Re: 159 Petrol or Diesel?
the reason a diesel engine cant rev highly is that compression is used to ignite the diesel (no sparkplugs). there is nothing different in a diesel engine that would stop it achieveing a higher rpm safely, you wont damage anything at higher rpm, you just have loads of unburnt fuel which leads to severe power loss, so there is no benefit in allowing it to rev highly.
yes diesels are heavier with stronger components, they need to be to take the higher pressures, but that doesnt mean they are any less well balanced. it is balance that dictates the safe rpm, it is manufacturing toleraces that dictate balance. there is no reason why the components of a diesel engine can not be made to the same tolerances as a petrol engine.
if you have more efficient ignition of the diesel then you could rev more highly, for example if the diesel had a higher cetane rating it wouldn't make the car run better but it could rev higher (with appropriate changes to engine management obviously).