Over boosting/ oil in turbo compressor

[HDTECH]

Hey guys, I am looking into why I'm over boosting. while I'm driving I can hear air coming out of the BOV (which I see is routed back into the the intake, downsteam from the MAF) on my gauge it shows that I'm boosting at 14 psi and its all stock.

I pressured up the BOV on the bench and it opens at 7PSI.

I pressured up the wastegate and it starts to move at about 13-14 PSI, it opens and closes fully.

That makes sence that its boosting at 14PSI but I thought it was all stock.

On the right side rocker cover there is some 5/8" hose that also leads into the downstream side of the MAF. In this small hose there is a little steel thing with a hole in it. There is a bit of oil coming through there and going into the turbo compressor side. The PCV that is on the intake manifold worrking correctly.

It does not consume oil and there is virtually no crankcase pressure/ blowby.

Also, what would be the lowest safe oil pressure reading I should see. With new oil, when its hot sometimes it drops down to 2 cm squared at idle... This seems low to me and I hope the main bearings aren't going!

[Skym]

Sometimes the BOV spring is weak and opens earlier than it should or valve leaks due to oil deposits not allowing valve to shut properly. Or gasket needs changing under stock BOV. Also manifold pressure helps to hold valve inside BOV closed.

Aftermarket internal wastegate actuator with stronger spring???? Have tested 2x RB20DET internal wastegate actuators on bench and both moved at around 12psi.

Should be around 1kgcm2 at idle. But sender / sensor on block for stock oil pressure gauge can be old and get inaccurate readings. Or oil is too thick (15w50 type of oil) and get up to 2kgcm2 at idle. I run 10w40 as oil temps don't go over 100 degrees C too often when on street. Factory is 7.5w30.

[HDTECH]

Okay thanks, any suggestions on what kind of BOV I should get? And from where?

I am using 10w-30 oil now, I will switch to 10-40 next oil change

[Skym]

I run a pull type (stock is push type), piston type (stock is diaphram which can be affected by engine heat) log style Synapse BOV and haven't had any problems for years. It solved drivability problems that had with stock, modified stock BOV.

Synapse sell a bolt on kit for RB20DET that can be set to run pull type or push type and has a better flange setup than log style Synapse BOV -

http://synapseengineering.pinnaclecart.com/products/Synchronic_Single_DV_Kit_for_Nissan_GTS_R32_R33_and_R34_with_Single_Turbo-646-16.html

Best to have aftermarket oil pressure (match to factory figures for stock engine in manual) and oil temp gauges to help in selecting correct oil for your engine.

Can buy english version of manual here (if you don't have one already) -

http://www.jpnz.co.nz/afawcs0131170/CATID=24/SUBID=273/page=1/products.html

Reading this PDF below helps to understand the cst rating at 100 degrees C (look at cst rating for factory w30 at 100 degrees C, as you don't want it to go thinner than that) -

http://www.opieoils.co.uk/pdfs/tech-articles/10w-60-oil.pdf

From what I understand, too thick with cst rating and oil won't get to bearings and result's in excessive bearing wear.

With most mildly tuned (intake, exhaust, FMIC) RB20DET engine, they can reach close to 100 degrees C on the street / motorway, as have no engine oilcooler. With engine oilcooler, shouldn't see above 90 degrees C under hard use.