[s-cars] article on horsepower conversion, rwhp to flywheel

[mlp qwest]

If you liked this, you might also find Dave Baker's (Puma Racing) musings on
heads, valve and the porting and polishing thereof interesting reading as
well.  He claims to be one of the few, maybe the only, head tunner to be
able to actually get more out of a "big" valve VW type heads.
http://www.pumaracing.co.uk/mainmenu.htm   He has some interesting
observations about heads etc., for example he cites involving VW/Audi heads,
".... The diameter of the lifter (or bucket) directly limits the speed with
which the valve can be opened and therefore the amount of valve lift that
the cam lobe can produce for a given opening duration. The maths behind this
premise is far too complex to go into here but is something which any cam
designer needs to take into account when designing a profile. The faster and
higher a valve can be opened, the more airflow potential the valve is going
to have and the better its ability to fill the cylinder. Some engines are so
severely limited in their power potential by having small diameter lifters
that it can outweigh any consideration of their power potential based solely
on valve area. Copyright David Baker and Puma Race Engines

For example the Ford 1800 Zetec and the VW Golf 1800 16 valve engine are the
same capacity and have identical valve sizes. Both have twin overhead cams
acting directly on buckets and similar bore and stroke sizes. An initial
view might be that, baring any major problem with port shape and size, that
both engines would have similar power potential when fully modified. The
Ford though only has 28mm lifters and the VW has 35mm ones. This allows the
VW to run much more radical cam profiles and achieve more "flow area" from
its valve lift curve. Copyright David Baker and Puma Race Engines

By contrast the VW 5 valve per cylinder engine has plenty of inlet valve
area from its 3 inlet valves per cylinder but space constraints mean the
lifters are only 24mm diameter. This limits the design of the cam profile so
badly that the power potential of the engine is reduced below that of the
much simpler 4 valve per cylinder design. In effect, this engine ended up as
nothing more than a very complex and expensive marketing exercise. "... from
http://www.pumaracing.co.uk/pp02.htm

~-----Original Message-----
~From: s-car-list On Behalf Of Jerry Scott
~Sent: Wednesday, October 08, 2003 11:04 AM
~
~I found this on the Viper page and thought the list might be interested
~in the article.
~http://vca2.viperclub.org/forums/showflat.php?Cat=&Board=UBB14&Numb
~er=328748&page=0&view=collapsed&sb=5&o=&fpart=1
~Jerry Scott
~
~