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1. 10:14 AM - Re: Fuel Injection (N395V)
2. 11:53 AM - Re: Re: Fuel Injection (Monty Barrett Sr)
Message 1
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| Subject: | Re: Fuel Injection |
Finally have some real data with what I believe are accurate numbers and extrapolations.
The data sheets for these numbers can be found at http://www.excaliburaviation.com/album_frame.asp?forum=open&menuID=8~8
Under either the M14P forum or the Radial Rocket forum
Bear in mind there will be some degree of measurement and extrapolation error and
your results may vary.
My initial estimates of fuel consumption of the M14PF using the AFP throttle body
vs the stock pressure carb were overly optimistic and based on skewed data
due to incorrectly calibrated gauges and observer bias.
I am running an M14PF on a Radial Rocket with an AFP throttle body as opposed to the stock pressure carb. http://www.radialrocket.com/
Initially I had a good deal of heat problems (CHTs) due to baffling issues; these
have been largely resolved.
Relative to the M14PF
The fuel consumption is statistically no different between the throttle body and
the pressure carb when running rich of peak. The AFP fuel flows are what were
needed to keep my hottest CHT at or below 380 deg F this was usually 100-150
degF ROP.
Given the engine is boosted there is room for fuel savings with the throttle body
but I have not yet experimented with LOP on this engine.
Relative to the Radial Rocket
Wit this engine, prop, and airframe combination running the pressure carb or the
throttle body ROP it appears that for a burn of 15 GPH we have a.
185-190 Knot (TAS) airplane below 8000
205-210 Knot (TAS) airplane between 8000 & 11,000
220+ Knot (TAS) airplane depending on how much fuel you want to burn
I have no numbers above 12,00 feet as I am still having a problem with abrupt and
significant power loss crossing 12,000. It appears to be related to either
Icing or decreasing fuel pressure.
I am going to crank the fuel pressure on the ground up to 55-60psi and or use the
boost pump above 12,000 to see what this doe. If that doesnt work I will try
ducting some heat into the induction system.
The benefits of the Pressure Carb vs the throttle body are.
1. Ease of operation.. 1 less lever and with the throttle body you need to make
adjustments before major power changes and manage it with ascent and descent.
2. Cost (an extra $3000 for the throttle body after you have sold your carb)
Downside of the pressure carb
1. Continued availability of carb, parts, service
2. Cannot run LOP
3. If your application during the early stages requires it you cannot use fuel
flow to decrease CHTs while working out baffling issues.
Benefits of the throttle body
1. Availability of the unit, parts and service.
2. Ability to run LOP (maybe) if you are a believer.
Downside of throttle body
1. Initial cost
2. Ill let you know the rest when I get all the bugs worked out.
As soon as I get this altitude problem resolved Ill start running LOP and post
those results
carb fuel flows are derived from Dennis Savareses data found at http://home.elmore.rr.com/yak52world/Power%20Settings.htm
Unless labeled carb all fuel flows are for the AFP throttle body.
CAVEATS
I am neither a mathematician nor an engine expert.
There is still some degree of measurement and extrapolation error.
This application required slightly higher fuel flow than optimal for cooling purposes.
Still have a lot of work to do and data to collect.
Any input or suggestions here or on the the radial rocket forum would be appreciated
--------
Milt
N395V
F1 Rocket
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=101646#101646
Message 2
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| Subject: | Re: Fuel Injection |
Milt, I believe you are correct in most of your analysis. Slightly richer than
" Best Power " mixture is a F/A ratio used by both TCM and Lycoming to control
CHT and to provide some " cushion " against more that " light " detonation.
While I am a believer of LOP operation under most condtions, I suspect that this
particular engine may not respond well to LOP F/A mixtures because the distribution
of fuel within the diffuser will likely not be homogenous, leading to
some cylinders running at different mixture strengths. To successfully operate
LOP the mixtures strengths need to be very equal. I have seen an M14 type engine
in Russia that had port injection, electronically controlled. The first
tests of the engine yielded a
" reported " 10 BHP increase with approximately 15% reduction in required fuel.
A Significant improvement.
Whenever additional fuel is used for heat control some power is lost. It may not
be much but there is some loss, depending on the ambient conditions.
One should remember that the Russian fuel scheduling takes into account their very
cold operating ambient temperature, wherein the air density is very high,
and they schedule fuel based on that possibility.
I also have AFP injection for an M14-P but have not run it yet.
Monty Barrett
Barrett Precision Engines, Inc.
-----Original Message-----
From: owner-m14pengines-list-server@matronics.com [mailto:owner-m14pengines-list-server@matronics.com] On Behalf Of N395V
Sent: Monday, March 19, 2007 11:14 AM
Subject: M14PEngines-List: Re: Fuel Injection
Finally have some real data with what I believe are accurate numbers and extrapolations.
The data sheets for these numbers can be found at http://www.excaliburaviation.com/album_frame.asp?forum=open&menuID=8~8
Under either the M14P forum or the Radial Rocket forum
Bear in mind there will be some degree of measurement and extrapolation error and
your results may vary.
My initial estimates of fuel consumption of the M14PF using the AFP throttle body
vs the stock pressure carb were overly optimistic and based on skewed data
due to incorrectly calibrated gauges and observer bias.
I am running an M14PF on a Radial Rocket with an AFP throttle body as opposed to the stock pressure carb. http://www.radialrocket.com/
Initially I had a good deal of heat problems (CHTs) due to baffling issues; these
have been largely resolved.
Relative to the M14PF
The fuel consumption is statistically no different between the throttle body and
the pressure carb when running rich of peak. The AFP fuel flows are what were
needed to keep my hottest CHT at or below 380 deg F this was usually 100-150
degF ROP.
Given the engine is boosted there is room for fuel savings with the throttle body
but I have not yet experimented with LOP on this engine.
Relative to the Radial Rocket
Wit this engine, prop, and airframe combination running the pressure carb or the
throttle body ROP it appears that for a burn of 15 GPH we have a.
185-190 Knot (TAS) airplane below 8000
205-210 Knot (TAS) airplane between 8000 & 11,000
220+ Knot (TAS) airplane depending on how much fuel you want to burn
I have no numbers above 12,00 feet as I am still having a problem with abrupt and
significant power loss crossing 12,000. It appears to be related to either
Icing or decreasing fuel pressure.
I am going to crank the fuel pressure on the ground up to 55-60psi and or use the
boost pump above 12,000 to see what this doe. If that doesnt work I will try
ducting some heat into the induction system.
The benefits of the Pressure Carb vs the throttle body are.
1. Ease of operation.. 1 less lever and with the throttle body you need to make
adjustments before major power changes and manage it with ascent and descent.
2. Cost (an extra $3000 for the throttle body after you have sold your carb)
Downside of the pressure carb
1. Continued availability of carb, parts, service
2. Cannot run LOP
3. If your application during the early stages requires it you cannot use fuel
flow to decrease CHTs while working out baffling issues.
Benefits of the throttle body
1. Availability of the unit, parts and service.
2. Ability to run LOP (maybe) if you are a believer.
Downside of throttle body
1. Initial cost
2. Ill let you know the rest when I get all the bugs worked out.
As soon as I get this altitude problem resolved Ill start running LOP and post
those results
carb fuel flows are derived from Dennis Savareses data found at http://home.elmore.rr.com/yak52world/Power%20Settings.htm
Unless labeled carb all fuel flows are for the AFP throttle body.
CAVEATS
I am neither a mathematician nor an engine expert.
There is still some degree of measurement and extrapolation error.
This application required slightly higher fuel flow than optimal for cooling purposes.
Still have a lot of work to do and data to collect.
Any input or suggestions here or on the the radial rocket forum would be appreciated
--------
Milt
N395V
F1 Rocket
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=101646#101646
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