I don't really see the problem. You can tune or re-engine a car as much as you like, so long as you don't increase the power beyond what was available in the top-of the line model of the same vehicle. I.e. if you bought a BMW320d, you may retrofit a 3L petrol so long as you also do the required upgrades on brakes and suspension and pay the power- and displacement tax. It takes some paperwork, but it can definitely be done. On the RR, the top of the line was the Overfinch so you have plenty to go on power-wise.
That being said, the two engines you want to swap are so similar that I'd do the conversion and keep it to myself. It would never be discovered, and if it were (in the event of an accident), your insurance company would have to "prove" that the increased power caused the accident. This is highly relevant for boy-racers in 350bhp Nissan 200sx's, but I can't see it entering the equation for a RR. You're simply bringing it up on a par with the 4.6 which has the same brakes and suspension.
Go ahead - it would make a good car if you can get the electronics to communicate.
Henrik
Hi Henrik,
I don't know in which country you live but it's not as simple from the law of the country point of view.
I know UK is the country of kit cars, modified cars and swaps because the legislation permits it...you guys are so lucky
Here in France and even Germany, we've a very severe MOT. (either french DREAL or German TUV)
Basically, anything modified should pass a test certificate as any new model of vehicule released on the market (not the MOT inspection). No matter top of the range has 100hp more and same components (that's often not true, bigger brakes and stiffer suspension)
And you can't pass that kind of test if you've gone too far in modification. Like fitting a diesel engine instead of a petrol one, fitting a V8 petrol instead of a V6 OR even fitting a tiny 4 cylinders instead of a V12 (who would do that
)
They don't even care about the power of the block...or if you upgraded other components to handle that much power.
Assholes french administration
I believe that in Germany, if the special component has the TUV certificate. It is ok to mount it on the car without passing full car inspection. At least, it's the way tuners such as Alpina or Brabus works...
Speaking of Overfinch, it's a modified car. Never released by Land Rover...
I know because i'm interesting by one of those but will never get any certificate in France.
Then there's only one thing to do : living with the risk and do the mods so the insurance expert can't see anything different...
Flo
