centrifugal supercharger vs. turbocharger

[sheek360]

Originally Posted by subzero05

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

i agree, any form of extra power is always a step forward

[El_mahone]

I look at the dyno curves for the centrifugal SC for the s2000 and the roots SC for the RSX/civic si on the comptech site. the centi is amazingly similair to the roots. minimally inferior at low end (3000rpm) and it sign superior above 6000 rpm, in terms of percent improvement from baseline. The centi do have a bit of an exponential increase in boost versus the roots with is very liniar. One could argue that when your racing/enjoying yourself, you lauch at 4000rpm and spend the rest of the time doing the 6000-8000 upshift thing, I think the centi would have the advantage, while mantaining daily drivablity in high boost systems ( because the boost is small in the 2000-4000 where you do your commuting ).

[sheek360]

Originally Posted by El_mahone

I look at the dyno curves for the centrifugal SC for the s2000 and the roots SC for the RSX/civic si on the comptech site. the centi is amazingly similair to the roots. minimally inferior at low end (3000rpm) and it sign superior above 6000 rpm, in terms of percent improvement from baseline. The centi do have a bit of an exponential increase in boost versus the roots with is very liniar. One could argue that when your racing/enjoying yourself, you lauch at 4000rpm and spend the rest of the time doing the 6000-8000 upshift thing, I think the centi would have the advantage, while mantaining daily drivablity in high boost systems ( because the boost is small in the 2000-4000 where you do your commuting ).

thats not a very good comparison man. both of those engines are differant. with a 8krpm the centi will be a bit slow to boost. and keeping a centi in boost between gears is impossible because they are rpm dependant/gear driven.

[Corpsman]

^^ But what he said makes sense.... If I am racing, I am going to be 5.5 - 8k, well within the centi's power range having kept the RPMs up. But if I am daily driving and not wanting to waste a ton of fuel, the lower RPMs help for this.

[El_mahone]

sheek360, I disagree,
1) between gear when Rpms drop a centi or roots will suffer equally, and when rpms drop so does exhaust hence your turbo will also loss boost.

2) the two engines are very comparable, although base line HP and displacement is greater in the S2000 engine, they are very similair, secondly what I want you to look at is the dyno sheets on the comptech web site and ignore the absolute HP and look at percent enhancement as a function of RPMs.

3) it sounds like jactson or some other company will have a rotech centi system out within a month or two and I'm sure they will have dyno sheets as well to compare directly to comptech,AJ, Greddy systems.

4) I could be wrong but I would bet the turbo offers by far, the best preservation of your civic's good HWY fuel ecconomy, with the centi system second and a high boost roots system last.

El_Mahone

[sheek360]

Originally Posted by Corpsman

^^ But what he said makes sense.... If I am racing, I am going to be 5.5 - 8k, well within the centi's power range having kept the RPMs up. But if I am daily driving and not wanting to waste a ton of fuel, the lower RPMs help for this.

IMO a centi and turbo would be best for fuel economy, atleast compared to a roots or twinscrew. i find it hard to stay away from boost no matter how hard i tried, i once sneezed and floored it a bit and i was almost at 5 PSI for that quick second. You still wont be at its full efficiency<man my spelling sucks today!> till right before redline.

EDIT!!!!!!!! we dont have the same engine, i forgot to mention that LOL. Maybe the roots will be better on fuel for the K vs my LSJ. Im sure Complex can add to this, i believe his SI is running the roots kit.

[sheek360]

Originally Posted by El_mahone

sheek360, I disagree,
1) between gear when Rpms drop a centi or roots will suffer equally, and when rpms drop so does exhaust hence your turbo will also loss boost.

2) the two engines are very comparable, although base line HP and displacement is greater in the S2000 engine, they are very similair, secondly what I want you to look at is the dyno sheets on the comptech web site and ignore the absolute HP and look at percent enhancement as a function of RPMs.

3) it sounds like jactson or some other company will have a rotech centi system out within a month or two and I'm sure they will have dyno sheets as well to compare directly to comptech,AJ, Greddy systems.

4) I could be wrong but I would bet the turbo offers by far, the best preservation of your civic's good HWY fuel ecconomy, with the centi system second and a high boost roots system last.

El_Mahone

1> yes, inbetween shifts they suffer, turbo aside for now. You gotta remember the centri's gearing wont allow for spool faster than a roots/twinscrew. They dont suffer equally. Hence the acceleration benefit of the roots/twinscrew/turbo vs a centri. Most turbos recirculate someboost to keep it going, then theres some that have a twinscroll style, and a couple that discharge it all. But power shifting will keep a turbo going.

2>Im sorry, those 2 engines arent comparable. Id rather see a SI with centri data versus a SI with some other form of forced induction. Atleast for accuracies sake, FYI that 4 banger in the S2000 is KING of the 4 cylinders! It dyno's higher than any other n/a 4 cylinder in the world! IMO the best 4 banger n/a ever made, a true sports car too!

3>yes, i cant wait to see the dyno sheets! it seems like they will have staged upgrades, i think its outstanding that they are taking such an initiative!

4> hmmmm, my moneys on the centi being better on gas. Im not saying that turbo and roots are gas hogs. just, for some odd reason, i think the centi will be better on gas. Its hard to say, we need 3 si's with 3 differant power adders<FI> that each equate<SP?> to 1000CFM's. Lets make em all white too!

outstanding discussion guys, its getting good now! Excuse the spelling, its too late 4 me LMAO!

[Reliant K20Z3]

taken from--

http://forums.clubrsx.com/showthread...=430925&page=4


"Just thought I would give you guys some ideas. I have shipped out both low boost and high boost Rotrex systems to Oscar from my company, TTS. To cut down his design time over your way. We have set up an agreement between us to mutually benefit customers world wide. The problem with the RSX you all know, thats the power steering pump. If you junk the aircon pump you can have Rotrex kits right away. I hope Oscar will be looking into getting round the steering pump problem, I don't have enough enquiries over here. Below is a dyno shoot out last Saturday, independantly testing customers cars. Note that the high boost Rotrex conversion was the most powerful (14lb boost, 93 oct but with meth/water injection) 440 bhp. the next was a stealth (Rotrex in place of aircon pump) low boost kit with no intercooler giving 8.8lb boost, made 330 bhp. Note the Jackson conversion was an almost identical 9lb boost set up, yet gave 48 bhp and 30lb torque less than the Rotrex. I hope Oscar makes a kit for you guys. If you don't want aircon you can have one almost immediately. Have fun "

-------------------------------------------------
I don't know anything technical about boost whatsoever, but...that mateo guy who is popular in the supercharger threads, says this about the jackson racing rotrex kit that will be coming out in the same thread...

"Just got off the phone w/Oscar J. This new kit is going to be no joke.
I'm getting a ear full of ideas..."
----------------------------------------------------
440 brake hp, on 8.8 intercooled lbs of boost ain't bad is it?
Oscar Jackson has this to say on his website, I'm sure you've read it:


"My new Supercharger systems are based off of a brand new, patented, Rotrex supercharger. This new supercharger combines the throttle response of the Roots supercharger with the compressor efficiency of a turbo, but without the lag."
-----------------------------------------------------

Oh, and on wikipedia, brake hp is defined as--

Brake horsepower (bhp) is the measure of an engine's horsepower without the loss in power caused by the gearbox, generator, differential, water pump and other auxiliaries. Thus the prefix "brake" refers to where the power is measured: at the engine's output shaft, as on an engine dynamometer. The actual horsepower delivered to the driving wheels is less. An engine would have to be retested to obtain a rating in another system. The term "brake" refers to the use of a band brake to measure torque during the test (which is multiplied by the engine speed in revs/sec and the circumference of the band to give the power).



Discuss

[sheek360]

Originally Posted by Reliant K20Z3

taken from--

http://forums.clubrsx.com/showthread...=430925&page=4


"Just thought I would give you guys some ideas. I have shipped out both low boost and high boost Rotrex systems to Oscar from my company, TTS. To cut down his design time over your way. We have set up an agreement between us to mutually benefit customers world wide. The problem with the RSX you all know, thats the power steering pump. If you junk the aircon pump you can have Rotrex kits right away. I hope Oscar will be looking into getting round the steering pump problem, I don't have enough enquiries over here. Below is a dyno shoot out last Saturday, independantly testing customers cars. Note that the high boost Rotrex conversion was the most powerful (14lb boost, 93 oct but with meth/water injection) 440 bhp. the next was a stealth (Rotrex in place of aircon pump) low boost kit with no intercooler giving 8.8lb boost, made 330 bhp. Note the Jackson conversion was an almost identical 9lb boost set up, yet gave 48 bhp and 30lb torque less than the Rotrex. I hope Oscar makes a kit for you guys. If you don't want aircon you can have one almost immediately. Have fun "

-------------------------------------------------
I don't know anything technical about boost whatsoever, but...that mateo guy who is popular in the supercharger threads, says this about the jackson racing rotrex kit that will be coming out in the same thread...

"Just got off the phone w/Oscar J. This new kit is going to be no joke.
I'm getting a ear full of ideas..."
----------------------------------------------------
440 brake hp, on 8.8 intercooled lbs of boost ain't bad is it?
Oscar Jackson has this to say on his website, I'm sure you've read it:


"My new Supercharger systems are based off of a brand new, patented, Rotrex supercharger. This new supercharger combines the throttle response of the Roots supercharger with the compressor efficiency of a turbo, but without the lag."
-----------------------------------------------------

Oh, and on wikipedia, brake hp is defined as--

Brake horsepower (bhp) is the measure of an engine's horsepower without the loss in power caused by the gearbox, generator, differential, water pump and other auxiliaries. Thus the prefix "brake" refers to where the power is measured: at the engine's output shaft, as on an engine dynamometer. The actual horsepower delivered to the driving wheels is less. An engine would have to be retested to obtain a rating in another system. The term "brake" refers to the use of a band brake to measure torque during the test (which is multiplied by the engine speed in revs/sec and the circumference of the band to give the power).



Discuss

so brake hp = BHP minus whatever % is lost transfering power to the ground? thats old school, I would really like to see charts, im sure everyone does. And I wonder how that bad boy would do on the 1/4. Its great that they could make all that power. But im wondering at what RPM did he make max boost. I hate the fact that they are running meth injecting as an intercooler though. I understand that the empellers are coated with a type of teflon or something, the alky/meth injection can really mess that coating up. Ive seen it myself in both roots/turbo's and centri's. Im also 100% sure that centi produces more CFM's than that jackson SC mentioned. Im not calling the author u quoted a liar, but if a centi civic races against a civic with a roots, the civic with the roots will jump ahead, till the centi catches up and walks/beats it. And thats the differance in gearing! I see it all the time, a SC cobra vs a single turbo supra. The supra will have to play catch up, then it explodes forward with power!

[sheek360]

something interesting, i was talking to Steig and PSE about the new TVS roots coming out next year. And i asked em about centri's and they both told me the same thing, but in differant words.

PSE no longer rebuilds or installs centrifugal superchargers due to the continuous poor reliability and high failure rate and only recommends the use of "ROOTS" or "TWIN SCREW" type superchargers.

And the Stieg guys said theyll mess with it, only cuz it makes em money. But they claim that the centri is the red headed step child of the supercharger world. Its unreliability is scary.

discuss?

[Kakashi]

i could see why they would say such a thing,

on a centri, the compressor fins are directly connected to the shaft which connects to the pulley which is belted to the motor. When engine RPM's increase the compressor wheel speeds up. but what about when engine RPM's fluctuate or drop drastically?

if one were to let off the gas suddenly, RPMS's drop like a rock, the PSI of charge air to the motor will also drop as well. THat transfers to the centri because the sudden change probably cause a kind of surge or feedback to the supercharger/motor shafts.

The motor is barely working at all, but the centri is providing "burst" PSI when not needed.

the more i think, the more im starting to like turbos again.

[sheek360]

Originally Posted by Kakashi

i could see why they would say such a thing,

on a centri, the compressor fins are directly connected to the shaft which connects to the pulley which is belted to the motor. When engine RPM's increase the compressor wheel speeds up. but what about when engine RPM's fluctuate or drop drastically?

if one were to let off the gas suddenly, RPMS's drop like a rock, the PSI of charge air to the motor will also drop as well. THat transfers to the centri because the sudden change probably cause a kind of surge or feedback to the supercharger/motor shafts.

The motor is barely working at all, but the centri is providing "burst" PSI when not needed.

the more i think, the more im starting to like turbos again.

well, the pistons will be sucking air in but i see where ur coming from. ill stick to my roots. For Steig and PSE to say such things really lit me up on what a centri really is. Ill stick to my trusty roots LOL

[Kakashi]

*bump for a good read*

[Sherpa]

Centri SC's = same headaches as TC's but with a lot less WHP.

[sheek360]

as soon as i get a chance, im gonna have my brother record my boost gauge while im at WOT so everyone can see a roots gearing. He'll also record my rpm tach. we have different engines but it should help in the roots/twinscrew/centri comparison.

[Kakashi]

Originally Posted by sheek360

as soon as i get a chance, im gonna have my brother record my boost gauge while im at WOT so everyone can see a roots gearing. He'll also record my rpm tach. we have different engines but it should help in the roots/twinscrew/centri comparison.

awesome. keep us posted

[sheek360]

and theres the video!

http://www.8thcivic.com/forums/showt...540#post357540

[Highrev1]

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