[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

Re: chargit

In a message dated 97-01-03 10:15:41 EST, you write:

<< In article <m0vfsW8-000BpXC@insti.physics.sunysb.edu> you write:
 >I always thought that non-turbo superchargers (;-]) are most noticeable
 >at the low rpm.  This is what they're going to tell to J.Q.Public. Btw,
 >doesn't VW Corrado come with a non-turbo supercharger?
 I seem to recall hearing that the Corrado came in a "traditional"
 supercharged configuration.  The late first-gen MR-2 also came
 this way.  Superchargers are just like turbos with one exception...
 The supercharger is always running, so you don't get turbo lag.
 This also means that you are using up more petro because the
 supercharger is always dragging the engine down.
>>>>>  The mechanical supercharger in the carrado is the G-lader type, and
tho is a great production item due to it's simple and less precision
execution, it also generates a LOT of heat, and this lends to poor
efficiency, like max of 60% (vs a turbine supercharger - turbo that usually
is higher than 70% at peak and not less than 65% off peak), which means only
60% of the energy produced actually goes toward engine performance....  The
compact design and high duty life made this an acceptable alternative to a
company  2years behind the 8 ball on the 6 cyl motor...  Never meant to be
anything more than a band aid  for the Vr6 six....  I have seen no Glader
installs that exceed 200hp, which is pretty low considering what the vr can
 Of course, a turbo constricts the exhaust, which doesn't help mileage
 either.  However, Saab claims that their turbo cars are actually more
 fuel efficient than a non-turbo engine producing the same power.
Don't agree with the first statement, the second is true as a general rule
for turbo vs non turbo cars, becuz supercharging air increases the effective
volumetric efficiency of a motor, and tho a turbo will use more gas while
"on" boost  the motor uses less when "off" boost....
 You can get somewhat around the supercharger inefficiency though.  You
 can bypass the supercharger (so it's just churning air instead of
 actually compressing it) which reduces the load and reduces fuel
 consumption.  You can get power back as quickly as the gate can be
 closed, so it doesn't have a huge lag either.
>>>>>>>>  Like that beyond thunderdome electromechanical clutch
arrangement....  This concept has been around for almost 30years....
 Suprised more  companies don't get this idea into production.....
 >On a related topic: I recall hearing that turbochargers can be balanced
 >(uh, that's a bad word, I guess... fitted, adjusted) to a certain rpm
 >range.  Could somebody explain what's going on in one paragraph? ;-)
 The change various parameters about the turbo, including the size and
 weight of the turbo.  A smaller turbo takes less time to spin up, but
 also doesn't produce as much boost.
.....  Not necessarily true....  Depends on your definition of boost....
 Smaller turbos tend to not be as efficient as larger ones as rpm's increase,
but a k24 can put 2.5 bar of boost to a motor @ 6500 rpm, so can a k26
based....  Boost level isn't a large component of the turbo equation,
temperature, or boost efficiency is....  Without getting into nerdy stuff on
turbo MAPs, what you want is the coldest air possible at the highest turbo
efficiency possible in the widest rpm band possible...  Remember 20vt sport
quattros only run 2 bar absolute (14.7psi) to get that 305 hp in stock
trim....  Should make ya think about boost a little more....  This
unfortunately is not a complete science (btdt).....