Iron/Alu Block and/or Head

So, I noticed in the Engine Designer that if I mix a Cast Iron Block with an Aluminum Head, or an Aluminum Block with a Cast Iron Head, the life expectancy of the engine pretty much halves. Is it supposed to do this, or am I doing something wrong? I know many car makers have used Cast Iron Blocks with Aluminum Heads for decades so it seems odd.

It should lower a bit if you’re building one in an old tech year as in the 1940s - late 60s era it was super hard to make alloy heads that sealed well on iron blocks, but at new tech years this should go away. It may be a bit bugged though, we’ll have a look at it during the engine designer revamp

Ok, thanks that makes sense. In the current version it’s taking until about 1990 before it stops being overly detrimental on the 1.4L I’m looking at.