Home made 4 stroke race outboard.

[Instigator]

I like it.

So here we are.
This is my Afghan street mechanic way of doing a highly precision trial fit up.
The idea is to check to see that the driveshaf does in fact pass through the center of the crank main bearings.
Now I'll pull it apart and weld everything.
Then draw file everything that Mother Merc would mill.
Same outcome.Attachment 543600Attachment 543601
This is a 2.5 box but a 3.0L will fit also

[NZ Sidewinder]

This photo is a milestone.
The leg is mounted on the clamp and at the yoke can be seen a new design feature.
The engine can be raised or lowered 2 inches without removing the clamp from the boat.

[NZ Sidewinder]

Back to the details.
Here is the water pump detail.
Because the 4 stroke has an oil sump in the leg, the water tube can't go up vertical.
The driveshaft goes through a tube in the sump but the water can't go that way, so it's piped out the side of the leg and upwards to the powerhead.
On this build, the pump in the lower unit will supply water for idle and slow going, but the main flow will come from transom scoops at speed.
This same system can be adapted to serve the 3.0L gearbox pump as well

[NZ Sidewinder]

This job is moderately difficult.
Ambitious would be to plant a Ford Barra straight 6 on the leg.
The Barra is the Australian Ford 6, around 4.0L
Turbo north of 800hp.

[VkingMike]

The Aussie 2JZ, that would be something.

[NZ Sidewinder]

No substitute for cubes.
2.0L might be a little light on torque, especially since this motor is probably destined for a 20fter.