Having owned the most powerful turbocharged car CC has ever made, I learned
a lot about turbos and how they interract with the engine. Functionally,
there is no difference between a turbocharger and a supercharger. They both
provide "boost" pressure to the engine. Where the difference comes in is how
they are powered to provide that "boost". We all know that superchargers use
direct drive from the motor to achive this. This means that at higher RPM's
they tend to suck more power from the engine than a turbo would. The turbo is
exhaust driven and puts backpressure on the engine every time there's an
exhaust flow change. The pressure is minimal at stable RPM's since little
power is required to keep the turbo spinning. This makes the Turbo better for
road preformance and the supercharger better for drag preformance.
A small turbo spins up and down more easily but provides less pressure.
This is fine for those little 4 cyl lawnmower engines but a large engine will
suck more air at high RPM's than a small turbo can provide so you effectively
destroy any gains you get in "boost". Large turbos are great for engines that
don't change RPM's much or have low RPM ranges (diesels) as they can provide
huge amounts of boost but have killer amounts of lag. CC developed a "large"
turbocharger with variable intake vanes that spun inward and outward with the
turbos RPM's. It pulled air like a small turbo at low RPM's and like a large
turbo at high RPM's and made lag nearly unnoticeable. This design was sold to
Honda who now uses it on the International GT circuit cars they race. A
variant of it lives on offered by Garrett Turbos. This design also eliminates
the need for wastegates, what might be called "engine matching" and such.
A pair of these turbos could be bolted on to the back of each side of a
header and plumbed up through an intercooler then on to the engine without
much mess. You'd probably need a custom engine controller to accurately
handle the boost (whatever system they use for superchargers would probably
work fine). You might also need a water injection system (or very high octane
fuel) to keep detonation and head temps down (for racing) but being
intercooled I doubt you'd need it for regular driving. Seeing as how some
twin turbo V8's are able to crank out over 800hp, I don't think your problem
would be power, but how many tranny's you go through in a week...
Shaun H.
---original message---
Unfortunately, I don't think it's that simple... the turbo(s) much be
closely matched to the engine, or you will run out of flow, overboost, or
have some horrendous turbo lag... I agree that turbos would really make the
engine scream, but there's some real engineering that has to be done... If I
find it again, I remember seeing a site a long time ago that carried some
equations for figuring the turbo variables (wastegate size, nozzle size,
housing size, etc) If I find it again, I'll post some info.
Gary Shook
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