I have been waiting a long time to get the Kenne Bell TS for my 05 C6. The more I read about the traction issues that will magically appear the more I have been considering a Centrifugal like A&A instead. Does it make more sense if you plan on staying with stock tires and wheel sizes to go Centrifugal. I know the TS will deliver far superior torque low but what good is it if you just spin? Seems that since the car will still spin the tires just fine 1st and 2nd with stock HP would it be better to bring on the increased torque you get from the Centrifugal gradually vrs 500ftlb @2000 with a TS. Just wanted to throw this out there for discussion.

John

 

Doesn't matter which you choose....traction limiting tires will always be a problem.

 

 

The problem is when you are cruising around at, say, 60MPH, and you want to pass someone. I will use my A&A Si-Trim via Z-51 gears as an example. This car made 597RWHP/518RWTQ:
In 6th gear at 1500RPM, I have circa 300ft-lbs torque at the wheels, via 0.57 reduction
In 5th at 1750RPM circa 330ft-lbs via .71 reduction
In 4rth at 2500RPM 375ft-lbs via 1:1 drive ratio.
In 3rd at 3750RPM 460 via 1.43:1
In 2nd at 5250RPM 518 via 2.07:1

So torque delivered to the ground at 60MPH becomes:

6th: 171ft-lbs => It will accelerate like, say, a Honda Civic in 2nd.
5th: 234ft-lbs => It will accelerate like a decent family sedan would in 3rd.
4rth: 375ft-lbs => It will accelerate like a stock C6 would in 3rd.
3rd: 658ft-lbs => It will take off hard.
2nd: 1072ft-lbs => It will most likely blow the tires off and go sideways. When it hooks up, the radar detector usually pops off the windshield. At that point, the car will not stay in gear for more than 1 second before it hits the rev limiter.

The point here being that with most of your torque arriving at the upper half of the power band, you will be forced to downshift more gears more often in order to harnes that spectacular FI acceleration you seek.

Now we run the same math for an LS2 equipped with a Magnuson MP122. This car made 561RWHP / 490RWTQ. A mild Twin Screw car would post similar numbers with less of a drop off in torque at the top.
Below are approximate torque numbers delivered at the wheels, with the difference in parenthesis:

6th: 200 ft-lbs. (+30)
5th: 284 ft-lbs (+50)
4rth: 445 ft-lbs (+70)
3rd: 672 ft-lbs (+ 14)
2nd: 993 ft-lbs (-79)

The positive displacement blower makes the Roots car act like it has a much bigger engine. With the additional low end torque it pulls harder and cleaner in higher gears, and does not need to shift as often.
However, it falls off up top. In a race where shifts are occuring at 6500RPM, the Magnuson car would lose every time. On the street, where most people aren't redlining their engines on every shift, it may be more pleasant to drive. This may explain why Callaway and Lingenfelter only offer roots as their supercharger of choice, and why Mercedes Benz, BMW, Ford, Pontiac, Mazda, Toyota and others all chose roots or twin screw blowers as their OEM offering for supercharged cars. The Centrifugal is more efficient, and it will make more power with less parasitic drag and less heat than a roots, but on a street vehicle that is sometimes not the main consideration. *I* would still chose a centrifugal over a roots any day, but what I want from my car may not be what you, GM, or maybe even the majority of Corvette buyers is looking for.
Now when you look at the Twin Screw, the decision becomes tougher... They are about as efficient as a centrifugal and still make the low end of a roots. It all depends on what you want... For me the aftermarket hood and extra cost of the twin screws has always been a bit of a deal breaker, but they are a better supercharger design; you get about the same efficincy as a good centrifugal, but with a lot more area under the curve since boost comes on right away and stays there.

Of course, as you pointed out, in the first gears all that low end torque really starts to work against you as it becomes nearly impossible to get traction on regular street tires. The point I am making is that we have 6 gears... Somewhere on that shifter all cars get traction, and when that happens, you can ALWAYS use more torque and more horsepower

 

I'm with powerlabs.

get a ride in one of each and choose the one you think works best for what you want is all I can say.
Last car I went centri, wish I had gone roots.

 

PowerLabs. Fantastic post and thank you for taking the time to write it. I really like your "real world" examples. It helps put things into perspective!

 

I usually stay out of these threads, but I do have to take issue with one statement PowerLabs said. While a centrifugal car will definitely pull harder up top, it does not beat a Magnuson car "every time". I have run against centri cars in the standing mile (and other venues) where we run to redline in 4-5 gears. I have beaten most or been within 2-3mph (1-2 lengths) of any centri car that is comparable in power....standard or automatic. I've heard that same statement before, and I think it is a little too "generalized". Other then that, good explanation PowerLabs.

To the OP, you definitley need to drive any combination you can. No one can make the choice for YOU. Good Luck

 

There's nothing like an articulate engineer who ACTUALLY OWNS a SC Corvette to explain and put things in perspective.

 

I'm sorry: that comment was referring to the two systems I used as an example on my post. Without doubt an M122 could be set up to make more than what that one does. It still won't match the numbers posted by the bigger blowers though, if peak power is your thing...

 

My understanding is that the Maggie is a roots blower, not a twin screw like the KB. There is a huge difference in the efficiency. The problem with both is the packaging / heat soak.

 

I agree with Bushongs 1000%!!!!
My Maggie blown Vette with cam,headers,smaller pully,meth,etc will kick *** on most other blown Vettes off the line!!

 

Please don't turn this otherwise very interesting thread into a pissing match. And btw you are making what any smallish entry level centri makes on a stock engine and straight pump gas. If you really feel the need to compare your car to others why not check what a centrifugal makes with cam, headers, smaller pulley and meth? I'd say a solid 100+ hp and torque than you, and for less money

 

If you are going to keep your stock tires.... stay away from the KB or a Maggie....especially if you have an automatic. My car doesn't make great peak power, but I don't get any traction under 60 mph with runflats.

If you can run some R compound tires or run DR's, that is the only real way to enjoy the low end power.

These centrifugal vs. everything else threads get old..... I've owned both and you really can't lose with whichever you decide. From my last trip to the drag strip though, I didn't lose.... centrifugal C5 Z06, 402 stroker C5, 500 rwhp C6 Z06.

To give you the best advice, you need to let us know how you plan on using your car. Drag strip, street, etc...

 

A roots will not match the peak power a centri is capable of. I just wish some people (not you PowerLabs)would learn that the system that makes the most peak power is not the best for everyone. I've owned a centri car and have driven many others. I would not buy another centrifugal....I just don't like the power delivery compared to a roots or twin screw....but I know many people that love theirs.
75% of the modified vette owners I know don't even race their cars......they built them just for fun. I think the best advice we can give someone with the "which is better" question is to do the research and drive what is available.

Just my .02

 

Hey Sam,,I'm not trying to turn this ugly!!
I know Vortech,Paxton,and other blowers make a good amount of power,,but from My experiance with My Maggie Vette,and what My other Vette Bros with Maggie's have aggred on is that our Maggies have killer tq off the line{more at lower rpm's},and yes,the other blowers will have plenty,if not more hp as well than a Maggie can make!
I see You have a Vortech blower and Your making 15 or so more rwhp than Me on the dyno,,but Mine's an "auto" with a high stall converter AND lower gears so I think My #'s are pretty good for a Maggie!!
Enjoy Your ride and I like the way You always put up a well written post!
George

 

Nothin but Great info comes out from this guy, Good Job! PowerLabs

 

Absolutely. That's what I was trying to illustrate by using real world data to show actual torque at the wheels per gear; in my example, despite making 36less HP and 28less ft-lbs torque at the wheels the Maggie would still accelerate harder and pull away from 60mph in every single gear but 2nd.
I could just as easily have created another exaple where both cars are launched from 4500RPM clutch drop and shifted at 6700RPMs, thus only riding in the 4750 - 6700RPM range... Now the relevant powerband for the centri car becomes 510ft-lbs to 480ft-lbs while the maggie makes 490ft-lbs to 430ft-lbs in the same range; the centrifugal car wins. Does that make it a better system? Sure, if you are building a car to drag race, or if you drive shifting at redline all the time... I think that's what most people think about when they claim centrifugal blowers are "better", but realistically, most people don't drive like that
I came into Corvettes from a couple of small engined, high strung, 8200RPM + redline turbo cars... My Impreza made 100ft-lbs of torque untill maybe 3200RPM or so.. There was NOTHING there until the turbo spooled. Then it took off and was super fast so long as I kept shifting it at redline... My C5 Z06 was a lot peakier than the LS2 also... I feel right at home with the centrifugal blower; the low end plenty good, and the top end is a huge rush... But I would love to try out a Maggie some time; I am sure they are spectacular setups and I know there is a very good reason Callaway and Lingenfelter use them...

And I also think that with the addition of the new TVS from Eaton and Kenne Bell's Twin Screw kits for the C6, positive displacement superchargers are going to become a lot more popular

Ultimately, we have to remember that if one system was clearly superior to all others in every possible scenario we wouldn't have so many options... The reason you can go out today and get a stroker, a turbo kit, a rear mounted turbo kit, a paxton, vortech, procharger, magnuson, kenne bell, etc etc for your car, is because each one of those systems excels in their own right... It is up to each driver to evaluate his budget and intended usage and find out which system is best for him

 

George,

Your numbers are fantastic for a Maggie... My comment was just because a lot of times when you try to make any kind of comparison between different systems, people take it as a challenge, and then the thread just degenerates into who has the "best" system, and no one really learns anything...
I really like doing these comparisons not to find out which one is best, but rather to see how different systems differ... Unfortunately any time I pitch any given system against another, it has a tendency to go really bad From experience: If I use my Vortech as a benchmark, someone will show up and say I am bragging. If I use anything by ECS, and then say it is anything short of god's own chariot, hoardes of ECS consumers and employees will show up and say that I'm bashing them and I don't know what I am talking about. If I compare a blower to a heads and cam car, the heads and cam fans will say I don't know what I'm talking about because H/C cars are faster with less power, and don't heat soak etc etc...
Oh, and if I quote a book, someone will show up and say that book examples don't work in the real world... If I use math, the response is usually the same.
If I use a different car as an example, someone will say that the example doesn't apply to Corvettes, like somehow the power and torque these cars make is wildly different from all other vehicles

But if I don't use real world examples for comparison then it just becomes hearsay and personal opinions... I'll say my car is "pretty fast" with a centrifugal, then someone will say that their car with a stroker and a nitrous shot "beats all the centrifugal cars at the strip", so that must be better, then someone else will say that their maggie car "beats strokers at the standing mile" and then we may all just line up against a wall and see who can pee the highest

I have found that the only sure way of not getting bashed on this forum is to give nothing but thumbs up or cheers at threads, not ask too many questions, specially to any vendors, not make comparisons, and never say anything negative about any mod or any system... Its a shame I don't work like that, because I've offended and upset enough people here with my posts that I hardly even start new threads any more.

 

Your a good Man PowerLabs!{and a good writter!}

 

My 08 Z06 is the very first car I have added mods. I wanted to make low, mid , and top range torque while keeping the car street civilized and w/o risking my engine (too much).

My (under hood) list:

D1SC Set @ 7 PSI
Mild Blower Cam (for low end torque)
Dual Valve Springs
Booster Pump + Extra Fuel Line
American Racing Headers w/Hi Flow Cats
Manifold
160# Thermostat
Borla Exhaust
Dewitts Radiator
A conservative tune
......and many more

I am not sure what you want to do with your car but my wheels spin thru 3rd gear and the car pulls VERY hard through 170 MPH (my top speed yet). I also added Nitto Invos and they provided much improvement related to ride quality and grip. I have never been in a roots/twin screw car but I am sure the result is similar - I am no expert ,as is Power Labs, but with FI your wheels will spin.

If I blow up my engine or my transmission fails - I can upgrade