After much thought and discussion, I’ve decided how I’m going to handle the pressure lines from the engine. Rather than have all of them go to a single manifold on the firewall, I’m going to route each of the three lines (fuel, oil & manifold air) independently.

For the Manifold Air Pressure, I’m going to simply use bulkhead fittings on the plenum and firewall and terminate it at the sensor inside the cabin. The oil pressure will be mounted on the fire near the oil cooler where the pressure line originates.

Oil pressure sensor mounted to firewall.

View from above.

For the fuel pressure sensor, I decided to mount the sensor inside the plenum. This will allow for a shorter pressure line and not require penetrating the plenum.

Because the manifold air pressure sensor is plastic, it has to go inside the cabin. So I’ll penetrate the plenum and firewall with bulkhead fittings.