Bottom end strength rb26 vs rb30

[khezz]

This purely a curiosity question. Are there any structural differences between the rb26 and the rb30 bottom ends that would make one stronger then the other?

 

For example, we all know that the N1 block is stronger then standard. Billet is stronger again. If we took a standard rb26 and a standard rb30 bottom end. Similar age, kms and condition, are there any distinct differences in the design, engineering, manufacturing of either of the 2 that would make one withstand more HP then the other. Taking sheer displacement out of the equation.

[GTSBoy]

You can't take sheer displacement out of the question.  RB26 rods are shorter, which works massively in their favour.  They (the rods) are also a stronger design (by a little bit).  Oil squirters and other little differences all contribute.

But, no there is no specialness added to the RB26 block that isn't really in the other RB engines.  Mass produced.

[khezz]

So things like wall thickness, any sort of structural bracing is pretty much the same on both bottom ends? Just talking about bare blocks.

[GTSBoy]

Give or take, yes.  You can't take it for granted though that the taller RB30 block is not inherently weaker due to the aspect ratio - like it would possibly need to be thicker to be equally resistant to deformation.  Know what I mean?  Shorter automatically = thicker.

[khezz]

Fare enough.

[KiwiRS4T]

RB30s built for big power are sometimes grout filled to the half way point - don't know if RB26s get the same treatment...

[khezz]

How does that effect the Engine?

Can it still be daily driven?

[GTSBoy]

Grout fill is only done up to a certain height in an engine that needs to keep working for more than a 1/4 mile at a time.  You can fully grout fill a drag only engine.  But RBs and other engines that need a stiffen up to keep the bottom of the bored from moving or bowing outwards are done "up to the welsh plugs" or to similar levels.  The coolant can still circulate above that, provided the grout doesn't go up as far as water pump ports, etc etc.

[khezz]

Didn't know that. I always thought if you go the grout rout, you can only do 1/4 mile runs.

Might look into that.

[jet_r31]

Nah grout up to welsch plugs

Fine for street

If youve got coin fit a bottom end girdle that ties into standard main caps and block

[khezz]

Thanks. I'll price it up.