Rb25 Vct Oil Feed

[GTSBoy]

9 hours ago, silencium said:

Lol what does that has to do about the question?

Well, putting the grey mush in my head to work, I cannot see how the 200ms that it would take to purge the air out of an oil gallery feeding the head when the oil pressure behind it starts to rise is going to make any difference at all to how much wear the head sees on start up.  I don't know if you've ever looked under a cam cover with the engine off.....but there's lots of oil sitting up there.

Check valves are a 0.0001% thing.

[silencium]

Lately I was testing a camshaft for run out with a dial gauge. For that I put it on flipped front an rear bearing cap with some oil in between of course. Well after turning the cam approx 10 times by hand, the caps already had scorring marks despite the oil.

So without oil pressure that is all much more delicate than one might think.

Also the cam installed an all, there is a lot of load on it from the valve springs.

If oem there are check valves, I want to go with them again

Thats why I want to know

[Ben C34]

The Japanese bit before 2.0 says Normal , as in original. That's not a check valve.

[Ben C34]

Also not a check valve.

[Ben C34]

There is a check valve in the oil filter. That would do all the check valving required to keep the oil up in the engine wouldn't it?

[GTSBoy]

Correctness is correct.

[silencium]

The check valves behind the oil filter have another purpose. These are pressure controlled and open only if the oil pressure reaches a certain point, for example when the filter would be clogged.

I have found these pics before also, but these are not original nissan, but from a tuner... Even though it is a japanese tuner, that doesn't mean its all superbe.

I get it that you two do not think there are check valves... But I still want to know what originally the case is.

[Dobz]

Oil filters have there own pressure release valve , they also have an anti drain back valve (check valve) that holds oil in the filter. 

I've stripped and cleaned three RB's (20,25,26) over the years and i can certainly say there were no check valves in any feed to the head what so ever. Brake cleaner and air pass easily back through the orifices without a problem.

There is simply no need for them.

 

[silencium]

Alright, thanks for the info Dobz

[89CAL]

The check valve on an RB25 is in the oil cooler not the block

I thought the standard restrictors had check valves but guess not. As I said previously, I never gave it a second thought. 5 years later and my head is still fine

As for the above about rotating the cams etc. And there being score marks - something else is going on there. I rotated mine several times while building my engine and no marks/scoring
Engines are not that fragile that they will die after 2 seconds without oil (at idle) on startup. Have you ever watched how long it takes for oil pressure to come up after doing a service?

[Dose Pipe Sutututu]

I concur with everyone else as I assembled my boat anchor.

[hardsteppa]

 

On 24/03/2018 at 6:47 PM, Ben C34 said:

The Japanese bit before 2.0 says Normal , as in original. That's not a check valve.

for anyone's future reference - the OEM oil restrictors on an RB25 are absolutely a 1-way valve. Floating-ball type, not spring loaded. Just under 1.5mm diameter.

[Ben C34]

58 minutes ago, hardsteppa said:

 

for anyone's future reference - the OEM oil restrictors on an RB25 are absolutely a 1-way valve. Floating-ball type, not spring loaded. Just under 1.5mm diameter.

You got a picture?

[hardsteppa]

Have a brand new one sitting in my garage, but it won't show much unless i cut it open. Air will only flow thru it one way; direction of flow to the head.

[Ben C34]

1 hour ago, hardsteppa said:

Have a brand new one sitting in my garage, but it won't show much unless i cut it open. Air will only flow thru it one way; direction of flow to the head.

What engine? Neo?

 

When are you cutting it open?

[hardsteppa]

nah just plain ol rb25 ..

wasn't going to cut it open but yeah ok I might do that, don't think I'll end up needing it anyway.

[sachin]

Currently in the process off building a rb25 engine but for some reason my rb25 block doesn’t have the vct oil feed plan is to put a rb25de head on it with the vct oil port can anyone tell me or give any advice to if it can work and what do I need to doo?

 

[TurboTapin]

On 9/12/2022 at 10:12 PM, sachin said:

Currently in the process off building a rb25 engine but for some reason my rb25 block doesn’t have the vct oil feed plan is to put a rb25de head on it with the vct oil port can anyone tell me or give any advice to if it can work and what do I need to doo?

 

NEO's did not have an external VCT drain like the S1/S2's. I also recall the NEO heads having chamber differences. With that being said, I'm not confident you can bolt an S1/S2 head onto a NEO block but wait for someone who's more knowledgeable on the topic to chime in. 

[GTSBoy]

You can bolt a vanilla 25 head onto a Neo block. But....

1. The Neo chambers are ~10cc smaller than the vanillas. With almost the same comp ratio, that means that the piston crowns are a lot lower on the Neo. Thus, Neo head on vanilla block makes for a low comp piece of shit. You then need to go to a lot of effort with pistons and rods to get the comp back.
2. The VCT oil drain thing.
3. And, lots of other little annoyances. Want to bolt the vanilla inlet manifold to the Neo? Can be done, but the port match is not the same. (I'm reasonably sure of that, but perhaps check). If so, then choosing between the Neo manifold and the vanilla manifold starts to impact on ECU peripherals, like the IACV. Again, not insurmountable - just shit you have to take care of to make it work (unless aftermarket ECU, in which case, it makes little difference).

[Dasmbo]

This is the mod for vct on a rb30 with rb25 head