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Rb20det Head On A Rb25det Block?

grippy

By grippy,
in Engines & Forced Induction

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grippy Collaborator

grippy

Posted
Posted

I have a RB25det block that I got for next to nothing and I would like to know if it is possible to fit the RB20det head to this block?

Reason being I have a damaged RB20det block from my R32 but the rest of the motor is in tact. $$$ are a big issue and I have not yet torn down the RB20 to see what will fit an what won't.

I would like to be able to fit my RB20 head with no variable cam timing if possible and use a RB25 crank to get the extra cubes.

Hoping someone can shed some light on this before I spend money onthe RB25 block.

Rgds

Grippy

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https://www.sau.com.au/forums/topic/178717-rb20det-head-on-a-rb25det-block/
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James_03 Mentor

James_03

Posted
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If its a silvertop ECCS head then water/oil and head studs will line up. The bore however is different so you will need to modify the combustion chamber to suit. I actually ran a 20 head on a 30 bottom end for a little while and modded the combustion chamber myself to suit.

One thing you will have to do with the 25 block but is you will need to drill and tap the VVT gallery in the block and block it off. What you can do is rip off the old rb20 HG and use that as a template on the 25 block like I did. Pretty much shows you straight away what will go and what wont.

But like I said, rb20 silvertop head from a r32, its basically mod the combustion chambers slightly and then block the VVT feed off.

grippy Collaborator

grippy

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Posted
Cost vs gain - simply not worth it.

Too much stuffing around as its not bolt-up

Thanks, As I thought too many problems. I will continue to source a RB20det block and transfer everything over. I'm not after any power gains anyway, just thought if I could do it for no extra cost why not seen I have a Rb25 block.

I'll plan for a complete RB25 build up on the block then after I get my RB20 running again.

Cheers,

Grippy

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