Roots blower vs Centrifical
07-06-2007, 03:18 PM
#31
4th Gear Member
Join Date: Apr 2006
Location:
Posts: 1,409
RE: Roots blower vs Centrifical
If they make boost its not a lot. I'm into boost at about 2700 rpm. But the second you go WOT all Vacuum disappears which is still power producing. Otherwise the car is still at roughly 20psi of vacuum and has to work to get that air (which is still not as much as if there is no vacuum in the system).
07-06-2007, 03:21 PM
#32
Underboss
Join Date: Jan 2006
Location: Helaware
Posts: 20,273
RE: Roots blower vs Centrifical
ORIGINAL: Gar4pt6
edit: nvm read^^^
[/quote] Not normally, but if you had say the smallest pulley available it's possible
07-06-2007, 03:27 PM
#33
6th Gear Member
Join Date: Jan 2004
Location: United States
Posts: 12,575
RE: Roots blower vs Centrifical
ORIGINAL: ASUSMC
If they make boost its not a lot. I'm into boost at about 2700 rpm. But the second you go WOT all Vacuum disappears which is still power producing. Otherwise the car is still at roughly 20psi of vacuum and has to work to get that air (which is still not as much as if there is no vacuum in the system).
If they make boost its not a lot. I'm into boost at about 2700 rpm. But the second you go WOT all Vacuum disappears which is still power producing. Otherwise the car is still at roughly 20psi of vacuum and has to work to get that air (which is still not as much as if there is no vacuum in the system).
It still makes a BIG difference under 3 grand. I was making more power at 3000 RPM on a MUSTANG DYNO (reads ALOT less than a dynojet) after the SQ than I was with an otherwise identical car on a dynojet at any point in the curve before. You don't notice it as much on a centri car since you get that big rush of power at around 3500~ RPM, but its there.
At 3K I am building about 1 to 2 PSI of boost, not sure exaclty where it starts but its a bit before that.
07-07-2007, 04:29 PM
#37
1st Gear Member
Join Date: Apr 2007
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Posts: 124
RE: Roots blower vs Centrifical
ORIGINAL: mylongvictor
Thats why you get one smaller turbo to spool up quickly, and one big turbo to take over at the high end!
ORIGINAL: 01snake
twin turbo would be nice as well
but the spool kills you, by the time you spool up your goin 100+ lol
twin turbo would be nice as well
but the spool kills you, by the time you spool up your goin 100+ lol
Thats why you get one smaller turbo to spool up quickly, and one big turbo to take over at the high end!
07-07-2007, 10:08 PM
#38
3rd Gear Member
Join Date: Nov 2006
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Posts: 641
RE: Roots blower vs Centrifical
ORIGINAL: ASUSMC
Besides roots or twin screw don't make boost til about 2k rpm either. they just go to full boost pretty much instantly
Besides roots or twin screw don't make boost til about 2k rpm either. they just go to full boost pretty much instantly
This is why I don't comment technicallyon centri blowers. As I have NO experience with a centri, I wouldn't know what the hell I was talking about.
07-08-2007, 04:16 AM
#39
5th Gear Member
Join Date: Jun 2007
Location: Decatur AL USA
Posts: 2,176
RE: Roots blower vs Centrifical
Roots are the least effecient of blowers. Whether they will make big power up top depends on blower and pulley size.
Screws are very effecient and tend to produce more linear boost than a centri.
Centris tend to ramp up with minimal boost in the lower midrange that gets higher and higher with rpm.
The following is a over simplified explanation but may halp those with little understanding of the differences.
Most street roots blowers tend to feel like a big low rev big block like a 455 Stage 1 Buick (530 Torque).
Most Screw type blowers tend to feel like ahigh performance Big Block like a 427/435 Vette.
The Centri tends to feel more like a hp small block like a Boss 302.
As to the limited power of roots blowers. They produce 8000 horsepower just fine. That wasnt a typo.
The primary thing is to make sure the blower has the right size for your displacement, desired rpm range, and boost level.
There is a big difference between the M90 (Original 3.8L Supercoupe, Early Saleen, and Roush) and the 14-71 (To large to be legal in Top Fuel) even though they are both Roots Blowers.
Having owned and driven, Roots, Screw, and Centris I vote Screw for a street car and Centri forDrag RadialCompetition.
Screws are very effecient and tend to produce more linear boost than a centri.
Centris tend to ramp up with minimal boost in the lower midrange that gets higher and higher with rpm.
The following is a over simplified explanation but may halp those with little understanding of the differences.
Most street roots blowers tend to feel like a big low rev big block like a 455 Stage 1 Buick (530 Torque).
Most Screw type blowers tend to feel like ahigh performance Big Block like a 427/435 Vette.
The Centri tends to feel more like a hp small block like a Boss 302.
As to the limited power of roots blowers. They produce 8000 horsepower just fine. That wasnt a typo.
The primary thing is to make sure the blower has the right size for your displacement, desired rpm range, and boost level.
There is a big difference between the M90 (Original 3.8L Supercoupe, Early Saleen, and Roush) and the 14-71 (To large to be legal in Top Fuel) even though they are both Roots Blowers.
Having owned and driven, Roots, Screw, and Centris I vote Screw for a street car and Centri forDrag RadialCompetition.
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