I'm just making up HP numbers here but let's pretend a stock LT1 block is capable of safely handling 600HP and beyond that it may last 1 pass or it may last 2000 passes... Either way it's a gamble each run.

Now let's assume you buy a rotating assembly that is capable of handling 1200HP and put it inside this block... What is the point? Regardless of how much HP your crank, rods, or pistons can tolerate the fact is you still have them in a block that is unsafe at half the HP level the rotating assembly is. Therefore you might as well just buy the cheaper stuff that is rated around the same limits as your block because you are simply wasting your money. The saying "a chain is only as strong as it's weakest link" applies here.

I'm not saying you can't go fast with stock parts - I and countless others have done it on a somewhat reliable level but it's still a gamble each pass

Lt1 blocks usually start grenading around 1000hp unfilled.

Why H beams?

Baxter ran his LT1 for years, 383, 18-20 Lbs of boost, he had documented 1,000+HP on the engine dyno and wasn't afraid to throw in on the chassis dyno and record 900+ at the wheels! This was a full weight car that still had the power options and convertible top and ran low 9s and never had a block failure, Frosythe's 381 CI LT1 is in the 900HP range with twin 175 shots ( reason it's a 381, to give a little extra for the side load on the cylinder walls). Again, full weight car, no failures. Neither are using block filler and spin into the mid-high 7,000 RPM range.

Quality crank, rods, pistons, bearings, sprayed caps and a good builder is what is needed. The LT1 is nothing more then any other SBC with reverse cooling. As long as you have the block checked and make sure it's a good one you should be fine.

The after market blocks we chased companies to build for years was really for more CI and taller deck, web/main strength and block flex really isn't an LT1 short coming except for the really hard core. The guys running deep into the 8's are suppose to be spinning well over 8Gs, I've heard some had issues with flex/bearings walking, there use to be stud girdles out there for the LT1s to fix this. But even without, the blocks aren't falling apart.

Most of the failures you going to see is in the crank breaking or rods twisting,. Power adders put allot of stress on these parts.

I could spend $800 on a set of I-beams that could hand 450ishFWHP and a 150 to 250 shot or I could spend $400 on a set of h-beams and have the same end result.

Except I would bet the H rods are heavier and require more clearancing to the block to fit in.

On a stock stroke motor? I would bet they require no clearancing.

:facepalm: Shouldn't you be shooting for Rear Wheel HP?

probably ment FlyWheel hp.

No... I didn't tell you?! My Z28 is front wheel drive. 8-)