View Single Post
911nut 911nut is offline
Metal Guru
 
911nut's Avatar
 
Join Date: May 2001
Location: Michigan
Posts: 2,511
Garage
Quote:
Originally Posted by 911st View Post
And the answer is:

From what I have recently read, it was because under the Group B rules, manufactures were not allowed to increase lift. They could however increase duration.

Thus, the Group B cams seems to be a compromise or work around and unless one it trying to fit into a class that requires them they are probably not a best of bread cam.
The Group B cams can be installed without changing the valve spring heights. Install an SC or 964 cam and the spring heights have to move up 1 mm.
The increased duration of the Group B cam will flow more mass over time since the valves are open longer. Same goes for the SC and 964 cams except that because of the greater lift, the cams are open longer yet.
__________________
Paul B.
'91 964 Turbo
Port matched, SC cams, K27/K29 turbo, Roush Performance custom headers w/Tial MV-S dual wastegates, Rarlyl8 muffler, LWFW, GT2 clutch & PP, BL wur, factory RS shifter, RS mounts, FVD timing mod, Big Reds, - 210 lb
Old 01-28-2010, 02:33 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)