Re: Rope-a-Dope, Again!

["Graydon D. Stuckey" <graydon@apollo.gmi.edu>]

On Wed, 2 Oct 1996, mike tipton wrote:

>> Mr.Stuckey wrote:
>>  Since the breaker bar on the crank 
>> pulley is a very gentle, smooth load, I think that it is still less 
>> dangerous to the head/piston/bearings/etc.
> 
> Remember the forces of combustion take place within a millisecond.

Precisely my point in the previous post.  Since these forces take place 
so fast, they act on the piston in the manner of a shock load, which is 
potentially MUCH more severe than a gentle load.

> Piston design, wrist pin design, conrods, and bearings are designed to
> operate through a very "predictable" range of operation.
> These forces impossed upon the recipricating mass, during operation, is 
> throughly engineered and every aspect is known and has a value given.
> 
> The pistons, piston pins, and bearings must be very carefully designed
> due to the combustion forces, the requirement that pistons weight be as 
> low as possable and the temperature which occur at the piston.
> Piston design usually borders on piston-material strength limits.(SAE)
> 
> With this mind, why would you put anything "foreign" into the combustion
> chamber to impose "unnatural stresses" on the pistons!
> 
unnatural, but quite a bit less threatening to the welfare of the engine 
IMHO.  I don't have any numbers yet to back up my opinion, so there isn't 
any point arguing yet.  :-)

Later, ---------------------------------------------------------- 
Graydon D. Stuckey 	'85 Mazda RX7 GS, no toys 
graydon@apollo.gmi.edu 	'86 Audi 5000 CS Turbo Quattro, has toys
Flint, Michigan USA	'89 Thunderbird SC, lotsa toys