Rb25 And 26

[tourer]

Hi guys,

I have a standard RB25 engine and willing to tune it to about 500hp. Currently, I've got RB26 N1 crankshaft, conrods and 87mm pistons. Is it possible to put it inside RB25 motor? Probably, 87mm pistons are too big, but if I buy new pistons, will it be possible to assemble engine with RB26 crank and conrods? What other mods would you recomend? I already have aftermarket oil and water pumps, large oil sump. What about camshafts and valves? I have complete cylinder head from RB26 (272 IN/EX camshafts, standard size valves), is it possible to fit valves and camshafts into RB25 head?

[SECURITY]

you could fit the rb26 crank and rods into an rb25 with no problems, as long as you use gtr spec pistons.

[tourer]

Ok, and what about camshafts and valves?

Edited September 11, 2006 by tourer

[CruiseLiner]

put the entire 26 head on if u got one complete???

[T04GTR]

yeah. you will need to use the 26 pistons aswell. but im not to sure on what copm ratio it will be. coz the 26 head has a bigger combustion chamber

[T04GTR]

woops, wrong way round.

26 piston dome is 5.1cc

25 piston dome is 15.1cc

so you will have 10cc extra chamber volume.

[tourer]

The best and the easiest way is to put RB26 head on, probably. Ok, thanks

[sweetr33]

i've done this with no problems so it can be done. i've got rb25 block. bored out to fit the 86.5mm pistons. using gtr crank n rods. 1.6mm headgasket and took 1mm out of each combustion chamber in the head. good luck

[humz]

sweetr33

was it worth it at the end of the day?

was a a lot more responsive or just a tad, what sorta power you making and what mods?

thanx thinkin bout this and scrapping my 25/30 idea, already got all the 25/30 parts sitting here.