? For the mechanics/engineers

[gavs]

I'll have to dig it up but it's not so much the fact that the engine is older, it's just that with compliance regs to emissions etc changing every year, you can't put an engine that has worse environmental credentials into a car that is complied with better compliance, I.e you can't put a euroIII compliant motor into a euroV compliant car. The examples you give are fine because a) they fall into the 'over 30 years' club which basically mean anything goes within reason and b) the conversions are on vehicles and motors that were looooooooong before anyone not wearing hemp or avoiding soap cared about the environment.