Peter:
"In re-siting the breathing from the catch tank to the cam cover you haven't really achieved much." - the point is that the scavenge pump is no longer working against a vacuum, it's circulating instead. I take your point about the filter not being required - a secondary catch tank would be more appropriate.
"Is it because they can get away with it, despite ignoring good practice in a number of areas?" - I guess it's because it works and that's good enough.
"What did your purple-pumped dry sump system do about breathing?" - Dave has answered this one. It's horrible, because if you overfill (how do you know you've overfilled) then any excess is shoved up from the belltank into the head, so you're chucking unfiltered oil straight into the head.
Dave:
"It now has a sealed cam cover with a breather from the bell tank to the catch tank .
This is without a tower." I assume you're still on the purple pump? I switched to the gold pump without a tower ('cos I didn't know it existed) and it simply threw all of the oil out in very short order.
"Whats the best option ( comprimise ) then" - it depends. Bear in mind that problems with the system only came to light with the VHPD. Prior to that the 1.6K race cars ran the purple pump system without any problems (not all of them ran it, it was an option). It seems that the engine-running-out-of-oil-because-it's-all-in-the-head problem is linked to sustained use of high rpm (and possibly high G-forces) - the SLR/VHPD race cars run slicks & 8000rpm. If you think you're likely to fall into that category (not likely on a hillclimb/sprint car) then switch to the gold pump & conning tower and blank off the tappet bucket feeds, this will bring you to the same 'standard' as the VHPD race cars. Even if it's not a brilliant piece of engineering it does seem to work. Your oil capacity with the purple pump could be increased just by fitting the conning tower, since it's propensity for blowing oil out of the top of the belltank is reduced.
Me? At some point I might unblock one of the cam cover breathers and put a dinky little filter on it - at least it will stop it clucking like a chicken, but then that would take away a source of amusement from all the start line marshalls in the world...
Mike
Mike