Building A Rb20det

[carl h]

lol latest news is i blew a hole in cyl 5's piston and am currently deciding on what pistons to go with, once its rebuilt and back together a good breakin and trip to the tuner should provide interesting results.

[Cubes]

Carl h,

If you are currently taking it to 8.5k... RB's live a short(er) life when taken over 7-7.5k. Not only are you hammering the bearings you are also risking oil pump failure at those rpm's.

I say

The head:

Drop a set of 1mm over sized valves in it, mild port/polish, clean things up a little and keep your 260duration cams.

The bottom end:

Throw a set of R33 GTR rods and crank (~2.4ltr) or if not available a set of Series 2 rb25 rods and crank (~2.3ltr).

Reason I say R33 GTR and not R32 GTR rods and crank is because Nissan rectified the oil pump drive failure fault and elarged the oil pumps drive. The same goes for the Series 2 R33 RB25.

Be sure to order pistons AFTER as you will have to sort out the pin height to have the piston sitting in the bore correctly.

All the above will help spool the tubo quicker and reduce the rpm that you use mean while increasing average power.

Bring the rpm down to 7.5k and the motor will last much longer than at 8.5k.

The GTRs @ Bathurst wouldn't take it over 7k when racing at the Bathurst 1000 due to reliability issues over ~7.5k.

[carl h]

Carl h,

If you are currently taking it to 8.5k... RB's live a short(er) life when taken over 7-7.5k. Not only are you hammering the bearings you are also risking oil pump failure at those rpm's.

I say

The head:

Drop a set of 1mm over sized valves in it, mild port/polish, clean things up a little and keep your 260duration cams.

The bottom end:

Throw a set of R33 GTR rods and crank (~2.4ltr) or if not available a set of Series 2 rb25 rods and crank (~2.3ltr).

Reason I say R33 GTR and not R32 GTR rods and crank is because Nissan rectified the oil pump drive failure fault and elarged the oil pumps drive. The same goes for the Series 2 R33 RB25.

Be sure to order pistons AFTER as you will have to sort out the pin height to have the piston sitting in the bore correctly.

All the above will help spool the tubo quicker and reduce the rpm that you use mean while increasing average power.

Bring the rpm down to 7.5k and the motor will last much longer than at 8.5k.

The GTRs @ Bathurst wouldn't take it over 7k when racing at the Bathurst 1000 due to reliability issues over ~7.5k.

<{POST_SNAPBACK}>

i wholey agree on the rev bit, redline was set to 8.5k but i tried to shift before that (usualy shifted round 7.5-7.8).

im looking into doing some head work and possibly a rb24 bottom end but the cost of the build may be out of my budget as im a full time student and work on the side to pay for my misc bits.

i did know about the r32 short snout problem and was looking for a r33 bottom end, if i were to go with the 2.4 i would just get tomei pistons and not even worry about it.

the oiling system is going to be upgraded as well, an oil cooler should help prolong not only oil life but bearing life as well by keeping viscosity up and some kind of highflow oil pump (n1 looks to be the pump of choice right now, nismo is *affordable* but still overkill and expensive) to suit.

there really wasnt any reason to rev the motor out to 8.5, but sometimes you miss a gear or just are trying to wind it out, upon visual inspection of the bearings when i tore the engine down almost all of them were nearly mint and frosty looking with very little wear on them a few did have some shine to them but nothing out of the ordinary, not too bad for a motor that was constantly thrashed end on end for over 4 months.

i like the displacement of the rb20 simply because it sips gas on cruise and i dont really need to push it hard unless i want to make power, altho greater average power certianly is much nicer than peak power (which was at 7k or so, so revving past only kept peak); but some how i have a soft spot in my heart for the little 2.0.

i suspect that the reason the car was laggy on boost and torqueless off boost (yeah yeah, its a 2l....) was also due to poor compression (140psi across) coupled with a bad tune, right now im in a bit of a toss up in what to do rb20 is fairly easy with just a good set of pistons or a rb24 with a bit more cash and time........

[Cubes]

140psi isnt bad considering the cams you are running.

My stock rb20det when it was fresh had ~145psi across all 6 with the stock cams that have 0degree's overlap.

As you increase overlap you bleed off compression, showing up low on the compression test guage.

If you like the 2ltr economy at least look at the series 2 rb25 crank and rods as this will give you the nice fat oil pump drive required for high rpm high flow/loading oil pumps.

One reason I stuck with the stock rb25det pump on my rb30det was to ensure not too much load was placed on the fragile short crank oil pump drive. I didn't have $600 at the time to waste on a JUN long oil pump drive adaptor.

Go for the 2.3ltr.. cheaper to get a hold of not to mention the added reliability should you miss a gear.

Why did it blow a hole in the piston? Lean?

With regards to economy... You will be pleased to know myself going to the 3ltr has hardly affected economy if I drive it around normally. Get stuck in to it and it definitely sucks more juice, all though it hasn't had the light and moderate load points tuned.

Economy went from 10.6l/100km's to 11.6l/100km's, it is on boost a lot more with the 3ltr.

At the moment its dropping down to just under 12:1 before it gets to zero vacuum. I prefer it to run stoich up until zero vacuum where it then drops to 13.5:1 until 2psi of boost is made then after that down to 12:1.

I assume mine is dropping out of closed loop early due to the pfc being calibrated for the RB20DET motor. The rb20det would hold closed loop (stoich) until a shade over zero vacuum.

Hopefully once its had a full tune it will return the same if not better economy than the rb20det.

Depending where it makes boost break the motor in with the wastegate wired all the way open. Make no boost so you can really load it up with full throttle. No in gear deceleration, drop it in neutral and coast to a stop.

Edited December 6, 2005 by Cubes

[carl h]

140psi isnt bad considering the cams you are running.

My stock rb20det when it was fresh had ~145psi across all 6 with the stock cams that have 0degree's overlap.

As you increase overlap you bleed off compression, showing up low on the compression test guage.

If you like the 2ltr economy at least look at the series 2 rb25 crank and rods as this will give you the nice fat oil pump drive required for high rpm high flow/loading oil pumps.

One reason I stuck with the stock rb25det pump on my rb30det was to ensure not too much load was placed on the fragile short crank oil pump drive. I didn't have $600 at the time to waste on a JUN long oil pump drive adaptor.

Go for the 2.3ltr.. cheaper to get a hold of not to mention the added reliability should you miss a gear.

Why did it blow a hole in the piston? Lean?

<{POST_SNAPBACK}>

140 is bad when you add some oil and it shoots up to 160psi........

i had thought of the rb25 crank tho, seems like a nice alternative to the rb24 bit but if i can source a rb26 crank and rods easier than the rb25 then its almost pointless to go with the rb25.....

a local (local to you guys) shop in au (proengines i believe) is making crank collars at a very nice price, i believe for me its a hair over 110$ usd, much nicer compared to the jun bit.

as for the piston melting, still a mystery, afr's were a nice 11.5-12:1 when it blew so not sure exactly why, suspect some damage done to the piston in past which inturn formed a nice 'hot spot' on the piston and was only a matter of time.

[TokyoTaxi]

One thing I would be sure to do if I was to rebuild again would be to increase the ability for the RB20 to drain oil back to the sump !!!! I don't know how but maybe porting the oil drain galleries or the like ( RB25's have a pipe that does this ). Since my rebuild, while on the track running at 6.5k RPM + for extended periods of time, it will fill the cam area up, push oil out, and fill up the catch can pretty quickly. Even though I have a 9L sump on the car I still don't like the idea of that much oil leaving the engine Now I just don't do track days any more.

BTW I've got Arias in mine and they are great ( with stock rods ).

[Cubes]

Thanks for the crank collar tip... I am definitely going to be finding out if its possible to fit one while the motor is assembled.

Fat32, sounds like the same issue GTR's have.. Any chance you are running an uprated pump? Throw smaller head oil restrictors in it, tomei do them.

Edited December 6, 2005 by Cubes

[carl h]

One thing I would be sure to do if I was to rebuild again would be to increase the ability for the RB20 to drain oil back to the sump !!!! I don't know how but maybe porting the oil drain galleries or the like ( RB25's have a pipe that does this ). Since my rebuild, while on the track running at 6.5k RPM + for extended periods of time, it will fill the cam area up, push oil out, and fill up the catch can pretty quickly. Even though I have a 9L sump on the car I still don't like the idea of that much oil leaving the engine Now I just don't do track days any more.

BTW I've got Arias in mine and they are great ( with stock rods ).

<{POST_SNAPBACK}>

agreed, it seems that the rb20 has a poor oil return system as i noticed oil leaking out of the back of my cam covers after a few hard pulls.

perhaps tapping out the head near the back like some rb26's are done for oil return could help this problem, i dont like the idea of oil pools in my head because that means less in the sump .

right now the piston choice if i dont go with a rb24 setup is a set of cp pistons or some arias pistons, from what ive heard cp's quality is almost if not that of arias....

what kind of mods did you do for the 9l sump is that a custom deal?

as far as rods go, i'll proly stick with stockers seems if you avoid detonation they will hold power just fine.

[TokyoTaxi]

Fat32, sounds like the same issue GTR's have.. Any chance you are running an uprated pump? Throw smaller head oil restrictors in it, tomei do them.

<{POST_SNAPBACK}>

I'm 99.99% sure it's a standard RB20DET oil pump. Mind you, my mate worked at nissan and got me the parts so he might have slipped me a bigger pump <_< I'm not keen on restricting the oil to the upper engine as I've seen a few sets of cams getting chewed from doing this ( wrong size / blocked restrictor maybe ? ). From what I understand, you can just bolt the bear head onto the bear block and port out the return galleries. This is supposed be the best fix for the problem

[Sydneykid]

Some tips;

N1 oil pumps don’t flow any more oil than standard R33GTR oil pumps, they simply have a higher pressure relief valve spring.

All of the oil supply problems that an RB26 has are the same in an RB20/25 when you rev them to the same rpm. So simply enlarging the oil returns to the sump won’t be enough. You will need to limit the oil flow to the head, RB26’s only have one oil supply the other is blocked. A restrictor is used in the one that is open, around 1.5 mm is sufficient if around 8,000 rpm is regularly visited. For long runs on the circuit (10 minutes plus) an external oil return is a good idea, direct from the rear of the cylinder head to the sump. Never in with the turbo oil return.

Most of the valve train wear we see is due to poor oil change regime, not insufficient flow. If you turn a standard RB26 off quickly after a 7,000 rpm blast, you will find the cam covers just about full with oil.

cheers

[MattSR]

The Gibson R31 skylines ran to over 9000rpm around Bathurst, might be worth while finding out some inof on how they did it

[Sydneykid]

The Gibson R31 skylines ran to over 9000rpm around Bathurst, might be worth while finding out some inof on how they did it

<{POST_SNAPBACK}>

No they didn't

cheers

[carl h]

ok so what should be done to prevent pooling in the rb20's head then?

you say fitting an external drain should help but where abouts should it be placed, ive no qualms about modding the head while its out of the car.

also i seem to remember a thread on this forum stating that the internals and over all design of the n1 pump were diffrent from that of a normal rb26 pump.......

[MattSR]

I recall reading Zoom a while ago, and I think this was what they were claiming.

SK - what RPM did they actually use?

[Turbine]

Would it be a wise choice to dry sump the 2.0L engine with an external oil pump to have it rev over 8500RPM?

[Sydneykid]

1. ok so what should be done to prevent pooling in the rb20's head then?

2. you say fitting an external drain should help but where abouts should it be placed, ive no qualms about modding the head while its out of the car.

3. also i seem to remember a thread on this forum stating that the internals and over all design of the n1 pump were diffrent from that of a normal rb26 pump.......

<{POST_SNAPBACK}>

I have posted this up a number times, but another one won't hurt;

1. Lessen the amount of oil that goes up via flow restriction, block one and restrict the other. Then drill out the oil return galleries in the head and the block, some 1 mm and some 2 mm. Machine around the oil return valleys t the galleries as the casting can be improved on easily.

2. The external oil return to the sump goes at the rear of the cylinder head, between it and the firewall. You will find a convenient flat spot in the middle of the camshaft valleys with galleries to both. On the RB26 cylinder heads there is already a threaded hole there so it makes bolting the fitting up very easy. I haven't checked RB20 or RB25 cylinder heads to see if there is the same convenient bolt hole on them.

3. I have had an N1 oil pump and a standard R33GTR pump on the oil pump flow tester and there is no difference in the flow rate at 3,000 rpm. They might look different but the flow rate is the same. The pressure relief valve opened a few psi higher on the N1 pump, indicating a stronger spring. The only RB oil pump I have tested that actualy flows more than standard was Jun pump and at $1600, a dry sump system had more appeal.

Would it be a wise choice to dry sump the 2.0L engine with an external oil pump to have it rev over 8500RPM

The 4 stage dry sump systems we fitted to RB26's would work. They have 2 sump scavenge and one cam cover scavenge plus one pressure stage.

Honestly for the cost, you would be much better off building a 7,000 rpm RB30 that would make more power and need nowhere near as many costly high rpm supporting parts.

Hope that helps

cheers

[TokyoTaxi]

Or ....... Build an RB20DET with higher compression and lower boost and limit the revs to say 7K ??? ( Similar concept to the Gibson RB26DETT )

[carl h]

Or ....... Build an RB20DET with higher compression and lower boost and limit the revs to say 7K ??? ( Similar concept to the Gibson RB26DETT )

<{POST_SNAPBACK}>

yah, i was also toying with that idea of raising static compression .5 point to 9:1, would provide nice off boost drivability and loads more power on boost.

as far as the revving deal, yes i know its bad for the motor, but this new motor most likely wont be going that high but will have the saftey functions to do so (uprated oil pump, stiffer valve springs,ballanced rotating assembly, ect...).