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Old 11-19-2009, 12:42 AM   #35
Checkers
Scooby Newbie
 
Member#: 188440
Join Date: Sep 2008
Chapter/Region: International
Location: desert
Vehicle:
98 1.6 Liters
of fury!

Default

The EJ205 heads have a smaller bore than the EJ257/EJ255 shortblock. That means that the 'dome' of the combustion chamber doesn't fit perfectly on top of the piston. So rather than the combustion chamber being a smooth dome, there's a sharp edge that is a detonation hotspot and screws up the combustion.

$300 gets you machining to match the dome of the head with the larger bore of the shortblock, making the engine far less prone to detonation per Maxwell Power.

$3000 gets you lots of machining of the intake and exhaust ports (what people usually refer to as 'headwork'). That's not what Maxwell is talking about. He's referring to a much simpler, much cheaper procedure specific to the hybrid engine rather than generic expensive head work.
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