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Registered
Join Date: Nov 2008
Location: Northern Ireland
Posts: 29
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Street cam -DC 30 or DC40
Hi
I have a backdated 81 Euro spec SC, currently the engine is standard spec except for 40 IDA Webers and SSIs with a sports muffler. The distributor has been swapped out for the non vacuum advance 78 model. The car is in Ireland and runs on the local 97 octane fuel and weighs in at 1130kg. I am overhauling the engine and fitting new pistons, which will be 10.3:1, along with a programmable MSD ignition. The car currently pulls cleanly from 1500 rpm with no hesitation, and this is a trait I'd like to keep, but was wondering what cam solution would make the most of the new set-up? With the increased compression would the std cam settings be OK or should they be adjusted? Looking at Dougherty Cams I was wondering if the DC40 would be tractable at low revs or would the DC30 be a better option to keep the drivability around the 2000rpm region? Any relevant thoughts would be appreciated Cheers Mike |
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06-10-2017, 08:53 AM
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3 restos WIP = psycho
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,665
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DC40. Your displacement and compression are perfect for it. Although a little high strung on a 2 litre, they are very moderate, torquey cam in a 3 litre.
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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06-10-2017, 08:58 AM
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Registered
Join Date: Jul 2005
Location: Atlanta
Posts: 1,241
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DC65! It's basically a high lift version of a DC60, which is also awesome.
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No physical quantity completely explains its own existence |
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06-10-2017, 02:04 PM
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3 restos WIP = psycho
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,665
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^ I'd go DC60 / 62 / 65 if my car, but that wasn't the question.
 Sent from my Nexus 6P using Tapatalk
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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06-10-2017, 02:15 PM
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Registered
Join Date: Nov 2008
Location: Northern Ireland
Posts: 29
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Thanks for the input, guys.
The 60 and 65 seem to have more radical numbers that the 40, as I mentioned low down tractability is important, I'd really like to be able to push the throttle at 1800 rpm and the car to accelerate without any hesitation or flat spots. So are the 60 and 65 improvements on the 40, I don't know much about them? Cheers Mike |
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06-11-2017, 04:48 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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Another option would be a GT-2 102. John can grind these, they are not listed in his catalog however. It has the same duration as the DC 30 but with more lift, the same as the GT-2 turbo cam has.
I'm running this cam in my SC motor. I have the same large ports as you but with 9.8 to 1 CR. The the DC 40 will produce its peak power about 500 rpm higher than the GT-2 102, or I guess the DC 30. Do you want a torquey motor or a peaky motor?
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Gordon ___________________________________ '71 911 Coupe 3,0L outlawed #56 PCA Redwood Region, GGR, NASA, Speed SF Trackrash's Garage :: My Garage Last edited by Trackrash; 06-11-2017 at 09:28 AM.. |
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06-11-2017, 09:26 AM
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Registered
Join Date: Nov 2008
Location: Northern Ireland
Posts: 29
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Gordon
The desire is a torquey motor, which is good for road driving, not a peaky race unit. What are the figures for this 102 cam? Cheers Mike |
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06-12-2017, 01:06 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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It's the same as John Dougherty's GT-2 turbo cam, but with a lobe separation of 102 degrees. Dougherty Racing Cams Porsche 911, 930 and 964 camshaft profiles
John will grind these cams for you, if you contact him and ask.
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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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06-12-2017, 01:20 PM
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My Garage
1971 Porsche 911
Baja Bug
