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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Again, the Group B cam is a cam of artificial restraints. For Group B racing Porsche was not allowed to exceed the lift of the stock cam.

There may have been other restrictions like stock internal, stock gear ratios or something else.

A 3.3 with stock rods and oiling will not live past 6700rpm for long.

A 3.3 that makes big peak HP at 7k is not going to work well with the stock wide ratio transmission.

With a low lift Group B cam might have come some possible side advantages like less stress on the valve train and also higher initial port vorticity for improved air fuel mixing but those are probably just side benefits and not of prime confederations.

However with a limitation on lift, I suspect that there was only so far Porsche could stench duration without trade offs in other areas. At some point with a long duration and limited lift the ramps would have to be so low an increase in duration is not going to add much. Alternately they could have tried to make kind of a flat top lobe but that might have taken them to to much duration or even added different stress to the valve train.

I have little doubt that if we move the TQ & HP peak up 1500rpm from 5500 with matched cams, ports, turbo, exhaust..., a 930 could make 25% more power. However, if we can not match the transmission ratios to it, we will may not achieve much improvement in average HP per gear and might end up slower in places that could cost us dearly on the track like out of a corner.


A 930 is a study in limitations and comprises while still having so, so much potential.

Last edited by 911st; 01-31-2010 at 01:25 PM..
Old 01-31-2010, 01:18 PM
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