for my use I wish I could of got a filled block. I found this water block and after 3 different pressure tests and having the sleeves installed, cam bearings, line bored, finished honed and then assembled found out it leaked coolant into the oil. So then after another 6 month go around of trying sealers and changing the oil and cleaning out valve covers, oil, pan and filter, I decided to fill it to the bottom of the water pump opening. No coolant, just a oil heater in the oil pan to warm it up before running. I made 3 back to back to back 1/4 mile passes and oil temps never got over 190 degrees. So the answer to why fill an aluminum block is how deep are you into it. Some day if I have to take a cylinder head off I will look and see how it lasted.Birdtracker

E-85 fuel and very little street useage. Its got way to much power. It will only get you in trouble. Birdtracker

I had an iron block 440 that was filled to the top of the freeze plugs that I drove on the street thousands of miles with no heat related problems. With all the aluminum blocks out there I can't see an issue with a 1/2 fill and running it . Birdtracker

Check out a morter product called Embeco 885 Darrin Morgan may have a video on it or a post with info but it has a lot of iron in it and little shrinkage and used on the space shuttle launch pad.