Just a few (it started off as a few anyway

) thoughts/ suggestions from myself;
1) Consider adding options for wet/dry sumps, the wet sump would be more reliable in low performance applications and much cheaper. The dry sump should add cost and servicing costs but increase reliability in high performance applications and allow for a more compact bottom end.
2) Are the grades of steel for forged and billet cranks uniform? If so the forged with it's better grain structure would be more resistant to long term fatigue for regular applications rather than the billet machined crank, which only has the directional flow of the original extrusion (that said you can impart this quality via heat treatment).
3) Will there be simulation of one off costs and tooling costs for the manufacturing processes later in the game? For instance to refer back to the crank, a forged option has a large set up cost but a much reduced material and labour cost in comparison to a machined crank which has negligable set up cost (providing the machines/ heat treatment facilities are available) but high tooling costs. I appreciate this may not add much fun to the game and perhaps add uneccasary depth but I thought I'd raise it anyway!
4) An option to choose between belt, chain and geared engine chests would be appreciated. It would provide an extra dimension in the cost/ reliability battle and another tool to get those extra pesky M/revs
5) Valve return systems, choosing between springs and pneumatic return systems would allow for more modern automobiles to achieve better fuel economy and performance and allowing much higher RPM's well beyond the natural frequency of valve springs (about 12krpm I recall). The opportunity to model Fiat's multi air engine or a 2006 21k rpm F1 car engine would be awesome!
6) More options to choose material will always be welcome to me though I appreciate this may not add to the wider appeal of the game, options for various surface and heat treatments would follow the same point. Maybe expansion packs of extra detail for the particularly anorack amongst us would be a long term option?
7) Will the option for clutch type be part of the gearbox tool or should that be part of the engine designer?
Finally, I just want to say what a fanastic game the demo alone is, it's been utterly engrossing from day 1!