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Yeah thats correct. Markdid the tune. He just got a new 4wd dyno set up in his shop. Dont know that brand off hand but I will check with mark today. All the paperwork with the "logged" runs are in the post on the way up to me now. I didnt want them sent with the car when it was transported from sydney to brisbane as things tend to go missing that way, andthats the reason i have not yet posted scans of the logged runs up here.

i have broken two n1 oil pumps

so i could not recommed them myself!

big pump or dry sump if you want to continually launch it! or start saving

cheers russ

Hi Russ, we have used 30+ N1 oil pumps over 5 years and not broken one. So I am very interested in getting to the bottom of why you have had 2 failures. I don't believe it is simply a case of you having been extremely unlucky or we have been unbelievably lucky. There must be a reason why we don't have problems, something we are doing different. Maybe not something obvious, maybe nothing to do with the oil pump itself.

So what I would like to do is list what we do and see if it is any different to what you did;

1. We always use a wide oil pump drive flange crank (late RB26) or a crank collar on RB20/25/30 cranks.

2. We use all sorts of different harmonic balancers, mostly standard RB26, but some RB30 and ATI.

3. We balance (to very fine tolerances) every up & down and round & round piece. Firstly individually and then as a group. This includes the harmonic balancer, the flywheel, the clutch plate/plates and the pressure plate.

4. All of our engines have oil surge prevention sumps, usually wings, baffles and one way doors.

5. We prime the oil pump on assembly

6. We are very particular about the torque of the harmonic balancer retaining bolt, and we insist that the tension is checked once the engine has been run for 20 minutes.

7. The blocks have the usual oil restrictor flow limits, various depending on the vehicle usage pattern (rpm limit, circuit, drag, road use etc).

8. All engines run oil coolers, most (but not all) run remote oil filters.

9. We insist on an oil filter change at 20 minutes running from new.

That’s about all I can think of that is remotely linked to the oil pump.

The reason for the N1 oil pump selection is for the extra pressure without excessive oil flow. Despite all of the oil return mods and upgrades (inc external return lines) we have found the aftermarket (HKS, Jun, Apexi, Trust etc ) oil pumps simply have too much flow. Plus they cost almost as much as a dry sump pump. So we never use them.

If you want to continue this discussion in another thread or via PM, please just let me know.

:( cheers :(

HI SK

I have done all of those items you posted, but we do run the tomei oil pump and to much flow is an issue as you know.

the configuration is

new n1 engine r33

brand new standard balancer'

19 row cooler

oil change every event and filter sometimes twice

my thoughts are that we were breaking them due to the amount of launches we do in them, for instances on a normal dutton event we would launch from above 6500 rpm more than 70 seventy times.

so in two rallies and maybe a hill climb event adds up to roughly 150 - 180 launches all whilst using launch control at about 6500. which as you can imagine is quite severe.

the oil pumps both cracked across the gear. we have not done a pump since upgrading, but do have flow issues( too much)

cheers Russ

always glad to hear other opinions & input too :(

Do I detect a common difference? High rpm and lots of rev limiter controlled launches. We don’t do that many launches, one per race, so 24 per year, plus a few practise launches. With only light use of the launch control rev limiter.

It could also be related to the crank moving inside the oil pump rotor, like a hammer effect. That would be very noticeable on the rpm limiter, like a jack hammer.

What sort of clearances are you running on the oil pump drive flange? I know on at least one crank we have to weld up and regrind the flanges, as they were worn. A couple of other cranks were rejected as they were too far gone. The crank collar (for RB20/25/30) has a much smaller clearance than the “standard” RB26 flange. It is actually a very snug fit.

:( cheers :(

thanks sk

oil pump drive is being resized, with better tolerence as we speak, so you hit the nail on the head i think.

yes and your right along with dirtgarage, we use i fairly harsh launch control limiter and think it might be the cause. but i really need to use it

as it does help off the line especially with so many starts.

it never ceases to amaze how good the clutch is in our car,if any one wants a clutch that is near industructible & will not slip, and it is that light we took the clutch booster off and it is still lighter than standard. then you should talk to doug at NPC in Brisbane.

cheers russ

HI SK

I have done all of those items you posted, but we do run the tomei oil pump and to much flow is an issue as you know.

I've heard from a separate source that he has seen N1 pumps fail and he attributes it to the material used in the N1 Pump coupled with the used of Launch Control and/or Anti Lag etc.. The chattering essentially breaks the internals? Is that the case?

But I'm also lead to believe that any of the other Pumps, be they Tomei, Nismo (different to N1?), JUN or what have you, all flow too much volume and end up filling the cam covers with oil (despite all the restrictors and back-of-head drains to sump etc...)

Is the Tomei Pump not externally adjustable? And is this 'enough' to tone it down for circuit? I imagine the problem doesn't happen so much in a 10sec drag car as it does in Targa like events..

Has anyone tried uprating the internals of the N1 Pump to better material? This link suggests there may be an option?

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

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