Crankcase Breather: Who Gets It?
Discussion
I've been talking to the creator of Krank Vent (www.krankvent.com) about implementing his device on my car, but I don't have the service manual section that talks about CBV/PCV operation, only the schematic.
After looking at the schematic he (we) don't understand what the vacuum line that runs from the FPR to the CBV is for and what, exactly, the Non-Return Valve does.
If anyone has a firm understanding of how this system works I'd love to hear from you.
Thanks!
Luke.
After looking at the schematic he (we) don't understand what the vacuum line that runs from the FPR to the CBV is for and what, exactly, the Non-Return Valve does.
If anyone has a firm understanding of how this system works I'd love to hear from you.
Thanks!
Luke.
Luke,
As I understand it, the vacuum line goes to the manifold and is under vacuum at low engine speed (idle) to recirculate the crankcase emissions back into the engine instead of the atmosphere when there is not enough airflow to pull it through the airbox and then to the manifold.
There is a one-way valve in the small line that closes once manifold pressure exceeds crankcase pressure and then the breather system flows through the cbv and airbox as normal.
Basically it bypasses the airbox and cbv under low air flow conditions.
Section EMH.2 page 21 in the emissions supplement.
Hope this helps,
Jim
>> Edited by jk1 on Thursday 10th March 01:56
As I understand it, the vacuum line goes to the manifold and is under vacuum at low engine speed (idle) to recirculate the crankcase emissions back into the engine instead of the atmosphere when there is not enough airflow to pull it through the airbox and then to the manifold.
There is a one-way valve in the small line that closes once manifold pressure exceeds crankcase pressure and then the breather system flows through the cbv and airbox as normal.
Basically it bypasses the airbox and cbv under low air flow conditions.
Section EMH.2 page 21 in the emissions supplement.
Hope this helps,
Jim
>> Edited by jk1 on Thursday 10th March 01:56
If there wasn't a check-valve there, boost would escape through that line.
karmavore said:
Basically what I'm saying is that the manifold reference line that feeds various sensors and the FPR also feeds the CBV (crankcase breather valve) through a "non return valve" and we don't understand why.
Luke.
His initial thought is to just splice it in-between the CBV and the air box and I doubt this new info (thanks guys!) will change that plan.
Have you read the literature on his site?
I think I may just do away with the CBV altogether and route the hose to a catch tank instead of the air box. The only issue I see so far is that the hose coming off the crankcase is 3/4" and the KV is 1/2" and I'm not sure how to step it down.
Luke.
Have you read the literature on his site?
I think I may just do away with the CBV altogether and route the hose to a catch tank instead of the air box. The only issue I see so far is that the hose coming off the crankcase is 3/4" and the KV is 1/2" and I'm not sure how to step it down.
Luke.
I just spoke with Ted (creator of Krankvent) and he is sending me his 1/2 inch unit. He thinks that deleting the CBV and replacing with a KV will net horsepower and help with ring sealing. For the cost (~$90) and the simple install (what, 20 minutes?) it should easily be "worth it."
Luke.
Luke.
Hi,
I have watched this thread for the past couple days. I have researched the website and have to tell you that it really brings out the doubting Thomas in me.
Since the dawn of the internal combustion engine, there has been no end to the number of innovations designed to do this, or increase that. Some have truly offered significant, real world, benefit. These shortly enter the mainstream while others, fade to the backwater.
We've seen any number of better sparkplugs, ignition systems, filters and who will ever forget the proverbial 100MPG carburettor which both GM and the US Govt. purportedly has suppressed for the past 50 years?
Then there are those which may actually work, but amount to little more than a solution looking for a problem.
My suspicion is that this Krank Vent falls somewhere in this mix. Does it truly offer any significant benefit in real world conditions? Sure they may have test data, but of course this is subject to two concerns, the validity of the testing methodology and whether these test conditions are met under real world application. Also, there is the question of how big a problem exists in the first place.
I find their anecdotal hype highly suspect such as '80 years in the making','a US Patent' (realize that patents have been granted on everything from tongue depressors to electro-shock weight reducers), and then my personal favorite - "The same material used in Nuclear Reactors!" - bit of overkill for a car engine don't you think?
Seems to me that if this problem was such an impediment to producing HP, and could be solved by the mere installation of a one-way valve, the automakers would have jumped on the bandwagon years ago. To my knowledge, they haven't.
To me, $90 isn't cheap, and a 3% gain in HP will be barely noticeable (realize that this increase may occur at some extreme in the power band where little time is spent, or benefit derived - what if it only occurs at idle or redline? the Test data would still be technically valid). Also, I am unclear as to how a partial vacuum benefits on the downstroke, but doesn't relinquish that benefit on the upstroke? Or is this where the valve comes into play?
I'm not preaching here, and for those wishing to experiment, please do and let us know the outcome - impirically, not just SOP - Seat of the Pants.
But, take a step back, breathe deep and think of what that same $90 could do to further your maintenance of the car, such as new HT leads, or true mechanical timing of the engine (the 9XX engine is notorious for being off a few degrees), to name just a couple things. These may yield far greater benefit in real terms.
Happy Motoring! ...Jim'85TE
>> Edited by lotusguy on Thursday 10th March 23:44
I have watched this thread for the past couple days. I have researched the website and have to tell you that it really brings out the doubting Thomas in me.
Since the dawn of the internal combustion engine, there has been no end to the number of innovations designed to do this, or increase that. Some have truly offered significant, real world, benefit. These shortly enter the mainstream while others, fade to the backwater.
We've seen any number of better sparkplugs, ignition systems, filters and who will ever forget the proverbial 100MPG carburettor which both GM and the US Govt. purportedly has suppressed for the past 50 years?
Then there are those which may actually work, but amount to little more than a solution looking for a problem.
My suspicion is that this Krank Vent falls somewhere in this mix. Does it truly offer any significant benefit in real world conditions? Sure they may have test data, but of course this is subject to two concerns, the validity of the testing methodology and whether these test conditions are met under real world application. Also, there is the question of how big a problem exists in the first place.
I find their anecdotal hype highly suspect such as '80 years in the making','a US Patent' (realize that patents have been granted on everything from tongue depressors to electro-shock weight reducers), and then my personal favorite - "The same material used in Nuclear Reactors!" - bit of overkill for a car engine don't you think?
Seems to me that if this problem was such an impediment to producing HP, and could be solved by the mere installation of a one-way valve, the automakers would have jumped on the bandwagon years ago. To my knowledge, they haven't.
To me, $90 isn't cheap, and a 3% gain in HP will be barely noticeable (realize that this increase may occur at some extreme in the power band where little time is spent, or benefit derived - what if it only occurs at idle or redline? the Test data would still be technically valid). Also, I am unclear as to how a partial vacuum benefits on the downstroke, but doesn't relinquish that benefit on the upstroke? Or is this where the valve comes into play?
I'm not preaching here, and for those wishing to experiment, please do and let us know the outcome - impirically, not just SOP - Seat of the Pants.
But, take a step back, breathe deep and think of what that same $90 could do to further your maintenance of the car, such as new HT leads, or true mechanical timing of the engine (the 9XX engine is notorious for being off a few degrees), to name just a couple things. These may yield far greater benefit in real terms.
Happy Motoring! ...Jim'85TE
>> Edited by lotusguy on Thursday 10th March 23:44
jim said:
…it really brings out the doubting Thomas in me.
Honestly Jim, do you really want to pretend your "doubting Thomas" is normally buried deep in your psyche?
jim said:
Then there are those which may actually work, but amount to little more than a solution looking for a problem.
From what I understand this device was invented for Harley crankcases that are, apparently, notoriously pressurized and have weeping seals as a result. Form what I hear this device makes a world of difference.
I believe their first foray into the automotive market was a kit developed for Ferraris with the 308/328 engines (308/328/mondial) which suffer from a similar issue.
jim said:
Also, there is the question of how big a problem exists in the first place.
True. Originally the idea for implementing a Krank Vent came up when I mentioned to a friend and Ferrari owner how disgusted I was by the oil in my air box. My original solution was to install a catch can (which I still intend to do) but my friend said that I should try to take care of the problem at the source and try to eliminate the pressure that is causing the oil to be spit out in the first place.
Ok, so how does the pressure enter the crank case... as I understand t two ways, right? Either as blow-by past the rings or, as Tend at Krank Vent explained to me, though the PCV (it looks like Lotus calls this the "non-return valve" in the service manual) which can't keep air from entering the case when on boost.
Of course, if the rings are bad there's not much KV can do I would imagine.
Originally, Ted wanted me to replace the Non-Return Valve with a small KV and then splice in a large one between the CBV (oil separator) and the air box. I decided, however, to just eliminate the vacuum line and the CBV and just run a hose from the crankcase nipple to a KV and then on to a catch can.
What do I think this will do?
Well, if the rings are good and the engine is tight then the gas in the case should be pushed out though the KV and a vacuum created...
Will a vacuum in the case be beneficial? I've been told yes, but you bring up a good point about it causing resistance on the upstroke. This, I guess, I'm taking on faith...
jim said:
I'm not preaching here, and for those wishing to experiment, please do and let us know the outcome - empirically, not just SOP - Seat of the Pants.
What would you like me to do to get empirical data? I doubt I'll put her on the dyno again after making just this mod.
Thanks for the discussion, JIM!!!
Luke.
>> Edited by karmavore on Friday 11th March 05:15
I take the crank case vacuum with a large pinch of salt, you can get depression at part throttle but how long will it take for blow-by gases to bring it back up to atmospheric pressure? Fraction of a second I would have though. Any check valve should be able to prevent boost from reaching the crank case.
Where this device may have benefits is in eliminating the tidal flow in and out of the crank case. The volume of the crank case is continually changing as the pistons go up and down, and that tends to pump air in and out of the breather. With this device acting as a one way valve, instead of pumping air back in, the crank case would go into slight depression. The average pressure would stay more or less the same, slightly over atmospheric pressure, but it would fluctuate up and down. This would cut down on the quantity of gas being blown out and sucked back in, which might allow you to improve the oil separation within the crank case, or reduce the amount of oil being blown out.
Where this device may have benefits is in eliminating the tidal flow in and out of the crank case. The volume of the crank case is continually changing as the pistons go up and down, and that tends to pump air in and out of the breather. With this device acting as a one way valve, instead of pumping air back in, the crank case would go into slight depression. The average pressure would stay more or less the same, slightly over atmospheric pressure, but it would fluctuate up and down. This would cut down on the quantity of gas being blown out and sucked back in, which might allow you to improve the oil separation within the crank case, or reduce the amount of oil being blown out.
I've been riding Harleys since 1979. I own two at the moment, and I have never heard of a problem with the cases preasurizing. They are vented, dry sump, and never had any type of PCV valve, just a hose from the case to the intake which everyone takes off and runs either to the atmosphere or maybe to a little air filter thingie. Oil leaks are a different story and were mostly caused by (earlier) poor tolerances, design, manufacturing and a chain oiling system designed to drip oil on the chain at all times, guaranteeing a leak by design. In their defense, the design goes back to 1936, and try to find me a 1936 anthing that doesn't leak oil. Since about 1985, quality is way up and the chain oiler was removed.
I have also never seen your gizmo at any Harley shop or even ralley such as Sturgis where every gizmo ever thought up is on display.
Dr.Hess
(another skeptic)
I have also never seen your gizmo at any Harley shop or even ralley such as Sturgis where every gizmo ever thought up is on display.
Dr.Hess
(another skeptic)
karmavore said:
Honestly Jim, do you really want to pretend your "doubting Thomas" is normally buried deep in your psyche?
From what I understand this device was invented for Harley crankcases that are, apparently, notoriously pressurized and have weeping seals as a result. Form what I hear this device makes a world of difference.
I believe their first foray into the automotive market was a kit developed for Ferraris with the 308/328 engines (308/328/mondial) which suffer from a similar issue.
Of course, if the rings are bad there's not much KV can do I would imagine.
This, I guess, I'm taking on faith...
What would you like me to do to get empirical data? I doubt I'll put her on the dyno again after making just this mod.
Thanks for the discussion, JIM!!!
Luke.
>> Edited by karmavore on Friday 11th March 05:15
Hey Luke,
Relax... we're all friends here! The only way this forum can offer any benefit as a learning tool is to have frank discussion. I was not lambasting you or your right to install this device should you wish. If this was your impression, I am dismayed. But there are many 'newbies' who lurk on the list and someone as knowledgeable as you can impart info. which quickly becomes 'law' to them.
I am challenged frequently, and am wrong on occaision as well. So be it, I learn, as do others. But the most important thing is that the correct information is passed along.
But, back on point, I have an '85 with no breather valve, just a straight hose take-off to the airbox and while there is an oily film inside, I have no liquid or excess oil in there at all leading me to worry that you may have other problems which this device will simply mask. If so, you're probably better off concentrating on these.
Also, it seems that I am not the only skeptic. I run an Internet Marketing firm and know full well how you can hype DogFood to sound like Filet Mignon, so I am somewhat naturally leery of any ads or websites employing these methods. Mea Culpa.
But, what's important is that in the end, whatever the discussion, ... still friends!
Happy Motoring! ...Jim'85TE
PS "Honestly Jim, do you really want to pretend your "doubting Thomas" is normally buried deep in your psyche?
" ... Frustrated Engineer with only Liberal Arts and Science degrees here... 
>> Edited by lotusguy on Friday 11th March 15:26
Who's not relaxed??? Seriously, did I give an agitated impression??
From what I read on the forums et. al. I don't think my air box is any more oily than most, but I think any oil is gross and this is part of my plan to eliminate the issue. I will also be installing a catch can as well.
I'll let you know how it works out...
Luke.
From what I read on the forums et. al. I don't think my air box is any more oily than most, but I think any oil is gross and this is part of my plan to eliminate the issue. I will also be installing a catch can as well.
I'll let you know how it works out...
Luke.
***UPDATE***
I removed the CBV and installed a Krank Vent in its place this weekend.
LSS: Is it maintaining a vacuum? No. Is it a better, cleaner, overall setup than stock? I think so.
Here's what I did:
I removed the CBC and hose to the air box and "tossed" them aside.
I then stuck a screw in the end of the vacuum line feeding the left side of the CBV. This is a stop gap until I remove the t-fitting and line altogether.
In the end of the short tapered hose that covers the crankcase nipple and in which the CBV is pushed,I stuck a short piece of 1/2 inch ID/ 3/4 inch OD hose. This is to act as a shim as the Krank Vent barbs are only 1/2".
I then stuck the KV into the shimmed hose and clamped it tight with the existing hose clamp.
On the other end of the KV I stuck another short piece of 1/2 inch hose and over that an short piece, maybe an inch, of 3/4 inch hose. I clamped this down tight with yet another hose clamp.
In the open end of this hose I stuck a -12 AN Aero Quip “socketless” hose end.
This is as it is now so that I can monitor airflow out of the KV and how much oil is dripping out. No need for a filter since the KV is a one-way valve.
In a bit I will run a stainless -12 hose from the fitting to a breather tank I have.
This will complete the install.
If any one is sincerely interested I will take pics.
Luke.
I removed the CBV and installed a Krank Vent in its place this weekend.
LSS: Is it maintaining a vacuum? No. Is it a better, cleaner, overall setup than stock? I think so.
Here's what I did:
I removed the CBC and hose to the air box and "tossed" them aside.
I then stuck a screw in the end of the vacuum line feeding the left side of the CBV. This is a stop gap until I remove the t-fitting and line altogether.
In the end of the short tapered hose that covers the crankcase nipple and in which the CBV is pushed,I stuck a short piece of 1/2 inch ID/ 3/4 inch OD hose. This is to act as a shim as the Krank Vent barbs are only 1/2".
I then stuck the KV into the shimmed hose and clamped it tight with the existing hose clamp.
On the other end of the KV I stuck another short piece of 1/2 inch hose and over that an short piece, maybe an inch, of 3/4 inch hose. I clamped this down tight with yet another hose clamp.
In the open end of this hose I stuck a -12 AN Aero Quip “socketless” hose end.
This is as it is now so that I can monitor airflow out of the KV and how much oil is dripping out. No need for a filter since the KV is a one-way valve.
In a bit I will run a stainless -12 hose from the fitting to a breather tank I have.
This will complete the install.
If any one is sincerely interested I will take pics.
Luke.
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