02/21/2022
The Bugatti Type 57 was a fast and luxurious touring car with a state of the art, high performance engine. It was created by Jean Bugatti, son of founder Ettore, along with other senior Bugatti engineers. About 700 cars were built between 1934-1940. The straight 8 cylinder engine was a 3.3 liter with twin overhead cams. The cylinders and cylinder head were all one casting, which was not unusual at the time. However, it is a difficult casting to pour, with complex water passages around the pistons, combustion chamber and valve guides. A long and slender casting, it can be tricky for some foundries to make without warpage and shrinkage tolerance issues. Bugatti siamesed pairs of cylinders together, with very little space for future re-boring or sleeving. It is common for existing cars to have cracks in the engine block around the valve seats and cylinder bores.
Four years ago, no new replacement engine blocks were available anywhere in the world. Stohr Design began CAD work and pattern making to produce high quality, reliably good castings in the USA. Initially castings were made using fully 3D printed molds, expensive and state-of-the-art. But even using the best modern software to predict the grey iron pour & solidification, our contractor could not solve shrinkage issues. I finally designed my own molds and cores, using experience gained from similar 1920's Miller Indy car engine blocks. Foundry and pattern shops were sourced in Detroit, USA. Cores are 3D printed in the same area. Machining is done in Colorado, USA. Complete engine blocks with valves/springs fitted are now in stock and available through Sargent Metal Works in Vermont, USA.
I don't always know where my castings end up, but I was happy to learn that one car made it into the best of show nominees at Pebble Beach last year.
This was quite a project. I appreciate the efforts of everyone involved who worked hard to get these engine blocks out there for anyone who needs them.
Some images below show the CAD design process.
