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JE Pistons and 3.2 swirled domes
In Waynes rebuild book (pg. 55) he says the JE pistons for CIS or 3.2 engines do not have the swirled piston domes that are distinctive to this model.
What are the consequences of using the JE pistons (part #212439) w/o the swirls? Will you lose horespower?
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Howard 2003 996tt 1997 911 Coupe Artic Silver (sold) 1988 Black 911 Coupe (gone but not forgetten) |
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11-27-2005, 11:23 AM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,122
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probably a good thing...as they were esp for cis.......are you staying cis??
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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11-27-2005, 12:10 PM
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PRO Motorsports
Join Date: Nov 2001
Location: Burbank, CA
Posts: 4,580
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The CIS pistons had domes that squished the combustion chamber over so that when the piston was at TDC, the effective combustion chamber had the spark plug near the center. This allows higher compression (due to shorter flame path) and leaner mixtures (without misfire) for lowest emissions and best efficiency.
It's not really a performance gain, as you can't run radical cams with these pistons, due to inadequate valve to piston clearance. You won't lose horsepower. You will lose some efficiency though.
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'69 911E coupe' RSR clone-in-progress (retired 911-Spec racer) '72 911T Targa MFI 2.4E spec(Formerly "Scruffy") 2004 GT3 |
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11-28-2005, 12:03 PM
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