mazda to supercharge the rx-8?
 

here is the link to the article for those that want to read the whole thing. for those with short attention spans here is the pertinent paragraph:

"Whilst Mazda's engineers are quick to deny that they will produce a turbocharged version of the RENESIS engine, principally because of the effect that process has on exhaust emissions, they do acknowledge that they are working on a supercharged version. This supercharged prototype is officially limited to 206kW, but produces an incredible torque, said to be some 375Nm at 4000rpm. Our sources also tell us that the supercharged version will in fact churn out 238kW, and in racing form will be easily capable of producing 298kW (400bhp). "

someone else do the math for us 'mericans please

;)

Very impressive! :)

206 kW = 276 Hp
238 kW = 320 Hp
298 kW = 400 Hp

375 Nm = 277 lb-ft

Thanks for doing the math. I can now procead to droll all over my keyboard.

im not a big fan of superchargers cause i dont how they are,
i know how turbos are but not superchargers
i wont mind having a supercharged rx-8:)

is it possible to supercharge the Rx-8 using after market parts?

Theres pros and cons with both
Pros for S/C
No lag instant go
Less heat made by S/C
Con
Eats power as most are belt driven on accesory belt.

Pros for T/C
More power PSI vs PSI ie 8 psi turbo will develope more than a 8 PSI S/C but thats if both flow the same amount of air. You can not compare a T3 turbo with a 112 CID Possitive displacement Eaton blower as the Eaton flows almost twice the air as the T3
You can make more boost with turbos

Cons
A lot of heat a intercooler is a must
The all fearing LAG!!!!:eek:
then the plumbing takes up room and after seeing how the Renesis sits down in not a lot of room for this.

I like the S/C because its boost is constent as the Turbo relies to much on exhaust gasses and the exhaust fluctuates with weather.

As long as there is a Mazdaspeed upgrade kit (with factory warranty) for us faithful Mazda buyers investing in the first batch of RX-8s to help Mazda finance further development and production I'll be cool with it....;)

Then again, the aftermarket can come up with some pretty amazing power adders as well. :)

A supercharger would work well in the RX-8 since it produces boost right off idle, where the RX-8 may need it most.

There is a lot to be said about a tweaked naturally aspirated engine though, especially a 3 rotor....:D

This is my understanding, small though it may be. Relative to piston engines, rotary exhaust is comparatively cool, and this this makes catalyzed exhaust scrubbing comparatively difficult. (ie, reaction rates are exponential in temperature and w/o the heat, the bad things don't get removed from the exhaust. )

Turbocharging, while more efficient than supercharging because you are using heat that would have been gone out the tailpipe anyway in a N/A engine, further cools the exhaust, and would make catalysis even more difficult for a rotary engine. It seems agreed that it took some Herculean engineering on Mazda's part to keep the rotary alive at all, and turbocharging just makes the emissions problems worse. Seems like supercharging is the way to go in this case.

'Course, I could be all wrong. Anyone? I vote for a third rotor if more oomph is needed, btw.

I would love to see how they would place the side ports on the middle rotor..
It's probably easier to increase the displacement by making the rotors wider..

A supercharged mazdaspeed rx8 or rx7 would be awesome DROOL! :)

Edit: I can only imagine the modding potential of a supercharged engine (think '03 mustang cobra) smaller pully, some exhaust and intake work, hello 400hp :D

Rotary exhausts are typically far hotter than their piston counterparts. Finding an aftermarket exhaust that will last on my 12A powered RX-7 is a hard task due to the heat and pulsations. Now, I don't know about the Renesis, maybe they've solved that problem, but historically rotary exhaust has been hella hot. ;)

As for the S/C, I'm all for it, because it seems that it supplies the torque the RX-8 needs to seriously whip any contender's ass. Plus the rotary doesn't need any more turbocharging controversy. At any rate, if Mazda goes to forced induction, they better test these motors and engineer them for similar longevity as the N/A.

Matt
1979 SA22C
"No rotor, no motor."

Supercharging sounds good to me...but I thought they didn't work to well with such a high redline?

Wankel,

The point at which a superchargers power "comes on" is proportional to redline.

While for a typical 6000 RPM redline engine they would design it so that boost comes on strong at say 3000 RPM. For a 9000 RPM they will up the pulley size so that boost comes on latter at say 4500 RPM.

You'll still have to drive it higher RPM but a supercharger will still be possible.

-Mr. Wigggles

EDIT: to clarify, I am refering to hard acceleration conditions where you need the supercharger to be on. With the Eaton superchargers, as others below have mentioned, with low throttle at crusing speeds the Eaton will be bypassed and not making boost regardless of RPM.

Most newer superchargers (Eaton Gen 3 and Gen 4) have a vaccuum actuated internal bypass that, when not needed, opens up and allows the supercharger to free-spin. This seriously improves cruising efficiency. I have even seen people install an electric clutch (from an A/C compressor) on the SC to allow it to be turned on and off when not needed. The best thing with a positive displacement blower, is it will keep the fairly flat Torque curve that is so great about the RX-8... just move it quite a bit higher. I have even seen an intercooled Eaton blower on a Ford Escort that made it push out over 230Hp....

Even my '88 Supercharged MR2 has a clutch on the SC to only engage it when necessary. A small light in the tach tells you when the SC is engaged. Pretty cool stuff. The SC clutch is controlled by how hard you want the engine to work, which seems to be a fairly elegant solution (sure beats having it turn on at certain RPMs or throttle positions). The light will come on right off idle if you give it enough stick. :D

The New AMG Mercedes has the electro supercharger.

I have been in a few and they are like the turbos, but with power on tap when u need it.

Really nice.

It appears they are doing their electro supercharger on a 12 Volt power system. I thought it took a 48 Volt system to do an electro supercharger.

Anyway the gas figures as stated on the Mercedes website are interesting:

12 MPG City / 25 MPG Highway

Which I guess are pretty consistant for a 4400lb car with that amount of engine displacement.

-Mr. Wigggles

The AMG system only uses an eletrically actuated clutch to engage the supercharger to the crankshaft driven belt drive system. Exactly as an air conditioner compressor. Once engaged the supercharger speed is fixed to the engine speed.

The 42 volt electric systems are needed to have a supercharger that is driven by an electric motor. With this system the supercharger speed is independent of the engine speed.

A 42-48V system is only necessary for weight/size considerations. You can make an electric motor produce the same power using any voltage, but the lower the voltage, the higher the current has to be, so you end up having to have much larger cables and windings, adding to size and weight. A true electric supercharger has some interesting advantages/disadvantages. When it is off, it puts virtually no load on the engine (only the larger alternator, which is required, is spinning), which greatly improves cruising efficiency. The disadvantages are the complexity and required robustness of the motor control circuitry. The clutched supercharger takes the best of both worlds and combines them. It has no major energy losses while disengaged, and when engaged, it turns 100% of the mechanical energy into boost, while the electric has losses in the mechanical-electrical-mechanical conversions. The Electric supercharger was a good compromise for a while, getting a SC without the HUGE hit in the milleage, but it has little place in a modern car.

someone should do the acceleration calculations for the supercharged RX-8

hp:276 (production limited HP)
320 - "sane" number
400 (max hp)


torque 277 lb-ft
________
Lovely Wendie

Positive displacement
 

I think that Mazda would probably choose this order of superchargers
1. Lysholm
2. Inertial (geared impeller)
3. Roots