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Rb21/22 Build Time

limpus

By limpus,
in Engines & Forced Induction

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limpus Mentor

limpus

Posted
Posted

Good day fellas,

The time has come for me to take on a new project...I was recently GIVEN a blown rb20det by a mate i figured it would be a good candidate for a mild rb20 build up...as the title states...it will be a RB21/22...

First abit of background info...its going to go into my HCR32 which currently has a reasonably healthy rb20det in it...it also has a hks 2535 and every required support bolt in it needs...at the last dyno session it made 223rwkw at 17psi...

I have spent the better part of the day searching and reading up on all relevant threads with any infomation i might need and have learnt a fair deal...the plan here is not to build a bulletproof rb20hybrid engine to rival the rb25 and other bigger cousins...its is more of an experiment i want to do reasonably cheap and if it works out will leave me with a slightly beefier and stronger engine...being a mechanical engineer and a trained auto mechanic...i will try to do what i can by myself to keep costs down as well...

I will be looking to use later model 4A-GZE pistons as they are about the right size and are forged and not to mention cheap...this will be a bore out job only and i do not plan to stroke the engine at this stage...i will be re-using as much as i can from the old engine and only changing things that need to be changed...the same turbo setup will be used on the new engine too...

As such...i am looking for any advice an opinions from those who have taken a similar path or have done enough research regarding this topic to know what they're on about...

I do have a couple of questions to begin with...

1. I understand that there is some work needed to get the 4A-GZE pistons to fit and work correctly in a rb20 block...can someone tell me what exactly needs to be done?

2. Using late model 4A-GZE pistons...what CR would the engine end up having?

3. Where can i find a headgasket with the correct bore size for this build?

I'm pretty sure i'll have heaps more questions as this goes along but this will do for now...as mentioned...could anyone who has taken a similar path please post up all the info you can to help me along with this...

Lastly...please do not post up saying that its not worth it doing this and that i should go to a rb25/26/30 or whatever combo because that is not the plan at this stage...Cheers all...

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https://www.sau.com.au/forums/topic/209174-rb2122-build-time/
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R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Here's a few to get you going, it was done in a bit of detail back in '05-'06 before RB25's became really cheap :)

http://www.skylinesaustralia.com/forums/Rb...-Qu-t90293.html

http://www.skylinesaustralia.com/forums/RB...B23%2A++RB24%2A

http://www.skylinesaustralia.com/forums/24...l&hl=stroke

http://www.skylinesaustralia.com/forums/24...l&hl=stroke

Some of the info overlaps through the threads (as does happen) but each thread above is worth the read.

murrayis Mentor

murrayis

Posted
Posted

Hi Mate,

I am in the middle of building a rb2.4 with nothing left untouched....

If you do a search for rb24 you will find my thread..

I wouldnt use 4agze pistons... the desk hight needs lowering, and the pin is about 3mm higher up the piston than stock rb20 pistons. I uses in mine 83mm Custom ROSS pistons... about $1300 worth and there perfect.

If you have any questions shoot me a pm, I have spent the best part o the last year researching... sourcing and purchasing parts for mine from Tomei 272 cams to the lil nit and gritty Jun crank Collar

cheers

Cameron

Proximity Motorsport Experienced

Proximity Motorsport

Posted
Posted

ok, now evryone got me thinking... instead of porting out a rb20 head... wouldnt you be better off using a standard rb25 head... as someone said somewhere a ported 20 head will flow approx 80% of a std 25 head. Are a 25 head direct bolt on with rb20?? This may be a mod for me to think about in the not so distance future... only thing that would put me off is my plazmaman plenum for rb20... but thats ok i can cut and weld a rb25 flange onto my rb20 runners.

sorry to hijack yourthread mate :domokun:

Proximity Motorsport Experienced

Proximity Motorsport

Posted
Posted
RB25 head doesn't bolt on without a lot of dicking around, hence why most argue just get the RB25 cost vs gain

dammit, for a second there i thought i was onto a good $500 mod for my rb20det.

limpus Mentor

limpus

Posted
  • Author
Posted

Ok...i have picked up the free engine and will start stripping it down shortly...after some research i have decided to give the 4A-GZE pistons a go once i find a place to do the necessary work...remember that i'm just doing this as an experiment so see what can be achieved...hence tomei 82mm pistons or other forged pistons are out of the question for now..

Does anyone have any recommendations for places to get 4A-GZE pistons from?

  • 2 months later...
limpus Mentor

limpus

Posted
  • Author
Posted

Ok...quick update...the spare engine is about to be stripped down and checked...in the meantime...i already have a rb25 crank and a set of rb25 rods to be used as well...pistons will be standard forged 4agze pistons...if it all works i should end up with a 2.2L capacity from the larger bore and slightly longer stroke...

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