RB20 Cheap turbo upgrade.. few questions

[browny]

The Rb25 high flow wont run on an rb20!

sydneykid has done it and says it works great

[Bl4cK32]

i give up. im just stating what i have heard, not from experience.

[browny]

Also RB30/25 costs...

This is an exaggerated example but....to claim that the rebuild cost is only $xxxx and then say "oh but i'm an engine builder and I get labour for free and parts at trade prices" is not really all that useful to the average joe who has to pay consumer prices.

Maybe we should talk about a range of costs.

eg DIY at the low end and "drive in drive out" at the high end

[rbs13]

yea.. seems to be common practice to put a rb25 turbo on rb20... but anyway.. yea sorry was a td06.. where i got rx6 from is beyond me hehe. you can compare 2000 for your motor to 10000 for us ppl with rb20's but only you can get it built and goin for 2000 not every one!! and if we could im sure a lot of people would be driving round with 300rwkw rb30/25s with 3037's or some thing..

[Bl4cK32]

I was talking about the gcg high flow stage 2 500hp rated turbo. Ive heard it would not run on an rb20.

Doesn't it always come down to its who ya know - not what you know (as people have proven)

[Cool Hand Luke]

great, so does anyone know any answers to my other questions?

Also GCG have told me that the 500hp hi-flow on a 20 does not work on a RB20, but im sure a 25 hi-flowed is not the same.

[Roy]

Im guessing with 220-250rwkws you would definitely be in the hunt for high-low 12s.

Thats assuming the car is well driven and using street rubber & suspension setup. With 250rwkws and the right tyres and suspension i imagine you could even give high-mid 11s a scare.

As for a 2K RB25/30 I guess it comes down to how hard you drive a car, but at $770 with no labour and trade prices, that is still very cheap. I agree that the 2k figure shouldnt be thrown around as a reasonable figure for the RB25/30 engine.

At $770 many of us would only be getting 2nd hand pistons, rods, cheap bearings/rod bolts, basic machining etc, etc. The sort of stuff for the mums VL, not a blokes turbo Skyline who is hoping for over 250rwkws and 7000rpm.

[silver gts-t]

cool hand luke:

im in the same boat as you and also tossing up wat to do and as i havnt heard much from these blokes about detailed facts on different turbo's i doubt u have either.

The bloke is right about the vg30det turbo, thats the one your after coz the turbos off the vg30dett are smaller, and ive been told it is a straight swap, except 4 lil changes in lines.

what i would also want to know is if the rb25 item iproves power by 20kw, wat does the vg30 do? or wat would b expected.

these turbo's arnt expensive (round $350-$500) at all considering u can sell your own turbo for round $200 easy.

cheap 20kw for sumone looking for not spending big.

john

[Bl4cK32]

Ok guys i hear where your all coming from. Im just stating what im getting done.

Roy - no offence, but dont comment on sh#t you dont know about. The rebuild is using ACL bearings, its a high quality large workshop here in Adelaide that specialize in rebuilding engines, the standard rb30e pistons are good up to 250 rwkw providing it is tuned well and not detonating. Who the f*k said anything about more than 250kw?

Why dont you concentrate on Cool Hand Luke's question rather than downing someone elses opinion?

[Cool Hand Luke]

Bl4cK32 - Think about what you said in this thread, then what you said about downing someone elses opinion, and how that relates to what people were saying to you. Im pretty sure you will find that they were just expressing theirs, and it seems like you got a very good price for your rebuild.

Anyway, how can i tell the difference between a VG30 Single turbo, and the turbos off the twin turbo engine?

[Bl4cK32]

Yeah well why donrt they just accept someone got a good deal insted of saying shi*t like "mum's VL" engine rebuild?

[Roy]

As for a 2K RB25/30 I guess it comes down to how hard you drive a car, but at $770 with no labour and trade prices, that is still very cheap. I agree that the 2k figure shouldnt be thrown around as a reasonable figure for the RB25/30 engine.

You say no offence, none taken because you have misread my post. Your fortunate enough to be getting a good deal, cool, i dont have a problem with that. What have i posted that has offended you?

At $770 many of us would only be getting 2nd hand pistons, rods, cheap bearings/rod bolts, basic machining etc, etc. The sort of stuff for the mums VL, not a blokes turbo Skyline who is hoping for over 250rwkws and 7000rpm.

Read it again... "many of us" im not referring to your car.

And as for who said more then 250kws.

Where now lookin at 260ish rwkw on 15 psi. maybe add a few extra $$ for some parts.

So relax and read what people have posted,

[Bl4cK32]

: Deep breathing : calm blue ocean, calm blue ocean,

OK, sorry man. For my case the 260 is an extra $1600 for forged pistons. But since im only going below 250 the std pistons are no prob.

Sorry if I misread the post, but I work the afternoon shift, by the time I get home, Im lucky to walk straight let alone read.

[Roy]

No drama,

Ive also been told that i could safely run 16psi with it as its feeding a 2l not 2.5, and therefore less stress, is this true?

Luke where did you hear this? Ive heard this a few times now and am curious myself. I Cant think why this would be the case,

Compressor flow is a result of shaft speed, and flow into a smaller internal volume could require less flow for a required pressure, is that the rough reasoning?

[browny]

I saw an argument on another forum that this is a myth.

I will try to dig it up.

[Roy]

Yeh i wouldnt want to be the person proving it, either mechanically or by running the turbo that hard.

[Cool Hand Luke]

Is the single turbo VG30 a steel or ceramic exhaust wheel?

Also i got that info about running higher boost with a 25 turbo on a 20 from meggalas site

[Cubes]

The RB30E bottom end is 30mm higher than a RB20/25/26.

At the end of the day it really depends on what you are after.

A car with a smooth power curve that allows you to control wheel spin easier or a vertical RB20DET power curve that is extremly difficult to control wheel spin.

To pull 250rwkw out of a RB20DET is a big task as you will soon see when you come to do it.

Besides the point what are we building the cars for?

Street or strip. If its the street then there's an old saying.

"There's no replacement for displacement"

A 200rwkw RB20DET will not accelerate quicker than 200rwkw RB30DET.

The RB30DET has shiet loads more torque and power in the mid range.

If you blow a RB20 or get sick of the lag and want to fit a RB25, look in to the RB30DET.

It works out roughly slightly cheaper and you get better drive-ability and a fresh motor.

If you check out the R33 RB30DET Conversion thread, a bloke has done it in new-zealand. He claims the upgrade is well worth while. The standard turbo now makes full boost around 1500 or 1800rpm I can't remember exactly.

Here's prices from City Dismantlers:

RB30DET Short motor supplied and rebuilt (ACL Bearings): $770.

Add $1600 for forged pistons.

RB25DE (Non VCT) Head: Adelaide Jap Imports $750

+ Water pump, + Thermostat, +Cam Belt.

If you want better rod bolts than Genuine Nissan's well they cost extra. ACL bearings are fine. Do a search in google and see what you come up with. Besides the point for Genuine Nissan bearings that Mathoon has been running in his R33 RB30DET making 320-340rwkw for the last year cost $250 from Nissan.

Not expensive peoples.

I have had quotes for rebuilds that have been extremly expensive. Those places all seem to be the smaller businesses, City Dismantlers are quite large and have good machinery. Better than most small engine rebuilding business have anyhow.

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If you have the RB20 use the RB20DET inlet plenum, exhaust manifold, RB20 oil pump and CAS on the RB25DE non vct head start it up and drive off on the stock ECU.

If you have the RB25DET (R33) well just rebuild the RB30 short motor for $770 slap forged pistons in if you wish, use the RB25 oil pump and off you go on the stock ecu etc.

It is a rather cheap mod that opens up a world of faster more tractable possibilites, especially when I look at my recipt to say I spent almost $1700 on an Exhaust.

No need to get defensive peoples.

Its simple if you can't mod the car your self or you are not willing to get your hands dirty expect to pay big bucks for a fast car.

There is a bloke that made a post on SAU a little while back that had issues with the 500hp GCG turbo surging. GCG pulled the turbo off and had to go down to a 450hp unit for it to run correctly on the RB20DET. Not sure what other issues there were maybe it was just his car?!?! who knows.. BUT the point is the 450hp unit works the 500hp unit doesn't and may require futher mods to run correctly, what they are I don't have a clue.

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With regards to running a larger turbo at a higher PSI on a smaller engine here is the theoretical theory:

An RB20DET requires less air at any given RPM compared to a RB25 or VG30 at that same RPM.

What kills ceramic turbo's in street use is shaft RPM.

A larger turbo provides more air flow at a lower shaft RPM speed.

SO... without getting in to it to technically to run a RB20DET at 16psi the shaft RPM will be the same as a RB25 turbo on the RB20 at 14psi. This is just a rough guide. Not exact but gives you some thing you can visualise.

Heat also kills turbo's.. So if you take your RB25 turbo on your R32 running 1.2 bar on the track it may very well Die. drop it down 2psi and it should be safe.

Same goes for the RB20DET turbo. I've been running mine on 1.1 bar or ~16psi since I can remember and it hasn't blown... YET..

Get some heat in to it on the track or some really really hard driving with no break and i'm sure the ceramic will slam in to my cat and stuff that in the process.

[Bl4cK32]

well said joel......heheh

[browny]

Found the thread:

http://board.performanceforums.com/forums/...readid=67145982