Rebuilding Rb 25det

[Abo Bob]

abo- what are these squish zones you talk about? what sort of head work? port? polish?

i was told head work was not needed for what i was after. Are there problems with using a thick head gasket to achieve 8.5 cr?

Ihave also been told that o-ringing the head and or block is noot needed for my power levels.

can someeone explain this also?

thanks simon

"The quench zones are the flat areas of the cylinder head where the piston comes in close proximity to at TDC. Pentroof DOHC cylinder heads typically have 4 quench zones at the ends of the combustion chamber. Quench zones promote more complete burning and reduce the likeliness of detonation by increasing turbulence of the fuel air mixture as the piston comes to TDC by squishing the fuel air mixture towards the sparkplug and away from the end zones of the combustion chamber. This reduces the amount of fuel air mixture near the ends of the combustion chamber where it does not completely burn, thus being wasted by pushing or squishing it toward the centrally located sparkplug where it can easily be ignited."

from here http://www.nissanperformancemag.com/january04/nerds/

Basically I'm talking about removing some material from the cumbustion chambers around the valves in particular but just generally. This means you will have a lower CR but you keep the squish zones which help with power and economy. It will cost a little more than a thick head gasket but not much and IMHO is a better solution.