[maus92]

I've started to install the various sensors for my G3X system upgrade on my flying RV-8A with a O360-A1A. The original builder had done some things with the old sensors that I've discovered is not the current practice, so I want to update their installation. And the G3X system adds a fuel flow and MAP sensor that adds functions new to the plane.

First the pressure sensors. The fuel and oil pressure sensors are mounted directly to the mech pump in the case of the fuel sensor, and the oil pressure sensor to a NPT tube tapped into the block over the right mag and terminated with a tee to add a port for the Hobbs switch. Currently, there is no MAP sensor mounted. I've read that engine vibration is not good for sensors mounted to the engine, and current practice mounts them to the firewall via a manifold or Adel clamps, with hoses spanning the distance from the port to the sensor. Questions: what types of hoses should I use for the various sensors, and recommendations for the pressure manifold should I decide to go that route vs. Adel clamps.

The oil temp sensor probe supplied with the G3X seems to be significantly longer than the temp sensor it replaces. The new one fits however - are there any issues with using the longer probe?

Magneto RPM pickup. There is basically only a 1" clearance on my plane to install this sensor. I'll have to remove the mag to get it in, and even installed, the cable will be jammed up against the block. I am concerned that this will rub and eventually short the conductors. Is this really a problem, or am I stressing over a non-issue? The original RPM sensor ran off the tach port. Should I consider using a UMA tach sensor instead?

The Red Cube. I've read through the installation history of this sensor in these forums, and it seems that the best current practice is to mount it either free floating or secured to the engine between the mech fuel pump and the carb. Mounting to firewall is not recommended because it is in a different vibration plane than the engine. I would love to mount it in the cabin between the selector and the electric fuel pump, but the manufacturer seems not to advise this. Comments?

Finally, is there any limitation running / clamping K type thermocouple wire near or touching spark plug wire?

Sorry for the long post... Thanks!

 

[Robert Anglin]

Long reply.

I've started to install the various sensors for my G3X system upgrade on my flying RV-8A with a O360-A1A. The original builder had done some things with the old sensors that I've discovered is not the current practice, so I want to update their installation. And the G3X system adds a fuel flow and MAP sensor that adds functions new to the plane.

First the pressure sensors. The fuel and oil pressure sensors are mounted directly to the mech pump in the case of the fuel sensor, and the oil pressure sensor to a NPT tube tapped into the block over the right mag and terminated with a tee to add a port for the Hobbs switch. Currently, there is no MAP sensor mounted. I've read that engine vibration is not good for sensors mounted to the engine, and current practice mounts them to the firewall via a manifold or Adel clamps, with hoses spanning the distance from the port to the sensor. Questions: what types of hoses should I use for the various sensors, and recommendations for the pressure manifold should I decide to go that route vs. Adel clamps.

The oil temp sensor probe supplied with the G3X seems to be significantly longer than the temp sensor it replaces. The new one fits however - are there any issues with using the longer probe?

Magneto RPM pickup. There is basically only a 1" clearance on my plane to install this sensor. I'll have to remove the mag to get it in, and even installed, the cable will be jammed up against the block. I am concerned that this will rub and eventually short the conductors. Is this really a problem, or am I stressing over a non-issue? The original RPM sensor ran off the tach port. Should I consider using a UMA tach sensor instead?

The Red Cube. I've read through the installation history of this sensor in these forums, and it seems that the best current practice is to mount it either free floating or secured to the engine between the mech fuel pump and the carb. Mounting to firewall is not recommended because it is in a different vibration plane than the engine. I would love to mount it in the cabin between the selector and the electric fuel pump, but the manufacturer seems not to advise this. Comments?

Finally, is there any limitation running / clamping K type thermocouple wire near or touching spark plug wire?

Sorry for the long post... Thanks!

Most of the pressure sensors will live a lot longer if you mount them off the engine. I like the three port manifold that Van's has in their catalog. Mine is clamped to the right side engine mount and hoses run to it there. I have seen a lot of different hoses used. I like the good braded hose that is also in Van's catalog or Spruce. Don't remember the number right now, AE-601 or 701 I think is the call out on it. If you lose the clamps on the Mag. most of the time the R.P.M. sensor can be screwed into the housing if you turn it all the way to the right "Clock-wise". I don't think it matters about the oil temp. sender being a little longer if it dose not bottom-out before it gets screwed in all the way. The Red Cube, now that is one that everyone has his own thoughts on. Even after you read the O.E.M. instructions, odds are you will not like an spot as being perfect. Mine is on the right side motor mount, on a bracket made just for it. It sets between the fuel pump and the throttle body so all the fuel flow can be read by it and the flow through it is smooth. This spot also keep it away from full engine vibration levels. I have seen a lot of people run all kinds of wiring along with their spark plug wires. I have also seen a lot of those same wires start leaking to those other wires that have been run with them. The automotive unshielded wires are prone to leak much more so than the aircraft grade shielded wires. The plug wires are very hi-volt discharge leads they love to leak if you give them an opportunity. I like the old aircraft wires, they are made the way they are for very go reason. Shielded and sealed, they can run through rain and they done brake down as quickly as the automotive type do. They may cost a lot more but it is hard to pull over to the side of the road after you leave the car wash when your 2,500' A.G.L. in your little air plane. Hope this helps. Yours. R.E.A. III #80888

 

[maus92]

Thanks for the reply. I ordered the Van's manifold this morning, and associated hoses for the pressure senders. Hopefully I can install these without much headache (the huge air oil separator apparatus might interfere, but it may be coming out anyway per Mike Busch, but that's another topic...)

As for the Red Cube, I may have identified a spot to mount it: there is a large bracket that supports the throttle / mixture cable as they attach to the carb. We'll see.