eccles

Something ain't right here. The dips as each extra port opens, suggest that the engine is spinning up too fast for the newly-opened intake paths to "catch up". I wonder if the results would be different on a variable-load dyno which would allow the system to stabilize at each point in the range. How long did it take to do these 3rd-gear pulls? Has anyone done one in 5th yet?

RX-Nut

Well, if we all were deceived, that's just wrong. I mean every other forum I browse just about says the 8 is all looks no go.. That's beginning to be it's rep..

It's getting obvious that all these dyno runs and such are on the money. They flat out tell us that we're not getting what we thought we would..

I wish Bern from Rotary News could chime in and ask his chums at Mazda.. Or someone.. there's got to be some source we can confirm or deny with.

Digisan

I agree Nut, time for damage control!

Digisan

Did I mention ASAP!?

kostas*

I think the dyno results are not important. The only think that really matters is how fast the car is. If you can achieve 0-60 in 6sec with only 180 rwhp it is fine by me.

Digisan

I think the dyno results are very important. I want what I paid for, which is fair. I'll give them the book and the mug back for the 25 missing HP.

MrWigggles

No one has been able to do that yet. I think the more aggressive fuel maps will kick in and allow for that, but for now that isn't the case.

Yes, ultimately acceleration, top speed etc are what's important.

-Mr. Wigggles

kostas*

I was only implying that because of the sometimes deceiving nature of the dynos we should focus at the road performance of the car. Of source we all want to get what we pay for, but first we must be 100% sure that we KNOW what we are getting.

RobDickinson

Hmm is it me or shouldnt the extra ports open BEFORE the drop in power?

2nd Should open at peak power @ 6250 instead of 6500
3rd should open @ 7250 instead of 7500?

Also if running rich then its a bad fuel map, which Mazda MUST have spent a long time working on.

Having the ECU change charictaristics at a certain milage should be mentioned in the owners manual, something like 'Car runs rich/low power until xxx miles' and def should be eithe rhidden or high milage (10k+).


This looks bad, esp for us euro's who only get 228bhp to start with.

86rx7

thats not a drop in power due to not enough intake, thats a loss caused by turbulence as the motor is switching intake configs. Also all second generation rx7's had a mileage switch that ticked over at 20k miles, and i dont ever recall seeign it in the owners manuel.

RomanoM

You know just for chuckles I'd love to see what the torque curve for the low power (207bhp) engine look like.

I know apples and oranges, but just for the hell of it.

Anyone?

loco4rx8

After reading all of this, my question is:

If this data is correct and Mazda will admit the car is missing some promised HP, is there a way they can "fix" the problem on the cars that have already been manufactured?

ChrisW

We have already had the power officially reduced to 228 hp in Europe. If we actually only have 200 hp for the first 20K miles (which is three years for me!) then I will give this car a miss.

What happened to the 250hp/155 mph sports car that I read about only 12 months ago?

pelucidor

The only cars that did 0-60 in 6 secs were the pre-production ones reviewed by C&D, R&T, Motor Week etc which probably had full power.

The production cars might be relatively slow, as evidenced by the Best Motoring video from Japan where everything but a Miata passes the RX-8 and the driver wonders where his 250hp is (I am paraphrasing)...

What, if anything, changed in the engine between pre-production and production? Can a Mazda employee (budaman, lfubar) find out?

compaddict

I'm quite happy with my car just the way it is. 180 HP at the rear wheels with a flat torque curve and a 9000 redline makes for a very nice ride.

One of my other concerns is am I paying to insure a 250 HP car or a 220 HP one?

I have included a dyno run from a stock 1994 RX-7 on my original post for comparison.

Vince

BOOSTD 7

I would almost guarantee that 100 eyes at Mazda have seen this thread. Somebody who KNOWS what's going on needs to get on here and straighten things out. Or else this is going to get out of hand. Silence is worse than anything, it leads to speculation. And the only thing I can speculate is that this is going to be another case like the Miata ... less power than advertised.

Kawi

Well part of it is the principle of it all. If they advertise a car to have 247 hp & 159 lb/ft of torque it should have numbers closer than what these dyno results are showing. Basically, the final product should be what they're selling it as.

One of my questions though is, what if it is a mapping issue but something that isn't switched on automatically by the ECU? Could it be something that has to be switched on by a Mazda service department after a diagnostic at a certain point? The reason I ask is because the test car had over 2200 miles on it but was showing lower than advertised numers. Also no one is sure if the maps switch over after 10 or 20 thousand miles. That's a heck of a lot of miles to have to hold an engine back.

TurboSE

The mileage switch in the ecu on earlier rx7s was mentioned in the service manuals. Anyone here who might work for mazda, please look one up for the rx-8 and enlighten us. On the one hand all the dyno numbers are consistently lower but on the other you have to believe that mazda engineers can't lie to such a degree and keep their jobs. I am not even sure if going from 12:1 afr to 13:1 afr will result in 30 rwhp at the top end

Charleston

If the car does not produce horsepower and torque consistent with normal friction loss, etc., isn't that false advertising?

eccles

Yep, and that's exactly what happened with the Miata recently. I can't believe that Mazda would make such a blunder twice, especially with as large a discrepancy as we're seeing, which leads me to believe that there must be something more to it. Either that or we may wind up getting free servicing or a buy-back offer, as they did with the Miata.

One last thought: a lot of folks are postulating that the ECU will automatically switch to a new map at some point. Isn't it possible that this switch is done manually by Mazda's diagnostic machinery as part of the first scheduled service? I remember a friend had a Nissan Pulsar Turbo (Australian market) which wouldn't produce more than half-boost until the dealership reset something in the ECU at the first service.

86rx7

The car would only have to make like 17 ft/lbs more torque by redline, i think leaning it out to like 13.3 or so would do that fine(maybe leaner dont know what the renesis likes) what id really like to see is an afr for this dyno run, so we can compare it to the other run.

dcfc3s

Some info from the RX-7 side of the fence -

The 2nd gens did have a separate odometer in the instrument cluster that tripped a switch at 20,000 miles. It wasn't well documented in the shop manual as to exactly what happened when the switch flipped - the only thing obvious was it changed the behavior of the air control valve. The ACV takes air from the air pump and ducts it to the main cat, to the exhaust manifold, or out to atmosphere. Nothing that really changes performance, just emissions-related.

But, there has been speculation that at 20,000 miles the ECU switched to a different timing map for more power. I talked with a guy that had an '89 GTUs that he bought brand new, and said he really felt the power difference at 20,000 miles.

Anyhow, I think there's a good reason to believe that this might be the case - the car will switch to a different timing map at some point in time. Considering end users can't get shop manuals as of yet (I've tried) we'll need someone that can access that information to see what they can dig up.

The air/fuel ratios at that RPM are actually pretty good - about where you want them to be. I have a feeling it's more of a timing thing, or maybe a difference in the behavior of the 6-port acutators or the like.

By the same token, I remember hearing/seeing that the page in the owner's manual that talks about engine break-in had a sticker over the original contents of the page - basically, they revised it somehow. I wonder what it says under the sticker? Anyone try holding it to a light, steaming the sticker off, etc.?

Might also want to see what people with 6-speed Miatas get for a drivetrain loss - the transmission and diff are similar enough that the drag on the drivetrain should be close.

Regardless, I wouldn't go into a panic over the situation. You have to remember all the caveats that Mazda designs a car with - has to meet very stringent emissions regulations, has to be reliable and easy to drive, etc. If Mazda could make the engine with 900 hp, but it wouldn't pass emissions or the like, they couldn't sell the car - it's that simple. By the same token, if they fiddle with the ECU to not allow full power until a certain mileage so the engine and all emissions equipment is fully broken in to insure a long, durable life for the engine, that's a good idea in their books.

That's my 2 cents .

Dale

eccles

Yeah, I held a flashlight up to it. The only difference that I could see was that they added "(over 7000 rpm)" to the sentence that advises against using high revs.

Ahura

I don't think there's anything to be worried about. ECU fuel/ignition map changes can make a world of difference. It's sensible for Mazda to do this so that the RENESIS is protected against harsh driving while break-in. Now, I do agree that 20k miles is a bit much (if this speculation is true). Maybe one of the high mileage people will have a big surprise at 5k or 10k miles. 20k miles will take at least 3 years for me I still have only 350 miles after 2 weeks, and that's a lot by my standards.

Just look at the change I made by tooling around with the timing (on the dyno) on my street ported 86 :p

pelucidor

I am becoming less convinced of the 'intentional ECU setting' the more I hear about it. In the case of the RX-7 it was apparently stated in the manual. In the case of the RX-8 (Mazda's most critical and scrutinized car in a decade) it is not mentioned anywhere. It may be a mistake that can be corrected with an ECU update (I hope) but who knows. Note that the preproduction cars tested by the magazines seemed to make plenty of power up top at under 2,000 miles, not 20,000.

I am surprised that nobody from Mazda has said anything to the dealerships, the customers or this forum about this issue, even if it is to only say they are investigating this. Releasing a sports car missing 40hp (20% peak power) is a disaster, and could sink the RX-8 (and the new rotary engine) before it had a chance to make its mark. If this is not resolved very soon Mazda will have the image of the company that consistently lies about horsepower (two cars in a few years) on the internet and eventually in the real world.

I am still hoping to pick up my car this week (now 5 weeks at port), but getting increasingly fed up with Mazda's attitude of silence - not even denial - rather than their (possibly faulty?) product. I think the car is still fast enough for me at 210hp, but I want what I will be paying for. The first lawsuit is probably only weeks away unless Mazda make a calming statement first.