Re: Header evac. bung...where to weld?
[Re: jlatessa]
#1594242
03/17/14 11:52 AM
03/17/14 11:52 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
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Romeo MI
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Quote:
Just one side, passenger, thinking to avoid trans. linkage.
Eight o'clock on that side and looking at it from the rear?
Thanks...Joe
Map out the hose routing and see where it works out the best... try to split the distance between the end of the primaries and the end of the collector... if you keep the check valve in the collector you will burn it out if you have back pressure from the exhaust and if you plan on running the exhaust at the track you better check the back pressure first... anything over 4"hg it would be a PROBLEM... if the pressure is to much you will start to pressurize the crank case
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Re: Header evac. bung...where to weld?
[Re: MR_P_BODY]
#1594243
03/17/14 12:04 PM
03/17/14 12:04 PM
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Joined: Aug 2009
Posts: 1,317 Ohio
jlatessa
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I'm running a 3" full X system out the back hoping I will still run 95 percent of potential. You think I will see back-pressure at that point in the collector?
But I will check for back-pressure before I use it, thanks. What type/brand check valve should I look for?
And should it be far enough away from heat so it lives?
Joe
P.S. this is an old MP .484" degreed to shift at 5500, trap at 6000
Last edited by jlatessa; 03/17/14 12:10 PM.
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Re: Header evac. bung...where to weld?
[Re: Clanton]
#1594245
03/17/14 12:20 PM
03/17/14 12:20 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Quote:
I put it to the outside of the car and you can Tee from both valve covers to draw from both sides.
Remember that with this set up your looking for volume.. the crank case is a fairly large area... the bigger the tube and hoses the better
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Re: Header evac. bung...where to weld?
[Re: jlatessa]
#1594246
03/17/14 05:30 PM
03/17/14 05:30 PM
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Joined: Oct 2003
Posts: 7,506 Az
Crizila
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Quote:
Hi guys, need to put a evac. bung in my headers and need some experiences on where it will have the least interference with floor pan, frame rails etc.
This is on a 70 Charger, 440, Hooker Super Comps. 1-7/8" 727.
Haven't had the engine in yet so don't have a feel for the best location.
I'm going to use the normal PCV to intake manifold for the street but want to hook PCV to the bung for the track to preclude any oil messing up my mixture.
Anyone have this set-up or can give me some guidance so I can do this once, correctly??
Thanks,
Joe
Despite what some may say, there is no correct way to to combine an open crankcase evac system ( PCV ) with a closed system (exhaust evac system ). The exhaust evac system is not ment to be run with a full exhaust system. No matter how sophisticated it is or where you mount your evac bungs, with a full exhaust system, your check valves will be under pressure most of the time - until they burn through that is. So, the exhaust system will, for the most part, just be going along for the ride. The exception might be at idle or maybe slightly above idle, when the flow past the bungs creates a vacuum greater than the back pressure. With the PCV tied in, manifold vacuum would probably pull the check valves closed anyway. At any rate, for the most part, the exhaust evac system will be pretty much useless and the PCV system will pretty much work as designed. The bad thing is the exhaust check valves burning through - not only pressurizing the crankcase, but possibly feeding hot exhaust gas in to the intake manifold via the PCV valve, which is tied in. In regards to running the combined systems with open headers; you just took a closed system (exhaust evac ) and put a hole in it ( PCV ) making it not very efficient. As far as bung location goes, most suggest an arera right where the primary pipes converge in to the collector and at a 45 degree angle down stream. I actually located mine in the collector extension. At idle with a very scimpy exhaust system, I can pull about 3-4 " of H20 vacuum. Anything above about 1500rpm, the check valves close under pressure and the crankcase starts to build pressure pretty rapidly ( closed system). Mine is a race only application. I only run an exhaust system past the collectors when I am running the engine in my garage at home for some other test purpose. Even at that, I test and once a year replace ) the check valves as a failure there can have bad consequences.
Fastest 300
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Re: Header evac. bung...where to weld?
[Re: Crizila]
#1594247
03/17/14 05:33 PM
03/17/14 05:33 PM
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Joined: Oct 2003
Posts: 7,506 Az
Crizila
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Water monometer testing my exhaust evac system with a "full" exhaust system installed. Goes under pressure at about 1500 rpm.
Fastest 300
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Re: Header evac. bung...where to weld?
[Re: Crizila]
#1594248
03/17/14 06:17 PM
03/17/14 06:17 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Quote:
Water monometer testing my exhaust evac system with a "full" exhaust system installed. Goes under pressure at about 1500 rpm.
From the data you show your exhaust is quite restricted and I assume you did that for the neighbors... I know my buddies son runs them on the street but I dont know how high he turns it on the street
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Re: Header evac. bung...where to weld?
[Re: MR_P_BODY]
#1594249
03/17/14 06:45 PM
03/17/14 06:45 PM
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Joined: Aug 2009
Posts: 1,317 Ohio
jlatessa
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Well, I'm obviously going to do some tests after I get this thing together. I may just use the vapor separator I originally bought to precipitate the oil vapors pulled in by the intake vacuum and be done with it!! Looks like too many negatives versus the positives for a full exhaust use. Thanks guys, all the info appreciated ...Joe
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Re: Header evac. bung...where to weld?
[Re: Crizila]
#1594250
03/17/14 07:22 PM
03/17/14 07:22 PM
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Joined: Oct 2003
Posts: 7,506 Az
Crizila
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Quote:
Water monometer testing my exhaust evac system with a "full" exhaust system installed. Goes under pressure at about 1500 rpm.
With all the exhaust system hype that goes around, wonder how many actually measure back pressure. A questions for your buddies. Off my 3" collectors my system is 3" to 2 chamber 3" in and out mufflers to turnouts in front of the axle. As I said, any back pressure at all closes those valves and then you got nothing except a pressurized crankcase - often accompanied by lots of oil leaks . In order for the crankcase to vent, it has to overcome the exhaust back pressure. Actually, the PCV system is a very efficient ( and forgiving ) system. It really wasn't designed as an evac system, but an emissions system ( why it often gets a bum wrap). When it's suckin, it does maintain a very slight vacuum in the crankcase. If your motor is a little tired, it will vent to the atmosphere ( breather), or the air cleaner ( inlet side of the carb )at higher rpm's. IMO, the next best thing to running a pcv system for the street is to just vent both valve covers to the atmosphere - via old school.
Fastest 300
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Re: Header evac. bung...where to weld?
[Re: Crizila]
#1594251
03/17/14 08:23 PM
03/17/14 08:23 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
Quote:
Water monometer testing my exhaust evac system with a "full" exhaust system installed. Goes under pressure at about 1500 rpm.
With all the exhaust system hype that goes around, wonder how many actually measure back pressure. A questions for your buddies. Off my 3" collectors my system is 3" to 2 chamber 3" in and out mufflers to turnouts in front of the axle. As I said, any back pressure at all closes those valves and then you got nothing except a pressurized crankcase - often accompanied by lots of oil leaks . In order for the crankcase to vent, it has to overcome the exhaust back pressure. Actually, the PCV system is a very efficient ( and forgiving ) system. It really wasn't designed as an evac system, but an emissions system ( why it often gets a bum wrap). When it's suckin, it does maintain a very slight vacuum in the crankcase. If your motor is a little tired, it will vent to the atmosphere ( breather), or the air cleaner ( inlet side of the carb )at higher rpm's. IMO, the next best thing to running a pcv system for the street is to just vent both valve covers to the atmosphere - via old school.
I just run a pair of breathers on the covers on my Rampage.. its a street mainly car
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Re: Header evac. bung...where to weld?
[Re: STEFF]
#1594254
03/19/14 12:34 PM
03/19/14 12:34 PM
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Joined: Aug 2009
Posts: 1,317 Ohio
jlatessa
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Well I've decided to run two breathers at the track and for the street, PCV through the precipitator bowl. Soooo, no drilling and welding on my new coated hookers! Thanks for all the input folks, Joe
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