I would like to know what the rated hp limit is for the following?
the crank
pistons
rods
i see vortech02 is hitting 255 on a turbo so is the stock 4.3L built rather strong to support say 300hp? I am just learning as i am a newb to the 4.3L. Also is there an aftermarket intake manifold that can support more then the stock plastic one that is rated at 10psi?

 

There are a lot of people putting down some impressive numbers with stock engines. I don't have exact numbers for you, but the 4.3L uses basically the same rods, pistons, wrist pins and crank journal sizes as the 5.7L (350cid) engine and they can take a beating.

As far as aftermarket intake manifolds, well that would have to be one off custom because I don't believe that anyone has found any information on one... There were rumors of a 4.3L marine crate engine utilizing an aluminum upper plenum with dedicated fuel rails and regular Bosch style injectors, but the only pictures I ever saw were on a 5.7L vortec marine engine, none with the v6 4.3L.

 

Much appreciated I am new to this, so i dont mind being called a newb.
Is there a fuel cutoff at exactly 6000rpms?
I am impressed to know this engine is a strong beast.

 

One thing though after talking with my mechanic friend, he informed me that the stock bearings are pretty weak and cant handle that much. Another thing he has mentioned would be like intake manifold that swartlkk has already mentioned.

Here is the Vortec Marine. Here