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RB25DET oil pump chat


WhangareiKE70

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Hi all,

I know this isn't the normal sort of engine on this forum, but I'm putting one in my OS project so here we are. 

I can not for the life of me, after a lot of internet searching, find a concise/factual answer to what is the go-to oil pump for an RB25DET in my sort of application. 

 

From what I can find, there are 3 options:

1) Standard oil pump.

2) N1 oil pump.

3) Tomei/Nitto/HKS/other good but expensive aftermarket oil pump.

 

Some quick facts for those unaware of what I am going for:

-Aim is somewhere in the 350-400hp range.   

-This engine is going in a 4wd, so won't be exposed to the type of lateral forces a drift car would be, but will occasionally have to rev to clear mud from tyres/will be on an angle sometimes. However, primary duties are weekend warrior and/or driving to work.

- I plan to run a modified winged sump for extra oil capacity. 

- The long block has been fully rebuilt, using new fasteners but seems to be standard parts as per below:

1124451141.jpg  

I am unsure if oil restrictors were put in the block when assembled (I would assume not).

-I plan to run a head drain to stop extensive oil buildup in the head, which seems to be a common issue on these.

 

I am unsure of whether or not I need an uprated oil pump, if the N1 pump is actually better, or whatever.

 

All I do know is I do need a new one because may as well while rebuilding, and the old one has wear.

Let me know if you have personal experience/technical knowledge. I will be going to hit up my engine builder today, and see if they have any experience with these.

TIA, 

Hayden,

  

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Go N1, or whatever pump it was they upgraded to between the 32 and 33 GT-Rs as oiling was a minor issue prior.  That power figure shouldn't be far and away from what a stock GT-R can make with a few tweaks so as long as you're using one that the 33 or 34 big dogs use stock you'll be fine. 

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Yeah, that's the one, the N1 is a Nissan factory upgrade.

Also, not sure, but do I need some sort of extended collar on the crank to engage properly with the pump gears? Also found mixed reports of that online.

And, if so, does the crank need to be removed to have that attached? Honestly, the idea of buying a professionally rebuilt engine was to avoid stuff too far outside my knowledge base when it comes to engine building, as I want it to get it running, then potentially build a spare engine to swap in for more power/reliability/a chance to learn with less risk factor. 

    

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Theres a very long thread at skylines Australia about oil pumps. It was up around 379 pages when I read it. (Around right years ago) the crux of it (back then) was that a crank collar was a must, and that with a lot of hitting the limmie /limmie bashing the harmonics cause crankshaft flex. Since tje N1 gears are sintered metal they break when flexed. @DJZ had an N1 pump in his rb26. And those gears broke,  while pulling big revs. Cost him a crank grind, but fortunately not a new BB turbo. What I took away from that thread was that actually the Nitro pumps were thw pick of the bunch. Sorry I don't have a link. If you search N1 you might find it. It's probably north of 500 pages now.

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13 hours ago, RUNAMUCK said:

Theres a very long thread at skylines Australia about oil pumps. It was up around 379 pages when I read it. (Around right years ago) the crux of it (back then) was that a crank collar was a must, and that with a lot of hitting the limmie /limmie bashing the harmonics cause crankshaft flex. Since tje N1 gears are sintered metal they break when flexed. @DJZ had an N1 pump in his rb26. And those gears broke,  while pulling big revs. Cost him a crank grind, but fortunately not a new BB turbo. What I took away from that thread was that actually the Nitro pumps were thw pick of the bunch. Sorry I don't have a link. If you search N1 you might find it. It's probably north of 500 pages now.

Nitto is the goods, but are $1850 NZD. Which is half the price I paid for the whole engine with turbo etc. If need be, I could get one, but it's going to slow things up a lot and potentially be overkill considering the rest is just standard 25det. 

That thread is pretty much what I was talking about when I said that I couldn't find a concise answer, as there are many opinions of people with little/no technical knowledge and/or little/no personal experience. Just lots of "ma bro had a standard one and redlined it all day and it didn't even blow up #RFB4lyfe", which made it hard to find the actual info hidden amongst it. 

I am pretty sure I will go with an N1 pump, and set a rev limit on it. Now I just need to find some info on this crank collar, i.e where to source and how to install/alternatively how much to get it installed.

I would be interested to hear from @DJZ.

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16 hours ago, Stu said:

All good mate, hopefully he can help

He got back to me just now. 

 

"Hi,

Unfortunately there is no set answer.

Any RB oil pump will supply enough FLOW for what you want to do.

They are replaced/upgraded for strength. Strength is required to cope with limiter bashing, high rpm etc.

I have used stock used oil pumps on several builds of 600-700hp without issue but I stay off the limiter etc.

If you can afford to, go Nitto.

If you can’t, get a good condition used, or new genuine Nissan oil pump (be careful of N1 Chinese knock offs) and stay off the limiter.

Good luck ,

Rob."

 

So I will just get a new N1 Pump, and set a rev limiter using the ECU. Just need to find an answer on the crank collar, will try do some more research myself if I can find the time today. 

Cheers for the advice from everyone so far. :thumbleft: 

 

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Just buy a set of reimax gears for your stock 25 pump. The n1 pump pumps a LOT more oil and this extra volume means there is less metal in the gears.

That's the best value upgrade. There are lots of copy n1 pumps about.

Edit- I know a few limmy bashing drifters who have had no issues with the reimax gears. You have to disassemble your pump first to measure the gears to double check the diameter

Also, the head drain that everybody does, is actually a sump vent.

The oil drain holes from the head are not huge and at high revs oil pools in the head as the blow by is trying to get back up the same holes the oil wants to gravity drain down.

Build a catch can and plumb it to the rocker covers and a tapping point on the inlet side above the oil level.

Have you got a r32 or 34 25det? The 33 has an extra oil drain at the front due to the vct being a constant loss system when it's not engaged. The 34 vents much less oil into the head

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21 hours ago, Stu said:

Just set the limiter settings so they are really soft acting in the ecu you are using.

 

20 hours ago, RUNAMUCK said:

Setting a lower limit might make it worse. (As I understand it) limmie bashing, powet on/power off/power on/power off (mang-mang-mang-mang)  causes the crank to flex more*

*might not be the case,  I've been known to be wrong.

Have seen a few threads and the common consensus seems to be about a 2-300rpm roll on ignition cut for the rev limit at around 7k?

 

16 hours ago, fletch said:

Just buy a set of reimax gears for your stock 25 pump. The n1 pump pumps a LOT more oil and this extra volume means there is less metal in the gears.

That's the best value upgrade. There are lots of copy n1 pumps about.

Edit- I know a few limmy bashing drifters who have had no issues with the reimax gears. You have to disassemble your pump first to measure the gears to double check the diameter

Also, the head drain that everybody does, is actually a sump vent.

The oil drain holes from the head are not huge and at high revs oil pools in the head as the blow by is trying to get back up the same holes the oil wants to gravity drain down.

Build a catch can and plumb it to the rocker covers and a tapping point on the inlet side above the oil level.

Have you got a r32 or 34 25det? The 33 has an extra oil drain at the front due to the vct being a constant loss system when it's not engaged. The 34 vents much less oil into the head

Pump is apart already, will give it a measure up tonight. 

When you say a tapping point on the inlet side above the oil level, do you mean the one that has the nipple on it next to the standard breather? Trying to find out what that one is for and not having any luck. It seems to plumb into the intake on the standard intake from what I can see in pictures, but I don't have a standard intake to compare (using a Freddy plenum).

Engine seems to be from a Stagea judging from the sump (alloy and has the holes on each side welded up). If you are referring to the oil drain on the exhaust side at the front, it doesn't have that one. The flange is there but no hole is tapped. 

 

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4 hours ago, WhangareiKE70 said:

 

When you say a tapping point on the inlet side above the oil level, do you mean the one that has the nipple on it next to the standard breather? Trying to find out what that one is for and not having any luck. It seems to plumb into the intake on the standard intake from what I can see in pictures, but I don't have a standard intake to compare (using a Freddy plenum).

 

Sorry I should have said into the sump, not the inlet manifold. It allows the blow by a path to the head then out through the breathers and the oil can flow back through the drain holes with no back pressure

4 hours ago, WhangareiKE70 said:

 

Engine seems to be from a Stagea judging from the sump (alloy and has the holes on each side welded up). If you are referring to the oil drain on the exhaust side at the front, it doesn't have that one. The flange is there but no hole is tapped. 

 

Nice! The 25det neo head is the best. It's a solid lifter head, same ports as gtr but with vct. Some people are making silly power with stock unopened motors

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Could do a few things to say away from the limiter,   run a light waste gate spring + boost control solenoid.   set it up so the last 500rpm so it tapers back to gate pressure.  then power will roll off before getting to limiter,  plus a little bit of ign retard and well setup limiter.
or run an e-throttle  and use that as limiter like a lot of  newer cars do
 

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