Home made 4 stroke race outboard.

[NZ Sidewinder]

Thanks
I need to grind all the welds and power sand them.
Get all the weld splatter off and get sand blasted.
I'll cove some of the internal angles and epoxy prime.
Then the leg can hang on the baseplate.
I still need to make the oil sump etc, but that's all easy stuff.
This mid needed to be carefully build because the line of the drive shaft needs to be almost perfect, especially with a short drive shaft.
The days here are getting longer, so progress will speed up.

[Greg G]

Very cool NZ that you could achieve that alignment tolerance on your midsection. Keep going!!

[NZ Sidewinder]

There is some machining work at the bell housing end ( top) but yes, the challenge is getting the gearbox fitted and located on dowels onto the adapter plate which in turn attaches to the bottom flange of the mid.
Tools like straight edges, scrapers, files, marking blue, scriber, marking out block etc are used.
Probably the most difficult and misunderstood part of precision fitting is drilling holes accurately.
When a random hole is drilled in metal, it's highly unlikely to be exactly where it's intended to be.
Drill bits wander, and getting the hole positioned accurately is a learned art.

[Instigator]

When we did my cut down mid, a buddy who is scientist level did it and he was clear w/what we needed.

I was fearless w/it and would not have been otherwise.

Thanks
I need to grind all the welds and power sand them.
Get all the weld splatter off and get sand blasted.
I'll cove some of the internal angles and epoxy prime.
Then the leg can hang on the baseplate.
I still need to make the oil sump etc, but that's all easy stuff.
This mid needed to be carefully build because the line of the drive shaft needs to be almost perfect, especially with a short drive shaft.
The days here are getting longer, so progress will speed up.

[NZ Sidewinder]

More small steps

[NICE PAIR]

"Nice work"

[LakeFever]

There is some machining work at the bell housing end ( top) but yes, the challenge is getting the gearbox fitted and located on dowels onto the adapter plate which in turn attaches to the bottom flange of the mid.
Tools like straight edges, scrapers, files, marking blue, scriber, marking out block etc are used.
Probably the most difficult and misunderstood part of precision fitting is drilling holes accurately.
When a random hole is drilled in metal, it's highly unlikely to be exactly where it's intended to be.
Drill bits wander, and getting the hole positioned accurately is a learned art.

this is a gigantic understatement. Even with best practices issues can arise. A lot of fab shops have switch to water, plasma, laser cutting because of this. Wire cutting is also extremely impressive if you need a certain fine surface finish.

I have an Altzmettal drill press with a box column. The best drill press in the world imo and even with it I sometimes get some variation on my hole location but I’m not building to this level often so it’s good for me. It’s rated for a 2.5” hole with a single twist bit. You gotta watch it when working with this beast. I have a dead man’s switch but haven’t hooked it up. Now that my son is getting curious it’s time to install it.

Anyways not to derail an awesome thread i just thought it worth the mention that we are all very impressed with your efforts and skill here.

[NZ Sidewinder]

I've pulled down the 135hp k24 outboard I got for 141 bucks.
Bought it as seized but it wasn't actually seized.
I had a feeling that it wouldn't be seized, as how does someone seized a Honda.
I found that the head gasket had been weeping due to corrosion around the dekkck area.
This had caused one cylinder to stick it's rings in storage or a period of no use.
Block is toast though
However I got some really good parts out of it.
4 marine pistons, 4 rods, starter motor, wiring harness, injectors, alternator, oil pump, crank, head, gearbox and leg, which is a story in itself, details in photos,
Clamp, and more.
I'm learning lots about how Honda made this car engine run in the vertical position.
The oil system on the k24 uses a oil pump mounted down below as already covered, but instead of piping the oil up to the top and feeding it into the motor where the car system does, and like I was going to, they feed it externally into the oil filter housing.
So that's what I'll do also.
The k24 crank uses the same thrust bearings in moth the car and outboard, so that's works.
The outboard has a very cool water coolef exhaust manifold tha is a bolt on item, so I'll use that to feed the turbo.
The exhaust runners are very short so not too much efficiently will be lost at the turbo by the cooling.
I'll fabricate the inlet side.
Interestingly the Honda gearbox is a preload type.



What's really interesting is that this 25inch motor has a 15inch leg system shown in the photo.
The missing section that makes it up to 25inch is the section with the oil sump in it.
This bit shown could easily be made into a really poor man's 15inch motor.
Just bolt that section up to a flat plate like the other 15 I did.
In fact it's less than 15inch.
The clamp and lower mouth are very well engineered also.
Down side is the large diameter of the gearbox and the 2.1 to 1 ratio.
It's all happening.

[NZ Sidewinder]

There's been a lot going on recently with this project.
The 135 k24 donor motor was an eye opener.
Honda filled the outboard k24 motors will the hi performance rotating parts.
So for 140 bucks I got most of what's required to build a 500hp boosted powerhead.
My k24 runner donor motor has good parts also, eg twin vtec
Here is a photo of a mock up to date.
The mid is not yet sand blasted but is now fitted true to the block and box..
That exhaust manifold is from the k24 outboard and is water jacketed.
I'll put a 180deg elbow on the bottom outlet of it and put the turbo up beside the block.
The crazy thing about this project is that there is a easy 600hp right there in the photo.
Just need a merc gearbox that would handle that.
One small problem is the throw of the gearshift lever at the box.
It's 8inches which is way more than the typical Morse shift cable can do.

[NZ Sidewinder]

[89LASER]

Maybe these people can make you one with a longer throw.

https://www.facebook.com/p/Baicour-D...0057358753945/

[LakeFever]

Baicour marine makes good product I bought my shifter from them. Good people

[NZ Sidewinder]

The cell is coming along.

[NICE PAIR]

Looking Good, do you have the plexi or can you make it fit what you've built?

[NZ Sidewinder]

We use Polycarbonate, not sure if plexiglass is the same thing.
For this class it needs to be 1/8 thick.
I have a male mold to bend it over with heat.