Rb26 Pistons And Decking The Block?

[Guishnu]

Hi folks

I have been trying to find this info and have looked in the RB30 conversion thread but it's 350 pages long and near impossible to navagate.

Does anybody know (or can work out for me) how much i would need to deck the block when using RB26 pistons in an RB30 block running and RB26DETT head to achieve an 8.5:1 or 9.0:1 compression ratio?

I know it has been done before, but i can't find an answer to this question

Thanks folks

Chris

Edited January 25, 2009 by Guishnu

[Adriano]

Use rb25 pistons and deck the block 40 thou(1mm), although i dont see the point when rb30 specific pistons cost about the same.

[Guishnu]

Use rb25 pistons and deck the block 40 thou(1mm), although i dont see the point when rb30 specific pistons cost about the same.

There is no advantage to using the RB25 pistons as the distance from the top ring land to the crown is so bloody small that they brake up at higher hp. RB26 pistons don't have this problem. Stock RB26 pistons can be had for next to nothing over here as well.

[shanef]

the problem with rb26 pistons is the dome, they are a 16cc dome whereas the rb30 piston is a -4.5cc dome

[Adriano]

And the deck height, you would have to deck the block too much to get the correct height. Rb25 pistons seem to crack at about the same power level as rb26's ie about 350rwkw without knock.

Edited January 27, 2009 by Adriano

[Drift Motorsport]

Spend the money and use forged pistons that are suited to the deck height and compression requirements. Many mainstream piston manufactures have a rb30/26/25 piston off the shelf.