No you look like someone who always has to try reply to posts even when it's not something you are familiar with or even understand. Otherwise you wouldn't be posting stuff that has little to do with the topic being discussed.
A centrifugal (belt driven turbo) supercharger has little in common with a positive displacement blower/supercharger other than it's belt driven. It's apples to bowling ***** comparison.

 

I always liked going down to the track and watching all those turbo dragsters run the 1/4 at sub 4 seconds over 330mph. They always have this big thing on top of the block that must be a turbo... you know because they are so badass it must be a turbo... obviously.

 

Ive always understood that Roots & twin screw are the same thing.
Is one of these centrifugal?

 

Roots blowers are equivalent to using a stone wheel as a tire. They are only used in racing fuel applications, like with nitro-whatever. I am not sure how roots blowers are relevant to our discussion in any way shape or form, at it's highest level their use is a decision based on simplicity and safety, not efficiency or practical daily application. I found pertinent applicable info: a supercharger somebody would actually try to use on the street in a daily application with pump fuels at high mileage.

Common knowledge is that roots blowers are inefficient compared with centrifugal blowers. When adiabatic efficiency is paramount (every street application) centrifugal always wins. And turbo on top of that.

Not quite, each blower is different, and each series of a particular blower has an improved efficiency based on tech and design. Like a roots blower in 60's wouldn't have the sealing power of a roots blower in 2018 because now we have access to multitude of materials science to choose from and better instruments for taking measurements, and computers to form models of materials as they deform under pressure which causes stress over an area.

The screw type is still found widely used in OEM applications so it must be at least comparable to a centrifugal in terms of reliability and efficiency (but still not quite as good) would be my guess. But roots are just the worst and typically restricted to novelty or godly fuel, you rarely see them in OEM application. Difficult to cool the air in that short distance too I think is a major issue. Even with just a straight pipe from one side to the next you would have some difference in Temp, and some reservoir of cool air.

 

The graph shows a roots and twin screw, They are similar but not the same in how the move air. Rather than type it all out I'll post a link.

In short a roots doesn't compress air in it's rotors and a twin screw does. It'sa way of accomplishing the same thing that's more efficient and less heating of the air.

http://www.superchargersonline.com/i...page=page&id=7

 

The graph contains no information about how many CFM of air is being pumped by each unit. The blower unit could be a 144 or a 6-71. 12psi from a toyota 2.0L blower is not going to use as much HP as 12psi from a chevy 6.0L blower.

I think its funny you are using the stone wheel on top of posting useless charts. It costs $250+gas to buy a harbor freight mig welder and you can get stainless pipe from the junkyard for what, $65 and mount a turbo these days, but it takes at least a tiny spark of creativity and ambition.

 

(1) Not quite, The engine (408ci) I pictured above with the roots blower made 923hp but torque was at over 600ftlbs at 2,500 and 750ftlbs at 3,500 and carried it to 7,000rpms.
(2) They work great on plain old gasoline but really shine with E85 and can actually ice up rather than heat up.
(3)The are relevant because a Twin screw is what we were talking about and they have always been considered a type of roots blower (just improved)
(4) They go for over a 200,000 miles without needing maintenance so if someone wanted to use one they will certainly work just fine.
(5) Never disputed.... In fact I posted a graph.
(6) Again not disputed but I can bet if we raced and I used my stone wheel roots blower you better have your **** running very well because I will stomp your *** otherwise.
(7)Again showing you're talking about **** you know nothing about, Look up blower icing and tell me they have heat issues when used with E85 dipshit.
IATs are very very low..... Lower than a turbo is able to accomplish short of running an water to air system packed with ice.
(8) Straight pipe? WTF are you talking about?

Again you show why you should refrain from posting when you obviously know nothing about the topic at hand and certainly have no first hand experience... PS google searches aren't always accurate lol

 

Again....what are we talking about???? Oh yeah it was a LSA supercharger (BLUE)
And a 6-71 (RED) as posted in the picture above!
Who cars what it costs to do a turbo build lol
Creativity??? I can go to any car show and see dozens of turbos ls combo's and have yet to see anyone else with an S10 with LSA supercharger or a roots blown LS engine if a 50's Chevy truck. I could care less what everyone else is doing, I do what I want to because I can. If you don't like it do you really think I give a ****!

 

I keep coming back to this thread for some reason. I've got to say I am definitely on Losingit's side on this one. Yeah turbos are cool and all... But I also prefer a huge *** blower sticking out of the hood over the turbo look.

And fwiw, my sarcasm about the "turbo dragsters" is just that, sarcasm. Because really, a large twin screw blower on alcohol is going to lay waste to even the larger turbos out there. There is simply no comparison there in my opinion. Probably why there are very few turbo pro-stocks, or at least in my experience with walking the pits and watching those land missiles bust 7 seconds. There are not many street cars running around with huge blowers sticking out the hood. Typically they are "tuned down" when you see one at a car show or something. However, at that same carshow, you'll see about 10x as many turbo cars. At least.

The funny part is, all it takes for one of those "tuned down" supercharged monsters to destroy everything on the street is a change of fuel, a tune, and a pulley. Then you have 2000+ hp. I think they are more unique, therefore more creative. Unless you go to an NHRA event, then the turbo car becomes the hard thing to find in the pits.