The MP90 is the better option, and they are not too hard to find for cheap. I purchased two brand new for $275 about 2 years ago.

The assumption that using a 112 is better is off. The Eaton units are only rated to ~13 K, but in reality are good to 20 K with no issues. The faster these units are spun, the higher the Ve. The drop in adiabatic efficiency at higher rpms is negligible as we're not discussing high boost applications. And the 112 would be more difficult to package. The 90 series is good for about 10-11 psi.

Someone else commented about sourcing a shorter snout - Magnuson or some other outfits that rebuild the units typically have them and the MP90 and MP112 snouts are interchangeable.

If you're going positive displacement, look for a MP90, get the shorter snout, and if possible run off a 6 rib or greater pulley to alleviate excessive belt tensioning.

 

The VE charts I have seen suggest otherwise.

So do the shredded blowers that have been spun over 16k. Maybe for quick drag use they will tolerate overspeeds like that, but the lobes WILL expand and scour the case.

The sweet spot in the efficiency curve is about 5-6psi.

 

This isn't drag use. This is year in year out daily driver and track day usage.

If I were building a setup, I'd be skeptical and not exceed manufacturer specifications. Having actually built from these units and first hand seeing how they've reacted, I now have much different thoughts.

Edit: Please post the maps where Ve is falling as rpm of the blower is rising.

 

I haven't found too many if any good feedback on superchargers on rotary engines. I would rather put a 75-150 wet shot nitrous system on a stock engine and put the extra $3000 in my pocket. Or if you wan't a good power system, then get a nice turbo setup. With the money you spend on a supercharger and the power and problems that come with it=

 

^I explained why in my first post. The only supercharger systems anyone has ever seen on a rotary used the most archaic and oldest (least efficient) types of syperchargers out there. While I'm not going to get into a technical debate of superchargers vs other power adders, I will say that a nice supercharger done properly can actually be quite nice and they definitely shouldn't be discounted. As far as nitrous goes though, it is my own personal opinion that they have no business whatsoever outside of a drag strip and are useless on a street car.

 

Well stated.

 

Superchargers on a rotary suck ***, end of story. If you can't understand why a nitrous system would work well on a street car, then you obvious now nothing about nitrous systems. You can drive on stock engine and get great fuel economy and then when you want to race someone next to you or just feel the need for speed, then all you would need to do is flip a switch. They have electric motors that even turn the bottle on and off. With a supercharger and turbo system you will always burn more fuel and get shitty fuel economy. The reason very few uses nitrous is because there are very few people out there that know how to set them up properly and tune the motor for nitrous. It's actually the cheapest way out there bar none to get the most horsepower, regardless of engine type. So useless? Think again.

 

I hate to pick sides, but I'm sticking with Rotarygod on this one also.

First what you're describing is street racing which isn't really legal at all.

Secondly, you constantly have to refill bottles. What happens if you run out through one of your races? Oh sorry I can't race you I ran out of juice?

Thirdly, if nitrous is so good for any car, how come only professional dragsters use it? You'll never seen anyone on a road course, rally, or auto cross use it. When was the last time you decided to over take someone on a road track on corner exist and said hmm ... I'll use up my nitrous now to sling shot from him.

Lastly about fuel economy, why do you think more an more manufacturers are putting turbo chargers on cars now a days? To increase engine efficency, in both power and fuel economy. Look back about 15 years and see how many turbo charged cars there are vs now a day. Its not like you have to be in boost all the time, you could be on the highway and still be in vacuum.

 

How many auto manufacturers offer nitrous as an option? NONE! Why? It's not a useful technology on a street car. Period. End of story. It's only useful on the street for street racing which is illegal and if you take part in street racing of any kind in any way shpe of form including even watching others do it then you are a complete moron. Game. Set. Match.

 

Uh, we are talking about a street car, not a roadtrack or rally car. Obviously a nitrous system would not work in a long circuit style race, but for street and drag racing use it is hard to beat.

How come Mazda has never and never will ever use a supercharger on a rotary engine. How come none and I mean absolutely zero top racers of any kind use a supercharger on a rotary engine? And if your not racing on the street or anything like that in any manner, then why put a supercharger or any kind of aftermarket power adders of any sort? So you can go fast up to the stoplight?

 

there actually is a few guys with chargers racing in the fore front of racing,

 

i agree that nitrous is useless on auto x and circuit HPDE nasa motorsport events, i would go to the supercharger route that your going rxcookie, i was wonder on your setup your thinking of are you going to retain the 5th and 6th ports as well?

so far on earth there is only one car that comes with nitrous and its a ford focus saleen from factory,
i can see why your going with the supercharger setup, i also had plans a few years ago about a linear powerband to feel NA around poconos raceway on hpde days. but i've driven some 6 port turbo setup using stock S5/s4 turbos with a rtek 2.0 tune makine around 230whp and with good suspension the car will handle great and not have a big impact on boost spiking when going into boost, you'll feel a minor pull thats about it.

 

http://www.magnusonproducts.com/mp90.htm

Ok, I took the time to pull some data for the mp90.

As can be seen in all of these units, you really need to get these things going past 10,000 rpms to take advantage of the Ve aspect that is so important to maximizing the benefit of one of these units.


As for the SC vs. Turbo arguments...these are just ways of adding power, that's it. The amount of emotion that gets thrown around the issue is out of place.

 

^I'm sorry, I somehow missed that you arent' drag racing. I saw track and thought drag racing. I also posted that nitrous would obviously be out of the question when circuit racing. My main point I was trying to get across is that for street/strip nitrous setups is the best bang for your buck.

But in regards to superchargers. I think you be would be much happier with a turbo setup than a supercharger. There's a reason why there's hardly anyone using superchargers on rotaries in the race industry or on the street for that matter. Just look whats' being widely used on the market. If superchargers were that good, then everyone would be using them, including all the top racers. I think with the low torque and small/ high powerband, the superchargers just don't work ideal with a rotary. Good luck on whatever you decide.

 

Just because something isn't used on the race track doesn't mean that it doesn't have merit on the street. The reverse it true as well. Just because something is used on a race track doesn't mean it has merit on the street. Nitrous being a good example and even then only in drag racing. It isn't the best bang for the buck for a street car because it has no place on a street car. It's not a viable option. Only 2 things are viable power adders for a street car aside from porting, a turbo or a supercharger. Regardless of which one wins the overall game on paper, it doesn't mean that this is the only possible viable option. A turbo isn't ALWAYS better!

What is that strange looking device mounted to the top of the Z-06 engine or the Cadillac CTS-V engine? (same engine) I don't want to get into a semantics argument of turbos vs superchargers because I know good and well the advantages and disadvantages of each. That's probably why I won't argue only in favor of a turbo. We all know that on paper in an all out no holds barred attempt at power and efficiency that a turbo is superior to a supercharger. Fortunately only a fraction of the people actually try to realize this potential. However a turbo isn't always the best option. It is usually the cheapest though mostly because there are so many of them out there and is a huge reason why they are the most popular. A supercharger certainly has it's place and there are times where it does have an advantage to a turbocharger. Obviously it isn't always better but where it does shine is on the street rather than the track. Keep the supercharger to the street. Keep the nitrous to the dragstrip. A turbo does have the most flexibility and could be used in any situation if designed well. It doesn't mean it is always the only viable choice though.

Why hasn't Mazda used a supercharger on a rotary before? What kind of logic is that??? Why hasn't Mazda ever used nitrous on their cars? Why was their most successful race car naturally aspirated rather than a smaller turbocharged engine? The rules would have allowed it and just so you know, the rotary was never banned. It was only limited, along with every other engine of a certain size. Come on man. That's a pretty weak argument.

Mazda has used a supercharger before. No it wasn't on a rotary engine but they also have yet to install a turbocharger on a rotary engine that isn't a complete piece of crap. The TII turbo is a terribly inefficient hairdryer. They could have definitely matched that turbo's max potential with even a modest supercharger. For reasons only they know, they chose not to use one though. Then again supercharger technology, as with turbo technology wasn't what it is today. Keep in mind Mazda has played with a roots blower on a Renesis. They have also played with a turbo on that engine. They know good and well that they each have their merits. The twin turbos on the 3rd gen were also terrible pieces that destroyed themselves from all of the heat. Yes they could make good power and had good drivability. When they worked. Their life was short though and will all the extra heat they produced, they also led to shortened engine life in those cars but there were also other issues that contributed to that as well. For a car manufacturer, a turbo is a cheaper option. Obviously there are some cases where they prefer a turbo to a supercharger and vice versa but the accountants have just as much say in the final product as the engineers and designers do.

The biggest thing hurting the image of the supercharger on rotaries is that the only kits that used them used horrible superchargers. We also don't see people building their own nice kits either as turbos are quite cheap today and many kits just directly bolt on with minimal work. A supercharger is going to require a greater degree of custom work to make fit. If there were more people installing them and doing them well, excitement for them would increase. Most people are budget limited though and a turbo is probably going to fit best within a smaller budget. Not everyone wants 400+ hp. Sadly if anyone does install a supercharger and doesn't hit 400 hp, many others will discount it as a complete waste of time which is again, sad logic. I'd be completely happy with 250 at the crank.

 

All I know is when my charger is going on the car ... I'll be aiming for 300whp tops, because having been in a car with that much power is quick enough for me. I'll never be a dyno queen.

 

The coming thing is twincharging. Postive-displacement blower with about a 1.5:1 pressure ratio, and a turbo running about 2:1 pressure ratio blows into that. (They aren't in parallel like VW does it)

The blower provides instant response, so the turbo can be sized for power instead of response. And the turbo is getting "30psi boost" worth of exhaust pressure but only has to provide 15psi boost by itself, (or "7psi boost" worth of exhaust before it's even doing anything) so turbo response will naturally be better anyway.

People who've done it say that, when matched properly, the engine can and will do a seamless 30psi from near idle to wherever you feel like putting redline. Needless to say, I've been aquiring the bits to do this with a VW four-cylinder, the main problem with which is having a transmission that can handle that kind of torque.

 

Quick correction: The ZR-1 is supercharged, the Z-06 is N/A.

 

Uh, the reason you won't see nitrous from the factory in a production car is because it's illegal in most if not all states. But then again driving on the fwy at 80mph like everyone does is too.

For the cost vs power made, the supercharger is last on the list. And yes race teams are a good aid to look at products on cars because they spend millions on research on what works and what doesn't. There isn't one drag racer that I know of that is using a supercharger. Mazdatrix even tried it on their 3 rotor car which was an abortion. They have been trying to sell that pile for years now. You can Bridge a 13b N/A and make the same amount if not more than stockport with a supercharger. Why spend thousands?

And the reason why you see many superchargers on v8's is because they have low torque and power to begin with and the supercharger works great with this combo.

 

There's power, and then there is power delivery.

Superchargers are awesome for drivable forced induction. Notice that even Audi is on the blower bandwagon. (The "3.0T" doesn't have turbos like the 2.7T did - it's got a blower nestled in the valley)

 

Superchargers are becoming few and far between with the low cost availability and reliability of turbo systems these days. There's very few production cars being made with superchargers. Most have gone to Turbo or N/A. I'm a master tech for Mercedes Benz of 16 years and Mercedes used to make many supercharger models in the V8, V6 and inline 4 engines. They have stopped making these years back and have now switched to turbo and N/A engines now. Remember it takes horsepower and more fuel to make a supercharger work and turbo's are driven from the exhaust. Better power and better fuel economy and cheaper more reliable= Supercharger last on list.

 

Turbo power isn't free, either. Just because the crankshaft isn't turning it does not mean that there isn't a power drain.

The main reason we're seeing more and more turbos is because turbo technology, combined with the mass availability of direct injection, is making it a much more seamless driving experience. This is not technology available to the aftermarket - the housings and blad shapes and so forth are being fine-tuned to each individual application, instead of just pulling existing designs off the rack.

Then the EPA will ratchet emissions down again, and the turbos will thin out again as the OEMs try to get even cleaner on the cold-start emissions...

 

I really like the idea of supercharging because of the simplicity, less clutter, and its different. Now Whipple has a new design out that is super efficient, the lobes dont contact the inner case or themselves, so there is very little "drive" loss but its pricey. Another thing i would love to see a top mounted setup with some kind of "sandwich" cooler, stock efi, with a M90 since i am very serious about trying it myself. Its just i dont have any parts what so ever and im wondering if i would have clearance with the hood and put the stock throttle body on the back of the unit.

PS: i have all the means of fabricating all of these small bits, i would just like to see some stuff before i attempt.

 

Nobody listen to what this guy has to say because he isn't reading the thread creators application at all.

superchargers on any ICE is awesome and have benfits and cons just like turbos or other modifications, more air more fuel more spark more power. Its a simple formula.

why would I want to drag race illegally or drag race at all? my car is setup for rallyX I like my mid range torque and if I was doing stage rally I would need more power to be competitive so I would likely go with a similar 300whp build using a supercharger to get even more linear powerband

yes it is true that the rotary supercharges that are available are ANCIENT! You don't see anyone using a centrifugal supercharger on a rotary that is of a recent design or hell even something like a rotax: http://www.rotrex.com/Home.aspx

I don't want, nor does the thread creator want a nitrous system, its completely impractical for his specific needs and application.

people have been using nitrous for years! the ****'s put it in their airplanes, its not that hard to set up even with the most advance nitrous kit, you just hook up some hoses, mount a bottle and wire up a solenoid or switch or two and thats it. If you **** that up, you probably shouldn't be putting nitrous on it.

so what if nitrous is cheapest power, it has a limit of practicality and useage and most of us choose not to do dumb **** like racing on the highway against some punk kid in a civic, we have better things to do and take our racing on the track where it is more fun and potentially more sideways.

And lastly, you drive a rotary, why do you care about gas milleage?

but yes S/C on a rotary is pricey, but then again. everything is and if you wanna do it right you gotta pay to play or you're going to pay more in the long run.

 

I already said like 2 times that nitrous is not an option for a road race car. Try and read next time. And my other main point is that you can make more power and more reliability and spend less money with a turbo setup so why buy a supercharger? No one or should I say very very few people are using them on a rotary for a reason! That's it I'm done, go waste your own money on a turd. Like they say, you can't polish a turd. Just remember when all the turbo guys are passing you I told you so.