**600hp sbm block limit? Or is it bs!!**

pink340swinger said
I had a 1970 340 block that I raced and it eventually made 602 HP on the dyno. I ran it for several years until the main webbing literally split the block in half! It had 4 bolt mains installed and all the other tricks done to it but it just could not handle that power run after run. It did run 9.50s @ 138 MPH shifting at 7900 rpm. 3.58 stroke crank in it. Naturally aspirated. I had a lot of passes on it over the years and refreshed it every year at the end of the season. It started out with W-2 heads and then W-5 heads which made way more power and it only lasted for 40 runs when I went that route making 602 HP. I have since went to an R3 block W-9 heads and have never looked back.

Thanks for your post.
There is alot of speculation that adding the 4 Bolt mains actually weaken's the webbing in the block. In your situation that may have been the case and I would think that is why it failed, but still that is only speculation.

Was there fatigue that you physically noticed or catastrophic engine failure from the cracking? or did you notice it when you took it apart?

And man you were revving the bageebers out of that engine! Damn