Or offer two pulley kits.

One could be a set of pulleys and a belt for +30hp (300-310hp) , and another one for +100HP which is a pulley kit and a bottom end.

I am sure Cosworth management might argue that adding another 30hp to the stage 2 with a pulley kit might make the full bottom end less appealing, but it might make the difference between someone purchasing the cosworth kit or the Harrop and Edlebrock which, word on the street, are brining out pulley kits to offer more power.

Fensport performance near me in Cambridgeshire were running ~370-400hp on stock internals (turbo charged with boost tapered up at high revs) for quite a while in the sprint series....

Im not suggesting at all that, that sort of "testing" is equivalent to what Cosworth have done, but it shows some level of endurance.

Could the hypothetical +30hp pulley kit could come with a tune to limit torque at lower revs for extra safetly?

I dont know the science behind it, but apparently lots of torque at low revs is what bends rods?

I do recall reading somewhere it was the torque that causes problems. But I think that was about the transmission and shearing gears. Oh well.

And tbh, I'd rather have less power than the other guys out there, but have the reassurance of long-term reliability vs the "well here's your pulley, good luck with your engine" attitude. Although, I would like to see a way to get around 320 at the crank. I'd be happy with that. Power of a Z with the weight of our cars is a good fit.

Ugh enough of us shaking our presents, just let us know what's in the box, Cosworth!

that sounds like a good idea

thing is the Cosworth management will probably be loathe to increase the power of the kit as the testing and endurance work was all done at the 280Bhp level
so its passed off at that and a known quantity on their tune
smashing on a smaller pulley would mean running through all that again

I think you are right Matt. It doesnt make sense to release just a pulley kit for +30hp unless it is validated on the stock internals.

I think 350hp would blow a stock engine pretty quickly because of the low end torque it would make.

alexisfire02 blew his stock motor with the sprintex 335.... 280WHP... on the way home from fitting

civicdrivr broke a rod using a vortech kit at about 286WHP on the 9th dyno run...

There are alot of people putting down more power, but those seem to be the lower power failures I have seen that couldnt be explained by anything other than mechanical failure.

Stock rods don't like big bottom end FI torque. To ensure reliability you'd either need to build the bottom end of the engine or detune the ECU in the lower rpm/high load areas.

Source: Guy who has installed, tuned and maintains 20+ FI kits on these cars.

Hence it's understandable if a company wouldn't want to simply rush out a smaller pulley and a reflash. You could, and many folks likely do with no issues, but it's not the most prudent approach.

so the kit is already making 280 +Bhp and about 250Whp to add another 30Bhp would push it into the danger territory by the sounds of it where you need uprated rods to survive

Now I agree the issue is probably not the top end power, rather the low end where there's no inertia relief from high rpm to help the rod stress

so a careful tune where you don't open the throttle fully or don't use MBT spark until 4000rpm 'should' save the rod

this would need cylinder pressure kit to do properly so I doubt 95% tuners will do this