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  #41  
Old 04-30-2018, 02:46 PM
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Quote:
Originally Posted by rcpaisley View Post
Boost pumps (including ours) are designed to backup the mechanical engine driven pump for mechanical fuel injection. These are for use with Bendix, Airflow Performance, Precision Airmotive or ECI mechanical fuel injection.
https://www.flyefii.com/products/boost-pump/
Thank you, but for the record, you dodged the specific questions.

Interesting sales page. Are you aware that the AFP module in your illustration has been obsolete for some time? A current AFP module looks like this:

http://airflowperformance.com/wp-con...mp-2090255.pdf

Photo on page 3, dimensions on 7. It's actually a little more compact, if measured apples to apples, i.e. without fittings. EFII dimensions here:

https://www.flyefii.com/products/boo...allation-tips/

Is your suction loss claim also based on the obsolete AFP module?

BTW, Airflow Performance boost pumps are continuous duty (first line, page 3), the question you were asked. Does your module get hot and quit pumping when run for an extended period? That is the OP's concern.
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Last edited by DanH : 04-30-2018 at 02:54 PM.
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  #42  
Old 04-30-2018, 03:17 PM
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RV7A Flyer RV7A Flyer is offline
 
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Quote:
Originally Posted by DanH View Post
BTW, Airflow Performance boost pumps are continuous duty (first line, page 3), the question you were asked. Does your module get hot and quit pumping when run for an extended period? That is the OP's concern.
So are the Andair pumps. Says right on their documentation.
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  #43  
Old 04-30-2018, 10:39 PM
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mfleming mfleming is offline
 
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Looking at the Airflow Performance PDF Dan linked to tells me the Airflow pump operates in an identical fashion as the EFii pump.

It seems to me the EFii pump I bought would hold up for continuous use just like the Airflow pump unless the EFii pump has a much higher GPM capacity and bypasses significantly more fuel.

Airflow and EFii do not mention the GPM capacity of their pumps.

EFii pumps advertises their pumps are suitable for engines up to 600HP.
I found a fuel consumption chart for HP vs fuel flow. 600hp equates to 33.86 gph or .564 gpm.

Since both pumps draw roughly the same amount of current and bypass at roughly the same pressure. They must both have a similar pumping capacity.

I can't see how the Airflow pump would not produce roughly the same BTU's as the EFii pump.

BUT its listed as continuous duty.

I'm guessing that Airflow is just not worrying about the BTU build up or has done some testing and thinks it doesn't produce enough BTUs to interfere with the pump operation.

I'm going to keep the EFii pump and put a thermocouple on it for phase I testing. I just need to find someone with a Airflow pump and instrument it up for a comparison...but I don't see how it could be much different.

The other thing that drives me to keep the EFii pump is it's American made and just looks like a quality piece of equipment.
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Last edited by mfleming : 04-30-2018 at 10:47 PM. Reason: Add content
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  #44  
Old 04-30-2018, 10:50 PM
lr172 lr172 is offline
 
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Quote:
Originally Posted by mfleming View Post
Looking at the Airflow Performance PDF Dan linked to tells me the Airflow pump operates in an identical fashion as the EFii pump.

It seems to me the EFii pump I bought would hold up for continuous use just like the Airflow pump unless the EFii pump has a much higher GPM capacity and bypasses significantly more fuel.

Airflow and EFii do not mention the GPM capacity of their pumps.

EFii pumps advertises their pumps are suitable for engines up to 600HP.
I found a fuel consumption chart for HP vs fuel flow. 600hp equates to 33.86 gph or .564 gpm.

Since both pumps draw roughly the same amount of current and bypass at roughly the same pressure. They must both have a similar pumping capacity.

I can't see how the Airflow pump would not produce roughly the same BTU's as the EFii pump.

BUT its listed as continuous duty.

I'm guessing that Airflow is just not worrying about the BTU build up or has done some testing and thinks it doesn't produce enough BTUs to interfere with the pump operation.

I'm going to keep the pump and put a thermocouple on it for phase I testing. I just need to find someone with a Airflow pump and instrument it up for a comparison...but I don't see how it could be much different.

The other thing that drives me to keep the EFii pump is it's American made and just looks like a quality piece of equipment.
I would expect the Airtex pump used by AFP has a lower flow rating than the Walbro and therefore less return flow.

Either way, caution still needs to be exercised. I doubt that AFP and Andair pumps can be run continuously at ICO. I would hope that they tested at the lower flows present at idle. I suspect 1-2 GPH would probably create an adequate dilution level to avoid most problems. The previous posters test at Osh seems to confirm that.

Larry
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  #45  
Old 04-30-2018, 11:20 PM
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mfleming mfleming is offline
 
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Quote:
Originally Posted by lr172 View Post
I would expect the Airtex pump used by AFP has a lower flow rating than the Walbro and therefore less return flow.

Either way, caution still needs to be exercised. I doubt that AFP and Andair pumps can be run continuously at ICO. I would hope that they tested at the lower flows present at idle. I suspect 1-2 GPH would probably create an adequate dilution level to avoid most problems. The previous posters test at Osh seems to confirm that.

Larry
I can't see how the Airtex and Walbro pumps can be much different in pumping capacity. They both operate at 12volts and pull about 4.3amps so that equates to 51.5watts...looks like their both doing about the same amount of work to me.

But to your larger point, "caution needs to be exercised", I do agree.
Any pump that recycles fuel looks like some test data is needed.
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  #46  
Old 05-01-2018, 07:33 AM
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I don't have the boost pump, but I do have the Full Dual EFII set up, I don't know if the pumps are the same or not but mine flows 45 GPH after the regulator set at 35 PSI measurement taken on the return to tank line. I don't see how the boost pump could overheat as there will still be fresh cool fuel coming into it and mixed along with what is being recirculated, could be as high as 8-14 GPH or what ever your fuel burn is.
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  #47  
Old 05-01-2018, 07:34 AM
rv7charlie rv7charlie is offline
 
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You have your answer from the vendor about the EFii. Why not ask AFP? I did, via PM, several years ago, and got a satisfactory answer describing how they actually tested their product. As part of the discussion, he also mentioned the characteristics of the certified Weldon boost pump, which has been in use for over half a century.

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  #48  
Old 05-01-2018, 07:44 AM
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mfleming mfleming is offline
 
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Quote:
Originally Posted by bret View Post
I don't have the boost pump, but I do have the Full Dual EFII set up, I don't know if the pumps are the same or not but mine flows 45 GPH after the regulator set at 35 PSI measurement taken on the return to tank line. I don't see how the boost pump could overheat as there will still be fresh cool fuel coming into it and mixed along with what is being recirculated, could be as high as 8-14 GPH or what ever your fuel burn is.
The BPM-1 boost pumps is not the same pump that’s installed with the full dual EFii setup. On the boost pump setup, typically there’s no return line for cooling.
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RV-7 Slider #74572
Started 11/2016
Empennage completed 11/2016 (sans fiberglass)
Ailerons and flaps completed 3/2017.
Wings completed 12/2017 (sans fiberglass)
Started on QB fuselage 01/2018

Last edited by mfleming : 05-01-2018 at 07:46 AM.
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  #49  
Old 05-01-2018, 07:50 AM
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DanH DanH is offline
 
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FWIW...

If a builder is really concerned about re-circulation heating, order an old-style AFP boost pump, and plumb the pressure relief return back to the tank via a duplex valve. The short path re-circulation systems came about because marketing gave folks the idea that a compact module was "better". Truth is the old style AFP boost could be plumbed for a re-circulation path of any length, including tank return.

Here's an example, from Andre Burger's build log. The line leading to the tee fitting is the fuel inlet. The blue cylinder closest to the camera is the pressure relief valve. Excess fuel exits the assembly through that valve. Andre has it going back to the tank selector valve outlet, a medium length re-circ path, which I suspect offers more than enough cooling.

http://www.mykitlog.com/users/displa...g=72641&row=85

As noted previously, EFII's comparison of suction loss at 15 GPH seems to be based on that old school AFP pump. The later modular pump has a different pressure relief valve. I don't know what the suction loss might be for the newer valve, but it hardly matters.

The stated values are 4.1" and 0.7" H20, which sounds like a big deal. Ok, so convert inches of water to conventional terms for liquid (psi or kilopascals), then pull up a chart of true vapor pressure vs temperature for gasoline with an RVP of 7 psi/50 kPa or less, the range for 100LL. The temperature advantage appears to be about 1.6 degrees F.

Quote:
Originally Posted by mfleming View Post
Any pump that recycles fuel looks like some test data is needed.
Go for it Mike.
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Last edited by DanH : 05-01-2018 at 07:54 AM.
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  #50  
Old 05-01-2018, 07:53 AM
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Quote:
Originally Posted by mfleming View Post
The BPM-1 boost pumps is not the same pump thatís installed with the full dual EFii setup. On the boost pump setup, typically thereís no return line for cooling.
Correct, but....the circuit is not dead headed running against the relief, there is some flow in and out allowing (some) heat to be carried away.
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