Shamblerock

Ike, a little more info comparison with the 2002 RSX which had 200 HP:

2004 2002
Make Mazda Acura
Model RX-8 RSX
Trim Type-S
Transmission 6-speed Manual 6-speed Manual
Theoretical Top Speed 154 mph 145 mph
Limited Top Speed 148 mph

0-30 mph 2.12 s 2.50 s
0-40 mph 3.46 s 3.40 s
0-50 mph 4.69 s 5.20 s
0-60 mph 5.96 s 6.50 s
0-70 mph 8.14 s 9.00 s
0-80 mph 10.02 s 11.00 s
0-90 mph 12.89 s 14.00 s
0-100 mph 15.91 s 17.40 s
0-110 mph 19.32 s
0-120 mph 23.45 s
0-130 mph 30.32 s
0-140 mph 38.77 s
0-150 mph 63.19 s

1320 ft (1/4 mile) 14.62 s @ 96.54 mph 15.20 s @ 93.6 mph


Here's the link so you can verify this one as well.


www.car-videos.com

Ike, please explain.

RX8-TX

Shamble....you got a little late to the party. Ike's been aroud since then, and he is probably well aware of it. It is not a matter of how rotary engines works. An engine is an engine [BIG PERIOD]

Having said that, there's gotta be a stick by which to measure things (distance, time, power output, etc...) - Engine dynamometers are one. To further enhance the validity and repeatability of those results we have standards than we can follow (SAE)

In our case -common, poor people- the sticks we have (dirty minded people!) available to measure and quantify are chassis dynamometers, quarter miles, eight miles and pretty decent GPS and accelerometer based electronics. And if you really want to use results obtained through those methods, other than for comparative purposes on the very same engine (or vehicle in this case), you better do things back to back under the exact same conditions. Otherwise, your results will be skewed.

And please don't quote numbers that were probably achieved by 2 different magazine publications (don't hold that against me..), and God knows under what conditions were they achieved.

rx8wannahave

First, Im as happy as a little kid with the toy he has been waiting for all year long, with my 8. Don't forget that...

I don't get the test drive argument because while test driving a car (at least for me) I don't rev a car to it's max nor push it too hard at all. I read the mag's for HP and performance times but my test drive is more for ride, comfort, and feel for the car.

I don't know about a lawsuit, but if I found out that my RX8 made significantly less HP than advertised then I would be upset. Why...not because of love my 8 less but becuase a lie is a lie...and we should not allow companies to do that.

But, with that said...IF someone was going to get lawyers about this...I wonder if Mazda would keep building sports cars? Maybe the 8 would just be too much work...not enough profit.

zoom44

its not a matter af what type of engine it is. its a matter of this engine with this engine management. What he quoted in his previous post was MAZDA's statement that they made when they intially lowered the HP from 247 to 238. That statement alone tells you that it would take considerable amount of time money and lawyers to prove them wrong. a lawsuit would fail miserably even IF a law firm could be convinced to take on the case.

RX8-TX

:o Thanks for synthesizing it.

Shamblerock

I understand conditions play a big role in results. But I am not hanging on these 2 magazines as conclusive evidence. Take a look at all the magazines and most will be in the close range of what I posted i.e. car and driver, road and track, motortrend etc.. who's livelyhood depends on how they test car and the drivers who test them.

That is part and parcel on how many people choose their cars, especially sports cars. As I am sure you will agree, we may not be as qualified and experienced as their drivers and would likely not be able to produce the same results. But for the most part the same drivers test all thier cars usually on same tracks and tools. Regardless what a dyno says, if the 8 is truly is only 200 hp as Ike and other claim, it sure outperforms the RSX which has similar power and engine performance characteristics (get the revs up to max acceleration due to lack of torque).

I am not 100% sure, but I also remember reading somewhere that the reason why they dropped the power from 250 to 238 was a result of a law in the uSA that was passed to increase the life of the cat. from 80,000 miles to 120,000 miles while these rotaries were already in production. Therefore, Mazda had to act quickly to meet these new regulations and as a result detuned the engine and made a mess of the ECU programming in the process. Now that they have had time, they come out with new flashes/fixes every now and again to optimze the detuned 238hp engine.


I also read somewhere that the prototype RX8 originally had 280 hp but they came out with 250 so they had room to increase power with a new flash for a new production year. Rumour, quite possible. Logical from a production/marketing standpoint? yes. As Charles Hill once said on this site, car manufacturers always give you production engines that could comfortably produce at least 25% more power.

RX8-TX

Believe it or not, you are somewhat making the same point Ike is trying to make. The car is not producing what Mazda is advertising -and that doesn't take anything away from the fact that in N/A form the Renesis is a big improvement over previous 6 port rotaries- And even like this, it manages to show some pretty darn good qualities. Nothing more, nothing less.

You and I know the same up to this point. Apparently emissions are to blame. No one is saying the engine is not capable of, or that it CAN NOT hit the originally advertised numbers. But, it is not doing so in its current state.

Ike

1.) Times don't indicate whp nearly as much as trap speeds do.

2.) Many of the RX-8 mag times were done with pre production cars, not all of them but all of the early ones, this was long before Mazdas screwup with the cat life and ECU changes.

3.) This law about the catlife was not made over night, Mazda should have had the problem taken care of long before they did. Making the car run pig rich was a band aid that shouldn't have ben necessary. How many times has Mazda come up with a new flash now? Seems like you guys have been beta testing ECU settings for the last year and a half.

4.) The 05 RSX Type S is trapping 95-96 mph with a good driver and they are rated at 210hp, the previous model regularly trapped 94mph with a good driver (this is the car you listed the numbers for, not the 210hp 05), the S2K traps 98-100 (more for the 2.2L) with 240chp, the WRX traps 93-95 with 170ish whp, would you like me to go on? The RX-8 traps 93-95, even the best run on these forums Polak couldn't break 94mph, and he and Ito are the only ones to come close to the mag times. Everyone else is high 14s and low 15s with most traps around 93mph. All the other cars I've mentioned have had several owners achieve or better mag times and trap speeds multiple times.

5.) You may have heard the 280hp from me or maybe the mags the I read about it in. I posted this last week "It's all speculation at this point, if everything the car mags wrote about prototype cars was true the RX-8 would have 280hp. Get a clue man, you're making youself look foolish, again." I don't know if the 280hp rotary ever even existed, it was most likely speculation or Mazda leaking some estimates before they had anything near a finalize product. That 280 number is a big reason why I and many others were so disappointed in the production cars performance, 280 and I'm sure I would have been happy with the stock acceleration and may be driving an RX-8 right now.

6.) Charles Hill is wrong if that's what he said. In many cases sure, but try getting 25% more out of an S2K or many many other older cars, and it ain't happening without major issues or big bucks in mods. The RX-8 could even fit into the group with the S2K, without aftermarket FI, major engine work, or juice, there's no way you're comfortably producing 25% more hp. When I think of the term comfortably producing 25% more power I think it has to be done with simple boltons that aren't going to risk decreasing the life of your motor in a big way, but maybe I'm reading into it too much. The RX-8 and the S2K both need some pretty major mods to get much more out of them, it's because they are already pretty highly tuned N/As straight from the factory.

7.) Shamble, let me know if you need anything else explained.

Ike

Shamblerock

1) Your wrong again because you never considered gearing. No further explanation required in this regard because you should know this. Nor did I state that time slips indicate whp. I was simply comparing 2 cars which you indicate have similar power.

2) Possibly but there were too many testers out there with the same kind of results. They couldn't all have had pre production cars.

3) I never said the law was passed overnight. Could Mazda have done a better job? Absolutely. Have we been testing the ECU for them? Absolutely? However, this does not change the fact that the RX8 in its current form is somewhat faster than the 05 RSX.

4) I presented the number I found and what was available. I doubt Polak and Ito are professional drivers. Given the nature of the rotary and how to maximize its performance requires some special skills/knowledge; that why professional drivers can get the max out of them. It does not run like a piston engine which works differents and has different performance charcteristics. But know ing you, you think its all the same! When to shift and how to shift is more critically sensative than a piston engine due to the high rpms the engine performs and the speed at which it rises. But you wouldn't know that because you don't own a rotary and don't experience it often to give valuable input.

5) Don't remember your post that you quoted. But I presume you were making new freinds at the RX8 club as a result of your psot, yet again. The last person I would beleive information about the 8 is you. So trust me, I didn't get it from you and I beleive it is a video that I saw by a British car mag testing the RX01.

Whatever you do, DO NOT BUY A RX8. You will be laughed continueously by several members here. But because we are decent people, we'll eventually welcome you to the community. But boy will you ever lose face in the process!

6) Perhaps I need to change one word to carify my point: Replace " produce" with "withstand" . My apology. Trust it is clearer now.


IKE, I am still waiting for your reasons why the RX8 is considerably faster than the rsx type s 2004 and 2005. If your reason is simply because the RX8's that were tested were per-production, you are weaker than I had ever imagined.

Shamblerock

Ike, and to further proove my point that the fastest quarter mile times are not necessarily the fastest trap speeds here are some stats for you:

16 1969 Corvette 13.56@111.1 427 L88 430 automatic 3.36 HR 4/69
17 1969 Super Bee 13.56@105.6 440 Six Pack 390 automatic 4.10 HR 8/69
18 1969 Boss 429 Mustang 13.60@106 Boss 429 375 4-Speed 3.91 HC 9/69
19 1970 Challenger R/T 13.62@104.3 440 Six Pack 390 automatic 3.23 CC 11/69
20 1970 Torino Cobra 13.63@105.9 429 SCJ 370 automatic 3.91 SS 3/70
21 1968 Biscayne 13.65@105 427 L72 425 4-Speed 4.56 SS 4/68
22 1964 Polara 500 13.70@107.37 426 4V 365 4-Speed 3.23 HC 2/64


Once again, you prove that you are all confused.

Ike

1.) What??? I said trap speed is a pretty good indicator of whp, what the hell are you talking about? I'm comparing cars with lower power from the manufacturer and showing you that they trap about the same as the RX-8 supporting that the RX-8 isn't making 238hp. The one car that has about the same manufacturers rating traps much higher than the RX-8, which means it has more HP. And no, gearing really doesn't have a whole lot to do with it. It is a factor, but not much of one. Lastly, I never said the RX-8 has 200hp, I've always said it has in the area of 215-220 which goes along well with the numbers I've pointed out.

2.) Just about all the early tests were done with the same car, this is pretty common.

3.) It's a little quicker due to the FWD disadvantage the RSX has, but the new RSX traps about the same or better than the RX-8 which in drag racing terms means it's faster. Lower time = quicker, higher trap = faster. So it traps slightly lower than a 210hp car which only supports my position.

4.) You don't have to be a professional driver to get mag times, it's not like mags hire professional drag racers to test their cars. Many many of todays mag times are bettered and matched by owners of various cars. The rotary is not so complex and different that just about any good driver can't get a good time after getting used to the car's characteristics for a few minutes. Any driver worth his salt knows you shift at redline, it's just not that difficult to figure out.

5.) You don't believe anything I say, and you dispute just about everything I say out of some dislike for me rather than actually thinking out the information I present. That's why I really don't want to continue this nonsense with you, you're on tilt and I'm just trying to have a good debate. You're letting emotions get in the way of logical thinking, you want to prove me wrong so badly that you'll twist whatever info you have to convince yourself that you're right.

6.) An elevator that has a maximum capacity of 3,000lbs will probably withstand 5,000lbs, doesn't mean it's a good idea to find out if that's true or not.

Ike

When have I ever said the QUICKEST 1/4 miles times mean the car traps the fastest??? As someone who has owned a few AWD turbo cars I know that all too well. Your example of old muscle cars with huge drivetrain loss and old technology is a weak one, but all they really do is support my claim that trap speeds are a better indicator of whp than time is. You're getting so random here and grasping at straws, I suggest you stop before you make yourself look even more silly. The gearing isn't nearly as much a factor with those cars as traction and technology, but again I agree gearing does play a small part.

You've proven nothing with your little cut and paste.

Shamblerock

Ike, you just confirmed that you obviously know **** about driving or racing if you state that all you have to do on a car to make it perform at its best is to shift at red line! What a joke. Are you serious??????????

You just confirmed you know zip about this stuff and I'm not going to even bother arguing with you because you are like a big hollow box; you make a lot of noise when struck because you are empty inside!

You must hang around drags strips fetching water bottles and hot dogs for guys who are racing and you pick up words here and there and throw them out on this site trying to make yourself look like you know what you are talking about, when really you are clueless and confused.

Furthermore, don't give me suggestions. Somebody who follows your advice should heed great caution! Your advise is dangerous, poorly thought out and 2nd hand at best!

IKE January 25, 2005 3:46PM: "Any driver worth his salt knows you shift at redline, it's just not that difficult to figure out."

This quote takes the cake! F--king UNBELEIVABLY STUPID AND IGNORANT REMARK! My 11 year old son even knows better!!!!

Ike

Talk about selective criticism, if you had actually read the whole thing... "The rotary is not so complex and different that just about any GOOD driver can't get a good time after getting used to the car's characteristics for a few minutes. Any driver worth his salt knows you shift at redline, it's just not that difficult to figure out." My point was that the RX-8 is not so different from other cars that a good driver that doesn't know much about rotaries can't get a good time.

Your point was that because the RX-8 revs so high that people without the knowledge of rotaries can't drive them well, and that "When to shift and how to shift is more critically sensative than a piston engine due to the high rpms". When to shift, you shift it at freaking redline when drag racing, how is that so different froma psiton car? It's important with every car how you shift and when you shift in order to get a good time, it's really not that different.

Never once did I say that shifting at redline is all it takes to get a good time, proper shifting techniques, and throttle modultation are important as well, but that's no different from any car. Yes it revs higher than a lot of other cars, but you make it sound like piston engines can't have a redline higher than 7k rpms. It's not rocket science man, the rotary is not so different that you need extensive knowledge of it in order to drive one well.

What about my other points, you seem to be diverting from the actual argument by taking these stupid little quotes out of context and going off on your silly little tangents. Lastly, how does any of this change the fact that the new RSX with only 210hp and WRX with only 170whp trap about the same as the 238hp RX-8? You freaking baffle me, work on your reading comprehension for god sake.

dmp

Ike - your efforts are admirable....yet some ppl just won't learn. To me, it's an easy concept:

Two cars with similar weight and gearing. The one with the higher trap speed has more power to the ground. Some tech-geeks may be able to find a VERY FEW cases, maybe...where that isn't an accurate statement; but ask any Racer.

zoom44

now we are back at power to the ground and not cHP. we still dont know what the percentage for drivetrain loss that MAZDA used when calculating their stated 238hp.

shamblerock and IKE please calm down.

dmp

semantics.

Assumptions are no car does as horrible a job of transmitting engine power to the ground than the RX8 MUST be doing, if what mazda says is true (238hp).

Ike

Drivetrain loss is pretty standard stuff nowadays, if Mazda thinks they have 25-30% drivetrain loss then maybe they should be selling something other than cars. Besides, why would they need to figure out transmission loss when they're rating a car at the crank? I challenge anyone to give me one good reason to believe that the RX-8 is losing anything more than the standard 16-17% due to the drivetrain.

The only thing Mazda should have used to calculate the 238hp was dynoing a few engines on an engine dyno, it seems pretty clear they never did so.

Ike

Doesn't the RX-8 have a CF driveshaft, it also has a 6 speed which should provide a little less resitance. These are things that would support that the RX-8 is losing less due to drivetrain loss than many other RWD cars, not more.

Gord96BRG

Why? What does driveshaft material have to do with powertrain losses? It rotates, no moving parts (bearings, etc.).

Why? How would a 6 speed have less resistance than a 5 speed or 4 speed? More gears, sometimes more layshafts, mean more bearings and friction surfaces being operated. That means more resistance, not less.

PS - How do you figure that there's a "standard" 16% - 17% drivetrain loss? Care to explain how you arrived at that? Here's an example for you to contemplate:

A stock Miata, rated at 142 hp, puts out ~110 rwhp. That's a loss of 32 hp, or 22.5% drivetrain loss. Hmm, so much for 17% right from the start, but let's continue this example. There's dozens and dozens of dyno runs that validate those numbers at www.miata.net and their forums, by the way, so that 22.5% loss is real.

Now we turbocharge our Miata, to generate ~220 rwhp - a very easy number to achieve with a FM II kit from www.flyinmiata.com . So, Mr. Standard Drivetrain Loss, if we follow your statement that drivetrain loss is a fixed percentage, you would insist that our Miata is now losing 64 hp through the drivetrain, and is making 284 hp at the crank, based on a standard 22.5% drivetrain loss.

So what's consuming the extra 32 hp? How can the identical drivetrain, which required 32 hp to run behind the stock engine, suddenly absorb double that amount of power? The clutch, transmission, differential, rear hubs, are all the same - why do they suddenly require more power to turn? It's simple - they don't. The notion of Standard Drivetrain Loss is a myth, it is not factually correct. However, drivetrain loss is not a fixed quantity either. In the Miata case, the loss will not remain at 32 hp behind the 220 rwhp turbo engine either. Rather, there is a fixed component of the drivetrain loss, and also a variable component due to the increased loads being transmitted generating increased pressure on the gear faces and bearings, which result in some additional power being converted to additional heat (and is the reason why race cars require transmission fluid and differential fluid coolers).

The exact numbers can be calculated if you know the crank output of the turbo engine, and heat measurements can give support to the calculations. However, it is very safe to say that powertrain losses are NOT a fixed percentage of engine output.

Regards,
Gordon

therm8

While not having dozens and dozens of validations. The auto transmission in the Volvo T5 power train was considered to have a loss of about 12-13%. Something based on how the Inline 5 was transverse mounted with the transmission located at the end, and it being front wheel drive. Drivetrain losses depend on the drivetrain, imo.

But Volvos are weird in many ways :D .

dmp

(Side note, sort of related)

Uh? Aren't you on Miata.net forums? ~26hp. That's the number 'most' miatas lose from the crank to the wheels.

MSMiata? 178hp? dyno's at ~150. Almost every 142hp Miata i've seen put down closer to 120whp. My 1.6L, rated at 116hp, crank, is a solid 100 with just an exhaust and cheapy hot-air intake and timing bump. Now that I've got a 'real' i/h/e, i'd bet to see 110 - there's no way the engine has 142hp with just those mods.

r0tor

iTrader: (1)

Well, you see here that a 27% final drive difference resulted in a 3% dyno difference. Lets just play a little numbers game here...

The final drive of 5th gear is 4.444, or a 64% difference from 3rd gear. If you do a linear extrapolation of the 3%/27% finding, that would be a about a 7% improvement from 3rd gear. However, is not really a linear relationship but rather an exponential relationship because inertial losses are proportional to the square of acceleration, so its probably more like 8-9%.

hmm... 25% - 8-9% for user dyno error and what do we get....16-17%, well look at that

MrWigggles

FYI,

I did a test with a precision accelerometer when I first got my RX-8. Myself and a colleague did a complete analysis of the acceleration and converted it to engine HP.

We removed the effects of the interia components which are huge for the RX-8 because of its heavy flywheel and high RPM. The only unknown was frictional losses.

Anyway, we were left with 218.4 HP at 8145 RPM. This means that the engine put at least that amount of power to the drivetrain and ultimately the road. This also means that if the car had 9% frictional losses* the 238 HP number for engine HP from Mazda would be accurate. 9% frictional losses is a little high but is reasonable. I am satisfied by my testing in which all calculations were peer reviewed.

The RX-8 doesn't dyno well, but thank god we don't drive our cars on a dyno. Street HP is all I car about.

-Mr. Wigggles

*Don't confuse frictional losses with total losses which include both friction and interial losses. Many people just multiply in a 15% value for total losses when they could in fact go a step further and take out interial losses. (done with a few extra acceleration tests in different gears.) Frictional losses (heat) should the be the only unknown left after performing an extensive "in-car dyno".

r0tor

iTrader: (1)

i also did something similar (but didn't go as far as you did) with actually driving acceleration numbers and calculated somewhere around 192hp at the wheels... so yea, sounds like its in the same ballpark as what i got