Several failures in Cosworth Vega high performance race engines were a result of horizontal fracture of the block in the thinner case cross section above the main oil gallery. It was believed the fracture started at the lower corner of block water pump area and progress rearward. Chevrolet developed a HD block design in 1974 that seems to have eliminated the failure type. The HD block was marketed as an "off highway" part in the "Chevrolet Power Catalog" it in US until discontinuing it in 1982. They are rare today and highly sought after. In the 1990's, a Michigan midget racer developed a rig using turnbuckles and plates to preload the block with the intent to create clamping load to eliminate the potential failure. Although the system had limited service (part of one race season) the block did not fail under high compression alcohol power at high rpm ( +8000 IIRC). Unfortunately the one-off system has changed hands and has been lost to time and no drawings or good photographs exist. Street CV HP motors do not appear to exhibit this failure mode. Most street motors fail due to rotating component or cylinder head issues. Hope the helps.