I lost a seat in my 5.9 cummins 03 block,it scratched the cylinder wall...may have to bore 40 over? Is there a negative to that if it doesn't make 20?

 

I have compound turbos....I do not run it hard,it has been used for towing...

 

You'll gain a whopping .1L of displacement, so there's that.

The general consensus is that .040" is the limit on these blocks, after which you'll need to sleeve the cylinders.

Boring the cylinders makes them slightly weaker, keep that in consideration.

You should be ok if you're not racing around, rolling coal on everybody.