Vacuum pumps were in use long before NHRA's muffler rule. Why? Because they make vacuum and evac systems do very little, with or without mufflers.Probably not...too much back pressure, that is what started the use of vacuum pumps, NHRA was making mufflers manditory so everyone put them on but couldn't evac the crankcase...enter the vacuum pump.
I had the same mufflers. All it did was make my car smoke... real bad. They wanted to check the track out cause they thought I was dumping oil. I disconnected the hose to the breather and the smoke screen stopped. I had full exhaust to the rear axle, mufflers at the end and turn downs before the rear.had them on bbc elcamino with 3 inch flowmasters worked fine
An evac system is only slightly better than a regular, old breather stuck in the valve cover. You might see 3 or 4 inches... maybe 5. Basically, you're trying to overcome the positive pressure caused by blow-by. You're trying to prevent oil leaks and keep the gaskets from being blown out of the engine.i wonder if anyone has checked the e-vac efficency? WTK