eliyarbrough
Legend
The SC's that come on the '03 Cobras, I mean. I think that is what they're called, just not for sure! Thanks!!!
Is it called a roots style?
- Thread starter eliyarbrough
- Start date
AaRoN
King Post Whore
Yes.
OnyxCobra
Post Whore
the stock blower is an Eaton which is a roots blower. KB and Eatons are both "roots style" in that they sit on top of the engine, but Kenne Bells are NOT roots blowers, they are twin screw SCs that work more efficiently than the Eatons.
http://auto.howstuffworks.com/supercharger2.htm
check out that link. should answer your questions. :thumb:
check out that link. should answer your questions. :thumb:
Roots style is not a category of supercharger, it's just a way of referring to them. A Roots supercharger uses 2 meshing lobes in order to compress air and force it into the engine - whereas a twin screw supercharger uses 2 screw-like objects that spin and progressively mesh together, pushing the air towards the bottom and rear of the supercharger while compressing it. Twin screws are much more efficient, and make much more power than Roots superchargers.
The correct term for these types of superchargers is "Positive Displacement Superchargers." Both of these superchargers are positive displacement superchargers in that they both displace, or move, a certain volume of air with each full rotation. So when you hear the term "a 2.4L Kenne Bell" That means that the Kenne Bell supercharger in question moves (or displaces) 2.4L worth of air volume per rotation, and the same holds true for roots superchargers, however they are commonly referred to using a system of sizing developed by GM when it first started including roots style superchargers on their cars a very long time ago. The term is 4:71, or 6:71, 8:71, 10:71, 12:71, and 14:71. This originally referred to the amount of cylinders and cu. in. size of the engine that the particular supercharger was designed to go on. So a 6:71 would be designed to go on a 6 cylinder engine that displaced 71 cu. in. This term is now just a common way of classifying supercharger sizing, and has nothing to do with what size engine the superchargers are meant for.
The correct term for these types of superchargers is "Positive Displacement Superchargers." Both of these superchargers are positive displacement superchargers in that they both displace, or move, a certain volume of air with each full rotation. So when you hear the term "a 2.4L Kenne Bell" That means that the Kenne Bell supercharger in question moves (or displaces) 2.4L worth of air volume per rotation, and the same holds true for roots superchargers, however they are commonly referred to using a system of sizing developed by GM when it first started including roots style superchargers on their cars a very long time ago. The term is 4:71, or 6:71, 8:71, 10:71, 12:71, and 14:71. This originally referred to the amount of cylinders and cu. in. size of the engine that the particular supercharger was designed to go on. So a 6:71 would be designed to go on a 6 cylinder engine that displaced 71 cu. in. This term is now just a common way of classifying supercharger sizing, and has nothing to do with what size engine the superchargers are meant for.
AaRoN
King Post Whore
Superchargers that are referred to as "Roots style" or "Roots blower" got that name because they are the "original" or "roots" design.
02GT
Well-Known Member
I'm in the same boat as reality, I always thought twin screw was a type of root style.
OP
OP
eliyarbrough
Legend
I don't know anything about this stuff though! I thought I heard that on a car show, probably! I just meant the kind that sits on top of the motor. Like the ones in the GT500s and '03 Cobras! Like I said, I guessed on the name!
TxCobrA98, thanks for that link! It's all foreign to me, but it looks cool though! Thanks guys!
TxCobrA98, thanks for that link! It's all foreign to me, but it looks cool though! Thanks guys!
OnyxCobra
Post Whore
Here's a good explanation of the difference between roots and twin screw; there are quite a few differences.
http://www.kennebell.net/techinfo/general-info/twinscrew-vs-roots-fromcatalog.pdf
http://www.kennebell.net/techinfo/general-info/twinscrew-vs-roots-fromcatalog.pdf
realitygt said:
Again "Roots Style" Is the same thing as saying "Blower" or something that covers a very broad range of several different things. Roots Style is just a term that people give positive displacement superchargers because the first ones were "Roots" superchargers, so anything that resembles a Roots blower will most likely be called a "Roots style" The only thing that's similar about the two is that they sit on top of the engine, and stuff spins inside them to create boost. There is no middle ground - Roots Style is just a saying, and not a technical term - much like the term "blower" can cover Roots, Twin Screw, or Centrifugal superchargers, even though they are all different.
Wow. Just wow.
It's called "Roots" because that was the name of the brothers that invented it and that is why the word Roots is always capitalized. It was designed as an industrial ventilation device.
When manufacturers say "Roots type" they mean it is not an original Roots Brothers blower but rather a more modern design that utilizes two rotors for the air displacement action, as opposed to twin screws, the same way the Roots brothers designed theirs. This makes it a "Style" of supercharger.
GMC used the Roots blower on their diesel engines in trucks. It was not used on cars. Other incarnations of the Roots style of blower was used on cars going back as early as 1907, but that was in a race car displacing over 1,100 cubic inches.
In the case of the designation of the blowers you are real close. In the case of a 6-71 blower it would function on a GMC diesel engine with 6 cylinders displacing 71 cubic inches each, or a 426 cubic inch engine.
However, these blower are rather inefficient and produce a LOT of heat, but modern automotive designs of it are better, yet compared to a twin screw type supercharger they still give up some performance. That is the reason for the popularity of superchargers such as Whipple and KB. The Lyscholm design is much more efficient. Lyscholm is responsible for the modern design of the twin screw style of supercharger. He patented it in Sweden in 1935.
Roots....
Twin Screw
Steve
It's called "Roots" because that was the name of the brothers that invented it and that is why the word Roots is always capitalized. It was designed as an industrial ventilation device.
When manufacturers say "Roots type" they mean it is not an original Roots Brothers blower but rather a more modern design that utilizes two rotors for the air displacement action, as opposed to twin screws, the same way the Roots brothers designed theirs. This makes it a "Style" of supercharger.
GMC used the Roots blower on their diesel engines in trucks. It was not used on cars. Other incarnations of the Roots style of blower was used on cars going back as early as 1907, but that was in a race car displacing over 1,100 cubic inches.
In the case of the designation of the blowers you are real close. In the case of a 6-71 blower it would function on a GMC diesel engine with 6 cylinders displacing 71 cubic inches each, or a 426 cubic inch engine.
However, these blower are rather inefficient and produce a LOT of heat, but modern automotive designs of it are better, yet compared to a twin screw type supercharger they still give up some performance. That is the reason for the popularity of superchargers such as Whipple and KB. The Lyscholm design is much more efficient. Lyscholm is responsible for the modern design of the twin screw style of supercharger. He patented it in Sweden in 1935.
Roots....
Twin Screw
Steve
02GT
Well-Known Member
thanks a lot steve, really cleared a lot up.
So you can tell which motor a blower went on by the number most of the time? Like you said a 6-71 went on a 6cyl or a 426. If you multiply 6 and 71 together you get 426. So is that how you determine the cubes of an engine? Like a 302 mustang displaces 37.75 cubic inches in each cylinder???
Yes, cubic inch displacement of your engine is the total amount of cylinder space, not counting the combustion chambers in the heads.
Area of a circle, or bore area, multiplied by the stroke of the engine gives you the volume of one cylinder. Multiply that by 8 cylinders and you get your engine size.
Area of a circle is easy. You learned this in school. Pi x R^2 or "Pi x R squared". Multiply Pi by the radius of your bore diameter, squared.
4.00" bore. Radius is 2. Two squared is 4. Four times Pi (3.1416) is 12.57 (rounding off). This is the area of your bore diameter, 12.57 square inches. Multiply this by the stroke, which is 3.00, and you get a cylinder volume of 37.71 (Of course where you round at will effect your exact final answer). Multiply that by 8 cylinders and you've got a 301.68 cu. in. engine, which we, and Ford, round up to 302.
Steve
Area of a circle, or bore area, multiplied by the stroke of the engine gives you the volume of one cylinder. Multiply that by 8 cylinders and you get your engine size.
Area of a circle is easy. You learned this in school. Pi x R^2 or "Pi x R squared". Multiply Pi by the radius of your bore diameter, squared.
4.00" bore. Radius is 2. Two squared is 4. Four times Pi (3.1416) is 12.57 (rounding off). This is the area of your bore diameter, 12.57 square inches. Multiply this by the stroke, which is 3.00, and you get a cylinder volume of 37.71 (Of course where you round at will effect your exact final answer). Multiply that by 8 cylinders and you've got a 301.68 cu. in. engine, which we, and Ford, round up to 302.
Steve
realitygt said:
Gotta be careful how you say that. :hammer:
Nah, I know some stuff about the old school blowers and I read up on the newer ones on the market but I have not messed around with them. I do understand the theory principles behind them and what the considerations are. I have plenty of book knowldege, for what it's worth.
When people put KB's on their Cobras I am always impressed at the numbers. I know a guy that put one on his and ran I think 21 pounds of boost. He was making over 600 HP at the wheels. He put in a solid axle to handle it too. Just amazing for a 281 cubic inch engine.
Steve
