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les_garten les_garten is offline
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Join Date: Jun 2003
Location: PSL, FL
Posts: 861
Originally Posted by fredmeister View Post
My question is why would Porsche go thru the trouble of designing a special turbo grind cam if the SC cam would have worked fine or even improved performance in the first place. The turbo and SC came out in the same time period of the early 70's as far as development was concerned so there must be a clear benefit of one cam versus the other with regards the SC versus turbo cam in the turbo application.
Now the turbo will alleviate the intake revursion issues to a large extent so that I think you are less likely to experience trouble with more aggressive cams and CIS in a turbo versus an SC.
I have just sold my 1979 911SC which I built with 964 cams and it ran great. The idle suffered oh so slightly from the switchover, and I gained alot of high end power versus the stock SC cams which ran out of power around 5500rpm. With 964 cams it pulled till 7000rpm!
I would think the same would follow suit with the turbo, but remember in that car you need low end response improved more than high end since the turbo is cramming in the air at high revs where lots of valve overlap may actually hurt you.
This is very involved theory and we need a cam specialist to chime in.
I've had the SC cams in mine and have 964 Cams presently. I agree with what you state about the RPM and where the SC's run out of Breath. Now I have 964's, I don't think I gave up much to the SC's on the Bottom, the midrange and 5500 plus are much more robust.

---Les Garten---85 930, Andial IC, GHL Headers, Fabspeed Dual, K-27 HF2, 3.4 JE Full Finned 7.5:1 CR, 964 CAM'd, Carerra 3.2 Manifold Cut/Flipped, Tec3r, Siemans 55#, GSF Fuel Rails, Clewett Crank Trigger, Clewett Cam Trigger,Dual Plugged, ARP Head Studs/Rod Bolts, Clewett Wires.Tial 46mm WG, Tial 50mm BOV, WEVO Shifter,934 Boost Gauge, Wideband EGO Sensor/Gauge, C2T Head Gaskets, '88 MB 300TE,BMW R100RT
Old 12-18-2007, 01:49 PM
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