Non-SE-R: GM OHV engines

[Rick Frey]

At 02:35 PM 11/27/2002 -0600, Steve Obert wrote:
>I can't figure out what has been discussed here.

>4. Any differences between motors has to to with airflow, not necessarialy
>where the cam is located.

One of the more knowledgeable should correct me if my diet is potassium rich.

I have always been told that one of the major advantages of 4 valve heads
lies with the pentroof (5 sided) combustion chamber configuration.  Having
more, smaller valves allows much more flexibility in designing the
combustion chamber shape.  Proper design allows running higher compression
w/o detonation, all other factors held constant.  I guess this would be
true regardless if a cam or rocker arm opens the valves, but how many DOHC
engines have less than 4 valves/cylinder these days and how many rocker
armed motors run 4 valves/cylinder?

Enough of GM engineer bashing.  I realize rocker armed motors in a vette
these days seems archaic but GM is moving on.  My wife drives a GMC with
the vortec 4200 inline six.  This is a 4.2L inline 6 w/ DOHC and 24
valves.  To me, this thing is a marvel.  It is silky smooth, quiet, and
when you wind it up, it doesn't gasp for breath.  Granted, it redlines at
6K or something, but I am sure it could be raced up quite a lot.  It runs
10:1 compression on 87 octane.  That suggests that this motor has been
designed to avoid detonation, a plus when hot rodding an engine.

My current dream car:   A pontiac solstice coupe w/ a vortec 4200 stuffed
in it.  Turboed of course.

Since that car doesn't yet exist (holding out hope), then I'd consider a C5
corvette w/ an inline 6 transplant.

I am a die hard GM fan, although I can easily look to imports for performance,

rick frey