SHOnuff93
SHO Member
60kmaintenance said:
again you are wrong, the screw type compressor is better than the roots in every way. and you can intercool a screw type compressor just the same as a roots.
Comptech roots style S/C for 3.2L Acuras? Work on a SHO?
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again you are wrong, the screw type compressor is better than the roots in every way. and you can intercool a screw type compressor just the same as a roots.
60kmaintenance
New Member
Yeah you can use a cooling system with screw. However a screw is not better then roots in every way, they are two different beasts.
Again, the screw has a rather flat amount of power produced, the roots on the other hand can build more, with more RPMs. That makes the roots good for drag racing, screw drastically is better for heavy vehicals or towing. Either one obviously creates more fun for any street car. Not that the like 50% effecieny is great but... You can still get the power you want.
Again, the screw has a rather flat amount of power produced, the roots on the other hand can build more, with more RPMs. That makes the roots good for drag racing, screw drastically is better for heavy vehicals or towing. Either one obviously creates more fun for any street car. Not that the like 50% effecieny is great but... You can still get the power you want.
SHO_Stop'r
New Member
Every time 60k posts in a thread it always comes to this..
AutoSHO
No SHO = Mo $$$
60kmaintenance said:
Again, you are incorrect. The screw type builds boost just as quickly as a roots blower, but does it with much better adiabatic efficiency. As you spin them faster, the gap only widens as the screw type compressor maintains its efficiency while the roots becomes a hot air pump as rpms increase.
I don't know where you get your info... But the source is no good.
60kmaintenance
New Member
I read books and articles......
You ever stop to think maybe some people that give you your information are bias?
If screw is SOOOOOOOOOOOOOOOOOO superior, and there is NOOOOOOOOOOOOO reason for roots, honestly, explain why they sell roots and still use them. Also a roots needs to be sized right, just like any forced induction system.
From what your describing it's theortical to begin with. A roots will surge and not work right before it becomes useless. Roots can provide more power at higher RPM, and not over work the engine at lower, like a not sized right screw will do as well.
Think about it, a roots compresses the air in the cylinders and plenum, there for as RPM increases it can consistantly compress the air in the cylinders and plenum. If it's sized right of course..... Now a screw compresses in the supercharger, it has more of a limit to the compression, that doesn't vary any, as the more RPM, the equal compinsation of compression to the original amount at idle. You get what I mean, the roots can build more power as the RPM increases (sized right) while a roots will keep a pretty flat power curve, which dosen't give it the top end some engines can take (mostly built drag cars).
You ever stop to think maybe some people that give you your information are bias?
If screw is SOOOOOOOOOOOOOOOOOO superior, and there is NOOOOOOOOOOOOO reason for roots, honestly, explain why they sell roots and still use them. Also a roots needs to be sized right, just like any forced induction system.
From what your describing it's theortical to begin with. A roots will surge and not work right before it becomes useless. Roots can provide more power at higher RPM, and not over work the engine at lower, like a not sized right screw will do as well.
Think about it, a roots compresses the air in the cylinders and plenum, there for as RPM increases it can consistantly compress the air in the cylinders and plenum. If it's sized right of course..... Now a screw compresses in the supercharger, it has more of a limit to the compression, that doesn't vary any, as the more RPM, the equal compinsation of compression to the original amount at idle. You get what I mean, the roots can build more power as the RPM increases (sized right) while a roots will keep a pretty flat power curve, which dosen't give it the top end some engines can take (mostly built drag cars).
SHO_Stop'r
New Member
yamahaSHO said:
"stoopid " hu , its ok i know u dont mean it
now about everything else.. well... 
its not even a joke... litterally every time..
jedhead
New Member
60kmaintenance said:
Ever stop to think that people who are disagreeing with you have "actual" personal experience in these matters. Cutting and pasting or rewriting from books and articles is no way to argue
Bob
Off Road SHO
Moderator
GoofSHO said:
And there are two different kinds of reality now. There's TV Reality and real reality. Television producers have absolutely no requirement or obligation to tell the truth. It's not required by law or their owners. If it (their show) sells advertisement time, it's a sucess.
The other reality, the one that is experienced, logged, measured, paid for in replacement parts when you melt the first one, is a much more honest reality. It's real, not hearsay, not heard it from "my ex-next door neighbor in-law twice removed but only put back once" kind of experience.
With that said....let's go melt some parts!
Tom
SHOnuff93
SHO Member
A roots style blower and a screw compressor are both positive displacement superchargers. With every revolution they move a fixed amount of air. So your idea that a roots blower builds boost as it spins faster is not correct, it will move the same amount of air per revolution at 7k as it will at 3k. A centrifugal supercharger is more like a fan, air can flow back through it at lower rpms, so as it spins faster the air is forced to go in one direction, thats why they build boost with rpms. The screw is much like the roots in that with each revolution it moves a fixed amount of air. The screw also compresses the air between the screws not in the manifold like the roots, this makes it more thermally efficient.
The reason they use roots blowers still is because they are simple and effective and relatively cheap to make. The typical roots blower uses 2 rotors with 2 lobes a piece. These blowers are what you usually find on "race cars". The roots blowers used in factory applications (GTP, SC...) are the newer style eaton blowers, that use 2, 3 lobed, twisted rotors. These eatons are much more efficient than the 2 lobe roots, but they both lag behind the superior screw design. Also because of the tight tolerances between the 2 rotors of the screw compressor (one male, one female) they are very expensive to manufacture.
As a simple display of the screw compressors superiority take a look at the 03-04 cobra websites out there. If the roots were superior you would think cobra owners would leave them in place, instead of swapping to kenne bells and whipples.
The reason they use roots blowers still is because they are simple and effective and relatively cheap to make. The typical roots blower uses 2 rotors with 2 lobes a piece. These blowers are what you usually find on "race cars". The roots blowers used in factory applications (GTP, SC...) are the newer style eaton blowers, that use 2, 3 lobed, twisted rotors. These eatons are much more efficient than the 2 lobe roots, but they both lag behind the superior screw design. Also because of the tight tolerances between the 2 rotors of the screw compressor (one male, one female) they are very expensive to manufacture.
As a simple display of the screw compressors superiority take a look at the 03-04 cobra websites out there. If the roots were superior you would think cobra owners would leave them in place, instead of swapping to kenne bells and whipples.
60kmaintenance
New Member
I never said roots was superior, I just said it has a purpose. SOOO you didn't do any thing but elaborate more on what I already said..... Who cares.
Just to clarify, you can strap on a bigger roots, the bleeds off, as you already mentioned, some air in the lower RPM's, yet doesn't with increased RPMs, so you do infact get more power with RPM's when it's sized right.
Besides most engines that you would use a roots on, the appplications, they don't even live at lower RPM so the very low end grunt doesn't mean any thing. The sizing of them makes it totally different for that reason, and for that reason they can sized to build more boost at higher RPM.
Like I said there is a reason for roots. If there wasn't no one with enough money to build race cars and other fun projects, would touch one. They spend more money on the low end of their motor then we buy our SHO's for.....
I'm not saying to put a roots on a SHO or any thing, just that they have a place, and it's hard to argue with one, when it's used for what makes it worth using.
Just to clarify, you can strap on a bigger roots, the bleeds off, as you already mentioned, some air in the lower RPM's, yet doesn't with increased RPMs, so you do infact get more power with RPM's when it's sized right.
Besides most engines that you would use a roots on, the appplications, they don't even live at lower RPM so the very low end grunt doesn't mean any thing. The sizing of them makes it totally different for that reason, and for that reason they can sized to build more boost at higher RPM.
Like I said there is a reason for roots. If there wasn't no one with enough money to build race cars and other fun projects, would touch one. They spend more money on the low end of their motor then we buy our SHO's for.....
I'm not saying to put a roots on a SHO or any thing, just that they have a place, and it's hard to argue with one, when it's used for what makes it worth using.
Off Road SHO
Moderator
SHOnuff93 said:
And turbos.
Tom
Mike Kopstain
New Member
Actually neither roots blowers or or twin screws are 100% volumetricly efficient. The roots will actually noticably build boost towards the upper RPMs as it's volumetric efficiency increases (quicker spinning impellers = less time for air to leak).
The main difference between the two style blowers is that a roots blower is just pushing air into the lower intake while the twin screw actually slowly compresses the air as it makes it's way from the blower's inlet to it's outlet.
The main benefit to a twin screw blower is adiabatic efficiency. More or less this is how hot the air is at the blower's outlet. With roots blowers adiabatic efficiency dumps off on the higher RPMs and the blower is just pushing hot air. This is why the M90 (especially the older supercoupe versions Gen I/II) is such a bad matchup for the SHO motor. These are notoriously innefficient blowers (They were also Eaton's first mass produced blower).
When you consider that knock is caused solely by heat outlet temperatures start to become really important. With the Whipples on the GPs we can make more power non-intercooled than we're making with the stock blower intercooled.
Why do they still use roots? Well, much like anything else it's a cost issue. Eaton blowers are cheap, much cheaper than Whipple/ Lysolm. Also when you consider that most manufacturers keep boost levels low the supercharger can be kept in it's power "island" quite easily.
A twin screw is hands down the better supercharger though. With the M90s we see torque peak at throttle tip in and drop like a ski slope from there. With the Whipples we're seeing torque curves similar to turbo cars. I don't know about you but when someone brags about having 300 ft/lbs at the wheels at 5000rpm it means a lot more than when they have 300 ft/lbs at the wheels just off idle.
The main difference between the two style blowers is that a roots blower is just pushing air into the lower intake while the twin screw actually slowly compresses the air as it makes it's way from the blower's inlet to it's outlet.
The main benefit to a twin screw blower is adiabatic efficiency. More or less this is how hot the air is at the blower's outlet. With roots blowers adiabatic efficiency dumps off on the higher RPMs and the blower is just pushing hot air. This is why the M90 (especially the older supercoupe versions Gen I/II) is such a bad matchup for the SHO motor. These are notoriously innefficient blowers (They were also Eaton's first mass produced blower).
When you consider that knock is caused solely by heat outlet temperatures start to become really important. With the Whipples on the GPs we can make more power non-intercooled than we're making with the stock blower intercooled.
Why do they still use roots? Well, much like anything else it's a cost issue. Eaton blowers are cheap, much cheaper than Whipple/ Lysolm. Also when you consider that most manufacturers keep boost levels low the supercharger can be kept in it's power "island" quite easily.
A twin screw is hands down the better supercharger though. With the M90s we see torque peak at throttle tip in and drop like a ski slope from there. With the Whipples we're seeing torque curves similar to turbo cars. I don't know about you but when someone brags about having 300 ft/lbs at the wheels at 5000rpm it means a lot more than when they have 300 ft/lbs at the wheels just off idle.
How about 400ft lbs @ 5000rpm?
Turbos baby!!!
Turbos baby!!!
95SE
New Member
Take a look at the Thunderbird SC.. The engine is limited in power by supercharger efficiency..
One of our local Thunderbird SC guys has a Coy Miller stage II Race engine with a fully ported magnaport M-90 supercharger. He dynoed 320ish rwhp and 430ish rwtq..
After changing nothing but bigger injectors for fuel support and adding an autorotor (whipple style, screw charger), he dynoed 427 rwhp and a bit more torque (can't remember torque figure off hand)..
That's over 100 hp increase on a modified engine, and he's actually spinning the supercharger SLOWER than he was spinning the M-90.
With the M-90 he ran 13.5's at high altitude, and the car fell on its face at 5,200 rpm..
Wtih the screw blower he is running 12.80's also at high altitude, the car feels the same up to 5,200 rpm, then really starts pulling and makes peak power at 6,400 rpm.
Jeramie
One of our local Thunderbird SC guys has a Coy Miller stage II Race engine with a fully ported magnaport M-90 supercharger. He dynoed 320ish rwhp and 430ish rwtq..
After changing nothing but bigger injectors for fuel support and adding an autorotor (whipple style, screw charger), he dynoed 427 rwhp and a bit more torque (can't remember torque figure off hand)..
That's over 100 hp increase on a modified engine, and he's actually spinning the supercharger SLOWER than he was spinning the M-90.
With the M-90 he ran 13.5's at high altitude, and the car fell on its face at 5,200 rpm..
Wtih the screw blower he is running 12.80's also at high altitude, the car feels the same up to 5,200 rpm, then really starts pulling and makes peak power at 6,400 rpm.
Jeramie
92turboshoprobe
New Member
Toolman said:
As in 2 right?
Good one!
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