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Registered
Join Date: May 2006
Location: Connecticut
Posts: 155
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911 SC port sizes
I hear that not all SCs were created equal in terms of injection port sizes. Can someone explain to me what differences exist between the various models? Also, what are the ramifications of these differences when it comes to tuning and power?
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Registered
Join Date: Dec 2002
Location: Dahlonega , Georgia
Posts: 14,921
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Someone will chime in with the fine details but basically the 1978-1979 SC engines are considered " big port " which is good for horsepower. The 1980-1983 are considered " small port " which is better for torque.
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2002 Boxster S . Arctic silver + black top/int. Jake Raby 3.6 SS engine " the beast ". GT3 front bumper, GT3 side skirts and GT3 TEK rear diffuser. 1999 996 C4 coupe black/grey with FSI 3.8 engine . Rear diffuser , front spoiler lip with ducktail spoiler . |
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Big ports were better for performance.
Small ports were better for emmissions and fuel economy. ROW SC's maintained the big ports through 83 for exports to unrestricted emissions areas.
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78’ SC 911 Targa - 3.2SS, PMO 46, M&K 2/2 1 5/8” HEADERS, 123 DIST, PORTERFIELD R4-S PADS, KR75 CAMS, REBEL RACING BUSHINGS, KONI CLASSICS |
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Registered
Join Date: May 2008
Posts: 2,948
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USA Specs:
1978-79 SC port sizes: I = 39mm/E = 35mm 1980-83 SC port sizes: I = 34mm/E = 35mm All models used the same valve sizes: I = 49mm/E = 41.5mm
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Keep the Shiny Side UP! Pete Z. |
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