Hi Guest!
Hey - did you know if you click on the title of a thread it will take you to the first unread post since you last visited that thread?
but were afraid to ask: 
STOP!! Never post your email address in open forums. Bots can "harvest" your email! If you must share your email use a Private Message or use the 
smilie in place of the real @
Pretty Please - add it to our Events forum(s) and add to the calendar! >> 
swift6
Yoda
Offline
[ QUOTE ]
"A supercharger builds boost linearly with RPM. So the higher the RPM the higher the boost. Turbochargers can build boost much faster. "
Its the other way around. You are correct that SC HP/Torque build in a liniar progression. This means that the power is prety much the same as rpm's increase. SC'rs boost remains pretty much the same through out the rpm range and generaly build no more than 10lbs for street use. A turbo starts low and builds boost as rpm's increase.This means lower rpm performance suffered.
[/ QUOTE ]
Something just clicked. Its the lower boost pressures that made me think that way. Since the boost is near maximum right off idle, that is why a mild supercharged car acts more like a normally aspirated engine than a turbo charged car. There is no lag.
Early turbos were pretty big and took a while to get up to speed and build the boost. Modern turbos are cabable of spooling up much faster so the turbo lag is greatly reduced. Turbocharged cars also generally run higher boost pressures. It seems that between 10-15 psi is pretty normal for factory turbocharged cars while tuners push them into the 20's. The higher the boost, the lower the initial compression needs to be so the lower 'off boost' rpm suffers from that lowered compression.
I recently read about a new supercharger designed by Alois Ruf (a Porsche Tuner) that acts more like a turbocharger. It still builds boost at low rpm for driveabilty, like a standard supercharger, then as rpm increases, so does the boost pressure. All driven through gearing, not belt or exhaust. The first one I read about was on a Boxster personalized by an Italian styling salon. That must make some 911 owners very uneasy.
Thanks for setting me straight Mitch.
/ubbthreads/images/graemlins/cheers.gif
"A supercharger builds boost linearly with RPM. So the higher the RPM the higher the boost. Turbochargers can build boost much faster. "
Its the other way around. You are correct that SC HP/Torque build in a liniar progression. This means that the power is prety much the same as rpm's increase. SC'rs boost remains pretty much the same through out the rpm range and generaly build no more than 10lbs for street use. A turbo starts low and builds boost as rpm's increase.This means lower rpm performance suffered.
[/ QUOTE ]
Something just clicked. Its the lower boost pressures that made me think that way. Since the boost is near maximum right off idle, that is why a mild supercharged car acts more like a normally aspirated engine than a turbo charged car. There is no lag.
Early turbos were pretty big and took a while to get up to speed and build the boost. Modern turbos are cabable of spooling up much faster so the turbo lag is greatly reduced. Turbocharged cars also generally run higher boost pressures. It seems that between 10-15 psi is pretty normal for factory turbocharged cars while tuners push them into the 20's. The higher the boost, the lower the initial compression needs to be so the lower 'off boost' rpm suffers from that lowered compression.
I recently read about a new supercharger designed by Alois Ruf (a Porsche Tuner) that acts more like a turbocharger. It still builds boost at low rpm for driveabilty, like a standard supercharger, then as rpm increases, so does the boost pressure. All driven through gearing, not belt or exhaust. The first one I read about was on a Boxster personalized by an Italian styling salon. That must make some 911 owners very uneasy.
Thanks for setting me straight Mitch.
/ubbthreads/images/graemlins/cheers.gif
