centrifugal supercharger vs. turbocharger

[Cookstar]

Since there are a couple of centrifugal superchargers on the horizon for our cars, I would like to know the advantages and disadvantages of each. A centrifugal supercharger is basically a belt-driven compessor while a turbocharger is an exhaust-driven compressor, right?

[sheek360]

u wont see 100% boost on a centri till ur about to redline, cuz its driven off the belt. also takes some hp away cuz its wasted attempting to spin the centri. honestly, i cant think of one good reason to go with a cetri except that u can fit one anywhere. if ur going to supercharge and sacrifice hp, then go with a twinscrew or roots blower, atleast ull have instant boost.

the following is only in the case of a properly sized turbo!!!!!
u will barely lag, trust me, from a digg, ur going to lag no matter what, but with a properly sized unit, u will barely lag. Outstanding topend too. the bad thing about a turbo is only in the case that u didnt have a pro install it. oil leaks, water leaks, boost leaks etc etc etc. if ur gonna dish out 3-5k on a turbo kit, get it installed by an actual performance shop! otherwise ull be doomed to leak like a mad man! dont be fooled by those cute ASE certifications!

[atruhondagrl]

There he is. I was wondering where you've been. Thanks for the info. And Ditto on an actual performance shop. Leaks. Thats the one thing I'm fearing going turbo.

[sheek360]

Originally Posted by atruhondagrl

There he is. I was wondering where you've been. Thanks for the info. And Ditto on an actual performance shop. Leaks. Thats the one thing I'm fearing going turbo.

there are so many outstanding performance shops in PA, philly, NJ and NY you shouldnt worry about it! When i had my mopar stage 3 srt4 i used to always have a boost leak on the same hot pipe! This was a stock pipe btw, it drove me crazy!

[Cookstar]

Thanks sheek360! I've got another question. Jackson Racing claims that their new Rotrex supercharger systems will have the throttle response of a Roots supercharger. Is that possible?

http://www.jacksonracing.com/home.htm

[sheek360]

Originally Posted by Cookstar

Thanks sheek360! I've got another question. Jackson Racing claims that their new Rotrex supercharger systems will have the throttle response of a Roots supercharger. Is that possible?

http://www.jacksonracing.com/home.htm

it doesnt matter how a centri is geared or pullied, and ive messed with many prochargers, it wont boost as fast as a roots or twinscrew. It doesnt really matter what FI route u choose, you will have improved throttle response. But not as fast as a roots or twinscrew, all i have to do is feather the clutch from a 1300rpm launch on my car and before 3krpm im seeing 80% of my boost. A centi's boost, like a roots and twinscrew, is rpm dependant because its belt driven. But its impossible to gear a centi like a roots or twinscrew.

[sickyute]

one thing i can say is....

i've never had a leak of any kind from day one...... not boost, not oil, not coolant ... no leak of any kind.

[F.I.A.T]

reason being i personally installed Marvie's kit. if you take it to someone who is experienced with installing turbo kits or you do it yourself and take the time to do it right the first time youll have a worry free environment.

[sheek360]

Originally Posted by F.I.A.T

reason being i personally installed Marvie's kit. if you take it to someone who is experienced with installing turbo kits or you do it yourself and take the time to do it right the first time youll have a worry free environment.

+1, AJ performance FTW! If I ever get an SI your kit will be on my shopping list! And I can definately make the 20 minute drive to have you guys install it. Ive heard nothing but outstanding things from your shop

[subzero05]

i know of no centri's on the horizon for this car...

[Cookstar]

Originally Posted by subzero05

i know of no centri's on the horizon for this car...

http://www.8thcivic.com/forums/showthread.php?t=18779
http://www.jacksonracing.com/home.htm

[Cookstar]

I did a little research. Let me know if I'm correct.

Roots superchargers produce a significant amount of boost early in the rpm range. Roots superchargers "blow" air in rather than compressing air in like turbos and centrifugal superchargers do.

Turbochargers have lag in the lower rpms but build boost very quickly once the exhaust flow is great enough to spin the impeller. When the turbo starts spooling is when it begins attaining near maximum boost levels.

Centrifugal superchargers, which are basically the compressor side of a turbo driven by a belt, start with a little boost and build it in a linear fashion, attaining maximum boost in the high rpm range. It seems like the worst of the three options to me because full boost comes so late in the rpm range. Especially in our high-strung cars would the centrifugal supercharger be at a disadvantage to the other two.

I don't understand the physics behind it all though. For example, why does the Roots supercharger make boost early when the centrifugal charger makes boost doesn't make as much boost until later. Also, why do turbos have lag in the beginning and seemingly suddenly start spinning when the exhaust flow is great enough rather than having a more linear boost curve.

[sheek360]

Originally Posted by Cookstar

I did a little research. Let me know if I'm correct.

Roots superchargers produce a significant amount of boost early in the rpm range. Roots superchargers "blow" air in rather than compressing air in like turbos and centrifugal superchargers do.

Turbochargers have lag in the lower rpms but build boost very quickly once the exhaust flow is great enough to spin the impeller. When the turbo starts spooling is when it begins attaining near maximum boost levels.

Centrifugal superchargers, which are basically the compressor side of a turbo driven by a belt, start with a little boost and build it in a linear fashion, attaining maximum boost in the high rpm range. It seems like the worst of the three options to me because full boost comes so late in the rpm range. Especially in our high-strung cars would the centrifugal supercharger be at a disadvantage to the other two.

I don't understand the physics behind it all though. For example, why does the Roots supercharger make boost early when the centrifugal charger makes boost doesn't make as much boost until later. Also, why do turbos have lag in the beginning and seemingly suddenly start spinning when the exhaust flow is great enough rather than having a more linear boost curve.

roots and twinscrews compress differantly, twinscrews compress at the supercharger and roots compress in the intake manifold. ur right about the centis disadvantage on a 8krpm engine. roots and twinscrews boost asap because of the gearing. you cant gear a centi like a roots. number 1 its impossible and 2 theres patent issues. turbos have lag in the begining because, at low rpm, there arent enough exhaust gassses to get it moving, u produce more exhaust gasses at 8krpm vs 3krpm right? a turbos boost isnt as linear than a roots because a turbo isnt rpm dependant. you can only spin a turbo so fast, no matter how hard u try. a roots spin is limited by its pulley size and max rpm. The new eaton tvs blower, coming out in the summer of 07, can spin to 20-22krpm. that means my car, at 7krpm redline, can utelize a 2.2 pulley <total amount of boost is unknown because of the new gearing>. due to that blowers gearing Ill be at a little over 450whp and 4 hundred something wtq. the current roots im running now wont allow me smaller than a 2.5 pulley <about 22-23LB of boost>. IMO, if u need someone to tell u wichone to go for, i say u go aj performance!

[Cookstar]

Originally Posted by sheek360

roots and twinscrews compress differantly, twinscrews compress at the supercharger and roots compress in the intake manifold. ur right about the centis disadvantage on a 8krpm engine. roots and twinscrews boost asap because of the gearing. you cant gear a centi like a roots. number 1 its impossible and 2 theres patent issues. turbos have lag in the begining because, at low rpm, there arent enough exhaust gassses to get it moving, u produce more exhaust gasses at 8krpm vs 3krpm right? a turbos boost isnt as linear than a roots because a turbo isnt rpm dependant. you can only spin a turbo so fast, no matter how hard u try. a roots spin is limited by its pulley size and max rpm. The new eaton tvs blower, coming out in the summer of 07, can spin to 20-22krpm. that means my car, at 7krpm redline, can utelize a 2.2 pulley <total amount of boost is unknown because of the new gearing>. due to that blowers gearing Ill be at a little over 450whp and 4 hundred something wtq. the current roots im running now wont allow me smaller than a 2.5 pulley <about 22-23LB of boost>. IMO, if u need someone to tell u wichone to go for, i say u go aj performance!

Sheek360, your knowledge of boost is really a great addition to the site, regardless of what you drive.

The twin-screw design sounds great but, unfortunately, I doubt anyone would ever step up and design one for the Civic. I've read that they are more expensive to produce because they must be designed with much closer tolerances so they will properly compress air while a Roots supercharger just "blows" it into the intake (hence, the name "blower).

[sheek360]

Originally Posted by Cookstar

Sheek360, your knowledge of boost is really a great addition to the site, regardless of what you drive.

no problem dude, any time!

[Kakashi]

the advantage of the centrifugal type is increased volume of boost, not the rate of it..

whereas roots type have higher rate and pressure, but lower volume?


or am i mistaken?

[sheek360]

Originally Posted by Kakashi

the advantage of the centrifugal type is increased volume of boost, not the rate of it..

whereas roots type have higher rate and pressure, but lower volume?


or am i mistaken?

as far as volume vs volume it depends on the size of the roots and its pulley. Centis do have great volume but not till almost redline, its like sticking a large turbo on a 1 cylinder engine, u really have to wind it up. The prochargers C1 is 1000 cfm's at about 24psi. where a eaton m62 5th gen is close to 800 cfm's with a 2.5 pulley <im taking a guess on the eaton m62 cfm's with a total of 20-21LB of boost>. It takes no rocket scientist to figure out that 2 identical cars, except one has a m62 and the other has a procharger c1 and differant tuning on both, will be fast. The one with the C1 will make more power, thats for sure. But the one with the eaton will accelerate faster and have a more broader and useable TQ and HP. A LSJ only needs a 2.5 pulley, 60LB injectors, tuning and slicks and he'll run a 12.6-12.8 <i forgot>. People choose turbo over supercharging for the top end. People choose supercharging over turbo charging for the instant boost. A centi doesnt offer the instant boost that a twinscrew and roots provide. and a centi doesnt have the topend that a turbo has.

what good is an increased volume of boost if u dont see 100% of it till about 1 second before you shift into the next gear?

[Kakashi]

Originally Posted by sheek360

as far as volume vs volume it depends on the size of the roots and its pulley. Centis do have great volume but not till almost redline, its like sticking a large turbo on a 1 cylinder engine, u really have to wind it up. The prochargers C1 is 1000 cfm's at about 24psi. where a eaton m62 5th gen is close to 800 cfm's with a 2.5 pulley <im taking a guess on the eaton m62 cfm's with a total of 20-21LB of boost>. It takes no rocket scientist to figure out that 2 identical cars, except one has a m62 and the other has a procharger c1 and differant tuning on both, will be fast. The one with the C1 will make more power, thats for sure. But the one with the eaton will accelerate faster and have a more broader and useable TQ and HP. A LSJ only needs a 2.5 pulley, 60LB injectors, tuning and slicks and he'll run a 12.6-12.8 <i forgot>. People choose turbo over supercharging for the top end. People choose supercharging over turbo charging for the instant boost. A centi doesnt offer the instant boost that a twinscrew and roots provide. and a centi doesnt have the topend that a turbo has.

what good is an increased volume of boost if u dont see 100% of it till about 1 second before you shift into the next gear?

ah finally, techno babble i understand

if only vehicles could implement turbocharging configurations that the planes i see use..

but a man can always dream.

[sheek360]

Originally Posted by Kakashi

ah finally, techno babble i understand

if only vehicles could implement turbocharging configurations that the planes i see use..

but a man can always dream.

i once saw pics of a private jet with 2 turbo rotaries on it! Those turboes were huge!!!!!!!

[subzero05]

Originally Posted by Cookstar

http://www.8thcivic.com/forums/showthread.php?t=18779
http://www.jacksonracing.com/home.htm

I think it will be quite a while before we see anything like a centri for the car, if ever...Would be a great addition though