Building an 8A... Where to put Firewall Holes?

[Tall_Order]

Hi all, starting to finish up on wiring with a number of "switch/sensor wire to nowhere" situations for the stuff that interfaces to FWF... Time to cut some holes soon so any input appreciated as to where and where not to penetrate the firewall and any experiences regarding the ideal place to mount stuff on the RV-8/8A.

A couple pictures below with the engine mount just resting on the firewall and proposed initial locations. Of note in this build, I will have an external lead to trickle charge the battery(I am in a cold climate) so frequent access to it is not required, will use SDS full-flow fuel injection (so no mixture cable but still a throttle cable to the butterfly valve and will need 2 fuel lines), constant speed prop cable, a heavier wire to an interior small breaker panel+VPX, and then the various small guage wires predominantly for the alternators and sensors. I see the firewall comes with some holes already but I am unsure of their suggested uses other than I understand the big hole (Hole #1) is for the air box. Appreciated if their suggested purposes can be confirmed? Planning vertical induction and already have the appropriate James cowl and their 360 plenum.

Shoot holes in my ideas... but more preferably... in the firewall

 

[azonic75]

Hi all, starting to finish up on wiring with a number of "switch/sensor wire to nowhere" situations for the stuff that interfaces to FWF... Time to cut some holes soon so any input appreciated as to where and where not to penetrate the firewall and any experiences regarding the ideal place to mount stuff on the RV-8/8A.

A couple pictures below with the engine mount just resting on the firewall and proposed initial locations. Of note in this build, I will have an external lead to trickle charge the battery(I am in a cold climate) so frequent access to it is not required, will use SDS full-flow fuel injection (so no mixture cable but still a throttle cable to the butterfly valve and will need 2 fuel lines), constant speed prop cable, a heavier wire to an interior small breaker panel+VPX, and then the various small guage wires predominantly for the alternators and sensors. I see the firewall comes with some holes already but I am unsure of their suggested uses other than I understand the big hole (Hole #1) is for the air box. Appreciated if their suggested purposes can be confirmed? Planning vertical induction and already have the appropriate James cowl and their 360 plenum.

Shoot holes in my ideas... but more preferably... in the firewall

I used the Van's layout and I think it works well. I have a pass through near the middle top to for sensor wires and such. Easy to run then behind the baggage door channel and to the panel from there.

 

[Jonnyb]

Hole 3 is for the brake reservoir.

Have a look at OP34/35

 

[gasman]

If you run wires from the motor (EGT, CHT, OP, OT, B lead, etc.) along the motor mount, it will keep them out of the way during maintenance.
Many builders pass the wires over the center of the motor to the firewall.... right above the oil filter??... The mount goes from the motor to each corner of the firewall. Just run wires along the mount... (it's already in your way!) and drill a hole near the mount to pass the wires to the cold side.

 

[Tall_Order]

Hole 3 is for the brake reservoir.

Have a look at OP34/35

Thanks for telling me were I can find the info; that was a huge help! Ok I read the suggestions as Hole #2 is for various electrical, Hole #3 is for brake reservoir as you mentioned, Holes #4,5 (and the pilot hole beside if req'd) are for throttle/mixture/governor, and Hole #6 is intended for fuel...

@azonic75 and @gasman, I can see advantages with either way and one of those options didn't even occur to me, thanks! Looking at some other threads, I see some builders are using the SA-05 pass-through for wiring https://www.aircraftspruce.com/catalog/hapages/ssfirewallkit12-04762.php?clickkey=444084
However, if using the outer holes(ie Hole #2 in the picture above), I don't think an SA-05 will fit so is this what people are using here?

Firewall Passthrough Shield, Stainless 3/4", 1/2"Hole

3/4" Grommet with 1/2" Hole

store.vansaircraft.com

If so, what are builders using as a "grommet"... A length of firesleeve? Is there an alternative to the SA-05 when minimal radius is available?

As usual, the more I learn, the more questions I have... ... I see drawing OP-34 depicts using a triangular Van's TG-10, however the Van's store seems to be suggesting a square shaped DL-01 as the heat selector air box. Any opinions on which might be the better way to go? The firewall is pre-cut with a 2" hole.