My experience with increasing crankcase vacuum...Not Good

[HP]

Hypothetically, increasing crankcase vacuum seemed to have only good things
associated with it. So I hooked up 2 Krankvents(one way vents allowing
air to exit but not enter crankcase) - one inline with PVC valve and the other
in the vent hole normally vented to the breather. Not only did my motor run
sick at idle - it seemed less responsive at other RPM's. The really puzzling
thing was an annoying whine coming from the front of my motor, like a dry bearing,high pitched, squealing noise. I pulled the dipstick to measure the
crankcase vacuum at which the noise started - and it appeared around 7in. HG
I e-mailed the Krankvent company - and they said the only other such complaint
was on a Z06 Vette. The report from the Vette was of a teapot whistle noise,
and they assumed it was from air being pulled in around the crank seal. My
noise was more like metal on metal. I'm stumped. Has anyone else adapted
some sort of vacuum assist for the crankcase - and if so - has anyone experienced anything out of the ordinary? Also at idle my car is usually right
on 14.7 A/F - but with the crankcase vacuum increased - it ran around 22 to 24
What gives?

 

[1TONY1]

What did they say about the car running bad and the a/f ? Did you check the vacuum in a rev or higher rpm ? Have you tryed taking the pvc out of line?

 

[HP]

What did they say about the car running bad and the a/f ? Did you check the vacuum in a rev or higher rpm ? Have you tryed taking the pvc out of line?

The Krankvent Co. was quick to respond to my first e-mail - but I haven't checked
for a response on my last e-mail about the A/F reading, and to emphasize that
my noise was metal on metal instead of a whistling vent noise.
When I first installed the Krankvents, I didn't get out of the driveway -
before the noise started - and when I was testing the car later - I was under
the hood - so even though I went through the RPM - there was never a load on
the motor. I'm sure at higher RPM, at real driving conditions, the response
would be different. It just seemed that the increased crankcase vacuum was
strangling my motor at no load RPM's, and idle, and it bothers me that I can't identify the reason. The first response from Krankvent - was to remove the second
Krankvent, and only leave one vent inline with the PVC valve.
Actually - I removed the PVC valve - because it was redundant next to the
Krankvent and seemed to only restrict air flow. The A/F ratio was only
lean at idle, the reading at higher RPM were ok.
I still think there are merits to this type of setup or other alternative
vacuum assist devices - but if the crankcase vacuum is more than 5in HG at idle- there may need to be some sort of bypass at idle -
such as a Hobbs switch that activates a solenoid to bypass, and vent, at low oil pressure(or low RPM).

 

[1TONY1]

Interesting, Let me know what happens. Which w/b do you have ?

 

[HP]

Interesting, Let me know what happens. Which w/b do you have ?

Tony, are you out of your memory pills again, you know I have a TechEdge 1.5

You do have a TechEdge --- right?

 

[1TONY1]

Memory.....what is that ? I knew somebody had the 1.5 but wasn't for sure it was you. Where did you pick up the signal to record rpm ? Mine is the 1.0 and will not record anything but a/f. I was going to get the 1.5 box but now they are working on a 2.0.

 

[HP]

Memory.....what is that ? I knew somebody had the 1.5 but wasn't for sure it was you. Where did you pick up the signal to record rpm ? Mine is the 1.0 and will not record anything but a/f. I was going to get the 1.5 box but now they are working on a 2.0.

I was just giving you a hard time - about the memory thing, but you did
trade e-mails with me on my install. I tapped into one of the coil (-) trigger wires off the PCM. However, I have only utilized the illuminated
display, I haven't had a chance to hook up a palm pilot. Easy install, works
like a charm - give me security. As a poser mod - it gets old, explaining
the function to onlookers

 

[MES]

I tried a krank vent with no problems. This was with the supercharger. No PVC valve (or other air inlet/outlet) krank vent connected to the air box, then to the "T" into the front valve covers. It seemed to have no effect either way (in or out) can't tell a difference.

 

[HP]

I tried a krank vent with no problems. This was with the supercharger. No PVC valve (or other air inlet/outlet) krank vent connected to the air box, then to the "T" into the front valve covers. It seemed to have no effect either way (in or out) can't tell a difference.

I HAVE USED 'A' KRANKVENT FOR A LONG TIME - the problem arises when you add
the second krankvent to the the other valve cover. It's the 'Boa constrictor
effect' - it allows each cover to breath out - but not breath in(which in theory - sounds good). The Krankvent, itself, is a good quality one-way vacuum valve and it has been
used with success for years in V-twin motorcycles(with sealed off crankcases). I am a loyal customer. The idea of using one
in the PVC (intake) line for S/C motors is also a good idea. I really don't
know how many car motors the dual setup has been tried on - they advertise it
for 2 car motors(only) with an S/C setup(any other use is, in a way, experimental).
Car motor oil circuits are far more complicated that a twin engine cycle motor.
There are, apparently, some variables that are unknown. It could just be
a fluke with my motor, so any info I can get on dual Krankvents(or any other
vacuum assist device) that pulls more than 7in crankcase vacuum at idle, on a Viper motor would be appreciated.

 

[Greg Good Cylinder Heads]

Hugh, just be careful with the total amount of vacuum you run on a wet sump system. 9 to 10 inches is about the limit. Anything above that makes it difficult for the oil pump to pick up oil from the pan, and can reduce oil pressure. The oil pump in essence has to compete with the vacuum pump for the oil. Dry sump systems aren't affected by this and you can run 20+ inches. It all has to do with pressure the differential between the pan and the innards of the pump.

All of the vacuum setups I have knowledge of don't produce much vacuum at idle and reach maximum vacuum after the engine is somewhat up in the rpm range. An engine with a lot of vacuum at idle, where the oil pump is not turning very fast, could cause an oil supply problem.

If you're worried about having hurt some parts, remove the oil filter and cut it open and see if there's anything in there other than the usual valve spring retainer metal, etc.

I'm not picturing real well how you have the pumps set up. Does the pump that is tapped into the PVC hose have access to the intake manifold? Could it be possible that the pumps are drawing air OUT of the manifold at idle and causing problems? Just a thought.

 

[HP]

Greg, the Krankvents are a one way valve only, much like a PVC valve. They
have been around a while, mainly limited to big V-twin cycle motors. But unlike a PVC setup - they normally are used on a motor that has all other vents
to the crankcase closed. They work wonders for what they were originally intended to do - control crankcase pressure, and stop oil leaks in Harley type
V-twin motors - with almost no crankcase air reserve, a semi-dry sump type
oil system, and cranks with roller bearings. Usually one vent is used on bikes but they recommend 2 vents for motors over 100ci(usually one to vent
the bottom end and one to vent the top end. These motors have a mechanical
vent(scavenging) system, but a lot of the effect is from the large pulsed, + and
-, that are inherit with the large pistons, and the vents allow pressure to vent, but hold in negative pulses(vacuum). V-twin bike motors don't use intake vacuum to vent the crankcase. Their use in cars, evolved from the
need of a better PCV valve to handle the intake pressure from S/C motors.
More info is available on their website. They promote the dual Krankvents
for two factory S/C cars - (can't recall which two)
The were quick to respond to my problems. My concern was like yours - Greg.
I wondered if the vacuum was working against the oil pump. They downplayed
that, and compared my situation to another complaint, from a ZO6 Vette, that
apparently was sucking air through the crank main seal - and getting a whistling noise. It don't take a lot of extrapulation to assume if air is
displacing oil on a main journal, my description of, metal on metal, noise is
not just my imagination. Is it just, my motor, or Viper motors in general,
I don't know. My motor seems solid and has never leaked any oil - ever.
The Krankvent company recommended I only use the vent to replace the PVC valve,
and to vent the other valve cover with a filter. Maybe it wouldn't happen with
another Viper motor, or maybe the vacuum profile of this product as related
to RPM is not the answer for the Viper. I'm not drawing any conclusions,
just stating what I experienced. I know I didn't hurt my motor because the noise was observed at no load, and I immediently shut it off.

 

[Greg Good Cylinder Heads]

Did you notice a drop in idle oil pressure with both pumps on? Just curious.

I think your idea of switching at least one off at idle is a good idea. That's not when they're really needed anyway.

I'd like to know how much vacuum these pumps are able to pull while making a pass. If they can maintain 8 or 9 inches between 4000-6500 that would be great. A guy could lower his oil ring tension and make more power from reduced ring drag without an oiling problem.

 

[HP]

I can't really say what the oil pressure gauge did, I meant to check it on the last go round. I'm satisfies at retaining the one as a PCV valve - and keeping
the mini-filter on the other valve cover. I'll just use the leftover vent on
my motorcycle. I have never noticed any signs of abnormal crankcase pressure,
I just thought the idea sounded good to seal the rings. The single vent should
help some.

 

[FE 065]

Where\'s my PVC?/Moroso adj vacuum relief valve etc

Sorry for being so blind, but I just don't see a PVC valve on my 2002GTS. I see the lines running from the valve covers and going to the airbox. but no PVC. Moroso makes two vacuum relief valves that are adjustable by shimming for the max vacuum you want to hold in your crankcase. Part #22639, go to their website and search by part#. The Krankvent sounds good, but you're engine is pumping out the pressure. I'm thinking of adding an electric pump, seems like there'd be more HP to be had. I'm not going to have it ON all the time, just when racing, so I'd need something to allow automatic switching from normal crankcase venting to when I turn the pump on.

 

[HP]

Re: Where\'s my PVC?/Moroso adj vacuum relief valve etc

It seems I've read that the newer cars don't have a standard inline PVC valve.
I would assume that if one of the vent lines runs to the intake - then there
is a one-way valve incorporated somewhere. Any setup that reduces crankcase
pressure at high RPM will aid ring sealing, just pick a system that does not
overwhelm the motor at idle - but still be effective at WOT.

 

[FE 065]

Re: Where\'s my PVC?/Moroso adj vacuum relief valve etc

Was your OEM oil fill cap okay when using the Krank Vent? I see there's an O-ring on it..the Krank Vent company mentions something about making sure there's no seepage thru the fill cap. Did you use their Turbo kit with the dual vents? (sounds like it) Though if Krank Vent recommends two vents on hi-rpm and bog bore motorcycles, how would two vents create a problem on your car if the vacuum reading was 10in or less?
Mated with the Moroso adjustable vacuum bleeder it might a good setup. Simpler to install than an electric pump and the associated hardware needed with it.

 

[HP]

Re: Where\'s my PVC?/Moroso adj vacuum relief valve etc

The Krankvent instructions are quite generic and try to cover a lot
of possibilities for crankcase leaks - BUT IN THE VIPER - THE CRANKCASE IS
ALREADY AIR TIGHT - At first I worried about my dipstick not sealing good
enough - but with the 2 vents and the motor idling - I could barely break the
vacuum seal and pull it out. The oil fill cap forms an air tight seal.