Why aren't our block zero decked? Is it simply because our aluminum blocks expand twice as fast (~2.4/1) as the rest of the rotating assembly after startup? This explains why piston slap goes away after the engine warms up.

It just seems strange that SBCs and LT1 motors had the pistons way in the hole, and now Gen III motors have the pistons sticking up in the air.

I think to calculate this, it would include the critical dimesions of the total deck height of the block and the length of the piston/rod/crank journal from the center line all multiplied by their respective coefficients, correct?

Ben T.

 

..and before someone else could come in and naively say "for more compression", there! I just did it before you.

Ben T.

 

Less quench area too maybe, which helps prevent detonation.

I dont think anyone here will be able to say 100% sure why they are out of the hole.

 

my guess is that they designed that part of the engine on friday morning.. after going to happy hour at the local bar on thursday night.. .. but honestly i agree with your first guess.

 

They did it for better quench because A: better quench means less sensitivity to detonation and B: it promotes a cleaner, more thorough burn which reduces emissions.

 

Don't forget to multiply by the change in temperature for the components

 

The LS based motors are more performance oriented. Compression and quench are major factors.