Re: [ST] Supercharge vs Turbo

["Chris Harwood" <Chris@xxxxxxxxxxxxxxxxxx>]

Sorry I can't accept the sweeping statement that a turbo won't create
added back-pressure.  It might not when compared to a poorly-designed
silencer/muffler system.  Simple gas dynamics mean that if the device is
compressing the inlet then is must be putting back-pressure on the
exhaust.  It is imperative that a free-flow muffler is then used so that
the maximum pressure drop appears across the drive turbine.

My point is that superchargers AND turbochargers have overheads besides
the power to drive them.

I think the important point for bikes is that getting that drive in the
first place is much simpler for a turbo.  The linearity of a
supercharger makes for a smoother power delivery which is more critical
for a bike than a car in my view.

Just my 0.04GBP
Chris Harwood
00 RS

Chris Harwood
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>>> buellrydr1@xxxxxxx 04/02/2006 05:39:38 >>>
Properly sized turbo has no added back pressure,turbo is sized
according to 
intended use,street,drag racing,ralley,etc.So a good turbo system
matched to 
your engine use,compression,etc. will work seamlessly.Look at the 
Mitsuibishi Eclipse,Rallye,Subaru WRX's etc.The added heat comes from 
compressing the incoming charge and is overcome with
intercoolers/charge 
coolers.Jim.


>
>What about back-pressure in the exhaust?  Particularly when
spinning-up.
>  Turbos must make it more difficult to clear the cylinder for the
next
>charge.
>
>Add Jaguar (Ford) to the supercharger camp.
>
>Chris Harwood
>00 RS
>
> >>> robertr@xxxxxxxxxxxxxxxx 03/02/2006 00:58:04 >>>
>This is always a contentious one.
>
>Supercharge:
>Almost instant response
>Usually heavier then turbo
>Usually requires case mods to get a drive to the pulley
>Sucks horsepower so the first bit of boost is wasted fighting
>mechanical
>losses, varies depending if Rootes or vane type
>Can put undesirable side load on case bearings not designed for the
>extra
>pulley hanging off the end.
>
>Turbo,
>Very little wasted boost
>Exhaust plumbing
>Lag
>Risk of overboost without a waste gate
>Can have problems with shutting down if you don't let it spin down
>before
>turning off the engine.
>Modern turbos minimise the lag problem.
>
>If you look at cars, Saab, Audi and others go with Turbo, Mercedes,
GM
>others go with Mechanical (though GM have also used turbo), so it
comes
>down
>to the Mfr in-house technical and marketing strategies. Fuel
dragsters
>use
>mechanical, Nissan and Ford used turbo in their group 'c' sedans that
>were
>almost unbeatable.
>
>Confused?
>
>Cheers
>R
>
><<

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