while your on Mark, on a race bike similar youd junk the breather system and blank off the outlet holes in the cam covers, minimal crank case pressure As it serves no purpose other than emissions, and pumping the oil vapour through the air box. Always wondered, if the breather system only0exists for emissions, if there is a way to vent crank case pressure to separate system or catch tank/bottle that does not feed the intake or block the system, there by not blow the cover seals.?
Chris, what you have to bear in mind with race engines is that they operate huge pressures compared with normal engines, which are designed for longevity / durability and minimal warranty claims!
Lets use an example - Suzuki GSXR 750WT TL1000R Kit and Ducati Corsa.
The psitons on the works engines or any race engine for that matter are designed for maximum efficiency and minimal weight, now what that means is that the piston normally has one ring as opposed to three due to it's skirt being so small, which is why, in the case of the Ducati, and the TL the breather systems are enlarged - standard breather bore 10-15mm with one way reeds - works spec bore - 25mm with open vent.
The normal working compression of works engines is around 13:1, and the motogp and F1 stuff even higher, which is why the buggers won't idle at anything less than 4k!
Also on a race engine remember that all fluid systems have to be hemetic, as to say if the car or bike shits itself it must attempt to keep spillage to a minimum - hence the breather tanks are huge under the seat units, Ducati's Corse crankcase breather tank was around three plus litres in capacity and was baffled in order to allow the oil to return as mist through whence it came!
The F1 engines also vent into a baffled catch tank, and the oil mist returns via the oil filter. The whole venting to atmosphere is a hotrodder's thaang! ; if you ran a racebike vented to atmosphere, when that bike goes down you've just dumped the contents of the sump all over the track - definite no-no, which is why race vehicles aren't allowed to run coolant and have to use water.
The race engine breather system still manages to keep pressures in the engine constant as Mark says, but it does it by effectively freeing the breathing system to be fully open, however the pressures allowed this whereas Mr Ducati 998 owner who just bought a corse exhaust breather and catchtank for his standard roadbike suddenly finds the torque curve is bugger all at anything other than 6k or above!
Essentially because the engine now breathes more freely, but the pressures are lower due to the fact that the now it's breathing too freely- and suddenly the so called tuner tells mr moneyed duke owner that he needs corse eproms cams and pistons (which of corse are high compression so the rods'll have to be changed) !
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