Rods, Pistons

[Tangles]

Wondering

do RB30 pistons fit into an rb25 block / head? with rb25 rods?

can anyone give me a heads up on that?

or is the rb30 bottom end needed, with the rb25 head, with rb30 rods and pistons

not sure ~

[r33 chris]

i beileve you will need a rb30 bottem end, with the rb25 head, with rb30 rods and pistons

[Cubes]

Compression height is too high on the rb30 pistons so they will poke out the top of the block.

RB30 bottom end is needed as what makes the additional displacement is the longer stroke and deck height to maintain a decent (better than rb26/25) rod to stroke ratio. 1.81:1 from memory which is near perfect.

You'll have to do a little fiddling with lowering the motor etc otherwise it will foul the bonnet. The RB30 sits 38mm higher.

BUT the difference is like night and day. Drive an rb20det then rb25det. Thats the increase in torque on top of the rb25det you see and the thing still rev's to 7k without issues.

Much more than 7k u need rods, pistons, balancer and then its good for 8.5k providing the manifolds, turbo and cams are up to the airflow required for those rev's out of the 3ltr.

[Tangles]

thanks cubes, was going to PM you the query but figured Id make a new post

good info, cheers