Porsche 917 flat 12 engine

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Foketry

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When assembling crank pin with flywheel under press, I discovered this error, the hardened material is too brittle, the pins break ! Diameter is 12mm (.43 inc)
This material is tool steel, used for reamers and taps: 115CrV3 ( European standard) , L2 Aisi/SAE standard (USA), easy to harden in water or oil, but after quenching at 790 degrees C , tempering at 250 degrees is required to reduce fragility.

this break is also favored by the sharp edge of the groove for oil distribution and the hole.
it would be appropriate to make a radius at the bottom of the groove, but now all the pieces are done

I'll do tempering at 250 C°

IMG_1396.JPG
 

Foketry

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I assembled the crankshaft : connecting rod , flywheels , internal bushings and gear.
To ensure perfect alignment of the flywheels I made a final turning on external diameter, I left an allowance of 0.5 mm
The space between one flywheel and the other has been filled with glued wood to avoid distortions between the tailstocks

IMG_1420.JPG


IMG_1422.JPG


IMG_1423.JPG


The original Porsche crankshaft

IMG_6643.JPG
 
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Alec Ryals

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When assembling crank pin with flywheel under press, I discovered this error, the hardened material is too brittle, the pins break ! Diameter is 12mm (.43 inc)
This material is tool steel, used for reamers and taps: 115CrV3 ( European standard) , L2 Aisi/SAE standard (USA), easy to harden in water or oil, but after quenching at 790 degrees C , tempering at 250 degrees is required to reduce fragility.

this break is also favored by the sharp edge of the groove for oil distribution and the hole.
it would be appropriate to make a radius at the bottom of the groove, but now all the pieces are done

I'll do tempering at 250 C°

View attachment 123887
Higher temper temp
 

Foketry

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Before final turning I checked if all the internal oil passages were open, the oil from a hole at the beginning of the crankshaft must flow to the last hole of the connecting rod and last flywheel.
I used WD40 for this test , a small gerotor pump and a cordless drill
before final turning



IMG_1418.JPG


IMG_1411.JPG
 

Foketry

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My 3D drawing of the engine block
they are 2 half crankcases almost equal, the difference is that the 6 cylinders on the right are displaced by 9 mm compared to the 6 cylinders on the left (the thickness of the connecting rod + 1 mm)
There are 2 slots for 2 distributors, one on one half crankcase, the other on the other half crankcase
The top transmission shaft drives 2 distributors and the fan, the bottom shaft drives the oil pumps and the large central seat houses the crankshaft.

semiscatola.jpg
 

Foketry

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for a whole night the printer created the foundry mold , compared to the finished engine block I had to foresee the machining allowances and the 2% shrinkage of aluminum.
I had to print the 2 engine casings in 4 pieces (2 + 2) because the dimensions of my printer are small
Then I glued the pieces together


IMG_1322.JPG

IMG_1319.JPG


IMG_1330.JPG
IMG_1331.JPG
 
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Alec Ryals

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I assembled the crankshaft : connecting rod , flywheels , internal bushings and gear.
To ensure perfect alignment of the flywheels I made a final turning on external diameter, I left an allowance of 0.5 mm
The space between one flywheel and the other has been filled with glued wood to avoid distortions between the tailstocks

View attachment 123991

View attachment 123992

View attachment 123993

The original Porsche crankshaft

View attachment 123994
[/QUOTE were did you get the shell bearings ?
 

jetstuff

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T
Napier dagger , it's an amazing engine, they look like 2 Porsche 917 engines stacked on top of each other ...
Your work is looking great, hope you get to complete it. Normans Dagger was manually machined from solid, No castings /No CNC .
 

michelko

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aarggh

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Fantastic work! The castings came out brilliantly!

Do you use any type of compounds to degas/flux when casting to get such a good result?
 

Foketry

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Fantastic work! The castings came out brilliantly!

Do you use any type of compounds to degas/flux when casting to get such a good result?
I have used sodium carbonate in the past, I also tried degassing flux tablets with not always good results
Now I use quality aluminum of a single type (AlSi9Cu) without degassers or fluxes, no porosity, no internal defects
I'm not very experienced but I realized that using aluminum scraps of unknown quality does not always lead to good castings
 

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