PCV bypass for VW 2.0 FSI Description/DIY (long)

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FYI here is my pcv bypass system as installed. This info might be helpful for those with the FSI or others who want to know about the "exhaust slash cut" pcv bypass for application to other cars. All comments welcome. I am especially interested to know if anyone thinks hp will improve with this system or if you have thoughts on how it will affect oil condition.

As you may know, this engine is really hard on oil and stalwarts such as GC, Redline, Amsoil, etc. all shear pretty quickly. I will test oil for TAN and TBN to try to see what affect (if any) eliminating the pcv will have on oil condition.

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Materials needed:

A. Moroso check valve Part No 97800

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B. Moroso exhaust nipple Part No 97810 (you could easily make your own but not worth the trouble for the cost IMO)

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C. 7-8 feet of 5/8” high temp heater hose and two hose clamps

D. One ¾” freeze plug for intake pcv

E. One ¾” freeze plug for pcv line on rear of valve cover

F. One 1” freeze plug and one hose clamp to seal off rear pcv line to turbo

Cost:

Moroso check valve $20
Moroso nipple $10
Hose $80
Exhaust shop to install nipple $50
Hose clamps and plugs $15

$175 total

Method:

1. Weld in nipple into exhaust pipe post-cat and post-sensor, screw on check valve to nipple. Orient nipple at 45 d3grees according to instructions located here http://www.moroso.com/catalog/...t.pdf I had an exhaust shop do mine. That is not a garden hose, before you ask ha ha, it's a silicon heater hose
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2. Remove engine cover and remove front “accordion” line from pcv to intake
3. Insert ¾” freeze plug into intake and tighten but don’t tighten too much. Or use some other plug method.
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4. Remove hose clamp for rear pcv line where rubber hose connects to back of intake manifold and pull hose away from valve cover. Note metal line bends easily making hose removal easier.
5. Plug valve cover outlet at rear pcv line with another ¾” freeze plug or some other plug method. Don’t over tighten
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6. Plug metal rear pcv line by inserting 1” freeze plug into the rubber hose and then hold in place with a hose clamp (probably better methods for this but this works fine and is fast). Or use some other plug method.
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7. Run a heat resistant heater hose from pcv on front of valve cover to the check valve on the exhaust. I ran mine around the engine and down by the exhaust and then back. Pretty easy to do. Very accessible. Secure with metal ties ideally or zip ties so hose doesn’t flop around. Secure both ends with hose clamps.
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8. Replace engine cover.

Objective:

Eliminate source of valve deposits while maintaining a maintenance free, simple system with adequate crankcase evacuation. VW themselves, in the patent for this engine, say that eliminating the PCV would solve the deposit problems but they can’t due to emissions:

"Gasoline engines with direct injection of the fuel into the combustion chamber, i.e., not into the intake port, suffer especially from the problem of the formation of carbon deposits on components.

...the successful ignition of the stratified charge depends to a great extent on the correct development of the internal cylinder flow, which ensures reliable transport of the injected fuel to the spark plug to guarantee reliable ignition at the spark plug. However, a coating of carbon deposits in the neck region of the intake valve may interfere so strongly with the tumble flow that ignition failures may occur there as a result.

...Furthermore, the coating of carbon deposits in the neck region of the intake valve causes flow resistance, which can lead to significant performance losses due to insufficient cylinder filling, especially in the upper load and speed range of the internal combustion engine. In addition, the carbon deposits in the neck region of the intake valve may prevent correct valve closing, which leads to compression losses and thus sporadic ignition failures.

...These deposits on the valve stem can result in flow deficits due to undesired swirling and turbulent flow around the globular carbon deposits. This may persistently interfere with the formation of stable tumble flow from cycle to cycle."

"A possible solution would be to keep these sources of deposits away, for example, from the intake valve, by completely eliminating exhaust gas recirculation and the introduction of blowby gases into the intake port. However with the combustion behavior of modern reciprocating internal combustion engines, at least external exhaust gas recirculation and the introduction of blowby gases into the intake port are absolutely necessary for reasons of emission control and fuel consumption, so that this approach is not possible. "


I’m also interested to see if oil life can be extended by eliminating pcv return but that is a long shot probably.

Method of evaluation: Only good way is to visually inspect valves. I am not going to do that but I am going to monitor the oil condition via TAN and TBN sampling.

Benefits/features of this method:

1. Eliminates PCV gases return to intake thereby eliminating largest source of deposits to intake valves, fuel injectors, etc.
2. Routes crankcase gases to exhaust post-cat and post sensor
3. No need to empty a catch can
4. No chance of freezing up, unlike catch can
5. Crankcase gases are removed under vacuum unlike catch can
6. Less chance of pressure drop as could occur with a catch can

Cheaper version:

If a person believes that vacuum is not needed to evacuate crankcase gases (such as anyone who wants to run a "race" catch can that vents to the atmosphere), you could eliminate all the expensive parts and just block off front pcv at intake, rear pcv line, and then simply run a hose underneath the car with no catch can. This would cost roughly $10 for the plugs, $15 for hose and clamp? for a total of around $25. the only thing you wouldn’t get is vacuum pull of crankcase gases. One BITOG member did this on his audi RS4 http://www.bobistheoilguy.com/...07413 and really likes it and UOAs look great. He reports no oil spots on driveway etc. from tube. I chose to have vacuum assist.

Some more reading FYI:

http://www.bobistheoilguy.com/...96487

http://www.honda-tech.com/showthread.php?t=1199935

http://www.bobistheoilguy.com/...art=1
 
I assume your aren't running cats. If so, dumping oil vapors into the cats isn't a good idea.
 
Could be dumping it Post Cat, where the exhaust temps are much cooler and it won't hurt anything. If anything it might help to keep his exhaust well lubricated!
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Originally Posted By: saaber1
...1. Weld in nipple into exhaust pipe post-cat and post-sensor...


I agree you don't want to dump in pre-cat or before the 02 sensor. Putting it in farther back on the exhaust also leaves room for a future potential downpipe upgrade if so desired.
 
Originally Posted By: StevieC
Could be dumping it Post Cat, where the exhaust temps are much cooler and it won't hurt anything. If anything it might help to keep his exhaust well lubricated!
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I'm sure that would help keep the muffler bearings lubricated
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No because there is a check-valve. Unless this fails there is no way for the exhaust to flow backwards. Also with the angle of the PCV pipe in the exhaust it creates suction because of the rushing exhaust.
 
Originally Posted By: StevieC
No because there is a check-valve. Unless this fails there is no way for the exhaust to flow backwards. Also with the angle of the PCV pipe in the exhaust it creates suction because of the rushing exhaust.
Ah, I missed the check valve. Cool, thanks.
 
is the checkvalve going to open easy enough for it to work properly? I assume the slash cut in the nipple is to promote the Venturi effect and cause a vacuum on the PCV, but will it be enough vacuum to open the check valve?

It would be neat to see if you can rig a vacuum gauge to the line to see how much is caused at different rpm's and load
 
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Originally Posted By: hooligan24
is the checkvalve going to open easy enough for it to work properly? I assume the slash cut in the nipple is to promote the Venturi effect and cause a vacuum on the PCV, but will it be enough vacuum to open the check valve?

It would be neat to see if you can rig a vacuum gauge to the line to see how much is caused at different rpm's and load


I agree the vacuum gauge would be nice, especially to see how the vacuum changes under varying speed, load etc. It seems to crack open easy enough based on if you blow through it, it opens without excessive pressure and also I can smell and see oil residue at the exhaust tailpipe which I didn't see/smell before. So it is definitely working but I can't tell you how much vacuum without rigging a gauge.

If you know of any leads on how to rig a slick vacuum gauge I would love to see that. I assume a coupler with a "t" and a small hose running to the cabin?
 
saaber1,
Congratulations! You finally finished PCV bypass.
Great write-up and thanks for sharing.
 
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a simple plastic tee fitting and a rubber hose going to a gauge. You could just do it temperarely and them cap off the vacuum line unless you want to perminently mount a gauge. If you cap the line, you can always hook the gauge back up to do periodic checks on the system. You could always hook the hoses back up like stock and plumb a gauge into those hoses to see how much vacuum the motor had befor you changed it and then compare the two readings.

Im sure you can pick up a cheap gauge from Amazon or harbor freight and the tee and vac line from the parts store for less than $20

http://www.amazon.com/Sunpro-CP7978-Mech...2623845&sr=1-16

If you can see and smell the junk coming out the tail pipe, it must be working.....I just like to tinker, so it would drive me nuts not knowing how it is "actually" working. lol
 
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I saw some vacuum measurements on this thread (it might be from the imbedded link in the first post I can't remember):

http://www.honda-tech.com/showthread.php?t=1199935

There is tons of good info. in that thread as "dasher" tested multiple crankcase evacuation methods and finally settled on the exhaust slashcut system. Skim for posts by "dasher" in about the first 6 pages. Well worth the time if this topic is something u want to research.
 
Originally Posted By: hooligan24
a simple plastic tee fitting and a rubber hose going to a gauge. You could just do it temperarely and them cap off the vacuum line unless you want to perminently mount a gauge. If you cap the line, you can always hook the gauge back up to do periodic checks on the system. You could always hook the hoses back up like stock and plumb a gauge into those hoses to see how much vacuum the motor had befor you changed it and then compare the two readings.

Im sure you can pick up a cheap gauge from Amazon or harbor freight and the tee and vac line from the parts store for less than $20

http://www.amazon.com/Sunpro-CP7978-Mech...2623845&sr=1-16

If you can see and smell the junk coming out the tail pipe, it must be working.....I just like to tinker, so it would drive me nuts not knowing how it is "actually" working. lol


The amount of vacuum on a crankcase is so low that we actually use really sensitive gauges, like this one: http://www.amazon.com/Labtron-Manometers...42752798&sr=8-2

These are so sensitive, if you blow around them, they can measure the pressure changes. We have a specification for the Volvos I work on, but it appears that we use the same system (pressure regulator and cyclonic oil separators), so I would imagine that you would fall into the same spec.
 
Grumpy Jenkins first used these in drag racing. Later GM adopted them OEM.

Now they're ..errr...unlawful
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. Do it, by all means ..but you're violating some EPA law.

All crankcase emissions go through the combustion process in one manner or another. They either enter from above or below the throttle body.

Oh, and make sure you've got adequate venting. They can pull such a vacuum ..that you can suck in seals.

 
Thanks Gary, I guess I assumed that this is a race only application is implied but that may not have be clear. For folks concerned about emissions, you may want to consider a good catch can system that still routes the pcv gunk back to the intake manifold which is better than nothing. That should help reduce, but not eliminate the buildup on the valves.

One should be aware that a catch can may not do the job adequately however. Looking at earlier posts by RL-RS4, there were examples of audi RS4's which have an efficient stock 3 step cyclonic "catch-can" system and they were inadequate to stop the valve buildup.
 
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