RE: coupla MC motor questinons..

["Peter Berrevoets" <peterb@mysysltd.com>]

Phils question seemed to be more in between - I don't think that he is
unaware of the technique you described although I don't want to speak on his
behalf.

The point I was making is this - IMO the technique you described has
inherent risks (even though it is commonly used - more successfully, I feel,
in push rod engines) at both higher lifts and higher rpms due to the change
in the way forces are acting at the cam lobe - valve actuator interface. The
cam and the valve actuator are subject to a higher level of wear and more
shear due to the overall reduction in lobe surface area.

At 2.3 litre the displacement won't deliver gobs of torque - that is best
achieved by a smaller turbo that will spool up faster IMO. The better
breathing created by a cam of higher lift and longer duration is marginally
(again IMO) effective on a turbo engine in the mid rev ranges, and is only
really effective at higher rpms where, combined with some good head work,
the charge delivery and exhaust scavenging increases horsepower
significantly.  IMO a cam alone isn't going to do anything but tighten the
power band and reduce overall driveability for minimal gains.

More boost and charge enrichment at higher rpms seems to be the ideal for
the 10V engine. IMO

Has anyone tried installing secondary injectors in the intake tracts, rigged
to kick in at a point where the primary fuel injection starts to max out, so
that the 10V engine can get enough fuel?

JMHO

I could be totally wrong here but hey, I'm open to new ideas and/or being
shown the error of my ways.

Peter

-----Original Message-----
From: OorQue@aol.com [mailto:OorQue@aol.com]
Sent: Wednesday, September 22, 1999 9:39 PM
To: peterb@mysysltd.com
Cc: quattro@audifans.com
Subject: Re: coupla MC motor questinons..


>  Except that you now change the forces acting on the cam lobes and when
>  stiffer springs are used - to handle higher rpms that are usually the
>  dwelling place of extra ponies - you end up with a highly stressed valve
>  train more likely to suffer a catastrophic failure at a most inopportune
>  moment.

Phil's question wasn't "why would you want to do this" but "how is this
possible," which I answered.  Compromise is a way of life and while
re-grinding a cam with a smaller base circle isn't the ideal way of getting
the profile you want, it is often the only way to accomplish when good
quality blanks aren't available.  (Besides, why would you want a cam that
makes power at higher rpms in a 10v MC motor?)

JG