Supercharger
10-12-06, 01:15 PM
#1
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Supercharger
i keep seeing superchargers mentioned as options for good low end power on fc's, but i cant seem to find any information on any type of kit, or is a supercharger application something you have to fab up? my tII isnt exactly slow, but i'd like something with a little more bottom end.
i saw a video a while back of a supercharged gxl (i think) running a track event and flying past a tII like it was a honda or something.
i recently aquired two gxls (the pair, both running, for less than $1000, how sweet is that?) and im thinking it'd be fun to supercharge one. any info, pictures, links, whatever would be highly appreciated. thanks!
also, while im posting, i got an eldebrock nitrous kit for next to nothing from a friend, was considering using that on one of the cars, but i dont know much about nos on rotaries, once again, any info is appreciated.
i saw a video a while back of a supercharged gxl (i think) running a track event and flying past a tII like it was a honda or something.
i recently aquired two gxls (the pair, both running, for less than $1000, how sweet is that?) and im thinking it'd be fun to supercharge one. any info, pictures, links, whatever would be highly appreciated. thanks!
also, while im posting, i got an eldebrock nitrous kit for next to nothing from a friend, was considering using that on one of the cars, but i dont know much about nos on rotaries, once again, any info is appreciated.
10-12-06, 01:21 PM
#2
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A blower is not much of a trade off from a turbo.
A little more mid-low torque, a little less top end.
A lot of money just to shift the power band some.
Weight reduction may be your best bet.
My personal preference - a 6-speed tranny with a short throw shifter.
A little more mid-low torque, a little less top end.
A lot of money just to shift the power band some.
Weight reduction may be your best bet.
My personal preference - a 6-speed tranny with a short throw shifter.
Last edited by SureShot; 10-12-06 at 01:25 PM.
10-12-06, 05:26 PM
#4
rotaries and turbo/super/nos: use caution, knocking will destroy the motor quick
turbo vs. super: high end power vs. low end power. Exhaust powered vs. direct drive (1st way quiets exhaust, 2nd way sometimes eats more power). It's a topic of debate, though I'd prefer turbo myself if I wasn't N/A.
nitrous vs. turbo/super: doesn't eat power or heat intake air like turbo/super, but the tank doesn't last very long and you have to keep paying for refills
turbo vs. super: high end power vs. low end power. Exhaust powered vs. direct drive (1st way quiets exhaust, 2nd way sometimes eats more power). It's a topic of debate, though I'd prefer turbo myself if I wasn't N/A.
nitrous vs. turbo/super: doesn't eat power or heat intake air like turbo/super, but the tank doesn't last very long and you have to keep paying for refills
10-12-06, 06:00 PM
#6
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Originally Posted by ericgrau
turbo vs. super: high end power vs. low end power. Exhaust powered vs. direct drive (1st way quiets exhaust, 2nd way sometimes eats more power)
10-12-06, 06:04 PM
#7
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i about to install mine once i finish ordering the rest of my exhaust! my plans with it are to get a megasquirt, bigger injectors, RB exhaust, 90% water/10% meth injection, msd A6, msd coils, someother stuff i cant remember. but ya should be pretty quick
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10-12-06, 08:09 PM
#8
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Originally Posted by staticguitar313
camdens Supercharger kit is highly ineffiecient, and expensive, dont buy it
superchargers on a rotary are more of a "neato" factor than anything, i might do one for giggles on my project car.
superchargers on a rotary are more of a "neato" factor than anything, i might do one for giggles on my project car.
Define "highly inefficient" because I have noticed that a lot of people around here poopoo the roots blower, but in reality have no idea what they are talking about.
BC
10-12-06, 08:30 PM
#9
I have heard that the camden kit works well, but doesn't put up the peak hp numbers people expect for that kind of money. Most of its gains are lower down and it will result in a very streetable car.
That said, for the price of the camden kit, you can get a j-spec, rebuild it, street port it, and get a megasquirt and supporting fuel mods. Depending on where you get the stuff, you might could get a BNR hybrid. That setup will put out much more power, and be more fun to drive.
That said, for the price of the camden kit, you can get a j-spec, rebuild it, street port it, and get a megasquirt and supporting fuel mods. Depending on where you get the stuff, you might could get a BNR hybrid. That setup will put out much more power, and be more fun to drive.
10-12-06, 09:01 PM
#10
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The camdon kit is definitely expensive. If you could get the kit without the blower it would be orders of magnitude cheaper. The M62 is NOT a hard blower to find, but new its expensive.
BC
BC
10-12-06, 09:43 PM
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will be building mine w/ a Mazda Millenia blower as soon as time will allow. A lot of challenges with the mounting of this beast of a blower but we'll see if it was worth it soon, I hope. Found the blower on ebay used for about 3 bills. Seen them for less.
I'm hoping that once I get this going I'll have enough interest to make a mounting kit for the S4.
I'm hoping that once I get this going I'll have enough interest to make a mounting kit for the S4.
10-12-06, 09:54 PM
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Should be interesting, but on a rotary I have to ask: Why? If its just for ***** and giggles I understand. Otherwise I dont. centrifugal blowers combine the worst of s/c and turbo into one. Late boost and parasitic loss. If you were making a highway stormer I could see it being a lot of fun, but otherwise you would be giving up a lot of low end for some high end efficiency.
Just wondering, not knocking. I have thought about the centrifugal blower for a rotary too, but like I said, for a highway monster. Something that is civil down low and mean as hell up top.
BC
Just wondering, not knocking. I have thought about the centrifugal blower for a rotary too, but like I said, for a highway monster. Something that is civil down low and mean as hell up top.
BC
10-12-06, 10:47 PM
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***** and giggles?
Not a chance. Dead serious about this project.
Picking the Millie twin screw was after a lot of research on it's characteristics. The twin screw was the most efficient compressor at least for superchargers. I'm only trying for about 6-8lbs. boost first time around but it should be good for up to 12-14lbs with the right pulley on a NA 13b at redline. Granted boost curves would be way different from a turbo but much more predictable (linear), at least from the graphs of the blower that I found online but for the life of me cant find again.
Secondly, At least I'm hoping, since the twin screw design is more efficient at compressing air without raising intake air temps (adiabatic efficiency) better than roots, centrifugal and turbos, I just might be able to get away with not having to use an intercooler and avoid all the extra plumbing. Shorter intake pipes might be better for throttle response. IMHO
Wont know how it'll perform until it gets built but I promise to build as soon as time will allow. I've got a buddy w/ a 91'vette convertible who's *** I intend to kick. lol. And if he doesn't chicken out we might even do it for pinks.
BTW, twin screws are definitely not centrifugal by any means. No impellers as in Paxton blowers or turbos. It's done with 2 synchronised twisted "screws" that mesh together at close tolerance w/ out touching. Sorta like a roots blower but with much tighter twists and much closer tolerances.
If only IntegraLS hadn't gone to a V8, I for one would have liked to see it dynoed. Even if just for ***** a giggles.
Picking the Millie twin screw was after a lot of research on it's characteristics. The twin screw was the most efficient compressor at least for superchargers. I'm only trying for about 6-8lbs. boost first time around but it should be good for up to 12-14lbs with the right pulley on a NA 13b at redline. Granted boost curves would be way different from a turbo but much more predictable (linear), at least from the graphs of the blower that I found online but for the life of me cant find again.
Secondly, At least I'm hoping, since the twin screw design is more efficient at compressing air without raising intake air temps (adiabatic efficiency) better than roots, centrifugal and turbos, I just might be able to get away with not having to use an intercooler and avoid all the extra plumbing. Shorter intake pipes might be better for throttle response. IMHO
Wont know how it'll perform until it gets built but I promise to build as soon as time will allow. I've got a buddy w/ a 91'vette convertible who's *** I intend to kick. lol. And if he doesn't chicken out we might even do it for pinks.
BTW, twin screws are definitely not centrifugal by any means. No impellers as in Paxton blowers or turbos. It's done with 2 synchronised twisted "screws" that mesh together at close tolerance w/ out touching. Sorta like a roots blower but with much tighter twists and much closer tolerances.
If only IntegraLS hadn't gone to a V8, I for one would have liked to see it dynoed. Even if just for ***** a giggles.
Last edited by ErixHvn; 10-12-06 at 10:56 PM.
10-12-06, 10:56 PM
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Whoa, hold on a sec. We are talking about 2 different blowers here. There is the twin screw, which is a positive displacement blower, and a centrifugal which is a compression blower. So which is it. You are describing a twin screw, sideways is describing a centrifugal.
If its a twin screw you do need to understand that at low boost it is not NEARLY as efficient as people like to say it is. if you are only planning6-10 psi you are better off getting a roots blower. Twin screws are notoriously leaky at low boost, where as roots blowers are notoriously inefficient at high boost.
BC
If its a twin screw you do need to understand that at low boost it is not NEARLY as efficient as people like to say it is. if you are only planning6-10 psi you are better off getting a roots blower. Twin screws are notoriously leaky at low boost, where as roots blowers are notoriously inefficient at high boost.
BC
10-12-06, 11:04 PM
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Ok. In that case I stand by what I said about the efficiency. If you dont plan on a lot of boost the roots blower is actually going to be a better choice. Much less lost pressure to "leaking" than a twin screw.
BC
BC
10-12-06, 11:14 PM
#19
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Originally Posted by anewconvert
Define "highly inefficient" because I have noticed that a lot of people around here poopoo the roots blower, but in reality have no idea what they are talking about.
Fortunately for those who "in reality have no idea what they are talking about", you can remedy the bulk of this problem with a modest investment of about $25-35 to buy Corky Bell's "Supercharged!" book.
10-12-06, 11:19 PM
#20
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Originally Posted by anewconvert
Twin screws are notoriously leaky at low boost, where as roots blowers are notoriously inefficient at high boost.
BC
BC
Just curious as to where the idea that a twin screw would be "leaky" came from.
10-12-06, 11:51 PM
#21
Twin screw compressors are more efficient than roots. Only downside is cost, I believe. They are good for getting power down low, where as centrifugal is good up top.
Even if you acheive 100% efficient adiabatic compression you will heat up the intake air. Summary of the what's below: At 7psi of boost you can increase your horsepower by another 16% with a perfect intercooler (any real intercooler will be worse, no matter how good it is).
Let's say you have air coming in at 550R (90F, Rankine = Fahrenheit + ~460) and 14.7psia (0.0psig, Absolute pressure = gauge pressure + 14.7psi) and you compress it to 21.7psia (7.0 psig). Using the adiabatic compression equation (which requires absolute temperature and pressure, such as rankine and psia):
T2 = T1 (P1/P2)^.283
T2 = 550R * (21.7psi / 14.7psi)^.283 = 614R = 154F
Using the ideal gas law:
PV = nRT, or n = PV / RT
i.e., The amount of air you can cram into your engine is proportional to pressure, and inversely proportional to temperature. V is your engine displacement, R is a constant. You can't change V & R. Again, these are absolute pressure & temperature.
So at 7psi of boost with an intercooler you can get up to 614/550 = 1.16 times as much power. i.e., 16% more power with a perfect intercooler (actual gains will be less).
NOTE: "absolute" means relative to absolute zero. So absolute zero temperature is 0R = -460F. Absolute zero pressure (perfect vacuum) is 0psia = -14.7psig.
Even if you acheive 100% efficient adiabatic compression you will heat up the intake air. Summary of the what's below: At 7psi of boost you can increase your horsepower by another 16% with a perfect intercooler (any real intercooler will be worse, no matter how good it is).
Let's say you have air coming in at 550R (90F, Rankine = Fahrenheit + ~460) and 14.7psia (0.0psig, Absolute pressure = gauge pressure + 14.7psi) and you compress it to 21.7psia (7.0 psig). Using the adiabatic compression equation (which requires absolute temperature and pressure, such as rankine and psia):
T2 = T1 (P1/P2)^.283
T2 = 550R * (21.7psi / 14.7psi)^.283 = 614R = 154F
Using the ideal gas law:
PV = nRT, or n = PV / RT
i.e., The amount of air you can cram into your engine is proportional to pressure, and inversely proportional to temperature. V is your engine displacement, R is a constant. You can't change V & R. Again, these are absolute pressure & temperature.
So at 7psi of boost with an intercooler you can get up to 614/550 = 1.16 times as much power. i.e., 16% more power with a perfect intercooler (actual gains will be less).
NOTE: "absolute" means relative to absolute zero. So absolute zero temperature is 0R = -460F. Absolute zero pressure (perfect vacuum) is 0psia = -14.7psig.
Last edited by ericgrau; 10-12-06 at 11:55 PM.
10-13-06, 12:39 AM
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Originally Posted by ErixHvn
How so? positive displacement yet leaky at low boost? In it's apllication in the Millie the Lysholm doesn't really see boost beyond 8-10 lbs. I highly doubt that Mazda engineers would be so stupid as to use a twin screw that would be that "leaky" at low boost.
Just curious as to where the idea that a twin screw would be "leaky" came from.
Just curious as to where the idea that a twin screw would be "leaky" came from.
Straight from Corky Bell.......
http://forum.miata.net/vb/showthread.php?t=193364
Post #20
I want to back track ont he roots being more efficient at lower rpm. I had my own wires crossed in my head. I blame the pain killers I am on for my wisdom teeth. They are just as leaky at lower rpm, but just a hell of a lot cheaper than a twin screw is. So if you have a cheap twin screw then by all means use it. However, both are inefficient at low rpm, so if thats where you plan on staying you may as well save a few bucks. thats where I meant to go with it.
BC
Last edited by anewconvert; 10-13-06 at 12:47 AM.
10-13-06, 12:44 AM
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Originally Posted by Evil Aviator
Most of the people on this forum who "poopoo" the Roots blower efficiency have a college degree in this subject area and/or many years of experience. They also happen to know the approximate range of "highly inefficient" adiabatic efficiency while you admittedly do not. I think that maybe you should reassess your list of who knows what they are talking about and who does not.
Fortunately for those who "in reality have no idea what they are talking about", you can remedy the bulk of this problem with a modest investment of about $25-35 to buy Corky Bell's "Supercharged!" book.
Fortunately for those who "in reality have no idea what they are talking about", you can remedy the bulk of this problem with a modest investment of about $25-35 to buy Corky Bell's "Supercharged!" book.
Oh Christ. Its amazing how many people on this board get so butt hurt over small ****.
1) A LOT of people who "poopoo" the roots blower DONT have any idea what they are talking about.
2) I was asking what staticguitar defined as "highly inefficient." Not you, or for a number. I was asking what his opinion of highly inefficient is.
3) where do you come up with the idea that i "admittedly" dont know what the efficiency of a roots blower is? I dont see me "admitting" to anything. I spent the first 3 years of my car obcession working on roots blown 3800 Buick engines. I have an "idea" of the efficiency of the roots blower, and its capability.
4)) Yes its a good book. So is maximum boost. However most of those who have no idea of what they are talking about still wont read it.
BC