Went to a drag racing expo yesterday and all the huge V8s had their valve covers connected to the ends of their 3 foot long 4-1 headers.

They were using a -10 or -12 an line from the valve cover on either side (not sure if theres a check valve in there or not). Does it use the exhaust to create a venturi like vacuum to work like a pcv valve? Does the exhaust burn off the vapors so it doesnt get on the track?

Anyone done this, anyone know why they do this, or know if it could substitute for a catch can?

 

Wow thats a great question, it would make sense if it was designed to burn off the oil to keep it off of the track. that would be my best guess.

Rob

 

it does burn the oil but the problem is u become smokey the bandit at the end of the track... anyone remember john brown's car?

 

the exhaust gas creates a vaccum and the crankcase vaccum promotes ring seal and in theory prevents blow-by and creates more power

 

Good point. Having vacum/lower pressure in the crank case would also help the oil returning from the turbo get back into pan. If you had alot of excess pressure in the crank that would push the oil back into the turbo causing leaking problems in the turbo.