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Discussion Starter · #1 ·
Hi All,

I've heard and read a fair bit recently that N1 pumps are made of a weaker sintered material (the gears I mean) and there have been a few instances of breakages over here in Aus.
IT 'seems' the the main reason for them breaking is when guys are using launch control/limiters and the like, or high rpm launches etc. The limiters essentially 'chatter' the drivetrain and crack the gears from what I understand.. and the big rpm launches - well that is self explanatory.
Obviously it doesn't happen in all cases.. but I don't want it to happen to me.

So! The solution, one would think, is simply to find a pump that has better materials internally and we all know Tomei, HKS, JUN etc have pumps to choose from.

The problem for me, is this. All these pumps are 'high volume' pumps and one of the problems with RB's is that they already pump far too much oil upstairs into the cam covers. My motor is having restrictors fitted to the head, an external drain to the back of the head and an 9L sump with gates and so on.. but I am still lead to believe that there can be problems with 'too much' oil be pumped up there..

I know that the Tomei is the only one adjustable, but it also starts off as one of the biggest in terms of volume! So I am not sure if this solves it. Can anyone who does some circuit racing tell me of their experiences?
Is it better for example to buy the Nismo Pump (as opposed to the N1 Pump) for longevity without the high volume of the Tomei? Or buy the Tomei and 'turn it down' as much as I can?

I also note that Reimax make an 'uprated' gearset for the N1 Pump. Maybe this is the best alternative as it keeps the volume down to 'enough' and fixes the possible weak point in terms of breakages...

http://www.reimax.com/eng-oiln1.html

Love you hear your thoughts and feedback.
My motor will be a 3Litre version (not OS) running about 650hp at the engine and limited to around 8000rpm - in case that has a bearing on the selection of pump.

Cheers! :)
Matt.
 

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I run an RB30 like you, about 600hp and 7000rpm.

I've opted for the Jun pump with a 1mm restrictor in the block, a 8l sump with gated baffles.

Looking at the size of the oil drain holes in the back of the block, I personally can't see this being a real life issue.

The area of the hole in the restricor in very very small compaired to the size of the 2 drain holes in the back of the block.
 

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if you put the 1mm - 1.2mm restrictor in the block, polish the oil returns at the back of the block you wont have any problems mate...... :thumbsup:
 

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R32TT said:
Hi All,
I've heard and read a fair bit recently that N1 pumps are made of a weaker sintered material (the gears I mean) and there have been a few instances of breakages over here in Aus.
Love you hear your thoughts and feedback.
Matt.
Well I have found it funny that in Japan the N1 pump sells for £410 plus shipping plus import taxes, but on some auction sites you can buy them for less than £200:rolleyes: . Cheap Chinese copys?:eek:
 

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Strongest pump I have seen is the HKS/Reinik/Reimax/Group A pump.
Rotor is 85mm diameter as opposed to 81mm in the standard pump and 81.5mm in the Trust/Jun pump.
The key is that there is more 'meat' on between the bottom of the pockets and the outside of the rotor. When they break they crack from the bottom of a pocket. I really do think that the engineers who put the Group A BNR32 together really thought long and hard about the design of this pump.
 

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Discussion Starter · #7 ·
bonez59 said:
ah, my N1 pump is sorry was 2500miles old, includes 1000miles running has just broken up. Bugger
Ouch. Not good to hear.
When the Pump let go, did it do any damage to your engine? Or were you able to shut it off in time?

My engine builder believes that the issue with N1 pumps can be avoided by paying close attention to the clearances of the crankshaft drive... he clearly states that I want to avoid the higher volume pumps for circuit racing - and I do respect his experience.

But what confounds me is that it appears no one here experiencing these problems of "too much flow"?
No one filling up catch cans etc?
 
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I reckon

The N1 pump only gives a problem with an over rev. The pump becomes oil bound, the relief valve cant cope with the excess at 9 or 10,000 rpm.

I have seen a few.Mostly with engines that are pretty fresh and built with tightish clearances.


Tony
 

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R32TT said:
Ouch. Not good to hear.
When the Pump let go, did it do any damage to your engine? Or were you able to shut it off in time?

My engine builder believes that the issue with N1 pumps can be avoided by paying close attention to the clearances of the crankshaft drive... he clearly states that I want to avoid the higher volume pumps for circuit racing - and I do respect his experience.

But what confounds me is that it appears no one here experiencing these problems of "too much flow"?
No one filling up catch cans etc?
Search Chris Wilson's posts, he was having problems, he has built a propper fast circuit car that is reliable, and too much oil up-top was one of his first problems........
 

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Hello,

I might be able to help you, i dont have experience with the skyline n1 pump, but i have just finished designing a custom dry sump system for a honda cbr600 f4 turbo, and we make our own gerotor scavenge pumps.

Does anyone have a picture of the failure? and also do you know if its a gerotor style pump?

As far as i understand it, you can never get enough oil volume. But you need a certain pressure to maintain the hydrodynamic lubrication / bearing journal for the camshaft. Now increasing your pum capacity will raise this pressure, but installing a restrictor / oriface will reduce the pressure. Dont forget the oil also provides cooling for the mechanical components. Enlargening the return line (like your addition of an external drain) will help reduce excess pressure also.

Now if it is a gerotor and the the internal rotor lobes are what are failing, its more than likely either poor material quality or shitty manufacturing tolerances.

If your worried about volume, and the pump is chain driven, you could always increase the size of the gear to reduce pump speed and thus lower volumetric flow (pump capacity).

Also all rotating pumps are suceptible to cavitation at high speeds and high pressure ratios (ie compressure surge on turbos) so at the high rpms ie on over rev the pump may be cavitating, essentially you would want to increase pump capacity but lower pump shaft speed

Hope this helps
 

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The GTR oil pump is a direct 1:1 drive off the crankshaft it has a small capacity but is run at a high speed (up to 9500 RPM in some cases).
 

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I think ill be lucky, was looking at the oil pressure and temp gauge when it droppped from 5bar to 0 bar, and turned it off as fast as i could, was only doing 50mph in 5th and the oil temp was 32C so was just cruising waiting for temps to come up, and cant rev my car past 7800 cause the limiter and being std rods. Think mine was just a faulty one, engine was built very well and by a well known builder.
 

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AndrewD said:
Also all rotating pumps are suceptible to cavitation at high speeds and high pressure ratios (ie compressure surge on turbos) so at the high rpms ie on over rev the pump may be cavitating, essentially you would want to increase pump capacity but lower pump shaft speed

Talking to several people about the problems. I see caviatation at the inlet side of the pump being the issue that breaks the gears.

They break on the flat- aka smallest area of the gear. Crack, and eventually let go.

Over revs. Over revs. Over revs. 73.7 mm stroke. 8k on an upshift. About 13 k on a blown shift. Easy. Very easy to see 13-15k on a downshift. I have datalogs showing fractions of a second as high as 19k.

The driver says hes not doing it. The logs and the videos show it to me. I don't think most people driving a car would realize how high they are spinning the motor on a downshift/ mis shift.
 

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so N1's suck? I bought one over a stock OEM pump thinking that it'd be better. It'd have been nice to save a hundred bucks if that's the case, but I'm far more concerned over longevity.
 

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ive just had one fail,only been on the car three months :mad:

worse than that i only picked the car up yesterday,i drove a grand total of 325 miles.

im now looking at a bottom end rebuild. :confused:

The pump was the cause or the effect ? Why did the pump fail ?

Even the best pump won't prevent you from killing it on an over rev.

The Tomei big gear pumps are pretty sexy.
 
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