Q. about the oil Breather?

[task 0]

can some one clear out this for me :?: .

I am still confused about why is there a breather on the engine and why is it connected to the supercharger through the bypass pipe ? I realize that the bypass tube lets excess boost return to the SC, but that also means that the air will carry oil from the engine to the SC, thus the SC will pump that oil back to the the Intake, which is Bad for the engine right?.

Thanks.

[billinjah 0]

its bad for the supercharger to have nasty oil vapour vented back in to it.

[stevemac 0]

its bad for the supercharger to have nasty oil vapour vented back in to it.

Venting the engine oil fumes back through the charger is GOOD for it - it lubricates the apex/scroll seals.

 

When the boost return is removed - it becomes necessarry to spray silicone grease into the charger inlet, periodically, to lubricate these seals.

[Scruffythefirst 0]

However, oil in the intake charge can increase the chances of det, which is especially fatal on forced induction engines.

[billinjah 0]

hang on i thought the boost rturn deletion was good fo the life of the charger? the spray you have to spray into the charger nobody seems sure what to use or where to get it from!

[Neil VR6 0]

Well VAG spent lots of deutchmarks developing the engine. I know I'll get shouted down for this but I can't see the point of deleting the boost return. Not only does it lubricate the charger but it also means that the charger is receiving air from both sides which it is designed to do. Unless you can fit a decent cold air feed to the boost return side then leave the boost return there. The reason it's so popular IMO is that it makes the car sound noisier & faster. I can't be good if you continually need to spray silicone lube into the charger because you removed a bit from the engine?

 

I think oil in the intake is "designed in". The biggest problem with the G60 intake is the pitiful size of the IC.

 

Task: Pitstop sell a catch tank which it routes the breather into and you blank off the bit where it would ordinarily go into the boost return. This way you can take away the oil fumes from the inlet tract and retain the boost return (you're still taking away the oil though):

 

http://www.pitstopdevelopments.com/catch-tanks.htm

 

You could probalby make something up like this as well without too much trouble.

[task 0]

Venting the engine oil fumes back through the charger is GOOD for it - it lubricates the apex/scroll seals.

I thought that the charger gets lubricated through the oil line from the engine block. isn't that true ? if it is I dont see any good reason why there must be oil vapor coming back to the charger.

I think oil in the intake is "designed in".

.

But by time the oil vapor will get stuck in IC and the pipes to the intake. Does this mean every now and then I have to clean the IC&pipes?

[Neil VR6 0]

You won't have to clean the IC pipes.

 

The oil supply to the charger is very specific in that it will lubricate the bearings via specific channels. I would imagine (slightly guessing you may have gathered) that the oil in the inlet tract will help to seal the charger together via the apex seals which is something the oil supply cannot do.

[Kevin Bacon 5]

Recirculation of crankcase fumes is a legal requirement under the Euro 1,2,3 & 4 Emissons guidelines, VW HAD to feed them back into the inlet, period.

 

As Steve says, this is a good thing anyway for charger lubrication but it's 'dirty' air and not so great for helping provide a clean burn, but the difference is quite negligable in all honesty. Leave things as they are and don't worry about it.

[Neil VR6 0]

Yup. Strictly speaking you'll also fail your MOT if you vent crankcase vapour into anything other than the engine. Still, I doubt if many MOT'ers give two hoots or would even notice.

[Kevin Bacon 5]

On my MK1 16V, the crank case hose was dangling down in the inner wing venting to atmosphere and it passed the MOT :roll:

 

MOTs are only as good as the person doing the checks, but that's a good thing when you want to lose the CAT and Carbon Canister :wink:

[Dubcharged 0]

but it also means that the charger is receiving air from both sides which it is designed to do.

 

Sorry for shooting you down mate but i should make a point on this. When you are under full throttle, the bypass butterfly is fully closed so that boost return hose is closed meaning the charger will only draw the air in from one side anyway. When under partial throttle the loop is open and hot air then circulates around through the charger again making the charger/ic/tubes hotter and hotter.

:cry:

 

 

The oil fumes do coat the inside of the ic making it less effective. You should take the ic out and clean the inside by filling it with a degreaser.

 

The lubrication by the oil vapour is very negligible and using a suitable ptfe spray does a better job.

 

The primary reason that VAG did this was for noise/emissions.

[Neil VR6 0]

That's OK :viking:

 

How come VW didn't design a SC which was either one sided by design or which had a proper 2nd air feed which pulled in cold air like the std airbox? Why make it how they did? Surely they could have "tuned" the inlet tract in order to make it quieter (g/f's MX5 has a very wierd convoluted inlet tract)? I suppose space was a consideration?

 

I've always liked the thought of the boost return mod as it makes the engine bay less cluttered and it means there are less things to go wrong. However, I've yet to be convinced that it's better than the std set up. Won't it make a tremedous racket when you're on "semi" boost as the boost will wastefully vent to atmosphere?

[Neil VR6 0]

Just found this on the Bahn Brenner website:

 

The boost return tube that passes the diverted air back to the g-lader supercharger when at partial or minimal throttle position also carries oil vented from the valve cover breather into the supercharger. This oil lubricates the wear strips or apex strips inside of the supercharger and it is an engineered in feature of the system. If you eliminate the boost return tube and block off the return side of the g-lader it is recommended that you also run an oil breather tube back into the block off plate from the valve cover breather. This will maintain the lubrication in the g-lader. It is our opinion that eliminating the boost return generates minimal to no gains in performance. Dumping the bypassed air to atmosphere can cause an air rushing sound when driving out of boost or when driving at partial throttle cruising conditions.

[Dubcharged 0]

Just found this on the Bahn Brenner website:

 

....... If you eliminate the boost return tube and block off the return side of the g-lader it is recommended that you also run an oil breather tube back into the block off plate from the valve cover breather. This will maintain the lubrication in the g-lader.

 

 

Yes, but the lubrication achieved with using a ptfe spray is better since its not "dirty" or hot, and sticks to the seals longer. Of course it means you have to manually apply it periodically.

 

 

....... It is our opinion that eliminating the boost return generates minimal to no gains in performance. Dumping the bypassed air to atmosphere can cause an air rushing sound when driving out of boost or when driving at partial throttle cruising conditions.

 

It doesnt produce a "gain" in performance, but it does allow you to maintain the performance you have. After driving about for a while, the charger/ic/hoses get heat soaked from the boost return pumping hot air back through the system. Also the oil vapours dilute the octane in the petrol meaning the ecu retards timing to reduce knock.

 

In terms of the noise on partial throttle, you can reduce/eliminate this by attaching a hose to the bypass side of the tb and routing it away from the bay. Perhaps someone could adapt an exhaust tube to attach to the tb then run down the chassis and end up next to the actual exhaust at the bumper! Now thats novelty value!! 2 exhausts, 1 for emissions, 1 for bypass boost!! :lol:

[Neil VR6 0]

Like the F40, separate wastegate in between the exhausts :twisted:

 

I see what you're saying and I can see what VAG were "saying". I still don't know what to do. I could just give it a try I suppose for the sake of about £40 for the kit.

[billinjah 0]

a lot of people do it coz it sounds mad! i did it as people said it would increase the life of the charger i didnt know about the ptfe spray but ill give it a squirt when i get some. it does get annoying on a long run tbh!

[Dubcharged 0]

I know what you're saying about the noise mate, it can be annoying on part throttle, just strap a hose onto the exposed tb and route it away from obstructions, should make a difference.

[Neil VR6 0]

Do you vent it straight out or fit a small filter onto the end?

[Chris M 0]

If you want to make it nice and quiet you need to fill the hole that tee's off the return valve just below the butterfly. This acts like blowing over the top of a beer bottle. You need to remove the TB to do a proper job and make sure when it sets it doesn't stop the butterfly from closing fully. I used Quick Steel and was very suprised at how quiet part throttle briving is now, but without loosing the dump valve noise on changing gear after full throttle 8)

 

I wish i'd have taken some pics when i did it. :roll:

[Neil VR6 0]

That's more pertinant when you remove the carbon canister and associated pipework though isn't it?

[stevemac 0]

If you stick a "90 degree bend" hose onto the bottom of the throttle body - excess boost helps cool the inlet manifold .. :D

[Neil VR6 0]

Vioce in head: "Is he having me on or talking sense?"

[Dubcharged 0]

Hehehe, yeah you could direct the air onto the back of the manifold, don't know how much of a difference it would make though?

[stevemac 0]

Sounds like an idea for the "unique mods" thread . :D