Rb25/30 Rods And Ecu Question

[tazzy]

Hey peep's

Building an rb30/25 hybrid on a budget and was wondering what pistons you are running?. Are they rb30 or rb25 or are they the ones specifically made for the rb30/25 conversion offered by some manufacturers. Secondly looking at using a gt35/40 turbo and was wondering if the standard ecu can be re-mapped? What would you recommend for a budget computer to replace the standard ecu.

[JonnoHR31]

nistune for budget ecu

most budget builds use standard 30e pistons but if your going to the effort of building it get some 9:1 30det pistons

[waxracing]

Im quite sure you cant remap the 25de and you will need a z32 ecu.

Unless you run a 20det ecu but then you dont have the cam control

[JonnoHR31]

yes you need a z32 ecu, used to have to swap a few wires around to make it work but now nistune sell them re pinned to suit 25s.

[tm_r33]

25 det pistons will give you a shithouse low comp ratio on rb30 rod/crank with 25 head.

30 e pistons still not ideal.

spend money on some pistions and buy a pistion to suit 25/30. i run the aries 9.2:1 piston in my race car. (to suit twin cam head on the rb30 stroke/rod)

it has a higher crown than the 25det and 30e piston. This lifts it closer to the top of the chamber and gets the comp ratio back up.

considering rb25det has a 9:1 comp ratio from factory, try and stay nice and close to this for some low rpm drivability. No need to lower unless running huge boost.

another benefit of buying a specific 25/30 piston is that if its got a nice high crown it will need some valve pockets. now being a twin cam suited piston, it will have 4 valve pockets (to suit the 4 valve per cylinder 25 head).

i also use gt35 turbo. (running .82 rear)

*all this is irelivant if u just buy flat top pistons but the flat top will have a lower comp ratio (say 8:1) as they cant lift as high in the chamber and sill have valve clearance.

**if your planning on running/plaining any alloy off the bottom of the head it will in turn bring the valves closer to the piston so u will have to make sure u have clearance.

[tazzy]

Thnx guys heaps of help!!!