Is the military gen set scenario possible in the demo?

Despite only having the demo (I'm getting the full game for christmas) I've managed to get decent medals in most of the engine scenarios, and at least complete all of the scenarios available to me, except for the military gen set challenge. I've managed to get reasonably close to completing it, with every requirement satisfied except for power, where I was ~7bhp off, but I haven't managed to get everything complete at once.
I understand that it is rated as insane difficulty, but having struggled to meet all of the requirements I looked for solutions online to see where I was going wrong. There is an engine that was suggested on the wiki, but it was too big, not powerful enough, not economical enough and not reliable enough. There are also some old forum posts with engines that passed the challenge, but the challenge had different requirements back then so they weren't relevant.
Is the challenge actually impossible without adding a turbo from the full alpha, or have I just missed a magic combination that will get me past the challenge?
I understand that it is rated as insane difficulty, but having struggled to meet all of the requirements I looked for solutions online to see where I was going wrong. There is an engine that was suggested on the wiki, but it was too big, not powerful enough, not economical enough and not reliable enough. There are also some old forum posts with engines that passed the challenge, but the challenge had different requirements back then so they weren't relevant.
Is the challenge actually impossible without adding a turbo from the full alpha, or have I just missed a magic combination that will get me past the challenge?