[DeTomaso] NPC: new motor development

Larry - Ohio Time Larry at ohiotimecorp.com
Mon Apr 27 13:11:31 EDT 2015


While the fashion in high-tech automotive developments might lean towards
hybrids and electric vehicles at the moment, there's still plenty of scope
to improve the good old internal combustion engine and one of the holy
grails of such development is the creation of a viable
variable-compression-ratio system.
Now Porsche is working on just such an engine, revealed in the form of a
newly-published patent, which will be able to alter its compression ratio.
It's partner in the project is engineering firm Hilite International, a
leading maker of engine components including variable valve timing cam
phasers.
Why is a variable compression system so desirable? Because, particularly
when allied to a turbocharged engine, it has the potential to maximize
economy and efficiency while simultaneously improving outright performance.
While turbos are great when it comes to allowing relatively small-capacity
engines to produce giant-killing performance, they do require a compromise
in terms of compression ratio. To accommodate the increased volume of intake
charge that the turbo supplies at full boost, a turbo engine needs a
relatively low compression ratio, which in turn means they can be lethargic
when boost levels are low. Increasing the compression ratio towards that of
a normally-aspirated engine helps that low-speed performance, but means peak
boost needs to be restricted because forcing more air and fuel into the
cylinder means the effective compression ratio is increased - if it gets too
high, the result is detonation, which is usually just as bad for the engine
as the name suggests.
By varying the compression ratio - in this case by putting the small-end
bearing into an eccentric adjuster, automatically tilted by
oil-pressure-activated rods either side of the con-rod - the idea is to be
able to use relatively high compression ratios with low levels of boost,
effectively making the engine behave like a small, normally-aspirated
design. When needed, swiveling the eccentric adjuster moves the piston down
a fraction reduces the compression ratio and allows the engine to cope with
far greater levels of boost, resulting in massively increased power.
 
<http://www.gizmag.com/porsche-variable-compression-engine-patent/37186/pict
ures#1> Porsche and Hilite aren't the first to attempt to make a variable
compression engine, but ...
On the Porsche system seen here, a solenoid directs oil to one of two rods,
rocking the eccentric small end bearing holder into either a "high
compression" or "low compression" position. The technology is very similar
to that used in oil pressure operated variable valve timing systems.
Porsche and Hilite aren't the first to attempt to make a variable
compression engine, but the two firms seem to have struck upon a relatively
simple, compact and workable method of doing it. A huge question mark still
hangs over whether the resulting engine will be cheap, effective and
reliable enough to reach production, but it's clearly a step in the right
direction.
Finally, it's worth noting that much of Porsche's work is in the form of
engineering consultancy, so the fact the firm's name is on the design's
patent doesn't mean the engine is being developed for a new Porsche-branded
car; it could just as easily appear in a machine from another firm.
 
 
Larry - Cleveland
 
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   While the fashion in high-tech automotive developments might lean
   towards hybrids and electric vehicles at the moment, there's still
   plenty of scope to improve the good old internal combustion engine and
   one of the holy grails of such development is the creation of a viable
   variable-compression-ratio system.

   Now Porsche is working on just such an engine, revealed in the form of
   a newly-published patent, which will be able to alter its compression
   ratio. It's partner in the project is engineering firm Hilite
   International, a leading maker of engine components including variable
   valve timing cam phasers.

   Why is a variable compression system so desirable? Because,
   particularly when allied to a turbocharged engine, it has the potential
   to maximize economy and efficiency while simultaneously improving
   outright performance.

   While turbos are great when it comes to allowing relatively
   small-capacity engines to produce giant-killing performance, they do
   require a compromise in terms of compression ratio. To accommodate the
   increased volume of intake charge that the turbo supplies at full
   boost, a turbo engine needs a relatively low compression ratio, which
   in turn means they can be lethargic when boost levels are low.
   Increasing the compression ratio towards that of a normally-aspirated
   engine helps that low-speed performance, but means peak boost needs to
   be restricted because forcing more air and fuel into the cylinder means
   the effective compression ratio is increased - if it gets too high, the
   result is detonation, which is usually just as bad for the engine as
   the name suggests.

   By varying the compression ratio - in this case by putting the
   small-end bearing into an eccentric adjuster, automatically tilted by
   oil-pressure-activated rods either side of the con-rod - the idea is to
   be able to use relatively high compression ratios with low levels of
   boost, effectively making the engine behave like a small,
   normally-aspirated design. When needed, swiveling the eccentric
   adjuster moves the piston down a fraction reduces the compression ratio
   and allows the engine to cope with far greater levels of boost,
   resulting in massively increased power.

   [1]Porsche and Hilite aren't the first to attempt to make a variable
   compression engine, but ...

   On the Porsche system seen here, a solenoid directs oil to one of two
   rods, rocking the eccentric small end bearing holder into either a
   "high compression" or "low compression" position. The technology is
   very similar to that used in oil pressure operated variable valve
   timing systems.

   Porsche and Hilite aren't the first to attempt to make a variable
   compression engine, but the two firms seem to have struck upon a
   relatively simple, compact and workable method of doing it. A huge
   question mark still hangs over whether the resulting engine will be
   cheap, effective and reliable enough to reach production, but it's
   clearly a step in the right direction.

   Finally, it's worth noting that much of Porsche's work is in the form
   of engineering consultancy, so the fact the firm's name is on the
   design's patent doesn't mean the engine is being developed for a new
   Porsche-branded car; it could just as easily appear in a machine from
   another firm.



   Larry - Cleveland

References

   1. http://www.gizmag.com/porsche-variable-compression-engine-patent/37186/pictures#1
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