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Blanking off the stock breather pipes?


mwilkinson

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If by accident a welder had remove the stock breather hoses when installing 2 12AN male unions for an aftermarket breather system, would there be a problem with running the car like this?

 

I'm assuming their purpose is to ensure pressure equalisation/ventilation. Thus with both linked to an aftermarket catch can the issue is sufficiently dealt with?

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i hear that if the breather system it not under some sort of vacuum to help suck out the blow bye it can build preasure and blow front main oil seals there was a massive thread on this when i was searching about breather set ups but some just fit a filter on them or catch tanks as you say

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First off if -12 fitting where being fitted to uprate the breathing system, which is pretty unnecessary, unless going for very high BP, they should have been fitted in place of the std breather fittings, why would you fit elsewhere and block the originals?

 

 

Secondly its fallacy that the breathing is responsible for FMS failure, i did some extensive testing, and there is no build up of appreciable pressure in the engine voids, the cause of 99% of FMS failure's is due to a worn oil pump, there is a big thread about it, but it sounds like you didn't read it.

Edited by Tricky-Ricky (see edit history)
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First off if -12 fitting where being fitted to uprate the breathing system, which is pretty unnecessary, unless going for very high BP, they should have been fitted in place of the std breather fittings, why would you fit elsewhere and block the originals?

 

The 2 12AN fittings are welded in place of the stock outer breather pipes. I'm running an aftermarket manifold so have dispensed with the feed from there. The engine will be running approx 800bhp or thereabout and plenty of cars have this setup running without issue.

 

Getting back on topic the issue is that accidentally the stock breather pipes under the spark plug cover were welded shut. Thus the only venting will now be via the 12 AN fittings and the catch can.

 

Will this be OK?

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With a big -12 on both covers you would think it would be ok without the dividing breathers, Id put them back in just to be safe though.

 

I was thinking the same to be honest Jamie. I would prefer to have the stock pipes running between the two regardless of the size of the aftermarket system but would having them there with such a setup make any difference whatsoever as both will be sufficiently vented at the same pressure.

 

Unfortunately replacing the stock breather hoses between the two will likely mean getting a second set of covers done, not at my cost. I was hoping I could save some bother.

Edited by mwilkinson (see edit history)
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Nothing to worry about. I think most people leave them because they aren't in the way and it's less work to do when sorting out the cam covers. Having them welded over will be quite good given that the rubbers go hard after a bit of time so it will save you having to check and replace them (only a small inconvenience but it's avoided regardless).

 

Two 12an fittings, one per cover, will allow a lot more venting than the stock setup ever would.

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Nothing to worry about. I think most people leave them because they aren't in the way and it's less work to do when sorting out the cam covers. Having them welded over will be quite good given that the rubbers go hard after a bit of time so it will save you having to check and replace them (only a small inconvenience but it's avoided regardless).

 

Two 12an fittings, one per cover, will allow a lot more venting than the stock setup ever would.

 

If this is the case then I'm happy to accept the covers and just run the setup as is. Would save some hassle that's for sure.

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The 2 12AN fittings are welded in place of the stock outer breather pipes. I'm running an aftermarket manifold so have dispensed with the feed from there. The engine will be running approx 800bhp or thereabout and plenty of cars have this setup running without issue.

 

Getting back on topic the issue is that accidentally the stock breather pipes under the spark plug cover were welded shut. Thus the only venting will now be via the 12 AN fittings and the catch can.

 

Will this be OK?

 

Basically you where not very clear on which breather had been blocked, and just where the new breather where situated, therefore i drew the wrong conclusion, i still however stand by my statement that for that sort of BHP i don't think the uprated size is necessary, see bellow.

 

That was Jevansio's thread, very interesting it was too. Youre not going to gain or lose anything fitting a pair of AN12 fittings.

 

If you read it i also added quite a bit of info from my findings of adding a low reading vacuum/pressure gauge, also spoke with him direct regarding my findings on this, and the conclusion was that there is no big crankcase pressure issue unless there is a ring/bore seal problem.

Jev went ahead and fitted an uprated system using i believe the Moroso Crankcase Evacuation System that we discussed.

Edited by Tricky-Ricky (see edit history)
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Basically you where not very clear on which breather had been blocked, and just where the new breather where situated, therefore i drew the wrong conclusion, i still however stand by my statement that for that sort of BHP i don't think the uprated size is necessary, see bellow.

 

 

 

If you read it i also added quite a bit of info from my findings of adding a low reading vacuum/pressure gauge, also spoke with him direct regarding my findings on this, and the conclusion was that there is no big crankcase pressure issue unless there is a ring/bore seal problem.

Jev went ahead and fitted an uprated system using i believe the Moroso Crankcase Evacuation System that we discussed.

 

From memory the -12 internal bore size is not THAT much larger than the stock breather hole when the pipe is pulled from the cover to leave just a hole, I think i would still keep the PCV valve though and run the breathers under a slight vacuum like my race car, a lot of race engines actually run a vacuum pump to create a suction that draws the crankcase fumes from the motor. Remocing the link pipes should be fine imo.

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From memory the -12 internal bore size is not THAT much larger than the stock breather hole when the pipe is pulled from the cover to leave just a hole, I think i would still keep the PCV valve though and run the breathers under a slight vacuum like my race car, a lot of race engines actually run a vacuum pump to create a suction that draws the crankcase fumes from the motor. Remocing the link pipes should be fine imo.

 

Yes i thought that -12 ID was about 1/2" so not much larger, i used to still run the outlet pipe from the catch tank back to the turbo inlet, to make the most of the vacuum effect once most of the oil vapor had dropped out,

If the link/balance pipe has been removed, and both valve covers go to a vented catch tank, it would be fine, but yeah i agree run it back to an intake vacuum source.

The PCV valve only operates at idle and non boost, so IMO does very little, other than draw a lot of oil vapour through the inlet in standard form, which i am not keen on, as oil seems to build up/ pool in the curve at the bottom of the inlet runners, and then gets drawn in once on high boost, not good IMO.

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Nop! "army navy" American pipe connector sizes, -12 has a 3/4" OD,

http://www.earls.co.uk/earls/technical/Thread%20Sizes.pdf

 

What about the ID though?

 

Found it myself..

 

http://www.speedflowshop.co.uk/100-series-stainless-steel-braided-hose--4-to--20-160-c.asp

 

AN12 hose is almost 18mm ID so the fitting will be way more than 1/2" but obviously no relation to the 12 as you said :D

Edited by Scott (see edit history)
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