Today's Message Index:
----------------------
1. 02:40 PM - Lycoming O-360 Fuel Flow Rate (Matt Dralle)
2. 03:26 PM - Re: Lycoming O-360 Fuel Flow Rate (Charlie England)
3. 04:30 PM - Re: Lycoming O-360 Fuel Flow Rate (Kelly McMullen)
4. 05:00 PM - Re: Lycoming O-360 Fuel Flow Rate (Charlie England)
5. 07:02 PM - Re: Lycoming O-360 Fuel Flow Rate (Linn Walters)
6. 09:07 PM - Re: Lycoming O-360 Fuel Flow Rate (Kelly McMullen)
Message 1
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| Subject: | Lycoming O-360 Fuel Flow Rate |
I'm still chasing down this weird problem with low fuel flow rates on the RV-6.
I've replaced the mechanical fuel pump and got a rebuilt 4-5 carburetor, both
of which were well over do for replacement/overhaul anyway. I haven't put the
cowling back on yet, but I did a static run up to about 2350-2400 and am seeing
about 9gph, which seems low to me?
I pulled the fuel line off the carburetor and turned the electric fuel pump on
and saw about 21 GPH flow. Is that considered "normal" or too low?
Thanks for the feedback,
Matt
-
Matt Dralle
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Message 2
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| Subject: | Re: Lycoming O-360 Fuel Flow Rate |
On 12/18/2015 4:38 PM, Matt Dralle wrote:
>
>
> I'm still chasing down this weird problem with low fuel flow rates on the RV-6.
I've replaced the mechanical fuel pump and got a rebuilt 4-5 carburetor, both
of which were well over do for replacement/overhaul anyway. I haven't put
the cowling back on yet, but I did a static run up to about 2350-2400 and am
seeing about 9gph, which seems low to me?
>
> I pulled the fuel line off the carburetor and turned the electric fuel pump on
and saw about 21 GPH flow. Is that considered "normal" or too low?
>
> Thanks for the feedback,
>
> Matt
>
> -
> Matt Dralle
Never paid much attention to my flow when doing a static runup, but that
doesn't sound too unreasonable. If CS & flat pitch, it won't take much
power to get to 2400rpm. What's the MAP? You should be able to use Lyc's
power charts to see MAP/rpm/power. 75% on a 180 is around 10 GPH, if
leaned. Obviously lower fuel flow if you're under 24".
I think that the FAA recommends 125% of max power flow if running a pump
(150% for gravity feed). Max power flow would be (180 * .6)/6=18GPH.
That would assume a very rich mixture of .6 lbs per HP per hour. So your
electric pump flow sounds more than adequate.
It's really odd that you didn't see any degraded performance when your
flow went from 17 down to 9 gph in climbout, unless it's some sort of
instrumentation issue giving false readings. Hard to explain two
different flow monitors making the same error, but hard to explain the
performance, too. :-)
Having said that, if you were seeing 9gph in a full power (2700rpm, full
rich, 29"MAP) before, and you're now seeing the same flow on the ground,
with less than full throttle, flat pitch & 2400 rpm, then *something*
must be better now.
Message 3
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| Subject: | Re: Lycoming O-360 Fuel Flow Rate |
While fuel flow numbers are good general indicators, EGT will tell you
more. On takeoff at sea level you should see 1200-1300 EGT with 1250
optimal. If your fuel flow is too low EGT will go well above 1300.
Assuming 180 hp version, Fuel flow for takeoff should be around 16-18
gph. Cruise at 75% should be 9-9.5 gph.
On 12/18/2015 4:25 PM, Charlie England wrote:
>
> On 12/18/2015 4:38 PM, Matt Dralle wrote:
>>
>>
>> I'm still chasing down this weird problem with low fuel flow rates on
>> the RV-6. I've replaced the mechanical fuel pump and got a rebuilt
>> 4-5 carburetor, both of which were well over do for
>> replacement/overhaul anyway. I haven't put the cowling back on yet,
>> but I did a static run up to about 2350-2400 and am seeing about
>> 9gph, which seems low to me?
>>
>> I pulled the fuel line off the carburetor and turned the electric
>> fuel pump on and saw about 21 GPH flow. Is that considered "normal"
>> or too low?
>>
>> Thanks for the feedback,
>>
>> Matt
>>
>> -
>> Matt Dralle
> Never paid much attention to my flow when doing a static runup, but
> that doesn't sound too unreasonable. If CS & flat pitch, it won't take
> much power to get to 2400rpm. What's the MAP? You should be able to
> use Lyc's power charts to see MAP/rpm/power. 75% on a 180 is around 10
> GPH, if leaned. Obviously lower fuel flow if you're under 24".
>
> I think that the FAA recommends 125% of max power flow if running a
> pump (150% for gravity feed). Max power flow would be (180 *
> .6)/6=18GPH. That would assume a very rich mixture of .6 lbs per HP
> per hour. So your electric pump flow sounds more than adequate.
>
> It's really odd that you didn't see any degraded performance when your
> flow went from 17 down to 9 gph in climbout, unless it's some sort of
> instrumentation issue giving false readings. Hard to explain two
> different flow monitors making the same error, but hard to explain the
> performance, too. :-)
>
> Having said that, if you were seeing 9gph in a full power (2700rpm,
> full rich, 29"MAP) before, and you're now seeing the same flow on the
> ground, with less than full throttle, flat pitch & 2400 rpm, then
> *something* must be better now.
>
>
Message 4
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| Subject: | Re: Lycoming O-360 Fuel Flow Rate |
135 hp & 9 gph would be .4 lbs per hp per hour. That's pretty
impressive, for an air cooled gasoline engine with 8.5-1 compression.
What do the Lyc charts say?
On 12/18/2015 6:28 PM, Kelly McMullen wrote:
>
> While fuel flow numbers are good general indicators, EGT will tell you
> more. On takeoff at sea level you should see 1200-1300 EGT with 1250
> optimal. If your fuel flow is too low EGT will go well above 1300.
> Assuming 180 hp version, Fuel flow for takeoff should be around 16-18
> gph. Cruise at 75% should be 9-9.5 gph.
>
> On 12/18/2015 4:25 PM, Charlie England wrote:
>>
>> On 12/18/2015 4:38 PM, Matt Dralle wrote:
>>>
>>>
>>> I'm still chasing down this weird problem with low fuel flow rates
>>> on the RV-6. I've replaced the mechanical fuel pump and got a
>>> rebuilt 4-5 carburetor, both of which were well over do for
>>> replacement/overhaul anyway. I haven't put the cowling back on yet,
>>> but I did a static run up to about 2350-2400 and am seeing about
>>> 9gph, which seems low to me?
>>>
>>> I pulled the fuel line off the carburetor and turned the electric
>>> fuel pump on and saw about 21 GPH flow. Is that considered "normal"
>>> or too low?
>>>
>>> Thanks for the feedback,
>>>
>>> Matt
>>>
>>> -
>>> Matt Dralle
>> Never paid much attention to my flow when doing a static runup, but
>> that doesn't sound too unreasonable. If CS & flat pitch, it won't
>> take much power to get to 2400rpm. What's the MAP? You should be able
>> to use Lyc's power charts to see MAP/rpm/power. 75% on a 180 is
>> around 10 GPH, if leaned. Obviously lower fuel flow if you're under 24".
>>
>> I think that the FAA recommends 125% of max power flow if running a
>> pump (150% for gravity feed). Max power flow would be (180 *
>> .6)/6=18GPH. That would assume a very rich mixture of .6 lbs per HP
>> per hour. So your electric pump flow sounds more than adequate.
>>
>> It's really odd that you didn't see any degraded performance when
>> your flow went from 17 down to 9 gph in climbout, unless it's some
>> sort of instrumentation issue giving false readings. Hard to explain
>> two different flow monitors making the same error, but hard to
>> explain the performance, too. :-)
>>
>> Having said that, if you were seeing 9gph in a full power (2700rpm,
>> full rich, 29"MAP) before, and you're now seeing the same flow on the
>> ground, with less than full throttle, flat pitch & 2400 rpm, then
>> *something* must be better now.
>>
>>
Message 5
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| Subject: | Re: Lycoming O-360 Fuel Flow Rate |
EGT varies significantly depending on where the probes are in relation
to the flange, and also radially. EGT is most valuable as a comparison
to the history ..... significant change in EGT will alert you to a
change in that cylinders operation, but the actual number (historically)
really doesn't tell you much. Properly calibrated FF and a MP gauge
will tell you far more about power.
Linn (IMHO)
On 12/18/2015 7:28 PM, Kelly McMullen wrote:
>
> While fuel flow numbers are good general indicators, EGT will tell you
> more. On takeoff at sea level you should see 1200-1300 EGT with 1250
> optimal. If your fuel flow is too low EGT will go well above 1300.
> Assuming 180 hp version, Fuel flow for takeoff should be around 16-18
> gph. Cruise at 75% should be 9-9.5 gph.
>
> On 12/18/2015 4:25 PM, Charlie England wrote:
>>
>> On 12/18/2015 4:38 PM, Matt Dralle wrote:
>>>
>>>
>>> I'm still chasing down this weird problem with low fuel flow rates
>>> on the RV-6. I've replaced the mechanical fuel pump and got a
>>> rebuilt 4-5 carburetor, both of which were well over do for
>>> replacement/overhaul anyway. I haven't put the cowling back on yet,
>>> but I did a static run up to about 2350-2400 and am seeing about
>>> 9gph, which seems low to me?
>>>
>>> I pulled the fuel line off the carburetor and turned the electric
>>> fuel pump on and saw about 21 GPH flow. Is that considered "normal"
>>> or too low?
>>>
>>> Thanks for the feedback,
>>>
>>> Matt
>>>
>>> -
>>> Matt Dralle
>> Never paid much attention to my flow when doing a static runup, but
>> that doesn't sound too unreasonable. If CS & flat pitch, it won't
>> take much power to get to 2400rpm. What's the MAP? You should be able
>> to use Lyc's power charts to see MAP/rpm/power. 75% on a 180 is
>> around 10 GPH, if leaned. Obviously lower fuel flow if you're under 24".
>>
>> I think that the FAA recommends 125% of max power flow if running a
>> pump (150% for gravity feed). Max power flow would be (180 *
>> .6)/6=18GPH. That would assume a very rich mixture of .6 lbs per HP
>> per hour. So your electric pump flow sounds more than adequate.
>>
>> It's really odd that you didn't see any degraded performance when
>> your flow went from 17 down to 9 gph in climbout, unless it's some
>> sort of instrumentation issue giving false readings. Hard to explain
>> two different flow monitors making the same error, but hard to
>> explain the performance, too. :-)
>>
>> Having said that, if you were seeing 9gph in a full power (2700rpm,
>> full rich, 29"MAP) before, and you're now seeing the same flow on the
>> ground, with less than full throttle, flat pitch & 2400 rpm, then
>> *something* must be better now.
>>
>>
>>
>>
>
>
Message 6
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| Subject: | Re: Lycoming O-360 Fuel Flow Rate |
I don't disagree with your points in general, but they are not
particularly relevant for this situation.
1. His fuel flow has demonstrated to be unreliable, so is not properly
calibrated.
2. At full power installation variations are minimized due to the
velocity and volume of exhaust, compared to cruise settings.
3. 1200-1300 are very reliable numbers. Whether it varies 25 degrees one
way or the other is not important. It is important that it be within
that 100 degree range to indicate combustion approximately 150-200 ROP.
Given he does not know if his fuel flow is working, only the EGT will
confirm fuel flow.
The actual temp will vary from engine to engine and with OAT. That is
why it is a range, not a single number. He wants to know if his fuel
flow is in the ballpark to safely operate the engine, not if it is optimal.
On 12/18/2015 7:55 PM, Linn Walters wrote:
>
> EGT varies significantly depending on where the probes are in relation
> to the flange, and also radially. EGT is most valuable as a
> comparison to the history ..... significant change in EGT will alert
> you to a change in that cylinders operation, but the actual number
> (historically) really doesn't tell you much. Properly calibrated FF
> and a MP gauge will tell you far more about power.
> Linn (IMHO)
>
> On 12/18/2015 7:28 PM, Kelly McMullen wrote:
>>
>> While fuel flow numbers are good general indicators, EGT will tell
>> you more. On takeoff at sea level you should see 1200-1300 EGT with
>> 1250 optimal. If your fuel flow is too low EGT will go well above 1300.
>> Assuming 180 hp version, Fuel flow for takeoff should be around 16-18
>> gph. Cruise at 75% should be 9-9.5 gph.
>>
>> On 12/18/2015 4:25 PM, Charlie England wrote:
>>>
>>> On 12/18/2015 4:38 PM, Matt Dralle wrote:
>>>>
>>>>
>>>> I'm still chasing down this weird problem with low fuel flow rates
>>>> on the RV-6. I've replaced the mechanical fuel pump and got a
>>>> rebuilt 4-5 carburetor, both of which were well over do for
>>>> replacement/overhaul anyway. I haven't put the cowling back on
>>>> yet, but I did a static run up to about 2350-2400 and am seeing
>>>> about 9gph, which seems low to me?
>>>>
>>>> I pulled the fuel line off the carburetor and turned the electric
>>>> fuel pump on and saw about 21 GPH flow. Is that considered
>>>> "normal" or too low?
>>>>
>>>> Thanks for the feedback,
>>>>
>>>> Matt
>>>>
>>>> -
>>>> Matt Dralle
>>> Never paid much attention to my flow when doing a static runup, but
>>> that doesn't sound too unreasonable. If CS & flat pitch, it won't
>>> take much power to get to 2400rpm. What's the MAP? You should be
>>> able to use Lyc's power charts to see MAP/rpm/power. 75% on a 180 is
>>> around 10 GPH, if leaned. Obviously lower fuel flow if you're under
>>> 24".
>>>
>>> I think that the FAA recommends 125% of max power flow if running a
>>> pump (150% for gravity feed). Max power flow would be (180 *
>>> .6)/6=18GPH. That would assume a very rich mixture of .6 lbs per HP
>>> per hour. So your electric pump flow sounds more than adequate.
>>>
>>> It's really odd that you didn't see any degraded performance when
>>> your flow went from 17 down to 9 gph in climbout, unless it's some
>>> sort of instrumentation issue giving false readings. Hard to explain
>>> two different flow monitors making the same error, but hard to
>>> explain the performance, too. :-)
>>>
>>> Having said that, if you were seeing 9gph in a full power (2700rpm,
>>> full rich, 29"MAP) before, and you're now seeing the same flow on
>>> the ground, with less than full throttle, flat pitch & 2400 rpm,
>>> then *something* must be better now.
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>
>>
>>
>
>
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