I have come accross a supercharger from a Kei car that has a 16,500 rpm limit, 500cc per revolution. Its a roots type, and the packaging has definite possibilities. My Miata has the stock advertised displacement of 1.8l and redline, and i am considering putting this thing in place of my powersteering pump. The specs say it will work for "1.0-2.2l" Any body able to tell me:
Will it work for 5 or so PSI of boost or become a hot air pump and/or a restriction?
What size pully should i look for?
Do you know other specifics, like the manufacturer or the direct name of the supercharger? The only Japanese manufacturer of roots-style blowers I know of is Ogura.
AMR500?
It's too small IMO.
It is, in fact, an amr500. Not looking for big power, just more than now. I didnt mention the name because of people dismissing it by name, not because they have done the math. Although, direct personal experience is good too, now that i think about it.
If your miata can spin at 7000RPM, and your supercharger can only spin at 16500 RPM, you'll end up with a best-case scenario of 2.35 rotations of your supercharger for each rotation of your crank.
That's only going to be 1.18 L of air from your supercharger, right?
In reply to the_machina :
Sounds good to me, but dont the pully sizes affect revs?
So i need 4 and ITBs!
In reply to the_machina :
Wait, not all 1.8l of engine ingests air per revolution, so it may work?
I'm not a doctor, so somebody else can correct me.
Edit: sure as E36M3, I screwed it up. Pretty sure the following is correct now.
.9l of engine needs to be fed per crank revolution, so you have to turn the SC almost two times to keep up with demand. To make 5psi of boost (.34 bar, for a total of 1.34 bar in the cylinder) you need to run a 2.4:1 drive ratio. With a 7k red line on engine, that puts you right at max rpm for the blower.
Equation is volume of (SC x drive ratio) / (.5 x engine displacement) = total charge pressure (bar) = 1 bar + boost pressure.
5psi (at 2.4:1), 70f ambient temp gives you a charge temp of 116f.
These things are so cheap, what if we hooked up two of them in a two-stage/serial arrangement? Discuss
therieldeal said:These things are so cheap, what if we hooked up two of them in a two-stage/serial arrangement? Discuss
Won't work since roots superchargers are external-compression, the first stage won't be able to feed enough air to the second stage to build any more pressure.
GameboyRMH said:therieldeal said:These things are so cheap, what if we hooked up two of them in a two-stage/serial arrangement? Discuss
Won't work since roots superchargers are external-compression, the first stage won't be able to feed enough air to the second stage to build any more pressure.
Thinking about this a little more after making the above post, I suspected/feared that this might be the answer.
Proof that I’m chock full of terrible ideas, I guess.
Look at it this way- it's only usable on an engine less than 1.5 Liters.
Like a motorcycle. Or a midget racer. Or a 4x4. Or a different Kei car. Or...
You can stretch the capacity of a supercharger by feeding pressurized air into it. I.E. turbo + super in a compound arrangement. Air would go through the turbo first, which at low speeds would not compress it. Then it goes into supercharger, gets compressed, and goes to engine. By the time it comes out the exhaust side it's more or less 2.4L worth of exhaust (1.8L of displacement + 5psi ~= 1.8X1.333=2.4L) at which point you can spool a turbo sized for a 2.4L. Then when that turbo spools you are able to compress the intake of the supercharger which stretches its hp capability. So basically, your supercharger may max at <200hp, but it only needs to make that number up to ~3000-4000rpm and then the boost from the turbo will extend it basically ad infinitum.
The reason why more people don't do this basically boils down to people using larger superchargers that physically interfere with turbo placement with any off-the-shelf manifold. If your SC is able to more or less fit where the PS pump goes then it doesn't preclude you putting a turbo in the usual spot. Oh, and people being scared! Forgot that part.
So sure, that supercharger will work great if you use it to fill in the bottom end and spool a big turbo on a compound setup... 
In reply to Vigo :
**Looks at holset turbo sitting on shelf**
**Looks at $200 AMR500’s on ebay**
**Looks at BP swapped escort wagon with non-functional a/c**
hnnnnnnnnnngggggggggggggggggggggggg
In reply to Vigo :
They also don't do it due to heat issues. You need to be careful with intake charge temps- there was a guy here recently who did a twincharged Foxbody/Merkur with an Eaton M90/turbo on a 2.3, and he had both an air to water AND air to air intercooler. AND the 2.3 has two spark plugs per cylinder, which also aids in cooling as well.
The only other engine I know of that has documented evidence (and people still running) twincharged systems is the 4AGE in the AW11 MR2. There's dudes that run ~30PSI of boost on them.
So have we concluded that i would need at least 2 of these in parallel to move enough air to be worth while?
In reply to therieldeal :
Look 3 posts above yours
No reason to talk about compound supercharging. That just creates a whole lot of heat for no particular reason. However, if they are a compact little unit, mount two, and make some cool tubes to have separate intakes and a Y pipe to feed the throttle body. Not enough boost? Add a third one, with even cooler looking plumbing.
there was a guy here recently who did a twincharged Foxbody/Merkur with an Eaton M90/turbo on a 2.3
I'm pretty sure i posted in every single one of his threads and i feel good about the level of detail i was able to offer on the topic of compounding as he sorted it out. The car works...
The idea that making a given power level with just this SC or two of them is somehow less heat than compounding with a turbo is... unfounded.
But hey, it's a challenge only a certain type of personality would want to take on. I suggested it semi-facetiously but nothing i said is untrue. 
The idea that making a given power level with just this SC or two of them is somehow less heat than compounding with a turbo is... unfounded.
Yeah, the harder you squeeze it the hotter it gets.
Here's the equation to figure the charge temperature. Note that temperatures will be in Kelvin and pressures in bar.
Me: "wonder what these folks are talking about"
googles AMR500 and AMR300, sees how cheap and small they are.
looks at the 1 liter mini in his driveway
Now thinking about scrapping the turbo setup I have built.
Yeah, the harder you squeeze it the hotter it gets.
Sure, but here's the thing. Turbos are more adiabatically efficient than positive displacement superchargers. So, to make part of your boost with a turbo would generally add less heat to it in the process than compressing by the same amount with the supercharger alone. Just ballparking the concept, if the turbo+super compound setup was 30% more adiabatically efficient, you'd have to run 30% more boost before you actually ended up with a hotter charge temp, or you'd have 30% less heat added at the same boost level.
Anyways, semi joke compound boost answer has become tedious and unfunny. One of my least useful talents!
Jumper K Balls (Trent) said:Me: "wonder what these folks are talking about"
googles AMR500 and AMR300, sees how cheap and small they are.
looks at the 1 liter GoldWing in his driveway
Fixed to reflect my situation.
In reply to JohnInKansas :
Its good to know my post wasnt completely useless
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