Supercharger drivability question
Joined: Apr 2009
Posts: 2,521
Likes: 1
From: Renton, WA
Roots blowers are positive displacement, they move the same amount of air at all RPMs, which allows them to build full boost at idle.
Our centrifigal blowers need to spin faster to get more boost... but since it is belt driven, we only get full boost at redline.
Our centrifigal blowers need to spin faster to get more boost... but since it is belt driven, we only get full boost at redline.
Joined: Jun 2006
Posts: 5,149
Likes: 17
From: Raleigh, NC
I think we have a little confusion on a few things and what the difference is between LAG and RESPONSE. Here is a simplifed way to explain it.
Turbo vs Supercharger on a highway pull. Both cars make 10psi max boost @ redline. lets also assume both cars make 350whp. Both drivers are holding @ 6,000rpm @ 45mph waiting for the 3rd honk so they can go!! (numbers are for example only)
S/C will be @ 6psi @ 6000rpm, all excess boost is being vented out of the bypass valve. The turbo however is not generating boost, because the load is very light, as the driver is holding the rpm steady and not accelerating. The supercharer makes instant boost and there for the car will pull forward first, the turbo will need a few hundred rpm to spool to full boost, but once it does will make more power than the s/c does, so it should begin catch up to the supercharged car.
LAG: press the gas and wait for the turbo to spool. Supercharger, boost is instant.
RESPONSE: now lets assume these cars are racing on mountain pass, with lots of on/off throttle inputs. The turbo car will constantly be re-spooling the turbo and waiting for that surge of boost, where as the supercharged car will always have boost instantly when needed. This will make the supercharged car feel like a more powerful version of its n/a counterpart. It make not make as much power at the same rpm as the turbo car but it will always have better on throttle response.
Turbo vs Supercharger on a highway pull. Both cars make 10psi max boost @ redline. lets also assume both cars make 350whp. Both drivers are holding @ 6,000rpm @ 45mph waiting for the 3rd honk so they can go!! (numbers are for example only)
S/C will be @ 6psi @ 6000rpm, all excess boost is being vented out of the bypass valve. The turbo however is not generating boost, because the load is very light, as the driver is holding the rpm steady and not accelerating. The supercharer makes instant boost and there for the car will pull forward first, the turbo will need a few hundred rpm to spool to full boost, but once it does will make more power than the s/c does, so it should begin catch up to the supercharged car.
LAG: press the gas and wait for the turbo to spool. Supercharger, boost is instant.
RESPONSE: now lets assume these cars are racing on mountain pass, with lots of on/off throttle inputs. The turbo car will constantly be re-spooling the turbo and waiting for that surge of boost, where as the supercharged car will always have boost instantly when needed. This will make the supercharged car feel like a more powerful version of its n/a counterpart. It make not make as much power at the same rpm as the turbo car but it will always have better on throttle response.
Community Organizer
Joined: Jun 2007
Posts: 31,070
Likes: 566
I think we have a little confusion on a few things and what the difference is between LAG and RESPONSE. Here is a simplifed way to explain it.
Turbo vs Supercharger on a highway pull. Both cars make 10psi max boost @ redline. lets also assume both cars make 350whp. Both drivers are holding @ 6,000rpm @ 45mph waiting for the 3rd honk so they can go!! (numbers are for example only)
S/C will be @ 6psi @ 6000rpm, all excess boost is being vented out of the bypass valve. The turbo however is not generating boost, because the load is very light, as the driver is holding the rpm steady and not accelerating. The supercharer makes instant boost and there for the car will pull forward first, the turbo will need a few hundred rpm to spool to full boost, but once it does will make more power than the s/c does, so it should begin catch up to the supercharged car.
LAG: press the gas and wait for the turbo to spool. Supercharger, boost is instant.
RESPONSE: now lets assume these cars are racing on mountain pass, with lots of on/off throttle inputs. The turbo car will constantly be re-spooling the turbo and waiting for that surge of boost, where as the supercharged car will always have boost instantly when needed. This will make the supercharged car feel like a more powerful version of its n/a counterpart. It make not make as much power at the same rpm as the turbo car but it will always have better on throttle response.
Turbo vs Supercharger on a highway pull. Both cars make 10psi max boost @ redline. lets also assume both cars make 350whp. Both drivers are holding @ 6,000rpm @ 45mph waiting for the 3rd honk so they can go!! (numbers are for example only)
S/C will be @ 6psi @ 6000rpm, all excess boost is being vented out of the bypass valve. The turbo however is not generating boost, because the load is very light, as the driver is holding the rpm steady and not accelerating. The supercharer makes instant boost and there for the car will pull forward first, the turbo will need a few hundred rpm to spool to full boost, but once it does will make more power than the s/c does, so it should begin catch up to the supercharged car.
LAG: press the gas and wait for the turbo to spool. Supercharger, boost is instant.
RESPONSE: now lets assume these cars are racing on mountain pass, with lots of on/off throttle inputs. The turbo car will constantly be re-spooling the turbo and waiting for that surge of boost, where as the supercharged car will always have boost instantly when needed. This will make the supercharged car feel like a more powerful version of its n/a counterpart. It make not make as much power at the same rpm as the turbo car but it will always have better on throttle response.