I'm in the process of collecting parts for my build. Getting a breather kit was on my list, but is it nessary for a 11.3.1-11.5.1 compression ratio?

 

Its not the cr what determines if you need a breather kit or not.

 

it has to deal with the crank case pressure right?

 

yes. It gives the pressure acting against the piston on its way to BDC a place to go instead of being bottle up to a certain pressure number to open the PCV. This relief of pressure on the pistons and rings frees up HP, theoretically.

I believe there is a more of a need with these kits when you have a r/s that is low and accelerates away from TDC faster than a long rod. The more it accelerates, the more pressure it builds as a force against the direction of the pistons. But thats just my opinion.

 

Oh okay so that breather kit helps out the PCV valve out with doing its job?

 

you are bypassing the PCV when you run a crankcase ventilation setup.

 

I always thought the higher the compression the more crankcase pressure it builds up?

 

no. Compression in the combustion chamber does not equal pressure in the crankcase unless you have very poor ring seal. If that's the case, a breather kit is hardly the solution to the problem.

 

Oh i see. Thanks for clearing that up for me.