will an rb20 head go onto an rb30 nd what will be the benefits if it works? i can get a full rb20 top end including turbo and stuff for next to nothin, so hopefully it will suit...

You can make it work, there's a car on here that is making good power with and RB20 head. The RB20 head is designed for smaller bore, has small valves etc so I reckon the time and money is better spent on an RB25 head.

it's up to you, but i would say it's a wast of time, as jet 88c had an rb20det head and that max out flow at around 200kw. also the bore size is different,

The 25 head is much preferred over the 20 for a few reasons but yeah, why not! Its cheap and you know its reliable so go for it mate!

also your going to have issues with what ecu will run the whole thing, as i don't think a rb20det ecu and elec's will run it with the 3lt bottom end. so add on alot of cash for ecu, injectors, etc.

Somebody else will be able to confirm the need for aftermarket management but worst case i'd imagine ~$2k on PFC + GTR injectors would get you out of trouble. At the end of the day, even if you can scrimp on a few bits here and there, modifying cars just isnt a cheap hobby.

This was just discussed not so long ago so i suggest you do a search. One member strongly advised against it too from personal experience due to the rb20 having heaps smaller bores than the 30. Closed.