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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,274
Originally Posted by midlife View Post
They are also water cooled, so their head temperature is MUCH cooler.
and they have 4 valve heads and twin cams with variable valve timing.

The 4 valve head has a spark plug in the middle instead of off to the side like a 2 valve head.
This lights off the mixture from the middle of the combustion chamber similar to dual plugging and the flame front spreads out evenly to the outer edges of the combustion chamber burning more evenly which allows a higher compression ratio before detonation starts in.

The digital electronic ignition and fuel injection along with twin turbos and much better intercoolers also helps them run higher static compression without detonation.
Old 02-01-2010, 10:12 AM
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