Rb20 Build Direction

[dangaz]

Hi all,

I have been green with envy whilst reading everyones posts on performance from there lines for the past two odd years.....I want to start chasing power. I have almost paid off an investment which has been taking up most of my income.....and the end is in sight (2mths)

Currently my rb20 has 195XXX on it and makes a healthy 175rwkw.

Due to the k's on this current engine I'm looking at building a 20 opposed to buying a 25, 26, 30 etc. I want an engine that I know the condition it is in to start as a base...I'm after a reliable 230-240rwkw all day everyday...don't need turbo advice

If you could answer a few of the questions below to point me in the right direction it would be appreciated

Thanks in advance...

cost of rb20 to 22 with parts labour etc??

cost of rb20 to 24 with parts labour etc??

I have heard of 9000rpm redlining 20's....what needs to be done to build something of this nature??

Your personal experiences with a 20 build what would you do differently??

[dangaz]

No replies?!?!.....I know that 20's take punishment but they do break...and do need builds surely someone here tonight has done one??

any answers or advice...give me direction...cheers

[z31 rb20]

Im new, and i have been reading these forums for about two weeks now, and from what i gather...just a stock rebuild would prolly suit you just fine...maybe go with some fg pistons so you can run more boost safely....Now i would think if you wanted 350-400kw everyday then i would think you would need a beefer engine...however the all RB's are said to be able to hold 300kw...hope i helped...

[HRthirtyone]

ok, go for a power fc, cheap and suitable for an all day everyday car.

i have had three tuned rb20s now and rebuilt two, and when you get to the 220rwkw mark, they dont last very long. You may start to spin bearings, and crack pistons, ringlands etc depending on tune. Definitely spend the money on the bottom end first if you have all the goodies. 220-240kw is the maximum i would expect from a daily rb20, if not a bit too much. Dont run more than 17ish psi on a daily either, especially in warm weather and traffic, its asking for trouble

you'll learn once you start breaking them

[z31 rb20]

Only 220kw? wow thats pretty weak..In my starion i have been running 15psi for three years no problems, other than a blown head gasket the first year.... I learn more everyday....

[Roy]

ok, go for a power fc, cheap and suitable for an all day everyday car.

i have had three tuned rb20s now and rebuilt two, and when you get to the 220rwkw mark, they dont last very long. You may start to spin bearings, and crack pistons, ringlands etc depending on tune. Definitely spend the money on the bottom end first if you have all the goodies. 220-240kw is the maximum i would expect from a daily rb20, if not a bit too much. Dont run more than 17ish psi on a daily either, especially in warm weather and traffic, its asking for trouble

you'll learn once you start breaking them

I would disagree with that. My old motor was happy enough with 16psi and about 220rwkws and it had 175,000kms on it and had ran the bigger turbo since 150,000kms

The motor died because of silly spanner work, not the engines fault. The wrecker replacement motor has now done about 10 track days, 10,000 road kms and just survived the 3 day Dutton Rally. At no time was it running less then 220rwkws and 14psi...at Sandown Raceway and for half a day it was running 1.5bar and about 260rwkws. The engine is fine, though i concede that boost level is above what i would comfortably use.

But if you can make that power without running the boost and revs i need then i dont see why a certain number is the limit of the motor. Again i think i was using an 8,800rpm red line and there is plenty of footage of the car giving it a tickle. Id say its 1,000rpm higher then i would be comfortable running if i wanted the engine to be reliable.

But at the end of the day, if you keep the std rev limit, and keep boost under 16psi and the thing has the correct support systems, then whatever power you can make out of the engine will be reliable. Thats my thoughts anyway....

So if you want an engine for a reliable 220-230rwkws then get a long motor from a reputable wrecker and put your gear on it. But i would wait until your current motor to go bang, if it goes bang.

If it goes bang, then look at what failed and consider whether it was a tune thing, driver thing, age/wear thing or whether it was an RB20 failure.

Whilst i would rather an engine with 20,000kms, the RB series of engines, particulary the RB30 etc has seen 250,000kms with no real problems, then been beaten around the head with an RB25 head turbo conversion and have still proven reliable.

So they are good bottom ends if you keep the servicing up to them.

[legend01]

Ok well

I had a bit of a look into doing this at the moment rang Hi Octane for pricing your 2.2 would be tomei pistons Quoted $2300 for pistond rings and pins had to go tomei couldn't find anyone else who made pistons for an rb20 in 82mm plus u'd have to go tomei metal head gasket think there round the $500 mark but shop around I got mine for $420 your nissan engine rebuild kit is about $370 rbsize your rods shotpeened and hardened round the $600 mark works out bout $100 a rod now high hp and reliable you would have to get n1 oil pump think just jap are doing these for $495 at the moment .

If you decide to run the n1 oil pump then proengines supply and fit and rebalance your crankshaft with the collar not sure but heard on these forums around $350 then look at rod arp rod bolts $250 head stud kit $290 and if high hp engine main stud kit $330 to keep it cool at least gtr water pump or an n1 once again bout $330 nismo thurmostat $195 plus machining of cleaning of the block decked and bored weel havn't got pricing there yet so wont comment and thats just the bottom end alow at least $1000 to get a decent porting job done on the head

Most of the prices for parts here , I've bought as I have all the bolt on's including the head work most of which I've done myself execpt the pistons which I bought arias 79mm for $1130 so hope this is a bit of an indication for you

Cheers Peter

[HRthirtyone]

I would disagree with that. My old motor was happy enough with 16psi and about 220rwkws and it had 175,000kms on it and had ran the bigger turbo since 150,000kms

The motor died because of silly spanner work, not the engines fault. The wrecker replacement motor has now done about 10 track days, 10,000 road kms and just survived the 3 day Dutton Rally. At no time was it running less then 220rwkws and 14psi...at Sandown Raceway and for half a day it was running 1.5bar and about 260rwkws. The engine is fine, though i concede that boost level is above what i would comfortably use.

But if you can make that power without running the boost and revs i need then i dont see why a certain number is the limit of the motor. Again i think i was using an 8,800rpm red line and there is plenty of footage of the car giving it a tickle. Id say its 1,000rpm higher then i would be comfortable running if i wanted the engine to be reliable.

But at the end of the day, if you keep the std rev limit, and keep boost under 16psi and the thing has the correct support systems, then whatever power you can make out of the engine will be reliable. Thats my thoughts anyway....

So if you want an engine for a reliable 220-230rwkws then get a long motor from a reputable wrecker and put your gear on it. But i would wait until your current motor to go bang, if it goes bang.

If it goes bang, then look at what failed and consider whether it was a tune thing, driver thing, age/wear thing or whether it was an RB20 failure.

Whilst i would rather an engine with 20,000kms, the RB series of engines, particulary the RB30 etc has seen 250,000kms with no real problems, then been beaten around the head with an RB25 head turbo conversion and have still proven reliable.

So they are good bottom ends if you keep the servicing up to them.

ok, sorry, i should have worded it like "in my experience....." because the way i wrote it sounds like you'll blow your engine if you run over 220kw daily on stock motor. This has been my personal experience, but may not be someone elses. WHAT I was trying to get at was, if you want reliablility in an engine putting out more than double the factory power @ the wheels, then please consider strengthening the bottom end.

i personally havent done this, because when i blow one, i just go get another from the wreckers, check the vital signs, and get it tuned. It sure is a hell of a lot cheaper than a complete build up, especially if you spend $3-4k on the engine and blow it anyway. It is very easy to change the engine your self if you have a decent crane and a spare weekend!

[Roy]

Yeh i agree with what you said about it being reliable. Id go as far as sayign if you need it to be 100% reliable then dont touch the turbo ir the ECU. Thats about as close to 100% reliable as you will get.

But i tend to think a motor will live happily at 220rwkws...lol again thats only my opinion. Wasnt trying to be snappy, i suppose the point i was trying to get accross is dont be worried about the power, but have a look at the boost and revs you are running and the quality/reliability of the parts you are using to make that power.

Of course motors can go bang at 110rwkws if the fuel pump dies

Out of interest can i ask what was failing on your motors?

[HRthirtyone]

yea id say your on the money.. the things that have failed on my engines have been cracked ring lands on piston no.1 with no signs of detonation on the piston tops (also signs of a failing oil pump?!), another was oil scraper rings, and my latest was I spun a bearing 2 weeks after buying an engine from a wrecker and getting it tuned.

[Spoolup]

Best option is to turn the RB20 into a crab pot. Put all that money into rebuilding an RB25 and bang that in.

[dangaz]

Thanks guys thats given me a heap of figures to mull over.

..as I said in the original post with 190xxx k's I rather start building a motor up and do a swap rather than blowing my only means of transport and go around like a mad chook trying to get the car back onto the road with a rushed job...

a short motor goes for around 900-1100 these days?

thanks again.......I'll start building my 220kw++crab pot.cheers

[Spoolup]

dude an RB25 short motor goes for around 1500-2000. With the right turbo comb you can easlily get 300 rwkw and the rebuild will cost you the same or less.

RB20's have an inferior head/port design, smaller valves, less cubic displacement, hence less torque.

Basically your wasting your dough rebuilding the 20 when you can rebuild an Rb25 or for a bit more you can build a real engine RB30det.

Im just trying to point you in the right direction and get you the best bang for buck.

[carl h]

why is he wasting his money, it is his choice and the motor isnt that bad.

my rb20 gets 26-28mpg highway and city, it sips gas off boost and is decent enough round town.

rb25 was designed to move the boat of the r33 chassis around simply because it was so farking heavy.

as far as motor failure, from all the 20's ive seen blown its always the pistons...very few have had spun bearings.

but even then the ringlands and piston design on the rb20's piston is quite robust, a motor that has been well tuned will definately live.

[andylaurel]

im sorry but in my experience, the RB20 is a complete waste of time.

Short Stroke, no torque, small exhaust pulses...

its just not on... plus they are the weakest of all the RB engines.

If your going to look for a reliable 240 RWKW then go and get yourself a $900 RB25DE and start adding your fancy name brand parts...

an RB25 making 240 rwkw is a hell of a lot less scared and stressed than the equivilent RB20...

and if your on the coast, i know of a RB25DE (catch is its the 4wd model) for $750.

Heres a picture to prove my point...

doesnt take me long to kill 20's

[Roy]

plus they are the weakest of all the RB engines.

If your going to look for a reliable 240 RWKW then go and get yourself a $900 RB25DE and start adding your fancy name brand parts...

an RB25 making 240 rwkw is a hell of a lot less scared and stressed than the equivilent RB20...

and if your on the coast, i know of a RB25DE (catch is its the 4wd model) for $750.

Can you explain why you think the RB20 is the weakest of the RB range...and how slapping turbo gear onto a high compression NA motor will give you more reliable performance?

[andylaurel]

because the rb20 has the weakest rods of the RB generation..

and the RB25DE is internally the same as the 25DET (save for the high comp pistons and oil squirters)

Do you understand that a turbocharger is just an artificial way of raising the compression of an engine? 10:1 compression on an RB25DE needs less boost to make the same power.

eg 1 bar boost on a factory turbo engine with 8:1 compression is effectively a 16:1 CR engine

whereas 0.6 bar boost on a 10:1 CR engine is effectively also 16:1 CR

another reason for choosing the RB25 is purely for displacement, as a 2.5 litre needs less boost and revs to make the same power as a 2.0 litre

[Roy]

because the rb20 has the weakest rods of the RB generation..

Who told you they have the weakest rods? My understanding is they are probably the strongest rods in the RB family?

Have a quick look at this for comparo with the GTR rods. http://www.skylinesaustralia.com/forums/in...=133747&hl=

Also think about how the short stroke means the piston speeds are well down on the bigger cc RBs at the same revs. And even the Grp A RB20DET engines used std rods...so they are not weak. Given their application they are probably strongest...or so i always thought??

...and the RB25DE is internally the same as the 25DET (save for the high comp pistons and oil squirters)

Do you understand that a turbocharger is just an artificial way of raising the compression of an engine? 10:1 compression on an RB25DE needs less boost to make the same power.

eg 1 bar boost on a factory turbo engine with 8:1 compression is effectively a 16:1 CR engine

whereas 0.6 bar boost on a 10:1 CR engine is effectively also 16:1 CR

another reason for choosing the RB25 is purely for displacement, as a 2.5 litre needs less boost and revs to make the same power as a 2.0 litre

...and sometimes ppl think i genuinely believe the RB20 can do anything...im well aware it has limitations, and probably more then i have stopped and thought about. Its just that i dont think they are as weak as ppl make out. So no doubt a bigger displacement engine is going to help all other things being equal. Hell the better flowing head helps the RB25 again.

The original post wanted 230-240rwkws. It has been my experience that an RB20 will give you that out of a std motor, and be cost effective. Will the RB25 make more grunt everywhere, yes. But it will also cost a lot more.

Also, i dont think anyone would advocate a high compression low boost turbo setup on an RB series engine. Maybe a later model engine with better head design...but not the old RBs. I hear what you are saying, but personally i would be more comfortable running 240rwkws in a std RB20 then in a std RB25DE. If you are going to strip out the internals then the RB25 would tear an RB20 a new a-hole...but at what price. We are only talking 230-240rwkws.

Definitely go RB25 if your shooting for over 250rwkws, but it will cost a hell of lat more...and dont forget the gearbox you may need behind an RB25, and tailshaft, and other tweaks.

Does changing engine cc pose a problem with registration? Or is it as simple as changing over the same engine provided it falls under the weight:cc rules? Or does it require an engineering certificate that encourages the brakes off the R33 etc etc

[andylaurel]

i think old matey who started this thread was actually going to be doing internals? unless i read wrong...

I understand your point of view, but i have killed 2 RB20s with only a little drifting and i consider them weak.

lets agree to disagree

[Roy]

Yeh, i think he was looking to build a motor. I guess my point is for the power he is chasing a nice turbo upgrade on a std RB20 should do it.

If he is going to be doing forged internals and building up a motor, may as well shoot for a lot more power and go the bigger cc motor. The cost of the new block and head ends up a pretty small percentage in a total rebuild.

LOL... i have some bits laying around for when my RB20 goes bang...it handles over 8,000rpm rev limit, 1.5bar and 260rwkws last Sunday at Sandown, and that was after 2.5 days of me and co-driver tag teaming the old girl at the Dutton Rally

Poor motor, i am going to blow it up, but im not trying to do anything silly in doign it....just keep leaning on it until it goes. Be interesting what fails first. I think it will be the bottom end bearing, mainly because of the boost and revs im running on the std oil system