Real HP loss numbers

[Shannen Durphey]

Ahh.  There was an article (maybe super Chevy?) on valve spring
testing done by Isky cams.  They use a block with no pistons or rods,
no plugs, and power it electrically.  The cam, oil pump, and
valvetrain are installed.  Oil temps still get to 210 deg even though
there is no combustion taking place.  And the noise level was
suprisingly high, too.  Gives a guy a little more respect for valve
springs.

Clive Apps Techno-Logicals 416 510 0020 wrote:
> 
> >
> > I have wondered about this myself.  I have heard anywhere from 15%
> > to 25% in drivetrain losses.  What I can't figure out is where the
> > energy is going.  If you have a 300HP engine with 25% drivetrain
> > loss, then you are losing 75HP somewhere.  Since it doesn't just
> > disappear, something has to be soaking up 75HP of energy.  My
> > guess is that the loss would be in the form of heat which would
> > mean of lot of drivetrain parts would have to be getting really hot
> > (assuming the 300HP load on the engine).  Since I have only seen
> > my transmission get warm, it doesn't really make much sense unless
> > I just haven't had the load on for a long enough period.
> 
> just estimate how much torque it takes to compress a valve spring
> multiply x 1/2 revs x # springs X length of valve travel x
> x losses in the vlave gear and add in the amount that it takes to
> move the valve train components around
> 15% sounds reasonable
> on 300 HP that would meav that another 52 HP was being eaten by the engine
> to move the valves
> 
> Clive
> 
> >
> 
> > I wonder sometimes if people don't estimate drivetrain losses on the
> > high side because they don't want to admit that their engines aren't
> > as powerful as they want them to be.
> >
> > Dan L
> >
> >