[Don Keefe]

That 700 horsepower threshold for a production block had always been a bit of a headscratcher for me as well. The question I would always have is "How are you getting to that level? Was it a NA stroker with a 4.5-inch arm and spinning to 7,500 rpm with 13:1 compression and an .800-inch lift cam? That's going to be a very problematic combo for a stock block. Failed cylinder walls, lifter bores, the chance of splitting the whole thing is very present.

Another problem combo is an overdriven 6-71 or 8-71 combo. Blowers will put enormous stress on the end of the crank and in turn will encourage block flexing. It's not a huge problem for a mild, low-boost street combo but things get very questionable as the rpms and boost go up.

A far friendlier setup would be a turbocharged short-stroke setup using a max of 3.75 inches. A combination like that will not put nearly as much stress on the block for a few reasons. One, the stroke will keep the stress on the cylinder walls down and will be less prone to cracking down the middle. There is also nothing on the end of the crank to cause stress and the cam can be relatively mild, so the lifter bores are not under the stress caused by a radical profile.

I have been a fan of turbos since I saw an 1800 cc VW make 460 horsepower in 1979 and lay down nine-second runs. Look up "Little Leroy." Then in 1996, I saw Marty Palbykin take everything I ever believed about turbos and make it come to life in Norwalk. He made 1,600 horsepower with a stock 1967 400 block without filling or block bracing, street-ported 670 heads and a 400 RAV crank. I will never forget that.

If you're looking for a street/strip stock block combo that would live, I would look to the 350. The smaller bore helps with block sealing, they tend to be a little beefier where it's needed and valve shrouding isn't an issue when under boost. Remember, Mopar went to a smaller bore for their supercharged Hemis. And GM didn't use the 427 LS7 as the basis for their supercharged engines. They stuck with the 6.2's smaller bore size for sealing and thicker cylinder walls.