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Old 11-15-2004, 06:12 PM
Daniel Jones Daniel Jones is offline
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> Are these Ricardo transmissions available in the aftermarket?
> Does anyone know if Ricardo build a trannie could fit a front engine - rear
> wheel drive configuration?

I believe the Shelby Series 1 uses the Ricardo transaxle. The engine is
front mounted but the transmission is mounted at the rear.

> Additionally, the article mentions that the GT uses a Lysholm twin vein
> supercharger.

The Lysholm is not a a vane type impellor. It's an intereshing screw
design which uses two helical rotors, one male and one female. The male and
female rotors intermesh but do not touch. As you move down the rotors, the
pitch gets closer together so the trapped volume of air is compressed. This
is know as internal compression (Roots and centrifugal compressors are
external compressors... they blow air into a plenum to do the compression).
The Lysholm is also positive displacement and is very efficient at producing
boost, much more so than a Roots, but tends to consume power even when not
producing boost since with internal compression, a bypass does not remove
parasitic loads.

Though the screw compressor patent was issued in 1878 (to German Heinrich
Krigar), it wasn't until the 1930's that Alf Lysholm developed it for gas
and steam turbine use. Lysholm was chief engineer at Swedish steam turbine
manufacturer Ljungstroms Angturbin which later (1951) became Svenska Rotor
Maskiner (SRM). Initial applications were primarily industrial: air
compressors, refrigeration, air-conditioning, etc. The earliest I can
find reference to automobile applications was in 1965, when British engineer
Mark Ransome proposed using one on a Formula One engine. That proposal
insired the development of the PSI drag race supercharger in the States.
SRM appears to still control most of the manufacturing licences with SRM,
Opcon, Sprintex, IHI, and PSI all making screw type superchargers. Earliest
date I can find for an actual application on an automobile is the 1980's.
Mercedes currently uses one and IHI made one for a Japanese vehicle, also.

> Lysholm is based in Sweden and specializes in both development and
> manufacture of air compressors.
>
> http://www.lysholm.se/en/business_obj.asp

Eaton is supplying the GT's Lysholm S2300 supercharger. In the GT
application, it's rated at 12 PSI maximum boost and uses a water-cooled
intercooler.

Dan Jones
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