rpm_pwr

I put my car (standard late 1994 build RX-7) on a dyno on saturday. Long story short it made 216rwhp @ 5250rpm or 161rwkw in the new money. It kept blowing off one of the intake pipes at about 5000rpm so it wouldn't make any more power above that. Either way it was clearly making a fair bit more power than the flywheel 177kW in the brochure.

This was done on a DD dyno in standard, corrected mode. No dodgy shootout mode here! Just prior to my run my brother's M3 punched out 242rwhp which is exactly what it should do.

If it wasnt loosing boost, it would have made a fair bit more power. The car is on the original engine, completely standard, with all service receipts for the last 9 years.

-pete

Hymee

iTrader: (1)

Interesting.

That is heaps more than my 120 rwkW.

Does that mean you are no longer interested in a Dyno day? I was going to PT this afternoon, and one of the thing on my agenda was about a Dyno Day for us.

BTW - where did you get it done, out of curiousity?

Cheers,
Hymee.

rpm_pwr

Still interested in a dyno day. I just need to come up with a way to stop the IC hose from doing its' levitation stunt. I jammed an old shirt between the strut bar and the pipe today just to see if that would fix it :D

Dyno was done at Redcliffe dyno. Chart scan is coming.

-pete

hostile

the cosmo got owned by the 180km/hr speedcut and only made 208rwhp *waits for more insults from ^ *

Hymee

iTrader: (1)

I had my SS on the Steves dyno a couple of times as well. He is a nice bloke.

Hostile - why didn't he run it in a lower gear then?

hostile

it was in 3rd in manual mode. Couldn't keep it in 4th to get a good reading I'll try to scan mine tonight

rpm_pwr

You may have noticed that I quite kindly didnt post your effort so as not to cause embarassment. :p

You have how many rotors?

-pete

hostile

[img]www.travelbuddiesworldwide.com/images/kleenex.gif[/img]

Hymee

iTrader: (1)

I am spewing over those figures (or how low mine was). I don't want to start a war, but rather discussion. 16kW drive train losses is not very much in the RX7. That is less than 10% What do you reckon? And I wouldn't think Steve should want to redline the Cosmos in top gear - surely it would be too fast for the dyno (safely)??

Cheers,
Hymee.

Edit - Just re-read your original post where you say it was making a fair bit more than the brochure figure. I wish that happened with the 8

rpm_pwr

We're having problems with the scanner, but you may have noticed it's mentioned that peak power was all the way down at 5250. Normally FD's make peak power at >6500 so you can see that when I get it dynoed with the air leak fixed (with something other than an old t-shirt ) there should be more power to come. As of yesterday, it now holds full boost to 7500rpm instead of 5000rpm.

While I can't prove any of it yet, I think it's possible some of the later s6's left the factory with quite a few series 7 parts. My inlet elbow (before the throttle) is black for example. As is a guy in melbourne's FD. Every other aussie rx-7 has silver piping. Both cars have put out surprising amounts of HP stock.

Theory: When mazda released the s7 FD here, they said it had 194kW then revised it down to the normal 177kW. It's quite possible that Mazda OZ lied about the power figure so as not to have to re-comply a car that was only selling around 30/yr. But none of this explains why I have a power curve that traces out closer to a 236kW M3 than a 208kW 20B Cosmo.

As for why yours was so low, I can understand your disappoinment. As a pre-order customer, mazda led you to believe that you were getting as much power as the recently departed RX-7. I'm happy to put them side-by-side one night, but I suspect we may already know the result.

Still, sending senior mazda OZ people a back-to-back dyno comparason between the two cars may very well elicit a more honest response. I gather L&L has a few email adresses.

RE Dyno speed. Not an issue. My car was pushing 207km/h when we shut it down early. It would have been pulling 232km/h at redline. I vaguely recall the M3 pushing 230 something. That's what happens when you put 7500rpm engines on a dyno in 4th! Wouldnt an rx-8 be pushing even more?

-pete

Hymee

iTrader: (1)

rpm-pwr,

Yep - I guess a proper back to back comparo is the best indication. On the same dyno, or on the strip. All I know is my car has made a 15.0 second pass. Have you had yours down the strip?

To run the M6 '8 in "top" is 5th gear. At 9,000 rpm it was too fast to be considered safe on the dyno. So we ran in a lower gear.

You have quite a strong motor!

Cheers,
Hymee

PS - I'm Talking today about a dyno day with PowerTorque.

rpm_pwr

Oh and hostile and I are just kidding around. His car would have made a heap more but the plugs were fouled and the ECU was pulling back timing as he approached 180km/h.

-pete

rpm_pwr

Hymee, never taken any of my cars to a drag strip. But I've driven past one quite a few times I'd like to do it once I get things sorted.

But I think a dyno might make a better comparason.

-pete

AMG

I have a s7 RX7 and an Rx8 (obviously) and I can tell you now that the RX8 is no match for the power and accelaration of the RX7. Mazda saying the Renesis brings out the same power as the twin turbo'd RX7 is just nonsense.

Maestro

Mazda said they have the same power. Which is correct.

However there is a big difference in Torque and a little in weight.

Mazda left those points out.

Its like Holdens GTS300.

Wow 300kW yet it weighs more than Rosanne Barr making it another POS taxi !!!!

And a whole second slower down the 1/4 mile than a stock RX-7

Its just marketing.

rpm_pwr

Here's some torque numbers I calculated a while ago:

RX8
1st = 3.760
diff = 4.444
Torque = 216
Peak RW Tractive effort: 3609N.m
tyres: 225/45/18
Peak pulling Force = 5471N (38km/h)

RX-7 (series 6)
1st = 3.483
diff = 4.100
Torque = 295
Peak RW Tractive effort: 4213N.m
Tyres 225/50/16
peak pulling power = 6672N (42km/h)

Just for laughs:

Commodore V6
1st = 3.83
diff = 3.08
torque = 305@3600rpm
peak rw tractive effort = 3598N.m
tyres = 205/65/15
peak pulling force = 5557N (@37km/h)

Holden Commodore VY SS
1st = 2.66
diff = 3.46
Torque = 465 @ 4400rpm
peak rw tractive effort = 4280N.m
Tyre size = 235/40/18
peak pulling force = 6634N (@58km/h)

Similar torque at the treads....yet an rx-8 would eat a VY v6 for lunch. Funny also, how long the SS takes to get going.

-pete

rpm_pwr

In case you missed my point - it's power that matters.

Hymee

iTrader: (1)

Exactly correct. There is no point in haveing all the torque in the world if it cant do it's work quickly enough. Think about a steam engine - Max torque at 0 RPM. Start it spinning and the torque drops off. Power is a product of torque and RPM. Power is defined as "the rate of doing work". It is power that gets you from A to B in the shortest possible time.

And sorry to say, a 300kW GTS is more than a full second quicker down the 1/4.

I spoke to Mark at PowerTorque today, and he is cool with hosting a Dyno day for anyone interested. $25 each. Date suggestions anyone?

timbo

Interesting data. Will plead ignorance in relation all of this other than to say that using my own custom coit dyno, two of the most impressive vehicles I have driven have been high torque, low (relative) power. Both were diesels.

The first was the BMW 330d Sport, which has around 400Nm of torque; the second was a VW Golf GTI 1.9 150ps diesel with about 300Nm. Both had amazing top end acceleration (admittedly on European autoroutes). I recall saying to my partner at the time "I bet you never thought one day you'd be sitting in a diesel VW, accelerating through 160kph, and changing into 6th!"

And both of them could do that all day, up hill, down dale while running about 6-8L/100k :p

Wildcard

Sat 20th Dec for the Dyno day is my suggestion. Do they work weekends? I'm guessing that most of us work during the week, so it'll most likely have to be a weekend.

Hymee

iTrader: (1)

The problem is they close on the 19th for Christmas until the 5th day of 2004. Can you come a week earlier?

Yes - he is often open Saturdays. The LS1 day we did on a Saturday.

Cheers,
Mark.

rpm_pwr

I can make saturday the 13th.

-pete

Hymee

iTrader: (1)

Unfortunately I cant And I also wanted to go and watch rx8-smooth at the Saturday afternoon sprints that day.

How about we plan for the new year? Then we can "prepare" for it a bit better, let people have some notice. Heat/Humidity might be a killer though.

Cheers,
Hymee.

rpm_pwr

Fair enough. I was thinking about doing both....

-pete

Maestro

Stock 1/4 for a GTS300

With SKaife at the wheel is 13.9 most can only master a mid 14 on a GTS300 (VT)

My FD running a catback and airfilter runs a 13.4 in full road trim.

A GTS300 does not cut a 12 sec 1/4 in road trim.