How did Nissan screw up the oiling system on the rbs so badly?

[Blakeo]

Did Nissan not test the RB26 with the wet sump in racing applications? I understand Nissan used dry sumps when they raced the 26 in GT. 

I pulled my 25det down this week, the oil pump design is terrible. About 4-6 thou of sloop in the gear from factory? Nearly no noticeable wear on the gear. 

I wonder why Nissan couldn't use a similar design to the LS pump design, they don't seem to have any issues. Also I'm now wondering if the Nitto crank collar and hardened billet oil pump is going to be good enough or if I should go with the Nissan Sine Drive. The billet pump gears have about as much play between the collar and the gear as the factory one ~5 thou. 

[Duncan]

Interesting question. Seems to me it was perfectly fine for the purpose it was engineered for; 100-206kw road cars.

I guess a better question is, why do people expect road car engine oiling systems to be adequate for applications with triple the factory power, or sustained high g/ high rev usage?

In my opinion Nissan's engineering on the RB series skylines is so good that people 30 years later expect to be able to operate them well beyond their design limits. Try that with an EB Falcon or a VN Commodore.

BTW the Group A GTRs ran wet sumps with baffles. Any serious race engine (no matter what the production base was) will run a dry sump if the regs allow it.

[Piggaz]

3 hours ago, Duncan said:

I guess a better question is, why do people expect road car engine oiling systems to be adequate for applications with triple the factory power, or sustained high g/ high rev usage?

This! If you use the car like a road car which it is and don’t bounce off the limiter like a bellend then they’re fine. Granted the design could be better but it is in a road car. Want to belt it at a track... then sort it out.

 

[Ben C34]

Should organise a class action against them.

Ls1 1000hp no worries

[joshuaho96]

10 hours ago, Blakeo said:

Did Nissan not test the RB26 with the wet sump in racing applications? I understand Nissan used dry sumps when they raced the 26 in GT. 

I pulled my 25det down this week, the oil pump design is terrible. About 4-6 thou of sloop in the gear from factory? Nearly no noticeable wear on the gear. 

I wonder why Nissan couldn't use a similar design to the LS pump design, they don't seem to have any issues. Also I'm now wondering if the Nitto crank collar and hardened billet oil pump is going to be good enough or if I should go with the Nissan Sine Drive. The billet pump gears have about as much play between the collar and the gear as the factory one ~5 thou. 

It was a very different era. Look at a 3S-GTE of comparable vintage, if you throw an MR2 GT-S in the corners with modern rubber it will similarly puke oil from the breathers and lose oil pressure in similar situations. Same goes for a lot of wet sump cars. The modern expectation of being able to throw Michelin Pilot Sport Cup 2s on a car and drive it to 10/10ths for a production car lap record without blowing up an engine is very recent. The idea of shipping a wet sump engine with dedicated scavenge pumps, tons of thought devoted to oil return, air/oil separation, crankcase ventilation, etc is something that was really only thought of starting with cars like the R35 where the design spec was 1.6g for 7 seconds without losing oil pressure. In the 90s that would've been ludicrous when ~0.9g sustained cornering was considered a big deal, you might see peaks of 1.2g tops. 

Keep in mind that the reason why the gears have play is because too little clearance leads to binding which will cause a catastrophic failure. It is a pretty delicate balance.

I do think Nissan could and should have thought harder about the oiling system but we're talking about a design from the 80s, we have the advantage of hindsight and orders of magnitude more computing power available at our fingertips.

[UWISSH!]

10 hours ago, Blakeo said:

 

I wonder why Nissan couldn't use a similar design to the LS pump design, they don't seem to have any issues. Also I'm now wondering if the Nitto crank collar and hardened billet oil pump is going to be good enough or if I should go with the Nissan Sine Drive. The billet pump gears have about as much play between the collar and the gear as the factory one ~5 thou. 

Ls1 first appeared in 1997, rb26 was already well established by then.

while we are at it, why didn’t they come with forged internals, dry sumps, bigger radiator, and everything else people change on them. 
Didn’t nissan foresee the future that everyone was going to be making 700+ Hp with them in 30 years time?

[joshuaho96]

Just now, UWISSH! said:

Ls1 first appeared in 1997, rb26 was already well established by then.

while we are at it, why didn’t they come with forged internals, dry sumps, bigger radiator, and everything else people change on them. 
Didn’t nissan foresee the future that everyone was going to be making 700+ Hp with them in 30 years time?

You jest but a mystery floating around in my mind is this Nissan heritage page: https://www.nissan-global.com/EN/HERITAGE/skyline_gt-r_bcnr33.html

Supposedly the R33 GT-R concept was going to have 405 kW crank power and 490 Nm of torque. What ever happened to that plan? That would've set the world on fire back in the day even if they only shipped 75% of that. My best guess is that they set that target internally but development budget limitations made it impractical and the 280 PS agreement would've been blown wide open even if they claimed it was only 280 PS.

[GTSBoy]

The 280ps agreement was already in the weeds when the RB26 came out. The R32 engine made more than that even without removing the bleed restrictor, and a lot more than that with it pulled. The R33 engine was more again. Those were nearly 400HP engines straight out of the factory. Everything on the RB26 was good for about that much power (the turbos, the injectors, etc etc).

The real reason why the RB oil pump is the way it is that it (and the engine it was bolted onto) was based on the older L6 engines, which trace their heritage back to the 1960s and Mercedes engines that Nissan borrowed ideas from. Engines from a simpler world with lower redlines. Engines that were mass produced on an engine assembly line with absolutely no special manufacturing/assembly/tolerance efforts put in. RB26s were no different from any other mass produced Nissan engine at the time.

So, as per others above, they were fit for purpose for the usage model expected of them.

[Blakeo]

7 hours ago, Duncan said:

Interesting question. Seems to me it was perfectly fine for the purpose it was engineered for; 100-206kw road cars.

I guess a better question is, why do people expect road car engine oiling systems to be adequate for applications with triple the factory power, or sustained high g/ high rev usage?

In my opinion Nissan's engineering on the RB series skylines is so good that people 30 years later expect to be able to operate them well beyond their design limits. Try that with an EB Falcon or a VN Commodore.

BTW the Group A GTRs ran wet sumps with baffles. Any serious race engine (no matter what the production base was) will run a dry sump if the regs allow it.

Agreed, in street form they don't have an issue. But really a GTR (Grand Turismo Racing) as coined by Nissan, they never expected people to race them? A 2JZ is a street engine, but the oil pump drive on those is nearly bulletproof. Don't get me wrong, I like RBs but theres not really a solution for the oil pump issues that doesn't cost over $12-15K and not reliable long term (i.e can't use dry sump on the street long term, as they require constant inspection and maintenance). 

 

4 hours ago, Ben C34 said:

Should organise a class action against them.

Ls1 1000hp no worries

Ls1 = gods engine

3 hours ago, UWISSH! said:

Ls1 first appeared in 1997, rb26 was already well established by then.

while we are at it, why didn’t they come with forged internals, dry sumps, bigger radiator, and everything else people change on them. 
Didn’t nissan foresee the future that everyone was going to be making 700+ Hp with them in 30 years time?

Because they had to work to a budget, I understand that. The japs are generally really good at making engines, everything else about the RB is great, but the thing that really mattered was butchered

3 hours ago, GTSBoy said:

The 280ps agreement was already in the weeds when the RB26 came out. The R32 engine made more than that even without removing the bleed restrictor, and a lot more than that with it pulled. The R33 engine was more again. Those were nearly 400HP engines straight out of the factory. Everything on the RB26 was good for about that much power (the turbos, the injectors, etc etc).

The real reason why the RB oil pump is the way it is that it (and the engine it was bolted onto) was based on the older L6 engines, which trace their heritage back to the 1960s and Mercedes engines that Nissan borrowed ideas from. Engines from a simpler world with lower redlines. Engines that were mass produced on an engine assembly line with absolutely no special manufacturing/assembly/tolerance efforts put in. RB26s were no different from any other mass produced Nissan engine at the time.

So, as per others above, they were fit for purpose for the usage model expected of them.

30 years later and the aftermarket still hasn't really fixed it though, I'm not keen on spending $20k on the engine just for it to have oiling issues. Nitto sine drive looks promising and I'll probably end up buying it for my build. 

[GTSBoy]

1 hour ago, Blakeo said:

30 years later and the aftermarket still hasn't really fixed it though

No, actually it has been fixed for years. Add a collar to short drive cranks. Use upgraded pump parts. Assemble carefully. It's the last part that has caught out so many. The majority of the failures* of good aftermarket pumps are attributable to people not paying attention to the fact that when they line bore an engine or do anything else that changes the relative location of the pump and crank, they need to make sure that it all still lines up.

*Not including the failures caused by knob ends beating the living shit out of their engines by manging around limiter bashing like 17 year olds.

[joshuaho96]

It sounds like the solution goes something like sine or spline drive, upgraded oil pump, deep + baffled sump, maybe relieving the oil returns to improve the flow, a big external crankcase breather instead of trying to rely on the existing ones in the block, oil restrictor in the head, a lot of attention paid to the air/oil separation at the valve cover/before the compressor inlet, using the engine to help pull blowby out of the crankcase, and not trying to go full hero with semi-slick R compound tires. Also avoid blowby to begin with by using a torque plate, picking pistons/ring packs/etc that don't require loose clearances.

If you want to go full race there are definitely dry sump kits out there. It's just a compromise, like anything in life.

[GTSBoy]

I'm not sure why you maintain the dry sump is race only and too much maintenance/work for the street. ALFA Montreal was dry sump ~1970. Street car. Many others the same.

If I were going to build an engine to make a lot of power and use that power frequently (as opposed to the 800wHP engines out there that only come out of the garage once a month to go to cars and coffee), I'd be thinking that the cost of a dry sump system was an expected part of the overall build cost. Spend a heap of money on rotating stuff and not do everything possible to ensure that the oil keeps going where it's supposed to go? Who thinks that that's a good idea?

What is it about a dry sump that makes it hard work in your opinion?

[Duncan]

I'll add that I've not had oiling problems in the race car for years (although I had plenty early on). I use hi octane extended/baffled sump, nitto oil pump, standard block (never line bored), drilled out block oil returns, a rear head oil return/breather, head oil restrictor, baffled cam covers, standard size cam breathers to catch can then atmo, and a big oil cooler with thermostat. And a carefully assembled bottom end.

Lots of RBs racing with wet sumps and surviving, I can think of at least 3 that did 6 days of Targa Tas last month (Liam, Golly and Jason). AFAIK none of them use standard (extended) oil pump drives, nothing fancy.

[joshuaho96]

35 minutes ago, GTSBoy said:

I'm not sure why you maintain the dry sump is race only and too much maintenance/work for the street. ALFA Montreal was dry sump ~1970. Street car. Many others the same.

If I were going to build an engine to make a lot of power and use that power frequently (as opposed to the 800wHP engines out there that only come out of the garage once a month to go to cars and coffee), I'd be thinking that the cost of a dry sump system was an expected part of the overall build cost. Spend a heap of money on rotating stuff and not do everything possible to ensure that the oil keeps going where it's supposed to go? Who thinks that that's a good idea?

What is it about a dry sump that makes it hard work in your opinion?

I don't think dry sumps are inherently orthogonal to street cars, it's just that it seems to involve quite a lot headache if you want to keep the OEM power steering + AC compressor. I also wouldn't want oil lines running under the car all the way to the trunk and a big hot tank of engine oil sitting back there. My use case is going to be pretty much entirely street use, track use is secondary and the only goal there is to keep the car reliable and not scattering conrods to the wind, it doesn't really need to be quick so options like just running lower grip tires are on the table. I'm not a good enough driver to actually drive a car at 10/10ths without making the news anyways. I think there are front-mount oil tank solutions, it just involves something like deleting the washer reservoir and other similarly kind of unsavory compromises IMO.

If I really wanted or needed a dry sump engine in a street car I'd probably just get one that has it from the factory.

Edited May 9, 2021 by joshuaho96

[The Bogan]

8 hours ago, Ben C34 said:

Should organise a class action against them.

Ls1 1000hp no worries

Is that on an 'merican dyno?

And yes, every engine bay needs a sewing machine, I mean a LS1

[Blakeo]

7 hours ago, GTSBoy said:

No, actually it has been fixed for years. Add a collar to short drive cranks. Use upgraded pump parts. Assemble carefully. It's the last part that has caught out so many. The majority of the failures* of good aftermarket pumps are attributable to people not paying attention to the fact that when they line bore an engine or do anything else that changes the relative location of the pump and crank, they need to make sure that it all still lines up.

*Not including the failures caused by knob ends beating the living shit out of their engines by manging around limiter bashing like 17 year olds.

You can't bash limiter in an rb, its not ideal but it happens in a drift car. The 25 in my 33 is tired, I don't want to spend 15-$20k building it just to suffer oiling issues drifting. Might be better to LS swap it idk. 

[joshuaho96]

5 hours ago, Blakeo said:

You can't bash limiter in an rb, its not ideal but it happens in a drift car. The 25 in my 33 is tired, I don't want to spend 15-$20k building it just to suffer oiling issues drifting. Might be better to LS swap it idk. 

If you're afraid of breaking oil pump gears there are some solutions that don't require pulling the engine. One is to use an ECU tune with proper soft limiting. The "best" method is DBW forcing the throttle to close, effectively idle control with the target RPM being just short of redline as long as the commanded torque from the APP is higher than the torque commanded by the rev limiter and engine RPM remains above the threshold for the soft limiter to kick in. I'm pretty confident this is actually the main rev limiting strategy used in a lot of cars these days, people complain that they can't bash the limiter in neutral anymore and instead the engine smoothly goes up to 3000 RPM and stays there perfectly.

Another option is soft limiting by fuel or ignition. I have never tried a soft fuel cut, no idea how that would work without causing weird behavior like high engine vibration and wonky O2 readings from effectively a random misfire. Soft ignition cut can also help, but there is no free lunch there. You will cause EGTs to skyrocket this way, rely on this too much and it'll really do some damage. You really just want to take the edge off of the hard cut by smoothing the transition into and out of it to try and reduce the shock loading.

You could also have high hysteresis on a hard fuel cut limiter. If you have to wait like 500-600 RPM before the ECU shuts off the rev limiter it'll be much harder to do a ton of damage compared to one that waits 50 rpm before going back to normal fuel/spark. This is probably very annoying though if you want to stay near the limiter for long periods.

[Dose Pipe Sutututu]

10 hours ago, Blakeo said:

You can't bash limiter in an rb, its not ideal but it happens in a drift car

If the correct strategies are in place, as well as a decent oil pump gear set you'll be fine.

Running a soft fuel cut is one of the options, sure it doesn't sound sick (bang bangs etc.) but it won't be lunching up motors.

If anyone has seen me at a skid pan, I literally just sit on the limiter

[GTSBoy]

8 minutes ago, Dose Pipe Sutututu said:

If anyone has seen me at a skid pan, I literally just sit on the limiter

^ This is the sort of knob end I was talking about.

[GTSBoy]