RX-Nut

Here's what someone can do.. pull out their engine and dyno it at the crank.. hehehhe.. that oughta tell us a boatload right there!!

I know.. I doubt it's easy, but wouldnt it answer some questions?

BillK

Actually I think a lot of this could be answered if someone in Japan could dyno theirs; if the same procedure showed 200 - 210 rwhp on a JDM RX-8, we'd have a solid lead.

Personally, I suspect Mazda's doing this very thing right now...

BRealistic

You people that already own RX8s: When you first drove it, did you think "There is no way this thing has 247hp?" or did you think "Wow! WHat a geat car!". Don't let a few dyno runs effect your enjoyment of your car.


On topic. Does the Renesis engine have a knock sensor? Just curious, since I don't think RX7s had knock sensors, and rotary lovers know one serious knock can compromise an apex seal. The turbo RX7s were the ones most sensitive, since simply upping the boost without working out all the subsystems (like fuel delivery) almost garanteed at least an occaisonal very lean condition- the POP! blown apex seal.
I ask about a knock sensor since the Renesis is a 'high compression' normally aspired rotary engine. If this engine has a knock sensor, it may be too sensitive, and forcing the rich mix and maybe even retarding the timing (what it does on psiton engines). Just a thought.... .. ..

jonalan

Easy answer - "Wow, what a great car!"

Yes, the RX-8 has a knock sensor.

TurboSE

For those who think 25-30% drivetrain loss should be expected are in denial. The drivetrain loss for new components should be under 20%. So what happens after say 80K miles when the clutch and drivetrain parts show wear? 50% drivetrain loss then?

Quick_lude

What we need is those that have dyno'ed at ~180whp to do a few 1/4 mile runs at a drag strip. If you cannot hit mid to high 14's constantly then the car is not producing 247hp.

Shamus

Turbo SE, no one is suggesting 30% driveline loss which would equate to like 172hp, but everyone is clinging to this 17% figure like it is gospel, when it was a marketing guy who gave Rotory News the number, not an engineer, and not in a twice checked press release. Maybe the guy was right, but sheesh how the heck would you or I or anyone know what the new Renesis and 6 speed etc. should have for driveline loss? As the motor loosens up, the loss should actually go down, not up.

Quick Lude, you're right. Pull some 0-60 times like the magazines did ( if I remember correctly, I read that R & T said they had to drop the clutch at around 7200-7500 rpm for optimal results, with very different numbers at a lower rpm) and see how close the semi-green motor can get.

BRealistic

Actually, the frictional losses of the drivetrain will become less and less as the components 'loosen up', not the other way around as you suggest.

RomanoM

30% parasitic losses from the flywheel to the rear wheels is excessive.

Outside of the rotary engine the RX-8 has the same type of transmission, driveline, rear diff and halfshafts of all other RWD cars.

BOOSTD 7

It also has a CF driveshaft that will decrease losses. Even 20% loss is excessive. The majority of mass produced cars these days are under 20%, usually around 16 - 17%. I don't care what anybody says, that's the truth.

This is all just speculation, until somebody from Mazda spills the beans we're all just left here holding our nuts with nothing to do but guess. And quite frankly, it's starting to **** me off. Somebody who knows needs to say something.

chinx

did anyone notice this thread on rotary news?

http://rotarynews.com/view.php?id=198

these guys got themselves a RENESIS, just the engine, and is developing a supercharger and has dyno'd it. why don't someone get in touch w/ 'em and see what their dyno results are...

BOOSTD 7

That's Paul Yaw's company doing that, he posts here as Yawpower. He doesn't know anything conclusive either unfortunately ... we're all still just waiting.

P00Man

but he does know what the engine dyno'ed at correct?
________
CHRISTIANITY FORUMS

RomanoM

Shamus

Personally I can't wait until Paul Yaw does dyno the thing. When he does, he'll be the first and only person on these boards who isn't guessing at what the driveline losses are.

I agree that 23% losses are excessive in a modern car, but that is precisely what Miatas lose on the dyno. No one has to take my word for it, there are many plots posted that 99-01 owners have pulled off their cars. You won't find more dyno plots or threads anywhere on the net than on the Miata forum. Those plots were one of the reasons Mazda had to offer to buy back cars not that long ago.

Does that mean the RX8 should come in at same figure? Of course not and I'm not saying that it will, just that 23% CAN happen. Comparing the RX8 to most cars may be completely wrong anyway. Maybe 12% is what this new rotary, new tranny, and all it's electro gee-gaw wizardry will lose, who knows? Not us.

I for one refuse to jump onto the freak-out bandwagon on the basis of a couple of guys I don't know who have dyno runs when no one has a baseline from an engine.

I sure as heck am not going to jump to the conclusion that Mazda has knowingly overstated the hp on this car by over 20hp after having to offer to buy back cars or pay $500 to anyone who bought a Miata that was overrated by 12hp. Majority owner Ford, has already been bitten by this too. The really ironic thing is that the number people THINK they should be getting... CAME from a Mazda Marketing guy! If there is a conspiracy to misrepresent the number then he didn't get the memo!

Frankly I'm frustrated too. If all this hoopla without any real hard baseline evidence wasn't so damaging to Mazda and the RX8, it would be funnier than hell.

eccles

Amen!

rpm_pwr

But he won't be using a factory ECU will he? What he'd have to do is tune for 247BHP then put the motor in an rx-8 and dyno it again. Anyway, I thought most inertial dynos could give a pretty good estimate of drivetrain losses anyway, no?

-pete

TurboSE

So you are telling me a tranny, clutch and rearend with 100k miles on it will transmit more torque than one with 5K miles on it? Damn, this is not what they taught me in engineering school!

rpm_pwr

That's what I was thinking! The engine may free up but surely the gears get more drag?

To lighten everyone up - here's the other side of the coin. A guy buys a 2002 "280" HP Spirit R rx-7 and throws it on a chassis dyno:
http://www.rx7city.com/FORUM/topic.asp?TOPIC_ID=2223
The result? 265RWHP. Now I'm the first to point out comparing RWHP number is futile but that would explain how a 1280kg car can get to 100km/h (0-60) in 4.5 secs wouldnt it? Nice to see that Mazda under-rate some things

-pete

BRealistic

Touche'

I wasn't really thinking about a 100k mile car, but in order to design a vehicle for a long useable life, the parts are built with the tightest tolerances possible when new. So even with normal wear, the tolerances will stay within 'allowable' specs for many many years and miles. Are these 'new' specs the most efficient? I don't know.

P00Man

actually, thats 0-62 so itd probably be around maybe...4.3?

anyone care to calculate losses?
i read somewhere on here that all japanese cars rated at 280hp are well above so i dont know what it would be.

also the mileage on the car would be nice

we could then compare %loss and see where the 8 falls as of now
sure it wouldnt prove anything, but it gives us another referance point, and with a rotary engine.
________
Lovely Wendie

rpm_pwr

It works out as 5.36% loss! Like you said, probably a little more than 280ps I think! (or a very optimistic dyno).

-pete

compaddict

Updated 1st post to show 1994 RX-7 HP and Torque.

Vince

BOOSTD 7

Exactly, and no ... I doubt he would be using a stock ECU. The motor itself isn't the problem. It's been proven without doubt to put that power down in the Formula Mazda cars that are blueprinted to 250hp (I believe) ... starmazda website is acting up or I'd confirm.

But the motor isn't the problem, it's the ECU. Which I suppose is a good thing, because an ECU swap is simple.

P00Man

smelled it...SMELLED IT ALL ALONG!
________
Stock Picks