supercharger question

mogs01gt · Oct 14, 2004

kah9911 said:
Mogs- Would you please go a bit more into why you dont like KB? I am on the fence about boost but if I did get a SC I am leaning toward the KB and would like to know what your experience was. Thanks- Kevin

Heat they produce
Weight
all that torque at low rpms. I would rather have torque higher up in the RPM band because you can use a taller gear. The torque at a higher RPM will give you a more usuable RPM band.

Kenne Bell is pretty much a master salesmen

stangman · Oct 14, 2004

my orange-gt said:
well he does run drag radials, but i am for sure getting 4:10 gears the only thing, wont nitrous really hurt my car

you may want to consider that gear choice. you might run out of gear at the end of the track with that gear, unless you get a taller tire to run at the track. 3.73 gears are much more suited for your wants IMO

showstopper2 · Oct 14, 2004

mogs01gt,

are you allowed to make such comments on this site about the KB and not be banned?? blasphemy I tell ya!!!

I am also a Centri supporter for basically the same reasons. the KB just seems to be hard on internals making all its power early. they make impressive numbers but I have not yet seen anyone run True Street with a KB GT and have often wondered why?? maybe heatsoak is an issue they don't care to talk about?? or is it there are downsides to the almighty KB as well as the upsides and they can't admit it??

as a Centri sidenote my car has made over 400rwhp and 400tq hot and cold on the dyno. I have made a true street style back to back to back dyno pull and it never dipped below that mark on either side. my car is very repeatable hot or cold which is really nice to know come track day.

just to be clear Centri's have their own upsides and downsides as well. they just seem to work better for what I want to do now and in the future.

340.29m/s · Oct 14, 2004

mogs01gt said:
Heat they produce
Weight
all that torque at low rpms. I would rather have torque higher up in the RPM band because you can use a taller gear. The torque at a higher RPM will give you a more usuable RPM band.

Kenne Bell is pretty much a master salesmen

Huh? I'm sorry, but this entire post (besides the heat/weight) sounds like a load of BS.

Just because they produce torque down low doesnt mean that there isn't still good torque up high.

"A more usable RPM band"? Usable RPM band, by definition, means that you have torque down low, up top, and everywhere in between - something you don't get with the centrifugals.

I will give it to you that you can create greater peak HP with the centrifugals, but your reasoning as to why KB's are bad is just plain aweful.

Cons of KB:
Heat
Cost
Not as widely used, therefore less skilled tuners
Possibly greater strain on internals
Placement of S/C (especially for those of us with shakers)
Limited growth
etc.

mrpositraction · Oct 14, 2004

I never understood why you people say you don't want torque down low. You put gears in your car so you feel more torque, don't you? And not to knock centrifugals, but on the street you are not always in the 4500-6000 range to make your boost. Nice thing about KB is that you can drive it normally and enjoy the extra power. Inertia is what kills engines, ringing it neck to get boost and power is what destroys engines. Do the math!!! We have another fellow engineer in here and if he knows anything about rotational dyamics he will agree. Inertia is multiplied dramatically with rpms, that is just how it works, you are much better off with the power down low than up high (for engine sake) The torque stays consistent throughout the power band, you have it low and high. Don't be mad cause you have centri and not a twin screw

mogs01gt · Oct 14, 2004

here is a good read that explains it very well.

http://www.modulardepot.com/?show=articlesdet&aid=44

Gearbanger 101 · Oct 14, 2004

I'm a big fan of the AED kits. http://www.allenengine.com They're based on the Eaton M-90 kit (which you either do, or don't like) but are among the best engineered kits i've ever come across. They may not make the overall power of the KB, but they are a nicer kit as far as I'm concerned. Not to mention their customer service is top notch....which is more than I've heard for KB at times.

On the Centrifugal note.....Yeah, most Centi's make more power up top, but why is it that most i've seen that are making 380+hp are still struggling to break 12's? A lot of them just seem to be dyno quees. I honestly don't think their able to put it to the pavement as well as a postitive displacement blower. Besides, not every one buys a blower to run at the track. Most just want a fast, reliable, fun, street car. And that kind of low end torque can only be had from a positive displacement blower, like a Twin Screw or an Eaton.

mrpositraction · Oct 14, 2004

mogs01gt said:
here is a good read that explains it very well.

http://www.modulardepot.com/?show=articlesdet&aid=44

That is a nice explanation but our cars all rev the same (assuming your engine isn't built) and the torque of a twin screw peaks early and holds there to the bitter end.

340.29m/s · Oct 14, 2004

LOL, I was about to type the same thing before I saw your post.

I had already type "That is an awesome explanation, too bad it doesn't apply to this specific case....."

prsrizdgt · Oct 14, 2004

Boy.....sure am glad I'm not in the middle of this one.

mogs01gt · Oct 14, 2004

why doesnt it? Why do you guys think our cars need all this torque?? We do not have heavy cars. We have lighter cars that like to rev high. So this gives us the advantage of running higher gears which produces torque at the wheels and still allows to rev higher in our RPM band.

Just because forced induction may change our cars power out put, it does not change how our cars make the power.

SOHC like to rev, use gears to make up the torque difference.

Gearbanger 101 · Oct 14, 2004

prsrizdgt said:
Boy.....sure am glad I'm not in the middle of this one.

Get your a$$ in here and help me stick up for the AED kit!

340.29m/s · Oct 14, 2004

mogs01gt said:
why doesnt it? Why do you guys think our cars need all this torque?? We do not have heavy cars. We have lighter cars that like to rev high. So this gives us the advantage of running higher gears which produces torque at the wheels and still allows to rev higher in our RPM band.

Just because forced induction may change our cars power out put, it does not change how our cars make the power.

SOHC like to rev, use gears to make up the torque difference.

"Why Doesn't it?"

Because the engine still revs to the same redline no matter which SC'r you have on it. You can have the same exact gearing on both SC'rs... it doesn't matter.

The only issue with having the 4.10's or 4.30's with the KB is that you will need some sticky tires.

We don't think that our engines NEED all that torque down low, we WANT our engines to have all that torque down low.

I'm sorry, but your case just keeps getting worse and worse.

WhiteDevil69 · Oct 14, 2004

I agree, your letting that article confuse you. It is comparing a 100lbs of torque motor that gets the max at 3000 rpms compared to one that makes max at 6000 rpms, a KB will make max at a lower rpm then a centri, but keeps it constant til long past our rev limiter, so this is irrelevant and not applicable to this argument.

prsrizdgt · Oct 14, 2004

Gearbanger 101 said:
Get your a$$ in here and help me stick up for the AED kit!

Gearbanger, this is a no win arguement. We all make our choices for differant reasons. I am sure I would love a KB. Hey, if it don't run like a big block, then why are you wasn't my time. Its a proven fact that if oem quality is a concern then AED's package is going to be a consideration. When making my selection I listened to people who had installed both types several times, driven both types many times, and had dealt with the pitfalls of each. AED didn't have any pitfalls for a primarily street driven car unless you MUST make 400rwhp.

mogs01gt · Oct 14, 2004

Well that is fine, you can go ahead and be wrong but low end torque is not needed for acceleration. I have posted facts of another person and myself.
If you think a car that makes 400rwtq at 2k will out run a car that makes 400rwtq at 4.5k, then you will be sad watching people blow bye you.

It is relevant to the subject because we are comparing power outputs of Blowers. Centrifugal produce their torque in the upper PRMS, which is better. a Roots or KB produce low end torque, which feels "better" on the street. In true performance, you want torque higher in your RPM band.

WhiteDevil69 · Oct 14, 2004

mogs01gt said:
Well that is fine, you can go ahead and be wrong but low end torque is not needed for acceleration. I have posted facts of another person and myself.
If you think a car that makes 400rwtq at 2k will out run a car that makes 400rwtq at 4.5k, then you will be sad watching people blow bye you.

It is relevant to the subject because we are comparing power outputs of Blowers. Centrifugal produce their torque in the upper PRMS, which is better. a Roots or KB produce low end torque, which feels "better" on the street. In true performance, you want torque higher in your RPM band.

All I was saying is the article you refered to is a lousy example at best in defense of your argument. I agree that a centri will beat a KB on a track, but that is usally dependent on the other mods and setup of the car. In idle conditions it would be a tight race. ie. both are completely pimped out and full out drag cars, then you can compare them.

340.29m/s · Oct 14, 2004

mogs01gt said:
Well that is fine, you can go ahead and be wrong but low end torque is not needed for acceleration. I have posted facts of another person and myself.
If you think a car that makes 400rwtq at 2k will out run a car that makes 400rwtq at 4.5k, then you will be sad watching people blow bye you.

It is relevant to the subject because we are comparing power outputs of Blowers. Centrifugal produce their torque in the upper PRMS, which is better. a Roots or KB produce low end torque, which feels "better" on the street. In true performance, you want torque higher in your RPM band.

But what you are not understanding is that the KB makes power down low AND UP TOP. Just because the KB has torque in the lower RPM's does not mean that it doesn't also make TQ up high.

a KB that makes 400 lb/ft from 2500-6000
is not worse than a centrifugal that makes 400 lb/ft at redline (and less all the way down)

note: I don't have a SC and am not stating that I would only buy a KB when it came time to get a SC. I just can't sit around and read posts full of BS.

prsrizdgt · Oct 14, 2004

mogs01gt said:
Well that is fine, you can go ahead and be wrong but low end torque is not needed for acceleration. I have posted facts of another person and myself.
If you think a car that makes 400rwtq at 2k will out run a car that makes 400rwtq at 4.5k, then you will be sad watching people blow bye you.

It is relevant to the subject because we are comparing power outputs of Blowers. Centrifugal produce their torque in the upper PRMS, which is better. a Roots or KB produce low end torque, which feels "better" on the street. In true performance, you want torque higher in your RPM band.

Mogs, I would like to get your answer on this question: If 2 cars have peak numbers that are the same, one a KB and one a Centri, which one would win a 1/4 mile race? Lets say they are both standard entry level blower kits making no more than 400 rwhp. Same suspension set-up, same tires, same tranny's, equally talented drivers.

Personally I do not think the top end charge of the centri would be enough to bring it back from the lead the KB would have.

WhiteDevil69 · Oct 14, 2004

prsrizdgt said:
Mogs, I would like to get your answer on this question: If 2 cars have peak numbers that are the same, one a KB and one a Centri, which one would win a 1/4 mile race? Lets say they are both standard entry level blower kits making no more than 400 rwhp. Same suspension set-up, same tires, same tranny's, equally talented drivers.

Personally I do not think the top end charge of the centri would be enough to bring it back from the lead the KB would have.

Exactly, the only way a centri in this situation is gonna win is if the KB is spinning the tires for 3 seconds because of the added low end torque

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