case and head vents, do I need to run a breather box? |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
case and head vents, do I need to run a breather box? |
wayne1234 |
Jan 22 2010, 11:23 PM
Post
#1
|
Member Group: Members Posts: 260 Joined: 6-April 09 From: indianapolis in Member No.: 10,238 Region Association: None |
Ok dual webber carbed 2.0, I think the PO had the head vents running to a T then to the oil breather near the oil cap... Is this right?? I did a search and now I'm really confused,,,,
|
Mike Bellis |
Jan 24 2010, 11:24 PM
Post
#2
|
Resident Electrician Group: Members Posts: 8,345 Joined: 22-June 09 From: Midlothian TX Member No.: 10,496 Region Association: None |
You could do what the V8 drag racers use. Crank case vacuum scavenger tubes welded to the exhaust. They create negative pressure in the crank case and help to seat the rings better and reduce blow by. This setup is not legal to run on the street but know one really checks for this set up. To use it correctly you will need check valves on the scavenger tubes. You would also run a sealed case, no vents other than the valve covers.
|
ME733 |
Jan 26 2010, 08:20 AM
Post
#3
|
Senior Member Group: Members Posts: 842 Joined: 25-June 08 From: Atlanta Ga. Member No.: 9,209 Region Association: South East States |
You could do what the V8 drag racers use. Crank case vacuum scavenger tubes welded to the exhaust. They create negative pressure in the crank case and help to seat the rings better and reduce blow by. This setup is not legal to run on the street but know one really checks for this set up. To use it correctly you will need check valves on the scavenger tubes. You would also run a sealed case, no vents other than the valve covers. .....................well you have brought up another way to vent the crankcase, which has been used. I disagree that this system helps to "seat the rings"..it,s an old wifes tale. Rings seat, or not, based on assembly, type,cylinder wall preperation, type rings,and poor/or good assembly techniques,among other factors, etc., and if there is negative crankcase pressure..it would tend to increase ring blowby not reduce it. I Have used , the (negative pressure) crankcase ventelation, to exhaust system...collector...on race engines in the past.(quite a few years ago). The problem with a stock exhaust system (on the 914) is there is no collector .(except the bursche) and it,s too far away.(a plumbing zoo).routing to just one cylinder exhaust tube would be the solution, but not very effective. The essence of this system is that it CAN create NEGATIVE crankcase pressure. this too can cause engine leaks, valve cover seal problems, etc. The best installation is to have an open -to the atmosphere-vent for the crantcase itself. (some v-8s) have valve cover "breathers". Replacing the filler cap, on a 914,(or something similar) with a filtered, screened cap would probabley work, or a filtered breather hose connected to the filler box, just something to help,equalize the the crankcase pressure...when routing to the exhaust system. Murray |
Lo-Fi Version | Time is now: 17th June 2024 - 05:11 AM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |