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Registered User
Join Date: Sep 2010
Location: Usually under a car
Posts: 131
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Suggestions on Hot SC motor build
Hello Gang,
I am in the process of building a hot SC motor for track use. I was wondering what some of the suggestions and results people have gotten. The car will be switched to PMOs, will only run 100 octane and will be twin plugged. I am looking for a good CR/Cam/Valve size combo. The end result I am looking for is to push the power band up to the midrange and a very aggressive upper band. Thinking maybe a GE series cam and CR of 9:5:1 as a start.Machine work will include shuffle pin, full balance and Boat Tail the mains along with notching the skirts. Open to suggestions. Thanks! |
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08-25-2016, 06:59 AM
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Registered
Join Date: Jul 2006
Location: Charlotte, NC
Posts: 1,964
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300hp @ the crank
98mm cylinders 10.5:1 pistons Mod-s cams 46 pmo Twin plug 3.2 heads (stock) ARP bolts Headers Todd
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'81 SC |
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08-25-2016, 10:01 AM
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Registered
Join Date: Jan 2004
Location: CT
Posts: 11,538
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You might consider this build.
Another RSR Clone Project - Dyno Day Has been running great for 10 years now.
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Tom Butler 1973 RSR Clone 1970 911E 914-6 GT Recreation in Process |
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08-25-2016, 05:04 PM
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Under the radar
Join Date: May 2007
Location: Fortuna, CA. On the Lost Coast near the Emerald Triangle
Posts: 7,129
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With twin plugs you can go 10.5 to 1 CR or higher with race gas. As far as cams go, it depends on how high you expect to rev the motor, and will the bottom end handle that RPM. Doubt you will need any larger valves than What SCs came with, unless you are going really wild.
There are a ton of threads on hot rodding SC motors. Spend some time searching.
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage |
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08-25-2016, 07:52 PM
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Registered User
Join Date: Sep 2010
Location: Usually under a car
Posts: 131
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I will have Carrillos in it and it will be shuffle pinned as well. I will have everything balanced as well. I want to have good power up to 7-7500 and shooting for over 300 FWHP. The question is the cam and valve combo at this point. I had run a RSR cam/ larger valves in a car a built years ago and it put down 300 FWHP and looking for something a little more than that this time around. I know cam designs have changed since then. I tried searching but can't find anything that overlays the exact path I am looking for.
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08-26-2016, 05:07 AM
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Under the radar
Join Date: May 2007
Location: Fortuna, CA. On the Lost Coast near the Emerald Triangle
Posts: 7,129
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Give John Dougherty, Camgrinder on this board, a call or PM. He will work with you.
Dougherty Racing Cams
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage |
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08-26-2016, 09:49 AM
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Registered
Join Date: Feb 2004
Location: California
Posts: 926
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Camshafts and compression ratio should be matched. Along with carburetor sizes. for example, the DC60 works with 46mm carbs and 10.5-1 compression. The old 3.0 RSR cam might make the same peak HP, but would have less mid range torque. A smaller 40mm carb would come on the power band sooner, but fall off early.
If you post a list of information like this I can give you some options, Camshaft Request Form for Porsche 911
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John Dougherty Dougherty Racing Cams |
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08-26-2016, 01:43 PM
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My Garage
1971 Porsche 911
Baja Bug
