[Steve1968LS2]

Originally Posted by Vegas69

I was considering doing an undersquare engine as well. I have a bore size of 4.280. My block will take a 4.375 stroke. Ultimately my engine builder didn't feel it was a good trade off in power vs. cost and longevity. I had to ask myself, why don't you see them in any high performance application from the factory? The only conclusion I had was longevity and warranty. I ended up with a 4.25 stroke with a 6.385 rod. Another thing is big block stuff is heavy and they are harder to turn rpm with. Adding more low end torque and less high end hp didn't make sense for me where it may very well for you. I love this stuff.

Because the factory uses inferior parts for the most part.. they certainly don't use forged cranks and all the other goodies that make a reliable under-square engine possible.

You combo was just barely under-square with a ratio of .978 ... I don't think it would have been a huge issue so long as you have good parts, especially the crank.

And you're right, there's a big difference between a big-block and an LS.. seems like you can get away with more on the LS side.