can running the crankcase breather and the rocker cover breather to a vented catch can cause any problems. The pcv system worked fine before with the rocker cover breather to the catch can and the crankcase to the pcv valve however a few people have told me to do away with the pcv valve (race cars do this, small gains in power).
I temporally set it up and i am suprised at the amount of fumes that come out of the catch can (can't be good on power). I am a bit worried that with no vacume the oil might not be drawn down through the engine.

thanks

not sure about the lack of pcv but i fit one into the cranck case and one into the rocker cover as my car is not driven daily and parked outside. I found that after a run and left to cool down in the cool night air i was building up condensation into the rocker cover.

Fitting a pcv into the line from the catch can to the rocker cover eliminated this condensation build up.

To disable the PCV system on a vehicle in Australia renders it [technically] 'unroadworthy' It's done on race engines for a number of reasons & these might include.

No manifold vacuum at full power. [so fumes are not drawn into the engine]
At high compressions & high speed there can be a surprising amount of blow by resulting in high crankcase pressure consisting of a lot of burned gasses that will not contribute to the power output of a race engine if they were returned to the intake.
At very high engine speeds there are a lot of oil droplets flying around in the crankcase & drawing these into the combustion chamber can result in detonation under certain conditions as oil has a much lower octane rating than petrol/gasoline.

For a race engine, the catch can is the way to go.

For a street car, leave the system operational. The reduced crankcase pressure also helps to prevent oil leaks past seals & gaskets.
If your engine is producing a lot of fumes & you are finding oil in the catch can, then perhaps a compression test will be a good idea to see if you have other problems.

In years gone by, there was a serious road hazard known as 'Summer Ice'
When it rained, the oil that was left on the road from older engines that used the old draught tube crankcase ventilation would float to the surface of the road & was the cause of many collisions, particularly at intersections where many cars would be stationary, .... dripping oil & fumes.
If the rain continued, or was a heavy shower, then this oil was eventually washed away & the surface was good again but for a short time, it could be deadly.

Motorcyclists & drivers everywhere reaped the benefit of PCV when it was introduced in the 60's

Quote:I've not heard that term, but I know exactly what it is. Caused the car in front of me to do a 360 ... I reckon it must have been more common back in the '60s.

The condition was probably known by another name in the US & was most common on sealed roads in urban environments up untill the numbers of PCV equiped vehicles was high enough to make a difference to the volume of oil spilled onto the road.

Interestingly, PCV equiped engines seemed to have far fewer oil leaks too & this also made the situation better.

i just went for a bit off a drive the fumes have droped right off so maybe it was because the engine was cold. idle has droped right off. but a bit of foot work can fix that for the time being.

this car is not my daily drive it used for sprints and hillclimbs i rev up it to 7500 so maybe the catch can isn't a bad way to go. any power gains i would love.
the last sprint I was nearly 2 seconds quicker than a caged wrx and only .4 sec behind a evo 5 i want to beat a few more cars (slowly getting there). First event in november last year i came last, the last event i had 20 cars behind me 60 in front. small gains seam to make big differences.


thanks again