hello everyone. i'm debating on either the rb25det or the rb26dett for my 89 240sx. i have done my research so please bear with me.
1 i know the 26 has more power than the 25 but can the 25 be built to be equal to the 26?
2 what parts are swappable with the 26 to 25?
3 can i use the internals from a 26 and put into the 25?
4 what needs to be done to drop the compression ratio?
the reason i don't really want to go with the 26 is cause it's a little bit more money than what i have.
thank you guys for your help.

 

You can get an rb26dett for 2500 and thats a complete engine... The rb26 is 2.6 litres and the rb25 2.5(look at the names, duh) anyways, the parts won't swap, the turbos intake and stuff like that will, heads, cylinders and stuff like that won't be the same size, but they could possibly originate from the same part, and why would you want to lower the compression ratio? high compression=more hp, you can get new head studs and a thicker head gasket to raise or lower compression

 

put the rb26 head on the 25 block.

done.

 

engine is not that identical, the heads should fit

 

They're the same block and same head practically everything is swappable.

 

I never said it wasn't...:finger and you haven't done much research on the engines obviously, don't get off the subject, so stop argueing with me and stay on the topic of rbvs 2jz

 

you want to lower compression to match the rb26 at 8.5 to 1 compared to 9 to 1. how about internals like rods and pistons will thoughs work.

 

what does puuting the 26 head on a 25 actually do for the engine. i heard this makes it a 26 but can i use internals annd what internals can actually be used

 

I am not sure because I have not had a lot of research experience with the rb engine, but the heads will give you the extra .1 litres of displacement, as for the rest I think mr. smartass that posted like above me could tell you, I would trust anything he says though...

 

I am not sure because I have not had a lot of research experience with the rb engine, but the heads will give you the extra .1 litres of displacement, as for the rest I think mr. smartass(pun not intended, as in he's really not that smart) that posted like above me could tell you, I would trust anything he says though... I have to go also, so I won't be coming back to this thread.... traveling to west...

 

The head doesn't effect the displacement. The RB26DETT has 2mm more stroke than the RB25DET.