I'm feeling a little bit more confident today about this. At some stage I will probably upgrade my rods but not at the moment. I have since got a little more information regarding this failure. It would seem that the engine had a rev limit of around 7000rpm. This combination of power and revs are what's more than likely caused the rod to fail. The failure occured at around 4000rpm but this doesn't conclude that the stress in the rod took place at these rpm's. The stress fracture may have occured at a quick blip of higher rpm's and then not failed until a later date.
The GM paper does state quite rightly so that the rods are tested to 250bhp and there will be a 'little' give or take either way on that. There are zlet engine running over 300bhp on stock rods and there is a possiblity of failure but not very often. I would suggest that running an SC on a road going car where the rev limit is set at 6300rpm is a much safer place to be. How often does a car run over 6000rpm on the road? I do sail close to the wind on that occasionally but at 6000rpm my engine is making 248bhp.
As I have mentioned before, the first Vectra has been running for years now with no problems, the Astra of Mark Watts has been running for over 18 months with no problems and this has been track abused. Dods Corsa has been running fine. Along with the many other conversions that have been done between the United Kingdom, Germany, Sweden and Greece.
If you are going to have your limiter raised to run at 7000rpm and above, and choose to run the engine in this range then I would totally agree to uprating the rods. As for us with road going cars, its something to keep in mind.
