Hi guys: Trying to figure a pan evac system other than the tube in header to valve cover breathers. This has always worked on my race oriented cars but I read somewhere on this board that a street car will not benefit from this system. Any ideas?????????? Motor feels like it breathes easily but could always pick HP from less back pressure in the crank case. Motor is a lightly built BB 462. Ken :grin: :grin: :grin:
pan-evac I have 3" mandrel exhaust with Walker Ultra-flo mufflers and my pan-evac works fine on the street. The other option would be to go to a vacuum pump, but there are some hurdles. 1) Front crank seal and rear main seal must be flipped around backwards. 2) The entire engine needs to be sealed well. I would suggest machining the rocker cover rails, using cast valve covers with no holes at all (makes oil changes a bitch), I would also look at making a reinforcement plate to clamp the oil pan better. 3) you have to seal the distributor shaft so that you dont leak vacuum through the distributor. 4) use low-tension oil control rings. Standard rings with a vacuum pump will leave the cylinder walls too dry. 5) don't forget to drain the puke-tank every so often. The next step up from this would be a full-on dry sump oiling system. $!$!$!$!$! But well worth it in the end. I just wish I could afford one.o No: ------------------------------Mark D.
I just thought of one other thing. When I had the Flowmaster mufflers on the car, the pan-evac didn't work that well, the a.i.r. valves would close and I would start to build positive crankcase pressure. I was going to try putting the siphon tubes in the exhaust system BEHIND the mufflers, but I built a better exhaust system instead. If the evac siphon tubes were in behind the mufflers (assuming you have enough velocity for them to work) then any restriction presented by the mufflers would be eliminated. With the better exhaust, I can pull about 1" of vacuum with the mufflers on. It ain't great, but it's better than nothin'.
I don't have a scanner or photo management software, but I'm working on getting some pictures posted soon. I finally got the car out and cleaned up enough to take some decent photos. I do have the full size photo I used for my avatar and I'll attach that.
pan evac system Mark: Thanks for the info. I don't understand why the Flowmaster system would not function properly. I am using flowmasters at the present an find tham very free flowing. The air valve is the unit welded to the header collector?.Does the air valve closed prevent exhaust flowing back to the valve cover breather? Ken
A.I.R. is what the manufacturers call air injection reaction. It is where they use a pump to force fresh air into the exhaust system to help burn any leftover hydrocarbons from combustion. They use check valves on these systems to keep exhaust pressure from going into the air pump and the motor. These check valves are what we use in our pan-evac systems. Ideally, your collector siphon is always pulling vacuum, but if pressure ever builds in the exhaust, the check valves close preventing pressurization of the crankcase. The only problem is that at this point there is no vent at all for crankcase pressure and this is where you start to push oil by the breathers and out the dipstick hole. What can I say? The car went 12.56 through the Flowmasters with the pan-evac non-functional after 4500 rpm and it went 12.33 through the Ultra-Flos two weeks later. This was in the Fall of the year, and conditions were similar. The following spring the car was running 12.0's uncorked in slightly better air. I haven't run it with the mufflers since, but we'll see what happens next spring. He he he. Maybe, just maybe, I'll need the mufflers to slow it down to 12.0's.
pan evac. Is the end result the ultra flow mufflers are superior to flowmaster? How could you tell that the pan evac system did not work after 4500 rpm?Trying to put all of the pieces together so I can use all of your testing and I won't have to. Thanks for the info. Ken
I plumb a vacuum gauge to the crankcase and watch crankcase vacuum. I have an adaptor that I made which screws in to the hole where the PCV valve used to go and I measure crankcase vacuum there. I have seen as much as 3"hg with open headers, but with the mufflers on it pulls less vacuum. With the Flowmaster mufflers, crankcase vacuum would reach zero at around 4500 rpm and then start to build slight pressure. It should be noted that the Flowmaster exhaust was non-mandrel bent. It should also be noted that most would no longer consider my motor a "mild" 455. It is a 4550 lb car with me in it and it does only have a 3.42 rear gear. Add that to a 70 lb two piece driveshaft with 5 u-joints and a hanger bearing along with as much frontal area as a Humvee and you are starting to get the picture. There is no doubt in my mind that in a 3400 lb, 4.11 geared GS that this motor would be capable of running high 10 second quarter miles. The only thing that this means to you is that my car is going to be very sensative to exhaust selection because of the amount of exhaust gas that I am trying to move. It's late and I'm starting to ramble :Smarty: I hope some of this helps. ------------Mark D.
panevac system Mark; You have provided me with a load of info. Hope I digest it all and put to use on my BBB. Thanks again.Ken:grin: :grin: :grin: :grin:
