where to drill firewall, need to install wiring into cabin Options

[mightyohm]

Hey guys,

I need to run some cables from the engine compartment into the cabin for my megasquirt/wideband O2 setup.

Some of these cables will come from the bottom side of the engine (below the tin) and some from the top side (fuel injection). I need at least one 1-1.5" hole so I can fit cables plus pass some of the smaller connectors through.

I am planning to install the megasquirt and wideband box as well as a small fuse panel under where the armrest goes, on top of the tunnel. Later on I'll make a box and raise the armrest up a few inches.

Any suggestions for where to drill a hole?

I am thinking about putting it down near where the shift rod enters the tunnel, so I only have to go through one layer of metal, and the wires will come out into the tunnel about where I need them. However, I am worried about interfering with all the stuff in there (fuel lines etc) as well as getting all the wires from the top of the engine compartment down to the bottom. I think that means drilling holes in the tin as well. I have way too many wires to use the stock harness "tube".

Thanks!

[Jeroen]

I'd suggest you drill the hole ABOVE where the engine tin meets the firewall
That is single layered sheetmetal

Below that is mostly double layered and could cause rust problems down the road (and we have enough to worry about already)

cheers,

Jeroen

[lmcchesney]

When I replaced my fuel lines in the centeral tunnel, I placed additional 3/8" fuel lines from the firewall to the front of the tunnel for wiring conduits. It has worked well. One advantage is that you can change wires or add wires later on. Drilled the holes 1/8" larger than fuel line and fitted hole with rubber grommet. No water leak. Easy to drill through the firewall there. Very neat finish.

[maf914]

Imcchesney, Good idea! It looks like you have already maxed out the two 3/8" conduits though. Would 1/2" have fit?

[Dave_Darling]

If you don't mind cutting the connectors off and installing new ones on the ends of the wires (also lets you cut them to the correct length so you don't have extra), you can simply run the wires alongside the main wiring harness. Poke them through the rubber boot and into the tunnel, then pull them through into the cockpit.

I've run at least 4 new wires that way, no problem.

--DD

[mightyohm]

Dave,

The wideband O2 cable alone is too fat for that (8 wires, sheathing, ground shield, etc.) and the megasquirt will have 10-15 wires as well, including some thicker power wires. I don't think it will fit.

Is the firewall doubled up where all the lines go into the tunnel? It didn't appear to be last time I checked.

[lmcchesney]

There is room for a couple more 3/8" conduits. Does the 12-14ga power supply wires have to come from the engine compartment for the Megasquirt? If it is a flat harness that cannot be seperated, you could place a slit in the firewall, reachable via the access panel at the rear of the centeral tunnel.

[mightyohm]

lmcchesney - Is the firewall double layered down there?

[lmcchesney]

Does not seem to be.
L. McC