If its a diesel, itl have a governor - probably around 5500rpm? i dont know with modern diesels, but with my bros old 405 diesel it used to rev to 5500 and stop there. Also when they MOT test diesels, they floor the accelerator to test the governor, so it cant hurt it. I used to drive around at work in a 205 diesel on the governor for ages, it was its cruise control, but pedestrians didnt like it! that 205 has done over 160,000 miles and its still going! despite my best efforts to destroy it...