Hymee

iTrader: (1)

Hi all,

I did some work yesterday with an mutual friend on a different idea on overcoming the "Safe Mode". I won't go into the details of what we did, as it was not my idea, and I don't want to take the kudos for the lateral thinking that was employed. Anyway - the results of that part of the test in unnafected by what my topic is really about.

After we tried out theory, and decided we had probably worked out another way to bypass "Safe Mode", we though we better check if we indeed got safe mode when we undid all of our work.

Suprisingly, on the dyno, my car WOULD NOT go into safe mode. I am using the ABS LIGHT comming on as my indicator of safe mode, as that is what we have witnessed before.

The I realised that my car had perhaps not thrown the ABS light on the dyno before, and I also recalled it was "Wildcards" car that was throwing the ABS light all the time.

So what is the difference between the cars? In Australia, we have a lot less to choose from, although our selection is pretty good. Basically it gets down to 2 things Manual or Auto, and Cloth Trim or Leather Trim. Wildcards car is a hi-power manual like mine, but his is the Leather Pack. Our cars were within 1% of each other on the dynop that day.

The "Leather Pack" gives you a few other things like a better stereo, aluminum pedals, Xenon headlights with washers. But other than those cosmetic things, the running gear is supposed to be the same. Both models have ABS and DSC/TC.

Here is my graph:



That equates to around 180HP at the wheels. Using the old rule of thumb that HP at wheels is a good approximation of kW at Flywheel, it would appear my car makes the 177kW Mazda say it does.

We did about 16 runs, and the car "drove over the top of itself" tima and time again. It is one of the most repeatable set of dyno graphs I have ever seen. The only way we could get it to differ was to turn the A/C on.

Anyway - lets try to explore more options as to why my car does not go into safe mode. Is it a cloth pack/leather pack thing?

Cheers,
Hymee.

Genom

I have the US Sport version, so pretty close to yours in most regards. Goes into limp mode every time. I have seen 181HP with a Greddy exhaust and a 184 with stock exhaust. Any bits you want to compare in particular?

Hymee

iTrader: (1)

Well, I wonder what we need to compare.

I have:

6 port engine,
6 speed manual,
18" wheels,
Traction control,
Dynamic Stability Control,
ABS.

How does the very top of your dyno curve look when you get a "safe mode" run?

The only time my car has ever gone into limp mode, it won't rev past 3000. That happened one time when we were fiddling with the front/rear sensors, but was worked around by turning off DSC/TC.

What else could we compare?

Did you run on a dyno with the back wheels raised off the ground? (i.e. the rollers when not under the floor, but on a ramp?)

Cheers,
Hymee.

PS Mine has done over 13,500 km

zoom44

hymee is a drop of @35 kw to the wheels "normal" , "good" or "bad" for a car with this sort of drivetrain? should the losses be this much?

george thomas

hymee its clear that our aussie rx8's have more power than U.S versions as is witnessed by the ramping of the power after the 2nd port opens.
Whereas power flattens off with U.S models.

I find it strange that when you tested a U.S version last year that you could not feel the difference however?

Finally You have mentioned that your car being cloth trim(so is mine) is approx 30 kg lighter than leather model.
In the specs our cloth trim cars list at 1337 kg as apposed to leather at 1354kg, a 17kg difference.
Have you weighed your vehicle to verify? and if so do you think that this weight reduction has much to do with with your better times than lock and loads car?

Regards
George Thomas
Veocity red cloth Rx8

Genom

I have a bunch of dyno data on a floppy, but it's a: At my fiance's house an hour away, and b: I have no friggin floppy drive so I need to go get the disk, remember it, and take it to work. I'll try to remember it tomorrow night.

When in limp mode, the ABS and little car lights go on and stay on, even if I shut the car down and turn it back on. It clears out after leaving the car off for 20 minutes and driving it about 20 feet. Havent tried pulling the battery to do it quicker.

Cant remember what the dyno plots looked like to be honest, so until I get that disk, I cant say anything about it.

Regards to the car. I have the same stuff you do, but add in the HID's. Other than that it's teh same setup.

Forgot to add, the dyno wheels are almost flush with the ground. So the rear end gets raised about 2 inches when you get it on the rollers. Their page is at http://www.cartek-tuning.com/ (can get an diea of the shop layout). The dyno is on the oposite side of where the red car is.

zerobanger

do you have stock dyno charts to prove this? I dont feel any drop off of power in my rx8 from 6-8500. It just pulls progressivly.

thanks.

Hymee

iTrader: (1)

George, I said the US car felt similar, but I did not get staight out of mine into it. Also, I don't have a butt dyno that can detect the small differences we are talking about (if there is any).

Zerobanger, What I posted is a stock dyno chart, and has much the same characteristics of the graphs I have seen from the US others have posted. It is very subtle, but I think I can feel the transition of the ports. We are only talking a momentary loss of 2 or 3 kilowatts.

Genom, you description of the "safe mode" is the same as we experienced with Wildcards car. I spoke to the other Dyno man who dyno my car originally on 2 seperate occasions, and he recalled the "safe mode" only showed with Wildcard's 8.

We found that as soon as we switched of and then went for a short drive, the lights went out again - i.e. we didn't have to wait 20 minutes.

Cheers,
Hymee.

Hymee

iTrader: (1)

George,

Yes, I weighed my car at 1420 kg with me in the drivers seat, and 1/2 tank fuel.

I stand corrected on the 30kg weight difference. Yes 17kg is the correct amount as per the specs. I thought I had checked, but clearly I got the difference between auto and manual figure. My appologies.

My reading of 1420kg seemed plausible. The car is 1337kg, and kerb weight is supposed to be with all fluids and a tank of fuel. Take off 20kg for 1/2 tank, and add 110 for me, and we are in the right ball park.

If I where to change the weight of L&L's car (down 13kg) in the MR Dyno plots, the calulated power figure would be even less.

A dyno is more accurate, but sometimes you have to use what is available...

I really don't believe that a 17kg difference in 2 cars would account for that 1 second difference in those 40-100 km/h tests.

Cheers,
Hymee.

ChrisW

All the US dyno results I've seen use the rule of thumb that there is 17% drivetrain loss. Taking your peak power figure of 132 kW from the graph, that would give you a figure of 159 kW or 213 hp at the crank. This is right in the middle of the range of the US dyno plots.

However, the top end power does not seem to flatten off as much as the US cars. It looks like you have slightly less torque than US cars, but the torque curve stays flatter for longer so you get the same peak power.

This is pretty much in line what Mazda's specs say (apart from the fact that everyone's numbers are lower than they should be): Australian torque is quoted as 211 Nm = 155 lb.ft versus 159 lb.ft for US spec.

pp13bnos

Well, this weekend I'm taking my car to the dyno and I'll report on how my car does. Also keep in mind that different dyno's will give you different hp numbers. CJ

Hymee

iTrader: (1)

Yes - ain't that the truth! For the foreseable future, I'll be using the same dyno.

Cheers,
Hymee.

Hymee

iTrader: (1)

A good question, although I think it is closer to 45kW (177-132 = 45)

45 is around 25% of 177.

I have seen a 300kW (flywheel rating) make of car put down 220 kW at the wheels, repeatably. That is a 80kW loss, or 36%.

So the RX-8 is perhaps not too bad.

Cheers,
Hymee.

zoom44

see that's why i let others do my math for me so 25% is a normal drive train loss. but considering the rotary, light flywheel and short carbon fiber shaft, i would have thought we would see less losses than that. thanks for getting back to me hymee. now back on topic- why did yours not go into limp mode?

Hymee

iTrader: (1)

Ahh - that is the whole purpose of this thread! Why???

The only thing I have seen different about 2 cars (one exhibited the safe mode, and one didn't) was mine is the "cloth" pack, and the other is the "leather pack".

I would like not to call it limp mode. I have experienced the real limp mode on the road, and the PCM won't allow the car to be driven over 3000 RPM. This safe mode thing appears to just be a bit of a saftey thing up the top end.

I have experienced it when I did have a fuel problem and got a real CEL, and also when we were frigging with the sensors.

Cheers,
Hymee.

zoom44

correct. i am sorry, safety mode not limp mode. perhaps your cars sensore are not working?

BRx8

have you checked VIN numbers? what is the build date of your cars? maybe yours was built midweek instead of a Monday morning or Friday afternoon? :D perhaps even the other way around and you got some different ECU that will not go into Limp Mode

Hymee

iTrader: (1)

It goes into limp-home mode all right, when there is really a problem. But we are not concerned about limp-home mode. We are talking about the so-called "safe mode".

And the ABS, the DSC and the TC all work perfectly well. And she even throws the ABS light when the sensors are disconnected.

Cheers,
Hymee.

Tony Orlando

Okay, Ito: What did you do to overcome it the first time?

:D