Omicron

Not since I last posted about it, but I'll see what I can find out when I get back from vacation.

Felix W.

No firm info,
just some rumors,
the procharger is the C-1
the smallest available...
puts out only5psi,
not good enough, needs complete revamp.
and don't expect it anytime 'soon'
did I menion it was being tuned by Canzoomer?

punishr

Just about every FI kit out there being produced right now is only putting out in between 4-6psi, so what would be good enough for you?

rotarygod

What's really pathetic is that it will only put out 5 psi at max engine rpm. Below that it won't do squat. Why spend money on a supercharger that won't even give you much benefit where you drive 99% of the time?

punishr

rotarygod, what is the reason these FI kits that are coming out are only putting out this type of performance?

rotarygod

First of all, I like Canzoomer and really appreciate his efforts for the RX-8 community but the only currently available unit I would use to tune a forced induction car is the Ric Shaw unit. This is assuming you don't want to completely replace it with a standalone such as a Motec. The Ric Shaw unit has far more control. Just being able to advance or retard timing across the board isn't going to cut it. We need to adjust timing split. We also need to do it based on load. We need a map sensor, etc...

If you are using a centrifugal supercharger, you are wasting your time. We need an upgrade that can provide a boost down low and hold it. A positive displacement supercharger or a turbo can do this. A centrifugal can not. Yes the car will be faster but for the money spent, it isn't worth it. it's not peak horsepower that makes you faster, it is average horsepower. Why upgrade to something that makes max boost only at peak rpm?

I think part of the reason why many forced induction kits are emerging with low boost is quite simply because of tuning. If you can't tune to the level you need to, you can't boost where you want to. The RX-8 fuel system also doesn't have much more potential left in it. If you release a kit for higher boost, you'll have to address fuel needs through new fuel injectors, pumps, etc. The other reason is probably just fear. These engines aren't cheap yet. If you blow one up you pay alot to fix it. It's all a matter of learning to walk before you learn to run.

I just can't justify paying $5K+ for a system that gives you the power output of a properly tuned ecu for a fraction of that price. The kit I am watching for street use is Hymee's. I feel his has the most potential. I am also watching Richard's axial flow supercharger project. Admittedly I don't like the fact that it will provide boost in the same fashion as a centrifugal supercharger which is increasing with rpm. The axial turbine is the most efficient form of compressing air though. It is also the lightest and requires the least amount of parasitic drag to make that power. If anyone ever tells you that it takes a certain amount of horsepower to compress a certain amount of air (people have said it on this forum before) just laugh at them. It does take power to make power. This isn't disputed. What makes me laugh are the people that thinks it always takes the same amount of parasitic power to make the same amount of more power. From this respect the axial flow is the best choice. I am more interested in it from a racing standpoint than anything.

Basically from a supercharging standpoint I want to see a twin screw for the street (Hymee's).

For the track I want to see Richard's axial flow.

I also like turbos so a nice turbo kit would be welcome. Please don't get into the complexities and problems of twin turbos though.

Tony Orlando

I agree completely regarding Centrifugals. I installed a Vortech V9-F trim on my 99 Miata. While it did produce more peak power, and the car pulled HARD above 4K RPM, it felt stock around town. This was on a car with RB headers, Flyin' Miata cat and RB exhaust. The "punch" that the car lacked down low was still not there. Sure, it was fun to wind out on the on-ramps and in the occasional "contest" at a stoplight, but it was almost like running a small shot of N2O: Useless for autocrossing and day-to-day.

Anyone wondering about FI and the "horrifying parasitic drag" of Superchargers should read "Supercharged!" by Corky Bell. The Twin-screw design is not only the most efficient, but will provide what our cars lack: Low end torque.

I applaud those involved for making this venture, and the car will no doubt be fun to drive with the revs up, but those of you looking to transform your car into a stoplight hero will be badly disappointed.

shelleys_man_06

Either way, forced induction takes energy to make energy, otherwise the First Law would be completely wrong. I have been skeptical of centrifugal superchargers. They seem to work well on large displacement engines, like the LS1 and the 4.6 MOD. I've seen one successful application with Vortech's Civic. However, that was the only example of a small-displacement engine with a centrifugal type. ProCharger has a decent kit for the 350Z, however, James Chen has a knack for destroying these things. Personally, I feel more comfortable with a turbocharger, or to a lesser extent, a twin-screw compressor.

Tony Orlando

They can work well, but don't deliver what most people are looking for: Seat of the pants improvement.

About a year ago, Car and Driver had their "Superfour Challenge". A bunch of aftermarket companies brought out massively modified 4-bangers and duked it out in 10 tests. The Winner by a landslide was a Comptech S2000. Peaky car from the factory with a Centrifugal added. My Miata was another example of a car that didn't feel as fast as it was. I ran a 14.0 in that car with practically no experience, but it felt sluggish around town unless I buried the tach on each shift.

Was it fast? Hell yeah. But I'll guarantee that most people would rather drive a car with a roots or twin-screw SC simply because of the punch it produces at low RPMs.

bowman

All this discussion on superchargers is great, but what about the Sunflower Mazda car? Any new info?

punishr

Thanks Rotarygod, I appreciate the info. I too am looking forward for Hymees' project to be completed so I can hopefully see some real results and numbers.

rotarygod

Actually I posted wrong info on the axial flow boost curve. I incorrectly stated that it's boost curve is similar to that of a centrifugal supercharger. That is wrong. It is actually closer to a positive displacement supercharger! Avoiding the complexities of how this is so I'll just say that it has to do with the gearing.

Jump120MPH

anyone know anything new info?

davefzr

Bump for a sweet thread.. Any takers on sharing info?

ie... Omicrom.. StealthTL..

Omicron

I'll see what I can find out next week. :D

davefzr

Sounds good to me!! Thankx for that...

I read in the latest issue of RX Tuner that both Sunflower and Pettit are taking orders for their systems. They must be pretty darn close if they are in that mode now.

Before I buy one though, I would want to test it out. Maybe a few trips will be in order to test these systems out and finally make a decision on which one is best.

As I understand it, both Pettit and Sunflower and producing about the same claimed hp/tq increase (50).... Is that still correct?

rotarygod

Don't judge performance based on numbers. If the Pettit kit averages 50 ft lbs of torque more across the rpm range and a total of 50 peak horespower more than stock, it is going to be faster than the sunflower kit. The sunflower car uses a Procharger which is a centrifugal supercharger. It is only running max boost at max rpm. Below this it isn't and at low rpms you hardly have any boost. Contrast this to the twinscrew arangement of Pettit. If they have max boost by 1/3 of the total peak rpm, they have a ton more usable power everywhere it counts. Remember that peak numbers mean absolutely nothing. They only help sell product to the uneducated. It is average power that makes you faster. If the Pettit kit and the Sunflower kit both make the same peak horsepower, the Pettit will absolutely walk away from it in a race. It wouldn't even be close. Why anyone anywhere uses centrifugal superchargers such as Paxton, Procharger, Powerdyne, Vortec, ect. is beyond me. The higher the engine rev limit, the worse of a match for an engine they become.

davefzr

The numbers on the Pettit car were terrible though. It only ran a few tenths faster than a stock RX8.

If it indeed made 50 hp/tq more than stock and max boost is considerably sooner than what the Sunflower kit is offering, why didnt it run faster?

Let me guess.. Tuning.. Tuning.. Tuning?

rotarygod

Yes, yes, yes!!!

davefzr

Anyone find out more info?

Icemastr

The strengths of a centrifigual supercharger are high effiency, ease of combining it with an intercooler, and easier adaptability for mounting it. Just because it doesnt reach peak boost right away doesn't mean it isn't making power, if you compare a centrifigual supercharger to a stock basemap it is going to make a power increase across the entire RPM band, of course you would expect this but I think if you compared data and dynographs on centrifugal superchargers vs stock you might be surprised how much more significantly power is raised in the low RPMS. No it isn't quite like a positive displacement supercharger but the higher top end is certainly a benefit. You are treating centrifugal superchargers here like they are peaky and only make decent HP gains from 7000-9000RPM or something when this is certainly not true.

The large problem seen with turbochargers on the track is not the RPM it takes to produce, although this is a slight problem, but rather load and keeping the turbo in boost, where when you left of the throttle and then get back on it it takes time before it builds boost again, a.k.a. poor throttle response. When you are racing whether it be autocrossing, drag racing, or road racing an engine like the rotary is going to be in the 4500-9000RPM range almost all the time optimally, exactly where a centrifugal supercharger is producing plenty of power, and because of the centrifugal supercharger being belt driven as long as you keep the throttle volume to a minimum you can still maintain excellent throttle reponse, exactly what you want for racing.

The centrifugal supercharger will definitely fill the need for a large niche of people to say that it is not way to go at all is ignorant. I for one am some one who would certainly spring for a centrifugal supercharger on an RX-8 because of its driveability characteristics. A slight increase in power at lower RPMS and a large linear power gain as the RPMS increase will liven the car up but still leave it easy to drive around town without roasting the tires off. For drag racing its high peak HP would certainly work well, in a road racing/higher speed situation I could also see it being very competitive, and in an an autocrossing situation I think a positive displacement supercharger might have an advantage, I think the centrifugal could hold its own. Its compact package will make it easier to install as well.

However as far as the RX-8 is concerned which forced induction you go with isn't as large of a problem as the tuneing, this is the most important key to building a powerful RX-8.

Take a look at this centrifugal supercharger dyno of a 1.8L Miata as an example. A 25% increase in torque at 3000RPM with a steady increase and maintaining the torque out to high RPM. Exactly what I would liek to see in an RX-8.

http://www.vf-engineering.com/images/mx5dyno.jpg

With my knowledge of centrifugal superchargers and research of its use on various engines I speculate the centrifugal supercharger will increase the qualities many of us like aobut the RX-8 so much, smooth high revving with strong building HP all the way to red line. If you want lots of low end torque why not just buy a car with a V8?

rotarygod

Or you can just use a twin screw supercharger and have the best of both worlds. If you like the centrifugals, you can keep them. You won't fool me into thinking a centrifugal at 4 psi at 4000 rpm has more midrange than a twin screw or a turbo at 8 psi there. More than stock, yes. More than anything else, maybe an inefficient roots but that's it. That's not ignorant. That's logic.

mtnpass

I have to agree, I know there are many variables dealing with proper sizing of turbo or twin screw but volume of air still exceeds centrifugal

globi

Now without discussing all the points over again. This is another example of a supercharger, where it would make sense to have it electrically powered (since it is independent of the engine speed).

davefzr

Find out anything Omi?