cc vs 495 cc was [FlyRotary] responses to
responses, not developing full power
Ed,
I think that the jumper wire is used to
short the injector to full open. That is how injectors are sized, by the
amount that they will flow at 100%. You notice that the jumper is moved
to a different location when checking for a leak. That is to assure the
injector is off. So you are checking for a leak at closed and
amount and spray pattern at full open.
So the problem with using the EC-2 to
modify the injector is that the injector can not flow more than will go thru at
full open. The EC-2 would be able to lower the output, but it would not
be able to get more than 100% out of it.
I think that the injectors are sized a
little small for the car knowing that you will only be WOT for a short
time. Our application is looking for max output continuously.
So what would be the output of an injector
if it should flow 295 cc at a pressure of 57 lbs if it were to be operated at
either 44 or 36 lbs instead? This would be a real drop in HP that could
be supported.
I looked at the fuel pump capacity for the
fuel pumps that Tracy
sells. They can output around 30 gph at 60 psi, so they should be fine if
the pressure is raised. They will pull about 9 amps under that condition.
Bill B
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Ed Anderson
Sent: Friday, June 19, 2009 2:28
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Perhaps it is
56 psi was [FlyRotary] Re: 295cc vs 495 cc was [FlyRotary] responses to
responses, not developing full power
Bill, you may be on to something. I initially thought you
might have misinterpreted the tests results and I thought that 29 psi
“hold” pressure might be the operating pressure.
Fuel hold pressure
200 kPa {2.0 kgf/cm2, 29 psi}
http://www.myrotarycar.com/portal/forum/uploads/RX8TX/Manuals/CD05-xx-03le/index.html
However, having said that - I then
found under “Fuel Injector Inspection” tab the following:
Test
condition
• Fuel
pressure: 392 kPa {4.00 kgf/cm2, 56.9 psi}
• Atmosphere
temperature: Normal temperature
Leakage
amount
|
Engine
|
Fuel injector
|
Leakage amount (approx.)
(1 drop)
|
|
Position
|
Color
|
|
13B-MSP
(Standard Power)
|
FP1, RP1
|
Red
|
110 min. or more
|
|
FS, RS
|
Blue
|
30 min. or more
|
|
13B-MSP
(High Power)
|
FP1, RP1
|
Red
|
110 min. or more
|
|
FP2, RP2,
FS, RS
|
Yellow
|
70 min. or more
|
So at least for testing for leaks it appears
56 psi is
also used and the next table in that section of the manual - at least implies
that the flow rate of the injectors is also based on this 56 psi. I draw
this conclusion since the manual does not indicate a requirement to change the
pressure from the 56 psi used for the leak test before conducting the
flow test (below). They show the red injector’s (15sec
test) = 69-78 or mid point of 73.5 * 4 = 294 cc/min – which as I
understand is the quoted value for the Red (primary) injector for the standard
power 4 port Renesis.
• If not within the specification,
replace the fuel injector.
Injection
volume
|
Engine
|
Fuel injector
|
Injection volume (approx.)
(cm3{cc, fl oz}/15s)
|
|
Position
|
Color
|
|
13B-MSP
(Standard Power)
|
FP1, RP1
|
Red
|
69-78 {69-78, 2.4-2.6}
|
|
FS, RS
|
Blue
|
118-133 {118-133,
4.00-4.50}
|
|
13B-MSP
(High Power)
|
FP1, RP1
|
Red
|
69-78 {69-78, 2.4-2.6}
|
|
FP2, RP2,
FS, RS
|
Yellow
|
89-101 {89-101, 3.01-3.42}
|
So I believe the 5 minute hold test (29psi)
is a test of the regulator (and likely the entire fuel system including a
check for leaking injectors?) to hold the decay to at least 29 psi after 5
minutes. But, it appears that the desired operating pressure might be
closer to 56 psi based on the fuel flow test (presumably conducted at 56 psi
sinces it comes right after the leak test at 56 PSI and no indication that the
pressure was changed for the flow test).
Looking at the fuel diagram and seeing no
indication of a manifold reference tube going back to the fuel tank where the
regulator is, I would bet a beer that the fuel pressure is controlled by the CPU
either through fuel pump speed control or perhaps electronic control of the
regulator in the tank. My bet is on fuel pump speed.
The only reason I hesitate at all is that
in the Fuel Line Pressure Inspection check, there is a jumper wire used to ground
a Fuel Pump related terminal. This might be just to provide signal to the
pump to run OR it might possible
by-pass the fuel pressure regulation function and drive line pressure up just
for the test. Could be either one.
8. Ground the check
connector terminal F/P using the jumper wire.
But, until I see/find or have someone point
out something that shows different operating pressure, I’m inclined to
agree with Bill’s conclusion. Most tests including the flow test appears
to be conducted with 56.9 psi as the value.
Good find, Bill, certain to stimulate discussion
on the topic – and somebody may know for certain {:>).
Assessing how much impact this would have
requires a bit of math Generally, if you have a fuel pressure change then
the new flow rate = old flowrate * sqrt(New Fuel Pressure/Old Fuel Pressure).
So if you were using 43 psi and 295 cc/min
injectors and then went to 56 psi, you would have
New Flow rate = 295 * sqrt(56/43) = 295 * 1.1411
= 336 cc/min. or about a 14% difference. However, I’m not
certain that would be signficant using the Ec2/EC3 as you have the ability to
tune the flow of your injectors in a number of ways. You can use the mode
6 in normal staging/operation mode, you can use the mixture control, and using
the EM2/3 change the fuel map bar heights.
So if the 56psi is the required pressure to
achieve the rate flow (normally 43 psi is used) then the injectors are passing
less fuel than rated – but, whether this would have any material effect
on good operation of the EC2/EC2 I personally rather doubt. But, only Tracy can authoritatively
respond to that.
Ed
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
http://www.andersonee.com
http://www.dmack.net/mazda/index.html
http://www.flyrotary.com/
http://members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.rotaryaviation.com/Rotorhead%20Truth.htm
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Bill Bradburry
Sent: Friday, June 19, 2009 1:13
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: 295cc vs
495 cc was [FlyRotary] responses to responses, not developing full power
By the way, I just discovered that the fuel pressure spec for the RX-8
is over 56 lbs! See the link.
http://www.myrotarycar.com/portal/forum/uploads/RX8TX/Manuals/CD05-xx-03le/index.html
Most of us have our pressure way lower than that and that will greatly
lower the output of the stock injectors since they are sized to deliver fuel at
that pressure. Could be why some of us are not getting throttle response
above 2/3 throttle? What about you guys with superchargers? Do you
go lean?
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bill Bradburry
Sent: Friday, June 19, 2009 10:58
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: 295cc vs
495 cc was [FlyRotary] responses to responses, not developing full power
Oh,
If you happen to be using the 6 port and plan to use only 4 of the
yellow injectors, they are only good for between 173 and 197 HP at 80% duty
cycle and BSFC of .5. You would have to use all 6 to realize that higher
HP that they are supposed to make.
I am thinking that they are sized small in the car because they
don’t expect you to be at WOT for long in the car and they will have a
chance to cool down. In our case they will be at WOT for hours and could
overheat if they were at a high duty cycle.
Thoughts??
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bill Bradburry
Sent: Friday, June 19, 2009 10:38
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: 295cc vs
495 cc was [FlyRotary] responses to responses, not developing full power
Bryan,
Well, ain’t that interesting!
That indicates that the injectors (according to calculators I found on
the web) will support between 183 and 206 HP with a duty cycle of 80% and an
BSFC of .5.
So much for all these wild guesses we have been making about how much
power we will get with the Renesis.
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bryan Winberry
Sent: Friday, June 19, 2009 10:03
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: 295cc vs
495 cc was [FlyRotary] responses to responses, not developing full power
Bill,
According to the manual, the flow rates
are:
Red 69-78 ccm/15s
Blue 118-133
Yellow 89-101
I’m assuming the 15s means 15
seconds. So, multiply these values by 4.
Bryan
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Bill Bradburry
Sent: Friday, June 19, 2009 9:44
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: 295cc vs
495 cc was [FlyRotary] responses to responses, not developing full power
What is the actual size of the stock Renesis injectors? I was
under the understanding that the red primary was 295 ccm and the blue secondary
was 610 ccm. I heard that the yellow injectors from the hi power 6 port
were a different size, but have never heard what size they were supposed to be.
Don, did you say you had your injectors cleaned and flowed? What
did they flow?
Where can this information be found? Is is listed in a Mazda book
somewhere?
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Tracy Crook
Sent: Friday, June 19, 2009 9:24
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: 295cc vs
495 cc was [FlyRotary] responses to responses, not developing full power
Mode 6 would handle it
but that is for normal staging only. The 'injector set
disabled' is a special case In which the EC2/3 does not know which set
has been disabled and therefore can't know exactly what to do. It's up to
the pilot to make the appropriate response on the mixture knob if the injectors
are not the same size.
Tracy
On Fri, Jun 19, 2009 at 10:17 AM, Al Gietzen <ALVentures@cox.net> wrote:
When
you switch the primary injectors off and secondary
injectors
on - the EC2 is still providing the same pulse duration (assuming
engine
manifold pressure, etc are the same) for the almost twice as large
secondary
injectors as it did for the smaller primary injectors. Ergo, you
are
feeding the engine almost twice the fuel (for the same engine
conditions)
as you did when on the primary injectors. The engine is choking
on
too much fuel.
Unless, of course, you have made the mode 6
adjustment to compensate for the difference in the flow rates – or will
mode 6 not handle such a big differential.
Al G
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