93celicaGT2 wrote: Question: Why the block guard? I have an extra D-series one lying around that i haven't used because i don't really trust them, on the pretense that they're not the same exact metal as the block/sleeves, so they don't have the same expansion/contraction properties. I could very well be wrong, i just can't get my head around why they would make much difference.
Because I couldn't afford full sleeving. I know some people don't like block guards. I've never used one, so my opinion could still change, but I like them. They keep the cylinder of the open deck from being able to shift. Is it likely? No. Could it happen? Yes. So there is a potential upside, with little downside. The downside you always hear about is overheating, and I could see that with some of them. The Golden Eagle has a lot of space for water to pass though. Also, I installed it 1/4" deep, so that there is a nice volume of water above it and no tendency for it to block the head gasket flow.
I hear you on the expansion / contraction concerns, but there are two reasons I'm not really concerned.
1. The block is aluminum. While it is true that cast and extruded aluminum expand at different rates, they are closer to each other than either is to cast iron, which is what the liners are. In other words, the liners should seperate before the block to block guard interface has any issues.
2. It is relatively low temp there. This is the water jacket. It should never see more than ~250 degrees.