"No special manufacturer requirements" glitch, help!

Certain engine scenarios have a “No special manufacturer requirements” requirement for the build. Even when all other parameters have been met, this remains red and thus the scenario cannot actually be completed. Has anybody else encountered this, and found a workaround?

Windows 7 Home Premium 32-bit
Intel Core 2 Duo 2.26Ghz
GPU: Intel GMA 4500MHD Chipset 764Mb

It means you can’t have parts that are made in a forge or CNC shop. Check your bottom end parts, they have to be cast parts.

No special manufacturing requirement means that you’re not allowed to use any forged/CNC parts in the bottom end section or the race exhaust manifold. Basically the parts where it says in the desciption that you need something like forge works or CNC shop

Yeah, we probably need to make that a bit clearer.