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Help with a plethora of sensors for my install.

akschu

Well Known Member
Patron
I need to order the following sending units for my Garmin G3X:

1. Fuel pressure
2. Oil temperature
3. Fuel temp (more on this below)
4. Oil pressure
5. Manifold pressure

The reason I would like fuel temp is because I'm running an airflow performance injection system with the typical engine and boost pump. I'm going to blast cool the fuel pump, have careful fuel line routing, but also have the output of the engine pump go into a stainless manifold. On the manifold I'll have input/output, fuel pressure, fuel temp, and a 1/8 line with a .020 restrictor on the top that bleeds 6gph through a duplex valve back to the selected tank.

The idea is that I can move fuel past the pump all of the time to cool it as well as give vapor a place to go. Another person on VAF did something similar and was able to run mogas without any vapor lock issues. If it doesn't work, I'll cap it off and press on, but if it does work, the temp probe would really help with my testing.

Anyway, here are the sensors I am considering and my questions:

Fuel pressure: p255-150g-e4a
This is the updated dynon unit that seems much more robust (stainless) and much cheaper than the garmin unit. Anyone see any issue running this sensor and selecting "Kavlico P4055-150G (0-150PSI)" from the menu? They are both 5v reference and linear output, so I think they will work the same way.

Oil pressure: P255-150G-e4a
Same as above, using "Kavlico P4055-150G" on the menu. Any issues?

Fuel Temp: Garmin says we need the UMA RTD style sensors. It would be ideal to use one with 1/4NPT which is what my manifold accepts, which would be part number 1B11R according to https://umainstruments.com/wp-content/uploads/2021/10/UMAspec1BxRevH.pdf however I can't find it any anywhere. I suppose I could use the garmin carp temp sensor (1B10R) but then I need this adapter: https://www.mcmaster.com/2684K684/ which is expensive and better omitted. As for settings, I would define it as "Carb Temp (UMA 1B10R RTD)". Any ideas on better ways to do this?

Oil temp: UMA 1B3-2.5
This is the standard garmin part so no worries here.

Manifold pressure: P4055
I think this one: https://www.aircraftspruce.com/catalog/avpages/garmin_10-05864.php
and select "Kavlico P4055-30A" on the menu. Price is more reasonable than the TSO unit.

Thanks to those that help, I'm hoping to get this right the first time and not later read that I should have done something different.

schu
 
I don't have them installed yet, so I'm in the same boat as you wondering if it will work, but I previously ordered the 3 pressure sensors (Fuel, Oil and Manifold) you reference, although since I have a carburetor my fuel pressure sensor is 0-15. I'm hoping the oil temp probe that I already have will be OK.

I'm hoping to have them installed in a month or so, and I'm pretty sure they're OK, since the sensor tables in G3X manual also say "Any voltage-output pressure sensor" can be used. Even if the P4055 setting doesn't work, I should be possible to enter a custom calibration.

What are seeing as sources for the Kavlico sensors that Spruce doesn't have?
 
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If you have a Kavlico pressure sensor that has the same pressure range and outputs a 0.5-4.5V signal over that range, you can select the equivalent "Kavlico P4055" sensor configuration and it should work fine. Otherwise, the G3X system allows you to enter your own voltage-to-pressure calibration for whatever pressure sensor your provide. A quick glance at the datasheet for the Kavilco P255-150g-E4A shows that it does indeed provide a 0.5-4.5V output.

The documentation doesn't say that you have to use UMA-brand RTD sensors specifically, rather that if you're going to use an RTD it must be of the (very common) Pt100 type. Any Pt100 RTD with the right threads and fluid compatibility for your application should be acceptable. Alternatively, you could use one of the thermocouple or thermistor sensors specified in the G3X installation manual, but I like RTDs for their accuracy and hassle-free installation. You also don't have to stick with the "CARB TEMP" label, as the G3X system allows you to specify your own name for the various "User Temp" sensor configurations.

Remember that if you are using a fuel system with a return line, you will need to install a second fuel flow transducer if you want an accurate fuel flow measurement.
 
If you have a Kavlico pressure sensor that has the same pressure range and outputs a 0.5-4.5V signal over that range, you can select the equivalent "Kavlico P4055" sensor configuration and it should work fine. Otherwise, the G3X system allows you to enter your own voltage-to-pressure calibration for whatever pressure sensor your provide. A quick glance at the datasheet for the Kavilco P255-150g-E4A shows that it does indeed provide a 0.5-4.5V output.

The documentation doesn't say that you have to use UMA-brand RTD sensors specifically, rather that if you're going to use an RTD it must be of the (very common) Pt100 type. Any Pt100 RTD with the right threads and fluid compatibility for your application should be acceptable. Alternatively, you could use one of the thermocouple or thermistor sensors specified in the G3X installation manual, but I like RTDs for their accuracy and hassle-free installation. You also don't have to stick with the "CARB TEMP" label, as the G3X system allows you to specify your own name for the various "User Temp" sensor configurations.

Remember that if you are using a fuel system with a return line, you will need to install a second fuel flow transducer if you want an accurate fuel flow measurement.

Appreciate the feedback. I'll dig through the menus again, I would like it to say fuel temp instead of carb temp.

As for the fuel flow transducer, that is mounted on the metered side of the fuel servo between it and the flow divider, so I think I'd still have accurate fuel flow because the bleed is well south of that.

As for a manifold, I'm thinking this guy in stainless.

https://www.dasservicesinc.com/image/catalog/pdf/New_Materials_Pneumatic_Manifolds.pdf

They seem reasonably well machined. Any issues with steel NTP fittings sealing against that stainless manifold?

Thanks,
schu
 
https://www.mouser.com/c/sensors/pressure-sensors/?b=Kavlico
Better price.
Why not use the Oil temp: UMA 1B3-2.5 for Fuel temp ?

Good luck

Thanks for the heads up on mouser.

The reason to not use the 1B3-2.5 for fuel temp is the probe is 2.67" long and won't fit in the manifold not to mention the 5/8 threads being huge.

Mile High Relic said:

That manifold won't work for my fuel stuff since I need shared ports and want stainless for safety, but good call for oil pressure and manifold pressure.

Thanks!
 
Sorry don't mean to hijack this discussion but Vans SB00006 warns Kavlico sensors can leak. Anyone know how to recognize them?

Don
 
As for a manifold, I'm thinking this guy in stainless.

https://www.dasservicesinc.com/image/catalog/pdf/New_Materials_Pneumatic_Manifolds.pdf

They seem reasonably well machined.

Those Das manifolds look like single input port with multiple interconnected output ports, so single pressure use. It seems like the Stein version isolates each sensor to 3 ports for each function and then gangs 3 of these manifolds into one machined body for 3 separate pressures use. So you would need to order a separate Das manifold for each type of pressure sensor at which point why not go with the Vans or Stein ganged version.
 
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The reason I would like fuel temp is because I'm running an airflow performance injection system with the typical engine and boost pump. I'm going to blast cool the fuel pump, have careful fuel line routing, but also have the output of the engine pump go into a stainless manifold. On the manifold I'll have input/output, fuel pressure, fuel temp, and a 1/8 line with a .020 restrictor on the top that bleeds 6gph through a duplex valve back to the selected tank.

The idea is that I can move fuel past the pump all of the time to cool it as well as give vapor a place to go. Another person on VAF did something similar and was able to run mogas without any vapor lock issues. If it doesn't work, I'll cap it off and press on, but if it does work, the temp probe would really help with my testing.
...

Not to change the purpose of your thread, but lots of people are successfully running mogas using the well-designed and thoroughly tested fuel system that Vans's and AFP provide. A full-flow fuel system with temperature monitoring is not needed, and introduces other possible points of failure.

The AFP purge valve can help with hot starts, and running the electric fuel pump on the ground can help with any vapor lock issues. I personally don't have a blast tube on my engine-mounted mechanical fuel pump, and have not had any trouble at all running mogas (so far).

According to my GRT logs, my hottest OAT has been just over 109°F (42°C).

Just a data point to consider.
 
Sorry don't mean to hijack this discussion but Vans SB00006 warns Kavlico sensors can leak. Anyone know how to recognize them?

Don

Here are links to the Dynon SB and the Garmin SB recommending replacement of the legacy Kavlico sensors with the updated Kavlico sensors. The Dynon SB has pics of the legacy and updated sensors. The updated ones have a longer body.


Other pics. Legacy sensors:

i-rPPT4Vq-L.jpg


Updated sensors:

i-tF9vPsc-M.jpg
 
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