What happens when I add a second supercharger?

[Kelly]

I think that two superchargers wont make twice the power, but will make twice the street cred.

[vrg3]

Yesh. Well, approximately twice.

[206er]

hmmm, maybe start thinking about a vortech for a mustang, or even a 6-71 to make a intake manifold for?

[Splinter]

Ok, that makes no sense. You don't save money by purchasing a wrx over a legacy, even a heavily modded legacy. You do however save money by working on your own car.

You save money in order to buy a WRX.

[dzx]

But you have to work to get money.

[free5ty1e]

Oh, man - but you need a car to get to work! Paradox! Unraveling of space/time continuum!

Crap. I shouldn't have done that.

[AWD_addict]

Two smaller FMIC side by side, or one on top of the other.

The charge tubes will then lead to a Y of some sort that then has a MAF.

Then spilt to the dual throttle bodies, or single throttle body.

This sounds like the better option.

[Splinter]

But you have to work to get money.

Or just spend less

[dzx]

lol, but by spending less, your not gaining money and can't afford a wrx.

[evolutionmovement]

What about adapting some form of plumbing from the twin turbo set up? There must be some intake stuff dirt cheap. What about quad throttle bodies if you want to get real exotic? Have the outlet pipes from the intercooler(s) go right over the heads to the TB pairs over very short straight runners. Tuning would be fun! Would look great, though. You could mount the chargers directly over the block or leave them to the outside and have the center exposed, really emphasizing the flat motor design.

Then you could put a jet engine with an afterburner ...

Steve

[dzx]

What about just making a y-pipe like a twin turbo setup uses?

[NICO]

is this twin supercharger going to happen or your seeing if its possible?

becuse i dont think it would be worth it. they run off the motor, i dont no about you but i got one belt and it goes like this crank pull to altenater = more hp.

but what rallitektech siad "but will make twice the street cred"

[sammydafish]

These are superchargers meant for 2.3-liter Mercedeses, right? They're positive-displacement blowers without any internal compression, right?

So plumbing two of them in parallel would ideally double the volume of flow at the inlet. But, as we've discussed before, there's a great deal of leakage around the lobes. This leakage becomes greater and greater as the pressure differential across the supercharger increases, too. That means you'll push a good deal less than 3 L/rev.

this is the issue you need to think about most. If you want to flow double the volume, you can't do it without raising the pressure. You dead head against the volumetric efficiency of the engine so flowing more air will result in pressure. The problem with this type of blower is that you quickly run into an issue with diminishing returns when it comes to pressure and you can't run more than a PR or 2 with any amount of efficiency. If you really wanted the coolness of twin superchargers, the ideal situation would be one eaton screw type like the MB unit and one Lysolm charger like made by autorotor or whipple. It would have to be a sequential setup and would be pretty damn complex, but theoreticaly would work as it follows the same principle as twin charging (SC and turbo). When you see two centrifugal SCs on a V8 it's similar to a twin turbo setup as that's the same kind of compressor a turbo is, just driven in a different way. If you ever saw two roots types it was probably just for the Frankenstein coolness of it and probably doesn't actually work very well.

[douglas vincent]

OK, but why are people are to put huge turboes on their rigs? Their PSI doesnt advance much but their volume does, correct?

And isnt the goal all about air flow, not PSI?

When/if I actaully do this, I will be using the better flowing heads, which in themselves would lower the psi (not by much), but raise the airflow into the pistons. Technically I will make more power at lower psi.

Theoretically, I could get an Eaton M112 which flows 1.5 per revolution and install it with my current pulley set up and get 3 liters per engine revolution via a single supercharger. I say theoretically because actaully getting that SC to fit would be very very difficult.

By the way, Rallitek has a nice big unit, and he is pretty proud of it, AND he has a nice new big turbo too!!!!

[Kelly]

What about an SC and TURBO

Would be easy so source yourself some pipes and a T series turbo for cheap.

And yes, Im glad you enjoyed my big unit. Your gonna have to take it for a ride sometime.

[sammydafish]

OK, but why are people are to put huge turboes on their rigs? Their PSI doesnt advance much but their volume does, correct?

not entirely. a larger turbo will be able to flow more air more efficently (less heat generated) In order to generate pressure the air needs to be pumped into a container with limited volume. In this case you could consider the intantanious volume of the container dirrectly related to the displacement of the engine and it's volumetric efficency. No matter how much the turbo/sc can flow, once you out flow the amount of air the engine can breath, the pressure needs to go up. If your turbo/sc flows significantly more air than your engine can breathe then if it's a turbo or centrifugal sc you'll run hard into the surge line and eventualy dammage the compressor because you'll generate massive amounts of boost nearly imediatly (once the boost comes on, it goes through the roof)

think of it this way. take a little bar straw and blow through it. Your lungs can flow a massive volume of air, but no matter how hard you try you just build up more pressure in your mouth than your lips can hold.

[Legacy777]

If your turbo/sc flows significantly more air than your engine can breathe then if it's a turbo or centrifugal sc you'll run hard into the surge line and eventualy dammage the compressor ......

I think you mean stonewall not surge. Surge is when you don't have enough air entering the compressor. Stonewall is when the compressor hits an imaginary wall and can't flow/move any more air.

[sammydafish]

nope, I mean surge. Surge is when the pressure is to high in relivance to the air flow. Look at a turbo compressor map and look at the surge line, you'll see what I mean.

[Splinter]

I dont know too much about turbo dynamics, but I'd imagine that surging is what occurs when a turbo tries to flow more air than whats availible, causing a drop in air density at the compressor, allowing it to spin extremely fast with no additional airflow.

[sammydafish]

In an attempt to put a quick closure to the speculation and imagination on what compressor surge is I tried finding a credible source to explain it and stumbled upon Garrett's totally new website. They added a bunch of technical info that's pretty cool there. All their explanations seem to be quick and to the point too, I like it. On surge, I found this

the following is from http://www.turbobygarrett.com/turbobyga ... ch103.html

Surge Line

* Surge is the left hand boundary of the compressor map. Operation to the left of this line represents a region of flow instability. This region is characterized by mild flutter to wildly fluctuating boost and “barking” from the compressor. Continued operation within this region can lead to premature turbo failure due to heavy thrust loading.
* Surge is most commonly experienced when one of two situations exist. The first and most damaging is surge under load. It can be an indication that your compressor is too large. Surge is also commonly experienced when the throttle is quickly closed after boosting. This occurs because mass flow is drastically reduced as the throttle is closed, but the turbo is still spinning and generating boost. This immediately drives the operating point to the far left of the compressor map, right into surge.

Surge will decay once the turbo speed finally slows enough to reduce the boost and move the operating point back into the stable region. This situation is commonly addressed by using a Blow-Off Valves (BOV) or bypass valve. A BOV functions to vent intake pressure to atmosphere so that the mass flow ramps down smoothly, keeping the compressor out of surge. In the case of a recirculating bypass valve, the airflow is recirculated back to the compressor inlet.
* A Ported Shroud compressor (see Fig. 2) is a feature that is incorporated into the compressor housing. It functions to move the surge line further to the left (see Fig. 3) by allowing some airflow to exit the wheel through the port to keep surge from occurring. This provides additional useable range and allows a larger compressor to be used for higher flow requirements without risking running the compressor into a dangerous surge condition. The presence of the ported shroud usually has a minor negative impact on compressor efficiency.

[vrg3]

Stop talking about centrifugal compressors trying to flow air. They produce pressure ratios.

[Legacy777]

nope, I mean surge. Surge is when the pressure is to high in relivance to the air flow. Look at a turbo compressor map and look at the surge line, you'll see what I mean.

Yeah you're right....I think I misread your post, or had a brain fart.

[douglas vincent]

Interesting, don't know if its true. From Sport Compact Car.

"Another fundamental difference between turbochargers and superchargers is how each regulates boost. Turbos use a wastegate to bleed off the exhaust gasses driving the turbo when the desired boost level is reached. What this means is that turbos run a fixed boost level, at least in theory. In a perfect world, a turbo system with the wastegate set at 6 psi would make 6 psi of boost under all wide-open-throttle conditions. A supercharger, by contrast, runs a fixed speed relative to the engine. If a supercharger is geared to pump 1.5 times more air than the car breathes naturally aspirated, the boost will be different at different rpm. In the parts of the rev range where the engine doesn't breathe well, the supercharger's insistence on pumping air will cause air to pile up in the manifold, increasing more pressure. In areas where the engine does breathe well, there will be less of a back-up, and less boost. The end result is that turbochargers tend to simply magnify the stock powerband of the engine they are attached to, while superchargers are more likely to totally change the powerband to reflect the characteristics of the supercharger.
"

[douglas vincent]

And I just found this SWEET picture of my supercharger

[sammydafish]

this is pretty freakin cool... two Lysolm chargers though
http://www.lateral-g.org/distad/