Omicron

Nice! Now if I can just find out how much, if at all, they change the feel of the car in daily driving...

neit_jnf

What about keeping the siamese port's pulses together (no baffle) using equal lenght runners on the header but different diameters? Wouldn't this be a way to tune the pulses?

rotarygod

Different diameters wouldn't matter and probably wouldn't be a good idea since you don't want to slow down the inertia that the exhaust gas has. Velocity over volume. What would be beneficial is to use a different length center runner with a dead leg pipe off of it to fool the center port into acting like the outers. I really need to draw a picture.

wakeech

^^ what i was talking about before ^^, but he's the only one that actually knows what's going on with it.

thanks for the info on the centre shaft bearing: is it just another bearing as you'd find in the end plates, or a part from one of Mazda's 20B's with the 2 peice e-shafts??

rotarygod

Custom needle roller bearing.

wakeech

oh custom, hey?? and you say 12k rpm on a roller bearing?? woah.

...how's it get an oil feed?? tapped from the e-shaft?? er, wait... if so, how does it drain??

and just a reminder: it's past your bedtime

Dr. Lightspeed

Having been somewhat involved in several aspects of the canzoomer project I will tell you this. It really makes that little rotary rock hard. Nice drivability and fun to drive.

Having seen the poorly designed apex seals of this engine. Put this in writing " There is no way that engine will survive any substantial amount of boost and one bad batch of fuel will finsh that engine.

Too much compression.
Too thin of apex
Too popr of material in the Apex( you would have though Mazda would have gone right to the ceramics)

rotarygod

I'd still just rather find a way to mill out the rotor to use the Rotary Aviation 13B apex seals.

Dr. Lightspeed

There is already a nice 3mm solution just bolt a turbo on stock and you gonna have issues

slavearm

Here is some stuff Racing Beat is currently working on performance wise...

- Lightweight Race Rotors
- Exhaust Headers
- Engine Balancing
- Porting


I am thinking what we might not need to reduce compression to get good boost. If we can get some stronger seals, we should be able to run 12-15lbs. At least this is the impression I am getting for Rotary Reliability. I think Christmas time next year the market will start to explode for the RX8. Should make things interesting.

Rx8Freehk

Well hell, im glad to see a tread about something other than intake/exhaust, I personally am ready for more soon as its available, dont think ill try the NOS angle as i learned the hard way on my 13B (tried to install myself.....ahhhhh ill just leave it at that)

Red Devil

I'm with you Omicron, a complete packaged 400-450hp setup would be great. But I imagine with that much power the transmission will need attention.

When I buy the car in the spring, after the winter, I think I will purchase Canzoomer's Stage 1, and then concentrate on Suspension and weight reduction.

As someone else said, will just have to wait and see all the power options around a year from now.

Omicron

By the time crate motors become available with this kind of power, I'm sure stronger transmissions will be available too. :D

Me too, except I'm probably going to go pretty quickly to the Stage II with a high flow metallic cat, and I've already added a cat-back exhaust and better intake.

If you're after weight reduction, when you purchase your car, you may want to go with just the base model + sport package only. This'll save you some weight in power seat motors and other doo dads. I'd also be interested in what other ideas you may have for weight reduction... it's been discussed before here, and short of gutting the interior (which I personally am not willing to do for the few pounds it'll save) not many good ideas have been come up with.

Red Devil

I've noticed there aren't many weight saving options right now. But I'll be hopeful and see what the more mechanically inclined can come-up with.

Some things I've seen through the years, or what's been mentioned on the forum already:
-Fiberglass Body Paneling
-Lightweight Seats (loss of side airbags, correct?)
-Sunroof Motor Removal (T/GT package - Installing a removable top model saves about 18lbs on an FC)
-Complete titanium Exhaust
-Titanium Bolts/Washers/Nuts/Wheel Stars
-Carbon Fiber Strut Braces Front and Rear
-Replacement Titanium Chassis Braces (saw custom fabricated on a Vette, probably $$$$)
-Ceramic Brake Rotors (heard they don't last long, though)
-Lightweight Wheel (I've seen that the 8's are already very light)
-Racing Battery
-Aluminum Engine Housings
-Aluminum Radiator (always seem to be lighter than OEM)
-Flywheel

Perhaps at least some of those have potential, and none of which would sacrifice comfort or driveability of the vehicle. And the custom Ti work, I have no idea what it takes, or who was involved in doing the fabrication. I'd like to remove another 100-150lbs out of the car. But I do think that may be difficult.

As for the transmission, I'm sure upgrades will be available; I was more stating it because I think it is a necessary cost that is often overlooked.

And Sport Package is almost definitely the way I'm going. Not the GT, don't appreciate leather anyway.

RX-jimenez

WHAT ABOUT RACING BEAT?? DID THEY HAVE SOME THING NEW????

wardie

besides engine mods the best performance you could get would be weight savings, it increases performance in every aspect breaking, acceleration, cornering whatever, the only performance peice Ive seen that uses this idea was the full titanium exhaust, I personally would like to see more performance peices with this idea in mind.

RX-8 friend

Let's see:
Ignition - possible but expensive as there would be four boxes required and four coils. Would need to address the effective "leaning out" (see my post in main discussion - multi strike iginitions).
Underdrive pulleys - these will work, though in my opinion they don't give HP, they allow the engine to loose less when speeding up, and they could be effective in reducing cavitation in the water pump (a la 3rd gen RX-7). They are also pretty I don't see any problem with the charging system.
Porting/polishing - RX-7 Specialties in Calgary are working on this (among others). Adam has crate renesis engines to "play" with. I hear via the "grapevine" of some good progress.
ECU mods - limited to "piggyback" systems for now due to the extent the ECU has it's hands into the entire car. Canzoomer's stage 1 is in production/shipping. Stage 2 still has work to be done, but preliminary results are scary (to 3rd gen owners) as it puts the RX-8 at or past 3rd gen performance without turbos. It is "on the edge" enough that altitude compensation will probably be necessary to avoid detonation. This is already in the car BTW.
Transmission - this is an area that will need work soon. It's a unit from the Miata, a car with 150-170 HP. Torque is close to the renesis, but once we start getting up above 250 HP at RPMs of 5000-7000 the torque will surpass the transmissions' abilities.
Weight reduction - this is an area we can really benefit from. It improves performance without stressing the car. Question is, what did Mazda miss or "cheap out" on. e.g. My 3rd gen has steel brackets holding small pieces on the engine. By making replacements out of aluminum, I was able to drop 10 lbs in a few hours of work. That is what we want to find on the RX-8. Don't scoff at just 10 lbs, it adds up. Quickly. Read Yamaguchi's book on the 3rd gen RX-7 to see how.
Wheels - if you want to drag race, go smaller diameter with larger aspect ratio so the sidewalls can flex. This can greatly reduce wheel hop. You can get lighter wheels too, but you have to have good credit
Battery - I'd consider moving it to the trunk, but only to improve weight distribution. You would need a sealed one if you did this, and Optima now make a size 50 series.
This is getting long so I'll continue it later.

Red Devil

What about replacement of the PPF, if I'm not mistaken they are made of steel. Switching to titanium or aluminum - not sure if aluminum is strong enough for the application - could save a lot of weight.

Omicron

Nice, well thought out post RX-8 friend, please continue where you left off.

Coupla thoughts...

ECU mods - Could you elaborate a bit on the preliminary results of the CZ Stage II mod? (OMG! The RX-8 at or past 3rd gen performance without turbos? :D) What's the best GTech time and HP/torque estimates that've been obtained with the Stage II so far? Also, you say it is "on the edge" enough that altitude compensation will probably be necessary to avoid detonation, and that "This is already in the car BTW." Do you mean the altitude compensation is already in the car? If so, then why bring it up explicitly?

Transmission - I know there are Miatas out there putting out 350+ HP, so what are those people doing about the tranny? Is there a pre-made, stronger unit already in existance that would work for the '8? If the trannys really are the same, I would think there would be...

Weight reduction - Great way to go about it... I will start looking for bracket and metal bits that can be remade!

Wheels - Are you talking like 17 inch rims, or 16s, or what here?

RX-8 friend

Well, the stage 2 tests took the car into dangerous territory last fall (burned out coil packs, overheating, etc.) so testing was stopped until stage 1 was in production and we could figure out how to safely proceed. I'm told MUCH HP was seen but I'll believe it when I see it myself. The tests were abreviated due to the above problems. Understandable at those power levels, BTW. We are beginning to understand what caused the problems, and are becoming confident enough to proceed in the spring. Any who go this route should consider carefully if they really want to go into this extreme engine environment. It will mean you have to watch closely what is happening at all times. You -will- be close to the edge. Just like my car <- .

If you look just behind the ECU you will see a small black device mounted next to the shock tower with a short hose going straight down. That is the pressure sensor for altitude compensation. Stage 2 may require an input from that sensor (it feeds the stock ECU only on stage 1).

From the Miata people I've talked to, those with stock transmissions (6 speed) break them when they add turbos. The 5 speed Miata transmission is from the RX-7, and is strong enough (most of the time). Most of the turbo conversions have so far been done on the older cars, so there isn't a lot of complaining yet.

For drag racing, 17s I think. I don't think 16s will clear the calipers. The "hot setup" on 3rd gens is 15" on rear only, with 3rd gen spare wheels on the front (weight and air resistance reduction). 16s may clear the rear calipers on the RX-8.

Exhaust - (yeah, I know, this thread is OTHER than intake and exhaust) - BUT, no-one has considered 2-stroke technology. Yes, the rotary including the renesis is "4 stroke", but really it's a "continuous combustion" engine. There are no "strokes". Many people like to compare it to a 2-stroke, but it's similar only because it is "piston ported" (rotor ported). Now, in a 2-stroke engine, to extract "unreal" power (how about 150+ HP from a 500 cc), we use the exhaust pulses to suck the exhaust out and force charge the combustion chambers. This is not possible with a turbo (it blocks or interferres with the pressure waves). With a NA however, it is possible. What you do is put in a pipe feeding a resonant chamber just after the exhaust port. The end of the chamber is shaped to reflect the exhaust pulses such that the pulse exiting the engine lasts long enough to suck fresh intake charge into the exhaust system, and when the pulse wave reflects back it shoves this extra charge back into the exhaust port. This requires one to design the porting and the exhaust as one system. Yes, it will start to sound even more like a "weedeater", and yes, it will almost double the engine output (if the internals can stand that level of power). Oh, and yes, fuel economy means you can get from one gas station to the next .
Something I've always wanted to try, being a 2-stroke M/C fan. I think I've got Maurice enticed (he also is familiar with 2-stroke tech). Maybe sometime later this year....
Aero - next time.
PPF in aluminum is a possibility. As I recall, aluminum has to be thicker than steel for the same strength, but not enough to be as heavy. Could save perhaps 20 lbs. I don't think titanium is a cost effective option (unless you think the titanium exhaust is inexpensive - then go for it .

Red Devil

I agree that Ti is very expensive, and I don't know if it is, or isn't, much more labor intensive than Steel or Aluminum. I just like to throw around the option because of its inherent strength and weight advantages.

Omicron

Great responses RX-8 friend, and MUCH appreciated!

Hmmm, not sure I want to be that close to the edge, especially when I'm certain some FI kits will be out by the end of 2004 that will give the same or more preformance without going to quite this extreme. But we'll have to see what exactly the Stage II looks like when it comes out... I'm sure hopin you and Maurice will be sharing the development of this unit with us. DAMNIT, now I wish I lived in Canada, so I could be directly involved in this! :D

Ok, nice to know exactly where it is. Thanks.

A 5 speed? Damnit, but I like the 6 speed! Now I'll have to start closely following Judge Ito's development on strengthening the factory 6 speed...

Hmmm, interesting. This might just solve the wheel hop problem the '8 has on a hard launch with stock tires and pressures. So if I were to run 17s on the rear and 18s on the front, how would that affect my car's handling?

Now THAT's interesting!!! I'm sure we all will be awaiting news of further development on this with baited breath!!! :D

Ok, it's NOW next time... care to elaborate a bit more?

Sorry to appear ignorant here, but metallurgy is not my field. What exactly is PPF?


Thanks for all the great info!

neit_jnf

PPF = Power Plant Frame
It holds the engine, tranny and diff together as one unit.

Ti is more difficult to work on than steel or Al that's why it's so expensive apart from the actual cost of the material, of which I think would need less because of it's strength...

RX-8 friend

To reduce wheel hop you want to let the tire sidewalls absorb the grip/release that induces it. Next time your tires are off the rim, check out the sidewall stiffness of the 18" tires. No give. That's why the RX-8 has such bad wheel hop. So, you reduce the wheel diameter and increase the sidewall height (not 35 series but perhaps 50 series), and maintain the same -tire- diameter. This is for drag racing, remember. It will affect the handling in corners because the rear will "lean" on the sidewalls a bit more, so I would predict more oversteer if you did the rears only, which would be considered dangerous if it's bad enough (understeer is safe, oversteer is bad because the car can loop on you). So what 3rd gen owners have been doing is just buy two wheels and tires for drag racing, and put them on when going to the track or when they get there. Wheel hop is death to the diff. on the 3rd gen. That and rear half shafts. But only for extreme modded cars (more than 300 HP).

PPF - yeah, it's short for power plant frame. A neat addition to car design by Mazda. It's U shaped and bolts to the rear of the transmission. The driveshaft runs in the U and it bolts to the diff on the other end. As for cost, we used to call titanium unobtanium. It can be pretty expensive, just for the raw material. It work hardens so easily, it's really hard to work with. Just drilling holes in it is a nightmare (they use spark erosion machines when cutting holes for military aircraft). Hey, I've got some aircraft grade titanium 8-32 screws. I guess I'm rich!

Aero - I'll just post a little as I'm having trouble thinking straight with the flu right now. Amazing how much energy it takes to think! The rear spoiler is mostly used as decoration. To be useful (downforce) it has to be up pretty high (12-18") and pretty large. Look at race cars. It also does almost nothing until you get close to 100 MPH. Further, it adds drag. Much more effective is a rear diffuser. It goes under the trunk and directs air flow out from under the car. It produces downforce (again, above 100 MPH), but doesn't increase drag. Still looks cool, too . We'll have to wait to see if the RX-8 can benifit from it. With cars entered in a few racing series this year, we should see some wind tunnel work results soon. RE Am. is famous for these things.

rotarygod

In regards to the 2 stroke exhaust technology, some of those guys can do some incredible things with an exhaust. However the design qualifications between the Renesis and a 2 stroke engine are the exact opposite. A 2 stroke engine has to have a perfectly designed exhaust to get the most power out if them. You can have too good of a scavenging system on a 2 stroke engine. You can't on a Renesis or any other 4 stroke engine for that matter. On a 2 stroke engine since there are no valves, the intake and exhaust ports are open at the same time but not for the same duration. The key with this exhaust design is to be able to promaote good airflow out the exhaust port rather than the intake port and to not make it flow so well that there is alot of fresh intake air pulled out of the exhaust port. The exhaust port is slightly high in the cylinder than the intake port so that when the piston moves down, the air finds the exhaust port first since it opens just ahead of the intake port. The exhaust design helps continue pulling it out and makes sure the chamber is completely clean of exhaust gasses. Since the intake and exhaust ports are open at the same time for a while some of the intake air gets pulled in too. The exhaust needs to make sure that too much isn't pulled all the way through. 2 stroke technology relies heavily on acoustic tuning in the exhaust. This is why the pipes expand to a chamber of a certain size and then contract out the tailpipe. The expansion acoustically promotes scavenging but the contraction puts enough backpressure in the system to control flow through the cylinder. It scavenges yet has a controlled amount of backpressure all at the same time.

The Renesis has no port overlap at all. Even other 4 stroke engines have a small amount of overlap. With no overlap, there is no benefit from a 2 stroke exhaust design. We want as little backpressure as possible. We can't get an exhaust that flows too good. The expansion is benefical but we can accomplish the same thing in a collector and almost all race engines do. We do not want to add backpressure. The 2 stroke idea may be a neat experiment on a peripheral intake/exhaust race engine but on the Renesis it is the last design that we would want to try. A good idea but the wrong engine to try it on. There is alot to learn rom the people taht do design 2 stroke engines though. It is a very interesting topic for the technically inclined. Barnes and Noble has a 2 stroke theory book. Well, at least the one by my house does.