pkurucz.list at gmail.com
Thu Mar 22 17:38:45 EDT 2007
On 3/22/07, R. Brown <r.c.brown at ieee.org> wrote:
> Tony and Lillie wrote:
> > So, what exactly keeps a diesel form being a high RPM engine. I understand the max speed is set at the pump, what I'm wondering is about the internals themselves. As it appears to be exactly the same as a 1.6 gasser, aside from the block and head castings.
> > What I"m wondering about is the crank, rods, and other rotating assys.
> > Tony Hoffman
> It is mainly due to the diesel combustion process. Diesel burns in more
> of a spreading flame front from the injector, while in a gas engine you
> have the air and fuel already mixed and a spark sets off the whole thing
> pretty much at once. Also, with the injector, it takes some time to
> inject all the fuel, so between the time to inject the fuel and the time
> for the fuel to mix with the compressed air and the flame front to
> spread, that is pretty much the limiting factor in top speed. The
> larger the cylinder diameter, the longer the flame front takes to spread
> across it, so larger engines generally have a lower top end speed than
> smaller engines.
If you watch the R10 promo video on the page above, @ 1 minute, 50
seconds there is a short clip of the diesel injection flame
propagation. I wish there was a high quality version of that clip.
More information about the Vwdiesel