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Speedy Squirrel Speedy Squirrel is offline
Rocket Scientist
Join Date: Jun 2008
Location: Detroit
Posts: 948
Classic engine "blueprinting" consists of:

1. Line boring. The true center of all the main bearing bores is found. Once the centers are known, the maximum deviation from a hypothetical line through the mean center is calculated. Half that amount is machined from each case half mating surface, the case halves are bolted together, and the main bearing diameters are re-bored so that they are all in close alignment. I do perform this step on the engines I build, and it can yield a few HP.

2. Next the crank indexing and stroke are corrected. The crank is reground, within the maximum allowed under-size, such that the appropriate throws are 120 degrees apart, and the throw (1/2 the stroke) is the same on all rod journals.

3. The piston compression height is measured. For flat-tops, the crown is machined down by a very small amount so that they are all the same. The rod for each cylinder is re-bushed at the small end so that the center to center length is the same. Now the tops of each piston are exactly the same distance from the crank centerline at TDC.

4. The cylinders are either machined so that they are all the same height, or custom base shims can be used. Now, at TDC the top of the piston is the same distance from the top of the cylinder for each cylinder.

5. The combustion chambers of each fully assembled head are measured, and a small amount of material is removed from the "small" chambers until their volume equals the largest chamber.

6. Cam and rocker arm surfaces are micropolished to reduce friction.

... and that is just the blueprinting part! I wouldn't even do some of this, especially the crank grinding. It is disturbing to take it undersize. If something ever happens, it is done for. With balancing though, you would have an engine exactly as Mezger intended.
Old 11-30-2014, 06:12 PM
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