Pics to compare RB20 to RB25?

[Swedish Mike]

Sorry if I sound like a newbie here but we never got the RB20 here, many of you talk about the "bad" RB20 head, do you guys have any pics? Would be nice to compare RB20 and 25.

/Mike

[mugengsr]

only bad part of an rb 20 head is the ports are smaller than the rb25 and the valves are only a little smaller ... nothing that cant be fixed with machine work but a little mild port job does make a significant diff ...

[Swedish Mike]

only bad part of an rb 20 head is the ports are smaller than the rb25 and the valves are only a little smaller ... nothing that cant be fixed with machine work but a little mild port job does make a significant diff ...

Can you port the RB20 head up to RB25 size? Nice! Pretty thick casting around the ports then.

This is the deal, I´m shipping a car from USA and I plan to swap engine before.Wanted the CA but people say they are hard to find and sometimes expensive.My idea was to use a RB20 instead, if I can find one...

/Mike

[SeVa-S13]

CA's are pretty much the cheapest and easiest swap choice available to the 240.

And if someone is having a hard time finding a CA, might I suggest the internet?

[Cubes]

The ports arn't the problem with the rb20 head.

Its the valves and how badly shrouded they are. Exh. valves are not so bad but the inlet valves are piddly.

The inlet valves are 5mm smaller than the rb25 valves.The exhaust valves are 2mm smaller than the rb25 valves.

The rb20 valves desperately need deshrouding. Thats if there's enough room. :S

[Swedish Mike]

As always, nice info. You can´t fit monster valves in a small bore engine, sad...

How much bigger can you go in the RB20, up to RB25 stock valves?

/Mike

[sean8564]

RB20DET

[sean8564]

and a front side

[SeVa-S13]

and a front side

Ahh, much better! Now I can totally see what the RB20's head's shortcomings are...

[AmoebAssassin]

Ahh, much better! Now I can totally see what the RB20's head's shortcomings are...

[rb20detsilvia]

Has sanyone built an rb20 head like put bigger valves and ported and polished what exactly did you do

[mugengsr]

when i got to that point (building my head up ) i will be deshrouding the head for the 83mm bore and then im going to chop an old head in sections to see exactly how much i can go bigger ... i got a feeling i can get a fairly large valve in there ..

i was not aware the rb20 intake was 5mm smaller .. i thought it was about 2mm tops and im still pretty sure of that ..

well ill post pics when i start my head and explain if it is worth doing ..

[Swedish Mike]

Pics from "piston view", to see valves or "manifold view" to see intake and exhaust ports would be great.

But as always, this is only a request to learn more.

/Mike

[Carl H]

i'll take some pics of my head tonight, the valves are TINY tho...

[sean8564]

[sean8564]

[sean8564]

[jdmser]

after my valve job http://nissaninfiniticlub.net/...t=500

[Swedish Mike]

Holy crap! Nice pics guys!

Only RB20 on these pics right?

/Mike

[sean8564]

yes all are rb20det

[Swedish Mike]

yes all are rb20det

Looks like you need bigger bore to fit larger valves.

The RB20 block looks rock solid, never seen a block with cylinders walls like that!I want one really bad!

/Mike

[sean8564]

it can be arranged