Firewall forward ground block

Airhead · #1 05-09-2011, 09:36 AM

I see many references on builders' sites and this forum regarding a multi tab grounding block on the engine side of the firewall, sometimes mounting a block with 12, 24, or even 36 tabs such as those sold by B & C. I am going to use an EMS (Dynon, if it makes any difference) to monitor all engine parameters. In looking over the installation manual I can find no reference to ground connections forward of the firewall.

My question: Can anyone with the same or similar EMS installed shed some light on what FWF ground connections they needed? I am thinking that the need for this large array of grounding tabs may be based on more traditional engine instrumentation.

RV10Rob · #2 05-09-2011, 09:42 AM

I installed a "forest of tabs" ground block on both sides of the firewall, and until last weekend had nothing connected to the forward side. The hall effect RPM sensor I just installed needs a ground, so now I have one. With a standard Dynon setup, you shouldn't need one.

-Rob

647jc · #3 05-09-2011, 09:44 AM

For my Dynon installation I did not find a need for a comman grounding block FWF. Most of the sensors either ground to the engine block or have a seperate ground lead going back to the Dynon EMS.

Mike S · #4 05-09-2011, 09:45 AM

I agree, there is no need for a lot of ground tabs f/f.

As I recall, I only grounded the tach sender and the solenoid diodes, and those times I used the mounting bolt for the device.

Other than these, there is the main ground strap to carry the starter load, but it does not go to a faston tab.

Good luck.

lostpilot28 · #5 05-09-2011, 09:49 AM

Hi Bob,
I don't use any of Dynon's products, but I wanted to point out that "ground is ground", regardless of whether it's forward of the firewall or aft. The reason a lot of builders (including myself) go with a ground buss (plate with tabs) is that it helps prevent ground-loops (No, not the tail-wheel kind).

Regardless of what EMS or EFIS system you go with, you would do well to have a centralized location for your grounds. Even though it's extra weight to run each ground wire back to the buss, I found that it prevents a lot of headaches. I'm completely guessing, but that extra weight was probably less than 1 pound.

Airhead · #6 05-09-2011, 09:56 AM

Thanks for the quick responses guys. I was going to mount a multi tab ground block on the aft side of the firewall (for avionics ect.) co-located with the battery grounding strap bolt, and based on the replys so far, it seems like this would suffice.

Greg Arehart · #7 05-09-2011, 10:04 AM

Bob,

For my ground, I used a piece of 3/16" threaded brass that goes through a hole in the firewall with a washer and nut on either side. I made it long enough that all my grounds (either side of firewall) go onto the "ground bolt" with multiple brass washers and nuts. This is grounded directly to the battery with a heavy copper strap. I used crimped rings rather than faston connectors.

greg