rb25 vtc-cam failure!!

[nick-nismo]

my guess: thoes shavings you found when you dropped the pan before all this, were the cause, could have been previous damage on head - cam surface. could have blocked the head feed on that side and caused it to seize, the heavy valve tick would have been the warning signs that the head didn't have sufficient oil.

[DatsunZ31]

did you have an oil restrictor installed? making me hesitant to buying one and fitting to my rb20 block.. normally the head is over oiled on the RB's... weird

This might be out of topic but how exactly do RB's have oil pooling isses in the head? i was looking at my RB and cometic head gasket and i cannot for the life of me see exactly how it can pool in the back of the head.

[speedfreak]

I can answer this for you.

If you look at the RB engine blocks you will see 2 larger oil return passages at the rear of the cylinder 6.
Under high rpm oil is pumped faster to the top end and only gravity can return it to the pan.
With acceleration oil will accumulate at the rear mostly.
However also at high boost levels blow-by increases and also uses the oil return passages to escape the crankcase.
This causes the oil in the head to not fall through and pools in rear of the head.
That's why the rear head drain came to light adding an additional passage.
Hope that explains it.

[Skym]

It's not a head drain as such (does act as a head drain as well), it's designed to help equalise pressure in sump, head, so oil returns through stock oil drains. With high boost levels (I think was up to 1.7 bar) the blowby going past rings pressurises the sump, hence the pressure blocks the stock oil drains (makes it harder for oil to return to sump). Equalising the pressure in head, sump (removes the pressure buildup in sump, as pressure goes to head and out the cam cover breathers) and allows oil to return to sump via the oil drains.

This is a basic diagram, explanation of what happens with too much oil going to head (scroll to bottom in link below) -

http://www.tomei-p.co.jp/_2003web-catalogue/e114_RB_oillube.html

To solve it properly (especially when running higher boost levels), run a dry sump setup (not many can afford a dry sump setup hence the above restrictor mod was created for mild tuned race engines).

[supersayianjim]

did you have an oil restrictor installed? making me hesitant to buying one and fitting to my rb20 block.. normally the head is over oiled on the RB's... weird

The only oil restrictor I have is the stock) oil turbo feed bolt(yes the same thread pitch as holsets). Other than that no limits on oil.

Iam hoping to pull the engine today and do some more disassembly!

[supersayianjim]

they seem like a good company. but i don't need a whole motorset, just a complete longblock so iam stuck on that one.

http://www.rawbrokerage.com/nissan-r33-rb25det-engine-motorset/

[DatsunZ31]

they seem like a good company. but i don't need a whole motorset, just a complete longblock so iam stuck on that one.

http://www.rawbrokerage.com/nissan-r...gine-motorset/

call them up for pricing, they will help you however they can if you buy a motor from them. they are very helpful and if you google their name for reviews they have the best customer service out of all the importers. I'm pretty sure they have long blocks but call and ask.

[supersayianjim]

Called and talked to "ricky" for 40 mins shooting the ****! Good people it seems(like always in the begining). But no longblocks in stock. Said he would let me know. But full heads are 500.

[nick-nismo]

The only oil restrictor I have is the stock) oil turbo feed bolt(yes the same thread pitch as holsets). Other than that no limits on oil.

Iam hoping to pull the engine today and do some more disassembly!

Oil restrictor and holset? I hope you didn't lol or you might be buying a new turbo soon.
Holsets need -4 an oil feed, no restrictor.

[supersayianjim]

ive used the stock t28 feed line for years on my hx30 and no problem, iam running a hx35 and it's the same thread pitch. iam not starving the turbo, if anything it's still getting too much oil.

so i put a deposit down for another motorset. iam going to part out and build thsi bottom end of the one i got. so look for the f/s thread comming up!!

i can take pre-bids now for the coilpacks/harness etc stuff.

[supersayianjim]

heres the next(and hopefully last) motorset iam getting. yes i know it's awd but i have a oil pan etc.

[nick-nismo]

nice looks good man!! good to see you didn't let the motor failure get you down

but im going to have to correct you on that one. if the line your using is restricted that's a no no for a journal bearing turbo, such as every holset out there.
The rb20 and rb25 both, ball bearing, have the restrictor right before the banjo bolt that threads into the turbo, also the feed through the banjo bolt is just as small.

picture i just took of my oem he341 size and the RB feed size. the difference is huge


not trying to call you out, just not good to have false information floating around the net

[92GTSTproject]

rb20 and 25 stock turbos are journal with the exception of the neo rb25 which is ball bearing, idk what type holset uses, but you seem to be the one posting the false info sir

[supersayianjim]

nice looks good man!! good to see you didn't let the motor failure get you down

but im going to have to correct you on that one. if the line your using is restricted that's a no no for a journal bearing turbo, such as every holset out there.
The rb20 and rb25 both, ball bearing, have the restrictor right before the banjo bolt that threads into the turbo, also the feed through the banjo bolt is just as small.

picture i just took of my oem he341 size and the RB feed size. the difference is huge


not trying to call you out, just not good to have false information floating around the net

yep, thats the feed line ive been using. along with the stock rb feed bolt.

[Skym]

Have no idea what Holset turbo's have with CHRA, but R32 GTR (from memory is a 270 degree thrust bearing), R33 GTR stock turbo's are non ball bearing, R34 GTR is ball bearing. R32 GTS-T, R33 25T, R34 GTT stock turbo's are ball bearing.

Hybrid RB20 turbo is non ball bearing, as they tell you to drill the oil feed out in the instructions that are with turbo from turbo rebuilder.

Only stock turbo on GTS RB engine that is non ball bearing is installed on RB20DET in the Cefiro.