high oil pressure. aw11 20v turbo, no oil cooler

[SHEPPO3930]

One will go into the other ok but not really the other way around.
Although if you use a brass fitting (and because pipe threads work essentially by cross threading) you will get away with it 9/10 and never have a issue.

Sorry but you're wrong on this one. Tapered pipe threads DO NOT tighten by cross thread'ing themselves, they tighten because the male fitting's diameter gets bigger (due to the taper), thus the clearerance becomes zero and it binds up... It never cross threads.

1/8 npt is 27 turns per inch, 1/8 BSP is 28. Screwing one into the other will cross thread, regardless of the taper.

[dnegative]

Sorry but you're wrong on this one. Tapered pipe threads DO NOT tighten by cross thread'ing themselves, they tighten because the male fitting's diameter gets bigger (due to the taper), thus the clearerance becomes zero and it binds up... It never cross threads.

Binds up, fucks the thread, splits the housing - take your pick!
Pipe threads are the dodgiest, shittiest way of air/fluid transfer known to man.
I still see dodgy fuckwits make stuff with them and you know the engineers a moron with it takes a meter of thread tape and a 600mm breaker bar on a 3/8 BSPT fitting to get it to seal at 200bar - I call that essentially cross threaded cause its fucked the threads on both just to seal.

NPT goes into BPST alright, done it 11ty with brass fittings. Don't think the 1 extra thread matters when by design even on the right combo, you damage the nipple putting it in and tightening it.

[SHEPPO3930]

Binds up, fucks the thread, splits the housing - take your pick!
Pipe threads are the dodgiest, shittiest way of air/fluid transfer known to man.
I still see dodgy fuckwits make stuff with them and you know the engineers a moron with it takes a meter of thread tape and a 600mm breaker bar on a 3/8 BSPT fitting to get it to seal at 200bar - I call that essentially cross threaded cause its fucked the threads on both just to seal.

NPT goes into BPST alright, done it 11ty with brass fittings. Don't think the 1 extra thread matters when by design even on the right combo, you damage the nipple putting it in and tightening it.

Whilst i agree with you regarding tapered threads being less than ideal to seal fluid systems, the whole "NPT goes into BSPT alright..." statement is misleading, especially for people with little to no experience on the topic. whilst you can get a turn or two onto the fitting and it may not leak, it's rooted from the get-go and you're on borrowed times until it fails. the OP has proven this nicely with a fitting that was only engaging 2 turns and has failed.

[webby]

With regards to the increase in pressure, if you have removed the original oil cooler, which is a pressure bypass cooler, then you will have a greater pressure on your gauge. The original cooler sandwich plates act as a secondary pressure relive valve for the system. Since 20v's didn't have such a cooler plate I would expect this to be normal.

[feral4mr2]

please do a remote oil pressure sender/turbo feed. please.

My crankcase breather filter isn't soaked with oil yet. I realised the PCV valve on the crank case is only a one way valve, allows air to be sucked out of the crankcase, but blocks up when pressure is against it the other way, so I wouldn't expect my 6psi boost to be a problem there.

could be that my coffee hasn't kicked in yet... but are you saying you still have the crankcase breather running to your inlet?

[adamaw11]

please do a remote oil pressure sender/turbo feed. please.


could be that my coffee hasn't kicked in yet... but are you saying you still have the crankcase breather running to your inlet?

By that I'm saying I've got it like this, and I'm trusting in the one-way valve preventing boost from going into the crankcase.




And I'm now planning to run the oil feed from the remote filter mount. Those holes are meant to be 1/8 NPT, so my oil line fitting should screw into it.

[adamaw11]

With regards to the increase in pressure, if you have removed the original oil cooler, which is a pressure bypass cooler, then you will have a greater pressure on your gauge. The original cooler sandwich plates act as a secondary pressure relive valve for the system. Since 20v's didn't have such a cooler plate I would expect this to be normal.

That would actually explain some things.
Before turbo, I was running 16v sandwich plate on the 20v. Oil pressure guage was always where I thought it should be
After turbo, no sandwich plate, no oil cooler, filter straight on block - guage pressure higher than it always was.

[feral4mr2]

While you are using the PCV valve to not allow boost into the crankcase, crankcase pressures cannot escape while you are on boost. The 4age engine is a positive crankcase engine. This IMO would raise internal pressures in the engine, I for-see seal leakage issues etc. if it keeps running this way.
Route it via a catch can to a vacuum source before the turbo.


The feral's 4agte had the filter directly to the block, the lil feral's a remote filter behind the rear tyre. Both run basically the same oil pressures according to the stock gauge.

[trdee]

the 20v has a second breather on the back of the head which is used at higher pressures when the PCV is closed (you can see it in the pic above with a little air filter on the back of the head). the PCV on the 20v only works under vacuum afaik so the setup is no different to stock in that sense. the issue is more that the breather on the back of the head is not going to flow anywhere near enough blowby gas to suit a turbo engine.

[feral4mr2]

ah yes I see the little breather now. for some reason 1/2 that pic didn't show last night.

for shits and giggles it wouldn't hurt to remove the PCV line, block it at the manifold and see what happens with the 2 open.....

[trdee]

that is what i have seen some turbo people do with 20vs yes.

[SHEPPO3930]

for shits and giggles it wouldn't hurt to remove the PCV line, block it at the manifold and see what happens with the 2 open.....

Plenty of us do it this way with no ill effects. Vent both breathers into a catch can, and if you must, plumb the catch can return back in before the turbo. Simples.

[bermy]

Plenty of us do it this way with no ill effects. Vent both breathers into a catch can, and if you must, plumb the catch can return back in before the turbo. Simples.

If you must? You must!!! Engines love vaccum, not only does it decrease windage loss, it also helps the rings to seal real good. With a turbo setup, best way would be to route both fittings to a catch can like said above and to get two extra lines creating vaccum in the can. First line goes before turbo and second one goes to the stock location on the intake manifold. By using one way valves on both lines, you ensure that the side with the most vaccum is always pulling while the other side is held shut by the one way valve because of pressure differential. So at idle and vaccum conditions, the inlet manifold line pulls vaccum out of the crank case and when you get in boost, the one way valve shuts and you start pulling vaccum from the "pre-turbo" line. Just ensure you use a decent catch can that will not allow oil vapor to get through : oil has low octane rating and gunks up manifold...

[trdee]

whilst I agree that the above is the correct way to do it. The only extra thing I would advise is to increase the size of the breather as on boost the engine needs to breathe a fair bit more. The stock pcv should be fine because at idle you shouldn't be breathing any more than stock. But the port on the back of the head that will be breathing under boost should really be increased in size

[bermy]

Not 100% accurate. The way I described it, both outlet in the valve cover will pull vaccum at all time. Vaccum gets sucked thought both fitting in the valve cover toward the catch can. It's the extra 2 line that will only pull one at a time, line #1 goes back to the port on the intake manifold which can be left stock for the reasons stated above, but the second line going to a "pre-turbo" that you could want to upsize. Luckily, you have to fab it from scratch as you're not using any of the original equipment on that line so get a -8 line or -10 if you want, both 3/8 fitting out of the valve cover will be able to handle the flow no problem