Hello!

This is my 6 boiler self sufficient steam engine that produces 867,584su at 256rpm.
Its size is: 33x16x21(LxWxH).
It is tested and working in 1.19.2, 1.20.1 and 1.21.1 with Create 5 and 6.
To prime it, feed the blaze burners manually or connect a power source to one of the 3 outputs which can be disconnected later, once the machine has enough lava stored. Watch out, it has to be clockwise.(if you look from below, if this is turning the wrong way, all belts run in the wrong direction and you will have to remove all steam engines, stop the machine and place all steam engines again) 
Dont forget to add empty buckets(at least 3 stacks) to the item vault.
I have attached a video of the priming process.

*Sometimes after the initial placing of the contraption, the pipes coming from the lava tank are not connected and have to be replaced manually.

Bill of materials:
1x Andesite Funnel
54x Blaze Burner
2x Brass Funnel
3x Brass Tunnel
99x Cauldron
4x Chute
49x Cogwheel
199x Cut Granite Brick Stairs(only decoration)
87x Cut Granite Bricks(only decoration)
99x Dripstone Block
48x Empty Bucket(at least)
30x Encased Chain Drive
268x Fluid Pipe
315x Fluid Tank
35x Gearbox
212x Glass
2x Item Drain
3x Item Vault
99x Lava Source(Lava above the dripstone, in survival you will have to place these manually)
6x Large Cogwheel
3x List Filter
1x Magma Block(for elevator)
6x Mechanical Arm
25x Mechanical Belt
16x Mechanical Pump
99x Pointed Dripstone
6x Polished Andesite(only decoration)
2x Polished Cut Andesite(only decoration)
24x Polished Diorite(only decoration)
6x Redstone Lamp(only decoration)
6x Redstone Torch(only decoration)
2x Rotation Speed Controller
184x Shaft
4x Smart Chute
3x Soul Sand(for elevator and decoration)
1x Speedometer(optional)
2x Spout
8x Spruce Sign(only decoration)
54x Steam Engine
4x Stone
12x Stone Brick Slab
92x Stone Brick Stairs
1219x Stone Bricks
1x Stressometer(optional)
x Water Sources in the pool the pipes lead to
2x Water Wheel(only decoration)