Has anyone heard of or used Hardblok Water Jacket Filler for race applications? This is new to me. I'd be leery about pouring this stuff into a super expensive race engine even though they claim that it has been track tested, since 1984, "with perfect success." According to its website, it is "a specially formulated, cement-based product with refined, size-graded iron particles combined at an optimum ratio to provide maximum strength, vibration dampening, and heat dissipation required in high performance race engines. Its coefficient of thermal expansion is identical to cast iron engine blocks. Product has been tested and proven effective in aluminum blocks. Easy to mix and pour. Dual, pre-measured packaging is convenient for typical V-8 installations. Detailed instructions included: Ample working time to pour and install torque plates. No high heat build up during setting to cause distortion. Rapid strength gain. Can hone and assemble 24 hours after completion. Does not shrink, does not expand. Optimum ratio of graded iron for strength, vibration dampening, and thermal expansion. Stable under water. Will not erode. Non-hazardous." HardBlok Water Jacket Filler - Increase Horsepower For High Performance Engines.