4.6L (1996-2004 Modular) Mustang Technical discussions on 1996-2004 4.6 Liter Modular Motors (2V and 4V) within.

Centrifugal vs. Roots

Thread Tools
 
Search this Thread
 
Old Aug 2, 2007 | 09:31 PM
  #1  
ajmodelski's Avatar
ajmodelski
Thread Starter
2nd Gear Member
 
Joined: Sep 2006
Posts: 183
From:
Default Centrifugal vs. Roots

I want to know the numbers. I know the roots has slightly lower hp numbers but better torque through the rpms. But I want to know, the acceleration numbers. I want to know how fast a 400hp roots blower is and how fast a 400hp centrifugal is. Quarter mile times or 0-60 times. I don't care. I want to know which is right for me. I'm hoping that 400 ish RWHP is going to be enough for me. But I do road racing and I want to know, which choice is right for me.
Old Aug 2, 2007 | 10:00 PM
  #2  
GT03 TJS's Avatar
GT03 TJS
3rd Gear Member
 
Joined: Aug 2006
Posts: 747
From: CT
Default RE: Centrifugal vs. Roots

both can easily make 400rwhp at around 8psi with a good tune and a few boltons.

what doesnt make sense is you're asking about 1/4 mile times then mention that you're into road racing.

if you were into road racing i would imagine that NO blower would be your best option and to just build one hell of an engine that can handle that type of abuse. The type of driving thats required for road racing (and i assume you mean cones-on-a-parking-lot type stuff, and not highway racing) would just cause most blowers to suffer from severe heat soak and after a few laps or runs or whatever with no cooldown period, your performance would basically suffer. Plus with the type of driving you do, you dont really have enough time to build and hold boost to make it worth while.

Someone please correct me if i'm wrong, but I cant think of any real successful road-race oriented cars that have a blower. I think your money would be better spent on a built motor and some serious suspension upgrades as opposed to 4k on a blower that doesnt really help you at all.
Old Aug 2, 2007 | 11:42 PM
  #3  
tbirdscwd's Avatar
tbirdscwd
5th Gear Member
 
Joined: Sep 2006
Posts: 4,039
From: CA
Default RE: Centrifugal vs. Roots

+1 First, I would figure out what you will be mainly using this car for. Is it a 1/4 mile car that you will occasionally road race, or visa versa. Or the most realistic scenario: is this a daily driver that you will sometimes take to either track? Figure out your ultimate goals for the car, then choose a blower or build a motor that most suits your type of driving.
Old Aug 3, 2007 | 12:12 AM
  #4  
01snake's Avatar
01snake
5th Gear Member
 
Joined: May 2007
Posts: 2,795
From: Michigan
Default RE: Centrifugal vs. Roots

ORIGINAL: ajmodelski

I want to know the numbers. I know the roots has slightly lower hp numbers but better torque through the rpms. But I want to know, the acceleration numbers. I want to know how fast a 400hp roots blower is and how fast a 400hp centrifugal is. Quarter mile times or 0-60 times. I don't care. I want to know which is right for me. I'm hoping that 400 ish RWHP is going to be enough for me. But I do road racing and I want to know, which choice is right for me.


[sm=dontgetit.gif]
Old Aug 3, 2007 | 12:16 AM
  #5  
2000GT4.6's Avatar
2000GT4.6
6th Gear Member
 
Joined: Jan 2004
Posts: 12,575
From: United States
Default RE: Centrifugal vs. Roots

ORIGINAL: GT03 TJS

both can easily make 400rwhp at around 8psi with a good tune and a few boltons.

what doesnt make sense is you're asking about 1/4 mile times then mention that you're into road racing.

if you were into road racing i would imagine that NO blower would be your best option and to just build one hell of an engine that can handle that type of abuse. The type of driving thats required for road racing (and i assume you mean cones-on-a-parking-lot type stuff, and not highway racing) would just cause most blowers to suffer from severe heat soak and after a few laps or runs or whatever with no cooldown period, your performance would basically suffer. Plus with the type of driving you do, you dont really have enough time to build and hold boost to make it worth while.

Someone please correct me if i'm wrong, but I cant think of any real successful road-race oriented cars that have a blower. I think your money would be better spent on a built motor and some serious suspension upgrades as opposed to 4k on a blower that doesnt really help you at all.
Your not going to make 400 WHP with a roots blower at 8 PSI on a 2v. hell, 03/04 cobras arn't making 400 WHP with a roots blower at 8 PSI.

Roots sucks. You may be thinking of a twin screw, which is much more efficent and doesn't fall off up top. The roots blowers for our cars are lucky to make 360ish WHP with 8 PSI + full boltons and custom tune, let alone 400 WHP.

In every single way, other than torque from 2000-3500 RPM, the centri is superior. A centri powered car, with all else being equal (same boltons etc) is going to W A L K away from a roots car. Its not even going to be a race.

Roots ftl!
Old Aug 3, 2007 | 12:19 AM
  #6  
GT03 TJS's Avatar
GT03 TJS
3rd Gear Member
 
Joined: Aug 2006
Posts: 747
From: CT
Default RE: Centrifugal vs. Roots

my mistake, i had KB in mind....twin screw...not roots......@ 8psi easily hits 400rwhp
Old Aug 3, 2007 | 12:32 AM
  #7  
2000GT4.6's Avatar
2000GT4.6
6th Gear Member
 
Joined: Jan 2004
Posts: 12,575
From: United States
Default RE: Centrifugal vs. Roots

BTW, if your wanting a mean road race car, a blower can definatly help. However, for road racing only I would probably go with a twin screw, of if I had no other option, a roots style. From what I have seen though, the roots kits are dammed near as much as a KB setup.

The reason I would not go with a centri on a road race setup is the lack of power down low. Unless you can keep your rpm in the 3000-redline range your going to have bad results with a centri on the road course. On a twin screw/roots setup it makes max boost down low, and will make lots of low end torque, so you wouldn't be so busy with the shifter. AKA, you come out of a turn and instead of having to upshift just apply throttle and the car will pull thru the bottom of the gear.

With the right suspension setup and a twin screw you would have one mean road race machine.
Old Aug 3, 2007 | 10:45 AM
  #8  
shadowfoxx's Avatar
shadowfoxx
3rd Gear Member
 
Joined: Apr 2006
Posts: 628
From: Florida
Default RE: Centrifugal vs. Roots

ORIGINAL: 2000GT4.6

BTW, if your wanting a mean road race car, a blower can definatly help. However, for road racing only I would probably go with a twin screw, of if I had no other option, a roots style. From what I have seen though, the roots kits are dammed near as much as a KB setup.

The reason I would not go with a centri on a road race setup is the lack of power down low. Unless you can keep your rpm in the 3000-redline range your going to have bad results with a centri on the road course. On a twin screw/roots setup it makes max boost down low, and will make lots of low end torque, so you wouldn't be so busy with the shifter. AKA, you come out of a turn and instead of having to upshift just apply throttle and the car will pull thru the bottom of the gear.

With the right suspension setup and a twin screw you would have one mean road race machine.
Yeah.. I would say IF you do go for a bloweron road racing events.. theKB would be my choicealso .. HOWEVER, to do any good with a blower on a road race car you are going to needto upgrade thecooling system on there. B/C like GT03 TJS said you will definetly run into heat soak issues in an open track environment using any time of blower, expecially a positive displacement type. if you plan on running either type of SC kitin an open track environment, I would plan on running a big efficient heat exchanger,a large capacity liquidreservoir (think of a 5 gallon cell in the trunk) and an engine oil cooler.[/align]
Old Aug 3, 2007 | 11:25 AM
  #9  
2002GTAUTOVERT's Avatar
2002GTAUTOVERT
5th Gear Member
 
Joined: Mar 2007
Posts: 2,441
From:
Default RE: Centrifugal vs. Roots

yeah, id say with a centri.. it NEEDS to be intercooled and you might want to consider other methods to keep the temperature down... id maybe consider getting a stock cobra hood to pull some of the heat out, if there are clearance issues then a cowl hood that is functional. honestly, for road racing your best bet is to build one hell of a motor with the suspension to boot, and maybe get nitrous for the straight aways...
Old Aug 3, 2007 | 12:18 PM
  #10  
SHO NO MERCY's Avatar
SHO NO MERCY
4th Gear Member
 
Joined: Jun 2006
Posts: 1,131
From: Oklahoma
Default RE: Centrifugal vs. Roots

bleh...nvm.



All times are GMT -5. The time now is 11:29 PM.