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PCV - Yes, No for Street

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Discussion starter · #41 ·
Steiner said:
If you are concerned about crankcase vapors leeching into the brake booster while running a single vacuum line for both PCV and booster, there is a very small canister filter that can be installed inline at the booster. It is in the Help! aisle at most auto parts stores and was used on C3 and C4 Corvettes. Part number is 80195 and I have one on my car. Also, the check valve on the booster should prevent most positive pressure from pushing anything into the booster.

I'll be the second one to say T'ing into the booster line is fine. What is the difference since they both are connected to manifold vacuum? They "T" inside the manifold anyway.

Image
Click to expand...
I assume this is just installed into line between line and booster and
not installed in the booster itself. Will it effect vacuum. Do not have
much now (7-8). Also, does having the pcv line "t" in effect vacuum
for my brake booster.

Few other questions: since i have no baffle in vc due to stud girdle,
worried vapors may be really oily and could"clog" filter which may
effect vacuum to booster. Next question: if pcv is "t" with booster
and fitting is in the intake, wold vapors foul out plugs. Most people
have pcv in carb or spacer and it gets burned off. As I said earlier,
no baffles so vapors may be more oily then usual and worried where
fitting is it can foul out my plugs. Incase you need to know, fitting in
the intake is located in middle of base behind carb (basically in front
or the distributor.
 
#42 ·
I tee'd my PCV into my power brakes once and the brakes felt funny, so I removed the PCv and moved it to the front. I just think the booster needs a to "see" a solid vacuum signal...or at least as much as possible.
 
#43 ·
Ramrodd 69 said:
I assume this is just installed into line between line and booster and
not installed in the booster itself. Will it effect vacuum. Do not have
much now (7-8). Also, does having the pcv line "t" in effect vacuum
for my brake booster.

Few other questions: since i have no baffle in vc due to stud girdle,
worried vapors may be really oily and could"clog" filter which may
effect vacuum to booster. Next question: if pcv is "t" with booster
and fitting is in the intake, wold vapors foul out plugs. Most people
have pcv in carb or spacer and it gets burned off. As I said earlier,
no baffles so vapors may be more oily then usual and worried where
fitting is it can foul out my plugs. Incase you need to know, fitting in
the intake is located in middle of base behind carb (basically in front
or the distributor.
Click to expand...

The vapors are the same baffles or not. What you would be more concerned with is sucking actual oil up with no baffles. That's what they do...they keep oil from splashing on the valve. What you could do is run a catch can or similar device like an air compressor water separator off the PCV if you are concerned. It is essentially a can with a port on each side. You install the PCV as usual then run vacuum line to the inlet on top of the catch can and then from the outlet on the top of the catch can to the intake. Oil pulled in would drop into the catch can and it would be drained periodically. If you've ever used a hand held brake bleeder vacuum pump you've seen the same thing in action.

Yes, the filter is installed in the line at the booster. It is just a charcoal filter and does not affect vacuum.

I have single vacuum port on my engine on the base of my EFI throttle body and run PCV, booster, and in-car vacuum gauge from it. My car makes around 11" at idle, over 16" at light load. This is what helps your booster charge. It doesn't take much time at a higher vacuum level to charge your booster, then the check valve keeps it charged. If you do nothing but sit in traffic, let off the brake, and then reapply the brakes the booster is going to get drained and not recharge to a high level of vacuum. With the engine off, I can use a hand pump to put 16" of vacuum on my booster and leave it overnight and it will still be at 16" the next day. Ever notice you always get a couple of good pumps of the brakes before they go hard when you shut the car off? That's the booster reserve which the check valve is responsible for.

The only issue I could see is if someone ran the incorrect PCV for their application and it was wide open all the time. If the main vacuum line supplying both the booster and PCV were undersized then the PCV might take all the available vacuum. I do not currently have this problem.
 
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#44 ·
Radcannon said:
The crank case has no ability to create pressure in the system unless there is a air leak to pressurize the case. The PCV system is more than adequate, Arent you the same guy that said he's seen a motor make 25kpa of base pressure on a dyno? that equates to over 3.5 psi.Do you think a pcv valve and line that are under no vacuum will ventilate a much larger and powerful engine at full throttle? An engine is an air pump both above and below the pistons.You can also gain 30-40hp on a 750hp motor with a vacuum pump as well as keep your engine bay clean .Its been proven many times.
Click to expand...
 
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#45 · (Edited)
vonzipper396 said:
Radcannon said:
The crank case has no ability to create pressure in the system unless there is a air leak to pressurize the case. The PCV system is more than adequate, Arent you the same guy that said he's seen a motor make 25kpa of base pressure on a dyno? that equates to over 3.5 psi.Do you think a pcv valve and line that are under no vacuum will ventilate a much larger and powerful engine at full throttle? An engine is an air pump both above and below the pistons.You can also gain 30-40hp on a 750hp motor with a vacuum pump as well as keep your engine bay clean .Its been proven many times.
Click to expand...
The amount of gain all depends on size and rpm of engine and the pressure change. A 25 kpa pressurizing of the engine crank case was due to sustained high rpm that clogged the PCV line with oil and was a combination of ring flutter too in one of the cylinders. Oil atomization in the valve covers was sufficient to be pulled into the PCV system and clogg it due to pulling vacuum through it at a high enough rate to have oil pool. A vent to atmosphere wouldn't have done this.

http://nutterracingengines.com/racing_oil_pumps/crankcase_vacuum_facts.html
There is info straight from the mouth of a racer. Read that and you should understand, no 40 hp on a NA engine. It is used to help seal rings mainly just like gas ported pistons. It increases pressure differential across the ring to allow low tension rings which is where most of the power will come from. It might be possible to get 30 hp on an 7500+ rpm motor that has low tension rings and is benefiting from windage losses too and piston work. On drag motors with power adders which require ring modifications such as larger gaps that produces higher blow by its more important.


Now if you want a street vacuum kit that looks good and makes maybe 15 hp more here you go... Only $610.
http://www.gzmotorsports.com/street-pump-kits.html

Here talks about it a little more. They claimed 30hp on a 555CI chevy using the sportsman pump at 20" of vacuum, thats huge. You need a relief valve, and that is the worst thing you can do IMO. Pull that large of vacuum and unfiltered air into the crank case significantly effects engine life, to me not worth 30 hp http://www.dragstuff.com/techarticles/vacuum-pumps.html
Click to expand...
 
Discussion starter · #46 ·
Steiner said:
If you are concerned about crankcase vapors leeching into the brake booster while running a single vacuum line for both PCV and booster, there is a very small canister filter that can be installed inline at the booster. It is in the Help! aisle at most auto parts stores and was used on C3 and C4 Corvettes. Part number is 80195 and I have one on my car. Also, the check valve on the booster should prevent most positive pressure from pushing anything into the booster.

I'll be the second one to say T'ing into the booster line is fine. What is the difference since they both are connected to manifold vacuum? They "T" inside the manifold anyway.



Image
Click to expand...
Thoughts on this idea. What if i put a filter in each line (thinking of
using clear fuel filters at local parts shop. This way I can see if I may
have any issues with each line. What I would look for in PCV line is
how much oil may be sucked from crankcase since have no baffles in
vc due to girdle and see how much oil or oily mist may go to booster
since the lines are "T" together. But also, would these filters also
effect vacuum which is needed for my power brakes. Of course, I
would replace filters when they get clogged, oily
 
#47 ·
Ramrodd 69 said:
Thoughts on this idea. What if i put a filter in each line (thinking of
using clear fuel filters at local parts shop. This way I can see if I may
have any issues with each line. What I would look for in PCV line is
how much oil may be sucked from crankcase since have no baffles in
vc due to girdle and see how much oil or oily mist may go to booster
since the lines are "T" together. But also, would these filters also
effect vacuum which is needed for my power brakes. Of course, I
would replace filters when they get clogged, oily
Click to expand...
You don't want a filter in both lines. The filter is stop fumes from coming back from the intake area into the booster. If you put one in the PCV line and tried to pull through it you would most likely clog it in short order.

Look around and see how guys set up an oil separator. It is back a couple of posts. Look into a catch can.

Please read this to get an understanding.
http://www.eliteengineeringusa.com/Catch_Can.html

You can find them less expensive if you search around. Lots of import sites sell them. You can also make your own using an air compressor water trap.


...
 
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#49 ·
Ramrodd 69 said:
Thoughts on this idea. What if i put a filter in each line (thinking of
using clear fuel filters at local parts shop. This way I can see if I may
have any issues with each line. What I would look for in PCV line is
how much oil may be sucked from crankcase since have no baffles in
vc due to girdle and see how much oil or oily mist may go to booster
since the lines are "T" together. But also, would these filters also
effect vacuum which is needed for my power brakes. Of course, I
would replace filters when they get clogged, oily
Click to expand...
I don't think that would be bad, a catch can would be better, but the clear sight with the fuel filter element removed should be great for you. Just when you see oil in there your only option is to remove it and replace the lines, because that means you have significant build up in your lines.

If you really want to T it to your brake booster you will need a catch can I wouldn't feel safe any other way. At one WOT pass for a sustained period you will fill that sight glass and put oil in the booster. Oil at higher rpms without correct baffling is pretty huge, especially if you are pulling vacuum from a source in the carb.
 
#50 ·
The chance of getting oil in the booster isn't anything I'd worry about, never does the vacuum drop below zero and turn to pressure so it's an insignificant concern.

This is pretty simple in my opinion, if you have enough manifold vacuum to run power brakes it's a no brainer to run a PCV off a baffled source there are no draw backs to it.
 
Discussion starter · #52 ·
What I did was the brake booster vaccum line is on the manifold behind
the carb and I drilled a port on carb base and pcv line was installed there Decided against "T"ing the lines together. Brakes are OK but a little less
braking power then before but I guess its from the bigger installed cam,
Engine runs strong, easily smokes tires. Thanks for all the replies
 
#53 ·
How the hell can oil or fuel get into the booster
The vac is pulling TOWARDS the engine...there is no flow towards the booster
Hence why there is no need for any valves or tanks other than the booster valve and all that does is trap the great amount of nothing (vac ) in the booster
 
#54 ·
Steptoe said:
How the hell can oil or fuel get into the booster
The vac is pulling TOWARDS the engine...there is no flow towards the booster
Hence why there is no need for any valves or tanks other than the booster valve and all that does is trap the great amount of nothing (vac ) in the booster
Click to expand...
I was thinking the same thing, it's kind of like how the heck do you get fuel into the vacuum advance unit since the vacuum is being pulled towards the carb... Maybe when the vacuum drops to near zero during WOT, but even then there should be a little vacuum still pulling whatever to the source.
 
#56 ·
Steptoe said:
How the hell can oil or fuel get into the booster
The vac is pulling TOWARDS the engine...there is no flow towards the booster
Hence why there is no need for any valves or tanks other than the booster valve and all that does is trap the great amount of nothing (vac ) in the booster
Click to expand...
How does oil get anywhere it doesn't belong? Take a look around your PCV valve near the valve cover. See that oily film?

Also on engine shut-down, no more vacuum is present and nasty crankcase fumes escape anywhere they can. These vapors include acidic blowby, a byproduct of combustion.

The brake booster isn't a good place for this foulness.
 
#57 ·
When I plumbed my booster to the manifold, I found an old line and fittings already setup for a booster in my box-o-stuff.

In the middle of the line was a check-valve. I think I pulled this off a 1980-ish Chevy pickup. I seem to have two of them with this check-valve inline to the booster.
I noticed it gives me a short period of time where I still have some vacuum assist even with the engine off. At least I assume that's why.

I'm wondering if this valve is helping to protect my booster from that blowby crap and nasty buildup?
 
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