engine/turbo theory question

[Todd Phenneger]

Thanks for the reply Simon,
  Thats interesting about the spiral groove, I didn't know that.
What I've noticed though with turbo's is even with High
compression 10vt's, higher than my old NA 4kq,  they still have
no power till the turbo spools up.  More than the Early MC's but
not as much as a 4kq.
l8r
 Todd

--- SIMON HOLTBY <sholtby at yahoo.co.uk> wrote:
> 
> --- Todd Phenneger <tquattroguy at yahoo.com> wrote: > No,
> >   The turbo does hamper flow and cause a power loss.  It
> just
> > makes WAY more power than it loses.   If you could have no
> > restriction at all, you'd get even more power.  Hence the
> > development by Garret of that Hydraulicly driven turbo they
> want
> > to make.  No restriction at all makes for FAST spool up, and
> > instant full boost at low RPM.
> 
> Todd,
> 
> I remember talking to a guy who was a diesel engine designer
> for Cummins
> and he told me that the exhaust system is carefully designed
> so  that the
> turbo uses a very small amount of power. You know how exhausts
> are tuned
> to scavenge from cylinders as the exhaust valve opens well the
> same can be
> done with a turbo, some how pulling the gasses through.
> He told me how some people who had failed turbos were removing
> them and
> running N/A but this was destroying the engine as the exhaust
> was totally
> out of tune.
> He also said that it is not the exhaust gas pressure but the
> heat of the
> exhaust gas that turns the turbine. I cannot remember his
> explenation as I
> was confused by it.
> Something else he said was that the turbo shaft has a spiral
> groove in it.
> This prevents oil from getting past the oil seals, as the oil
> is 'wound'
> back in.
> His latest project was designing a JET engine that can run on
> coal dust
> for countries without oil. Its use being for electricity
> generation (not
> aircraft!)
> Biggest problem with turbo engines is their lower compression
> which means
> that they are inefficient when the turbo is off boost. I read
> an article
> about a new Saab engine with variable compression allowing
> very high boost
> pressures without detonation and efficient running at low
> boost. It does
> this by raising and lowering the cylinder head, wow!
> 
> Regards
> 
> Simon Holtby
> 
> 
> 
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