Question on which connectors to use (Firewall Forward)...

[Reflex]

I've come to the point of wiring the Firewall Forward components. My goals are:

• Safety
• Longevity
• Serviceability
• Neatness

I've reviewed numerous web sites, blogs, etc. and find that there seem to be as many ways to connect wires firewall forward as there are builders. Each connection creates a potential failure point yet we need to have serviceability. I've seen some really nice wiring jobs and some that have connections that look like a snake that swallowed a mouse.

I'm looking for feedback on what the brain trust here likes for wire connections firewall forward. Note: I'm talking about the wiring for the used for engine monitoring. In my case, this is a Garmin GEA-24.

My idea was to use D-sub pins covered with high temp shrink tubing (PTFE) that has a 500F degree temperature rating (655 to shrink). However, I don't like the idea of hitting the surrounding wires/materials with 650+ degree air. In addition, I'm not sure this is an accepted way of joining wires firewall forward.

I had the good fortune to visit with a frequent poster on this board this week and saw his beautiful wiring job. He used Raychem D-436 series connectors and they look great, are small, and very weather/water/chemical resistant. I love them. However, they have a maximum temperature rating of 302 degrees F. I think I'd prefer to have something has a greater working temp rating.

What did you use or what do you recommend?

Thanks,

Fred

 

[mburch]

Unless you're right next to the exhaust or cylinder heads, temperatures under the cowl are generally under 250F, so I wouldn't be too concerned about extreme heat tolerance. Remember that the typical Kavlico pressure sensors used in countless RVs have plastic housings. Just don't put your wire connections right up against something red-hot and you'll be fine.

Many pressure sensors most commonly encountered in EFIS sensor kits these days will come with their own built-in connectors, usually something like a Weatherpack connection. Solder sleeves (properly applied) or crimped butt splice connections plus heatshrink are a perfectly fine way to connect these to the rest of your wiring harness.

For sensors that are provided only with a wire pigtail - e.g. oil temperature - and which may have to be replaced in the future, my favorite connector these days is a Deutsch DTM. You can use the name-brand ones, or Amazon will sell you an inexpensive kit of good-quality knockoffs.

For thermocouple connections in particular, many people just use good old ring terminals, but I like Omega miniature connectors. I've noticed that various aircraft OEMs have switched to using these, and you can now buy CHT/EGT probes with Omega connectors already installed. Or, it's easy to convert from ring terminals to Omega connectors like I did.

 

[Walt]

I use the ring terminals that come with the egt/cht probes and butt splices for everything else. No connector means higher reliability. Easy breezy to cut out a couple of splices if it ever becomes necessary to replace a sensor.

 

[wirejock]

Blade terminals

I use the ring terminals that come with the egt/cht probes and butt splices for everything else. No connector means higher reliability. Easy breezy to cut out a couple of splices if it ever becomes necessary to replace a sensor.

My EGT/CHT harness came with fully insulated blade type connectors so that's what I used.
The EMS harness is a 37-pin D-sub. It's terminated pin for pin to match the factory end. If I need a new sensor, I just have to add the pin to the mate. Easy to open the connection for testing.

 

[rocketman1988]

Deutsch

Almost all the connectors on my -10 are Deutsch connectors.