i just read that the 3G Prelude SI has a B21A in it...my question is does it compare to the B20B/Z at all and would it be a good candidate for a LS-CRV/VTEC type build up? taking in mind that all new internals would be bought being the block would be over 10 years old...thanks in advance for any feedback.

 

its been done already, they are low revving motors and they are not
built for the VTEC rod angles at the RPMs we are used to. the rods
will hit the block at the rpms you would want 8-9K no doubt. look this up
at http://www.ludespeed.com

http://ludespeed.com/products/prelude/articles/vtec/

Tom explains it all as he has successfully done it, he doesnt reccomend
it as it is a difficult job to get right.

 

They also have a terrible rod/stroke ratio, and they are notorious for heavy oil consumption.

Andrew