Sauber C9 dumb question

[hoffman66]

Can anyone explain to me how Mercedes were allowed to use a 5 litre turbo V8 in their Sauber cars, when most turbo teams ran something like a 3 litre or smaller?

I know teams like Aston, Jag etc used big cc N?A engines, but how come merc were able to use such a big engine>>

Presume it was based on fuel, and they found it could be fuel efficient to a point, or speed meant it would be mega fast, pit more often but still win?

[red131]

Basically engine design was free, but.....

You were limited to a max fuel tank capacity 100L and 5 fuel stops per 1000KM race - which gave 600L / 1000KM

These did change over time - which upset Porsche in particular.