RE: Mystery cam

["Buchholz, Steven" <Steven.Buchholz@kla-tencor.com>]

> First, if it is indeed from an '82, it is not a hydraulic lifter cam.  In
> the second place, unless you want the torque peak to happen at a lower
> rpm,
> then this isn't an upgrade. Factory Audi turbo cams do not have any
> appreciable overlap. Generally they have none.  As a rule, as the overlap
> increases, the torque curve moves higher in the rpm range.  With a turbo
> obstructing the exhaust (read back pressure) the cam is designed with
> little
> or no overlap as an anti-reversionary  measure. Also, because of that
> obstruction any scavenging effect from the exhaust pulses which would be
> beneficial to a normally aspired motor are lost.
> 
... well ... as was discussed on the list some time back, it certainly
appears that the cam for the MC engine is identical to that of the
high-compression NA 2.3 liter engine.  I did confirm this with both the 5000
and 100/200 Bentleys (NOTE: The high compression MC in the late '89-'90 200Q
is different).  I realized that I had the fiche for all the cars, so I
looked it up.  Sure enough the NF and early MC engines all use the same cam
(034 109 021 K) while the later MC's use (034 109 021 AK) and the normally
aspirated KZ engine uses 034 109 021 P.

Seems like Audi thought that the cam worked fine in both turbos and NAs ...
what it will do in a 4k's JT engine I can't _yet_ say ...

HTH!
Steve Buchholz
San Jose, CA (USA)