Charles R. Hill

iTrader: (7)

I am fairly confident that the Renesis is most likely able to handle the same levels of boost as seen in the FD. The thing is that the lighter rotors may be a limiting factor and may need to be replaced. One other thing is engine management and the systems that have yet to be made available. In other words, I think the engine, itself, can handle some serious levels of boost(minor problems such as the intake manifold aside) but we don't have the ancillary items such as EMS's or fuel controls that may be necessary to derive the full benefits of FI, yet. That's why I chose nitrous; there is much less extra-curricular hardware needed to achieve similar levels of h.p. boost(also less hardware to upset the 50/50 balance). In had a feeling that the "w.h.p." question would come up. My opinion is that the h.p. drag inherent in the RX-8's driveline doesn't change when the h.p./tq. of the engine is increased. So, the answer to the above question regarding wheel h.p. is that the 80 h.p. boost at the engine that comes from FI should be fully realized at the rear wheels, as well. Of course, this 16 h.p. per pound formula ignores such variables as intake/exhaust manifold design, intercooler efficiency, and other things that must be modified to make a turbo/s.c. system work on the RX-8. It's an over-simplified formula that is only useful for "bench racing" or guessing what the performance numbers might be with certain levels of boost. Many members who have actually dynoed their 8's are reporting r.w.h.p. numbers around 178. I use that as my basis for calculation so adding 80 h.p. would result in a r.w.h.p. figure like 258. It seems reasonable enough to me, anyway. Anyone with a different perpective?

Charles

RX8_Buckeye

I was going to disagree with you on this point, but as I was writing my response I realized that you're right. The friction loss in the driveline is only a function of rotational speed, so any increases in flywheel horsepower should be seen at the wheels. I remember people claiming that the RX-8 has a poor driveline design because there is as much as 15% power loss from the flywheel to the rear wheels. But really, it's the absolute horsepower loss that's important. A 30 hp driveline power loss in a stock RX-8 is roughly 15% of flywheel hp (assuming 210 fwhp and 180 rwhp). If the Renesis generated 300 hp at the flywheel, the driveline loss in terms of percentage would be 10%. So it's actually invalid to evaluate a driveline based on percentage of flywheel horespower lost at the wheels.

davefzr

Yeah.. all that being said.. over $10,000 installed with all the bells and whistles.. any takers?

I know I cant do it right away.... Thats just too high for me.

Magic8

That is waaaaayyyy out of my price range. I can't even think on how I can justify it to myself, nevermind my wife! $4000 to $5000 seem more in my price range. Why is the cost so high? I imagine these places are trying to earn back some development dollars, but that's a lot of $$$.

TALAN7

I think you'd be better off waiting for Mazda to come out with te turbo or sc RX8.
I know it's going to be a while but in the meantime if other systems come out and the prices drop then one of these systems seems feasible. I knew when I purchased the car that I was never opting to purchase a turbo system. It's just too expensive. For 8 grand I'll just by a faster car. I'm looking for a reliable ecu or retune, a cai, exhaust, and ligtweight flywheel. I figure this will give me acceptable power.
Are superchargers cheaper than turbos? If they are, that may be the way to go.

Spazm

7-8k would be pushing me...but 10k? I know pissing on the last 2k seems irrelevant once you hit that level of spending, but really 7-8k would really be pushing it for me. Once I have a turbo, wheels, and all the bells and whistles...you'd be talking nearly 50k. I love my RX8, so I'll eventually get there...but I would much rather get there with a SC/Turbo that is in the 4-6k range.

But when all is said and done, I will definitely give this a look anyway. After all the flack that others have given you (including myself) SSR is really going out on a limb here, and I wish them the best of luck!

Charles R. Hill

iTrader: (7)

Buckeye, it seems as though we, and other cars as well, have roughly 60 h.p. lost between the fly and the wheels. I am guessing we might drop that 60 to 40 or 45 with a 9 lb. flywheel and maybe another 2 or 3 with pulleys. I can't see how people can complain about our drivelines when they come from the factory with a carbon fiber shaft. That brings up a strange dichotomy with the 8. When I look in the mags at what others do to raise the performance levels of their respective vehicles, I see that we RX-8 owners already have it from the factory. 18x8 wheels, 13" and 12" rotors front and rear, short shifter, and on and on. That doesn't leave much room for improvement, does it?

Charles

IKnowNot'ing

Nope, superchargers are not cheaper than turbos, sometimes even more expensive. However, their integration is sometimes easier and requires fewer and less expensive parts (a new exhaust maifold is not needed for a start). At low boost, with efficient s/c, you can even live without an intercooler. You will therefore find s/c kits at a lower price than turbo kits.

punishr

I think the price of these kits will definately come down a bit when more than just one company in the US is selling a turbo kit. It seems to me they are trying to get every penny they can right now knowing they are or will be the only ones that has a kit available at this time....

shelleys_man_06

The best advice right now is to sit back and let the competition between turbo kits increase. $6000 is way to much for a turbo kit. This doesn't include installation . I wish I could say that the turbo kit is a sound one, not to mention worth the kidney, but I haven't seen any performance numbers as of yet. I am also concerned about the tuning aspect of it. From what I hear, turbo kits aren't as flexible as custom-made, though the latter is much more expensive. I wonder if these companies figured out the PCM? I will always believe there is some power to be found in the computer. There is one day going to be a point where piggy-back controllers are useless. Nevertheless, 7 psi would make this car a real competitive street machine . If anyone here is concerned about the air sensors, check out this ongoing thread I started. Oh, and BTW, I don't think the RX-8 needs a MAP, according to the responses I received .

https://www.rx8club.com/showthread.p...0&page=1&pp=15

RX8_Buckeye

My understanding is that lightening the flywheel and/or driveshaft does nothing to reduce friction loss in the driveline. Instead, it increases performance by allowing the powertrain and driveline to achieve higher rates of angular acceleration. The simple equation explaining this is: (Torque) = (Torsional Inertia)*(Angular Acceleration). Rearranging yields: (Angular Acceleration) = (Torque)/(Torsional Inertia). So by reducing flywheel inertia and/or driveshaft inertia, a higher rate of powertrain & driveline angular acceleration is achieved, thereby increasing overall vehicle performance.

I could see how the pulleys would have a direct impact on power loss due to friction. In terms of reducing powertrain & driveline friction loss, bearings are probably the single most important components. However, I am not very knowledgeable about any potential gains that could be made by upgrading engine, transmission, and driveline bearings. If anyone has knowledge in this area, I'd be interested in learning more.

The size of the wheels brings up an interesting point of discussion. I just read in another thread that better straight-line acceleration can be achieved with smaller, lighter wheels. I'd definitely agree with the "lighter" portion of this statement, for the same reasons as a lightened flywheel or driveshaft. However, I'd debate the "smaller" portion of the statement. For any given amount of torque at the wheels, having smaller diameter tires gives you more tractive force, since (Tractive Force) = (Torque) / (Rolling Radius). However, the car will travel less distance per revolution of the tires. Larger diamter tires give you less tractive force, however the car travels further per each tire revolution. Which is better for acceleration? This is along the same lines as the age old "horespower vs. torque" debate--torque doesn't take time into account, while power does.

Genom

However those smaller tires also require less force to turn then the normal ones, hence the engine can rev up faster.

Charles R. Hill

iTrader: (7)

Jeff, thanks for the specific numbers.

Buckeye, I come from less of an engineering background and more of a background in drag racing. Of course, I have some level of engineering knowledge as a necessary component of understanding why certain things work and don't. You and Shelley's Man are way ahead of me in the engineering department. The point is that I am less concerned about some specific numbers such as driveline loss and parasitic loss and more concerned about what can be done to lessen the effects of each. I don't recall using the term "friction" in previous posts, btw. As far as calculating driveline loss I wonder why some still prefer to throw percentages around rather than evaluate these losses as a specific number. I apologize for the digression but I am trying to understand how certain lines of thought are construed and developed.

Charles

olddragger

iTrader: (3)

Hey Buckeye
You sound a whole lot smarter than me but I 've always thought that the smalled diameter wheels affects the final drive ratio allowing quicker acceleration. There are of course limits to this but isn't that the basic principle? For some, changeing to a 17" vs an 18" is much easier than changing the diff gears to find the "zone" needed for better times in the 1/4. Oh an by the way we are talking about the 8 here. Torque is a word we don't use very often!
olddragger

shelleys_man_06

Haha. I wish . Heck, I'm only a junior. Two more years and I can be a professional BS-er :D.

RX8_Buckeye

Charles: I understand what you're saying. The lighter flywheel will definitely increase the responsiveness of the powertrain/driveline, even though it does nothing to reduce friction losses. I just assumed you were talking about friction loss because it is the main source of driveline power loss. Regardless of terminology, I think we're on the same page. As I stated earlier, I agree with you that driveline loss should be stated in terms of horsepower at a given engine speed and gear position. The percentage method of representing loss can be misleading.

olddragger: I'm sure I'm no smarter than you. Maybe I know a few more engineering equations than you, but I'm sure you have more practical car know-how than me. You're right--using smaller tires is essentially increasing your final drive ratio (more tractive force at the wheels while sacrificing vehicle translational motion per engine revolution). What I'm questioning is how useful is this increase in final drive ratio? Maybe a small increase is useful for the RX-8 because of its relatively low torque output--but there has to be some limit at which increasing final drive ratio only hurts performance. For instance, you wouldn't want to use the final drive ratio of the RX-8 in a torque monster like the Ford GT. That would kill its straight line acceleration performance.

GeorgeH

iTrader: (2)

When viewed in an absolute sense, a lighter flywheel will not generate additional power. However, when you measure horespower by parking the car on top of some heavy rollers, and then recording how fast the car can spin the rollers up, reducing driveline intertia should result in higher power readings. Which is to say, the lighter flywheel "frees-up" torque that can then be used to spin the rollers up faster, hence the higher power readings. The actual increase may or may not be measureable, depending on the gear you use during the dyno run (lower gears will show greater improvements) and the weight of the rollers.

Also, smaller diameter wheels will absolutely increase overall performance by increasing tractive forces. Just ask a CSP'er Miata owner - going to 13" wheels really makes the car much more punchy. It is the functional equivalent of a lower final drive ratio (as already noted). Of course, you've also lowered the peak speed of each gear. So, to be completely correct, the car will accelerate better with smaller wheels at all speeds, except those where you would have been in a lower gear with the larger wheels. So, dropping the gears 5% would make the car feel faster, but dropping it by a much larger percentage would just make you shift too much and kill any advantages. Make sense?

RX8_Buckeye

Yep, exactly. Nice summary.

shelleys_man_06

I made a post somewhere in this forum about flywheels. But, I believe GeorgeH explained it quite well. No one likes math . But, for those who are interested,

https://www.rx8club.com/showthread.p...light=flywheel

IMO, the only real numbers that matter are the track results.

bam_bam_39

I "curb checked" my rims about a month ago and I was forced to put some 17s off my old 99' prelude on my car( the 8). I could tell a lot of difference in the straight line performance. I look at it like this since it takes less power to turn the smaller radius it helps in acceleration, but it also takes longer to hit the top speed "wall" that everyone has hit. With 18s on a closed course road my speedo said 149 with the 17s it said 156-7(it went up, then down, then up, then way down again).
So im figuring that the top speed would actually be about the same since your prolly closer to the engines peak horse power and it takes more to hit the "wall" even though your not covering the same distance per revolution. Your just getting more revolutions out of the engine.

punishr

Come on August 1............
Can't wait to see some #'s......

SSR Engineering

We had it on the dyno and something is wrong with the MAF Voltage, it's uncontrollable even with this ric shaw computer :o, it could be a number of things ranging from pipe diameter, length from the turbo, the ric shaw ecu etc.

SSR Engineering

We now have revised pricing as well, this turbo kit will cost $5995, 5495 during introductory pricing

rotarygod

There are problems even with an aftermarket ecu? That is just plain scary! I have an idea but it may just be plain stupid. If the airflow across it is messing with it, how about installing a tornado. Don't do it from the sense that you are trying to get more power out of a snakeoil product but rather from the standpoint that it will setup a different airflow turbulence pattern in the pipe through the maf. You never know.

SSR Engineering

It's maxing voltage at like 50% throttle.