The Fabled N1 Oil Pump Debate

[Guilt-Toy]

a little off topic. But...

this is the gear from my rb25det stock oil pump thats been on my engine.

Its done 300,000km's and has had 363rwkw for the last 12 months or so... its done lots of limiter and launch controll stuff...

I was putting a near crank seal because the seal broke... pulled the seal out cos i put it in crooked and the small piece fell out of the pump...

So yeah all day takin the pump off while engine still in car (did not drop xmember) and pput a N1 pump in its place.

Hope the N1 pump dont end up looking the same as this one!

[Adriano]

You are one lucky bastard

[Guilt-Toy]

yes well for once something happened in my favour, i was lucky i was not going to risk the seal leaking because it was in crooked and decided to take it out again otherwise it woulda been put back together cracked and would have destroyed my engine.

Sooo lucky.

On another note, how the hell are you supposed to get those crank seals in, the one ive got keeps folding inside itself and wont go in

[Duncan]

no idea I just swear at it and have 100 really careful goes until one of them works. there may be a better way lol.

I take it you hadn't noticed any oil pressure problems with that pump? you gtst owners have it too easy for jobs like that.......

[Guilt-Toy]

no oil pressure issues at all with the cracked pump. the only symptom was 1 litre of oil over the cam gears / timing belt and another litre of oil on the ground. another 300v chrono spill.... it had only done 2000kms too

[The Dan]

On another note, how the hell are you supposed to get those crank seals in, the one ive got keeps folding inside itself and wont go in

The seal should go in without a problem. Make sure you are using Silicon spray around the inner surface (also helps to spray liberally around the outer edge - that way the seal will slide in easy) and put the seal on the crank at the slightest of angles. Preferably from the bottom in first. Then gently work your two thumbs around the inner edge of the seal (like putting on a tupperware lid) and it will slide on. Then just push it home.

[Sydneykid]

Cheers, I'm not saying an N1 pump is definitely going to fail, more so making the point that they do, even on 'low km' engines. I have no reason to lie, it really doesn't bother me either way, but thought some of you might appreciate a picture

Negative.

The decision was made to chase ~600hp at the wheels. Obviously an N1 engine isn't going to handle that with cast pistons/rods. Instead of grenading a perfectly good motor (and possibly damaging the block in the process) it was stripped down and rebuilt.

Originally I was going to retain the N1 pump, lucky I didn't.

Yes, the car saw a few limiter launches, but no more than any other GT-R I would suspect.

If the oil galleries are blocked with machining swarf, I'd expect to see worn bearings. My bearings had almost 0 wear. Bore was only 2-3 thou worn on each bore, and the head shop said it was the best RB26 head they've ever seen.

I keep going back to the hammer witness wear on the oil pump flange, that's either a worn crank flange or a lot more than "a few limiter launches". I have an 8 year old N1 oil pump out of a race car that has way less wear than that. Did you measure the crank flange before you assembled the engine? Check the clearance to the new pump?

Cheers

Gary

[unique1]

I had a brand new JUN oil pump on my engine, it had done 1000km run in with 4000rpm limiter and then a dyno tune of about 60km or so, i took it out and gave it a couple of good runs after the tune and noticed oil pressure dropping slowly, i pulled the motor the next day expecting the oil pump backing plate screws to have come loose and we pulled the plate off and the inner gear like Guilt Toys one was split in 2 pieces.

We found the harmonic balancer bolt had come loose and the balancer was sliding up and down the crank nose (jun 2.7L crank) and welded itself to it from getting sooo hot.

Im very very lucky we checked that pump gear on i could have wrecked a very very expensive bottom end in a short period of time.

ive had another jun pump on the motor for a long time and no issues, but we make sure we put a heap of loctite on that balancer bolt.

[GTR1993]

I had a brand new JUN oil pump on my engine, it had done 1000km run in with 4000rpm limiter and then a dyno tune of about 60km or so, i took it out and gave it a couple of good runs after the tune and noticed oil pressure dropping slowly, i pulled the motor the next day expecting the oil pump backing plate screws to have come loose and we pulled the plate off and the inner gear like Guilt Toys one was split in 2 pieces.

We found the harmonic balancer bolt had come loose and the balancer was sliding up and down the crank nose (jun 2.7L crank) and welded itself to it from getting sooo hot.

Im very very lucky we checked that pump gear on i could have wrecked a very very expensive bottom end in a short period of time.

ive had another jun pump on the motor for a long time and no issues, but we make sure we put a heap of loctite on that balancer bolt.

What torque did you do the balancer bolt up to, i know in the manual its a HEAFTY torque and you need one big arse torque wrench to go to their specs.

just checked the manual, 460 Nm!

Edited May 18, 2008 by GTR1993

[Guilt-Toy]

my crank collar was fitted incorrectly which made the back plate behind timing gear wear through and the result was a loose harmonic balancer bolt which stuffed the keyway in the crank.

I had to replace the crank. Maybe my pump would have lasted longer if this did not happen?

[T04GTR]

got harmonics??????? time for a better harmonic balancer..... the factory rb30 redline should be observed to avoid this. nothing wrong with the crank. just the harmonics of it killing it.

[T04GTR]

this is a good picture from ati showing what your crank does when revved past redline and what the damper does to combat crank whip.

[T04GTR]

this is a "sfi" balancer on a ford xr8 boss 260. it shows quite clearly why they break the oil pumps in these motors too :

and this is how the group A rb26 got around the same problem, with a nice big balancer. this is a gibson motorsport engine :

[T04GTR]

What torque did you do the balancer bolt up to, i know in the manual its a HEAFTY torque and you need one big arse torque wrench to go to their specs.

just checked the manual, 460 Nm!

rb20/25/30 is 180nm.. 26 is 460nm

[T04GTR]

oh, rev limiters kill the pumps too. if you have a "soft cut" limiter its not as bad. but a hard cut. (power fc) wont be helping. your crank is ok. it just dont like the revs and or limiter. and if you are reving it past 7k id be getting a better balancer. a r33 gtr n1 one at least

[unique1]

yep ever since the first pump issue, i have installed an ATI balancer and no dramas

[GTR1993]

rb20/25/30 is 180nm.. 26 is 460nm

Cheers wasn't aware of the much lower amount on the other rb motors

[Angus Smart]

Can someone tell me by looking at this list what partnumber would be needed for a r32 gtr with r34 n1 engine

probably somewhere near 400kw, and is going to be pretty much a race only car with next to no street use.

http://www.atiperformanceproducts.com/prod...s/damnissan.htm

I've gotta get one of these before i put the motor in.

this is for Ati damper.

Cheers

Edited May 19, 2008 by Angus Smart

[T04GTR]

are you running aircon?

[Angus Smart]

I guess i could remove it aswell,

2-5 on the pulley page all run a/c

but the first one doesnt.

i guess the best one for both ac and no ac would be good.