PaulFitzwarryne

The forum frequently has threads showing dyno results when a member is boasting/proud of the power of their highly modified and unique RX-7. Its rare to get data on a typical stock set-up.

I was very interested to see the results of a recent dyno day run by the South Australian rotary club, a set of typical enthusiasts. The summary results were posted on their website.

A total of 14 gen 1s were put over the dyno.

There were 8 relatively stock and their rwhp was
56, 62, 62, 65, 66, 71, 72, and 75

Even in stock form with people who are RX7 enthusiasts the variation is remakable. Ex-factory it would have been 70-72rwhp a 28% drop in power from the flywheel reading. These are all the Australian version which had slightly more power than the USA version.

There were 6 modified gen1s and their rwhp was
80, 87, 90, 90, 105, and 135

The 105hp was for a Gen 1 with a 13bt engine which is way down on what I would have expected, a new gen 2 with the 1987 13bt engine gave 128-131 rwhp.

The results for gen 2s with the 13bt were just as varied everthing from 90 [must have been really badly tuned] to a 168hp for a moderately modified 13bt.

As these results were obtained on an accurately calibrated dyno, on the same day and with the same weather conditions, I believe they are a true representation of RX-7 performance. It would be great to get the results from another club dyno day.

SilverRocket

It's fine to examine the relative differences among the cars, but your (actual and implied) inferences regarding absolute numbers and drivetrain power losses (comparison to Mazda quoted figures) are not relevant in my opinion.

The type of dyno used can have dramatic results on the scale of the power figures, as can the other variables inputted on the particular day by the dyno operator. I don't think it is appropriate to speculate on driveline losses given only that info above.

Personally, I think the interesting thing above is the variation among 'stock' cars, but that's about as far as you can take it.

PaulFitzwarryne

I agree its the substantial variation between cars that is the main interest.

Many dynos, especially those of tuners, are optimistic so the absolute figure is subject to a level of scale variation. However, the only figure I gave for driveline loss was for factory data relating to new cars.

A calibration error would have a 2 1/2 error impact on powertrain accuracy but for the average person all they get is rwhp while the factory normally only quotes flywheel hp. Its the same problem as the difference between implication and inference!.

snakes99

its still amazing how much power you can get out of 2 little rotors, with a better carb and exhaust! and the hp doesnt have to be all that high to get a 2300 pound car moving.

smnc

I thought non GSL-SE 1st gens made 100-101 rwhp from the factory?

PaulFitzwarryne

smnc, all the 12a powered RX-7s sold in North America were rated 100-101 SAE bhp at the flywheel, the rwhp rating was much less due to powertrain loss. The Australian version had bigger ports and gave some 110hp at the flywheel

smnc

Ah...

I was always told the factory HP numbers were rear-wheel readings...?

Oh well... Live and learn...

thorin

56hp... ouch.

Kill No Cone

iTrader: (6)

Thank you for posting this, it is great to have some kind of baseline to work with. So often we here about incredible numbers, but rarely do we get something to match them up to.

AJC13B

So mine is making a bit over 500hp (Dyno dynamics) to the back wheels now, so thats around a 400% increase in power over standard? Or is my maths wrong?

Either way...

I wonder what the person who designed the first generation 7s would say if they saw mine, or Directs or HITmans car....that would be funny

error402

Look at it this way, when you beat someone else's car you can tell them you beat them with a car that is 20 years old car, cost $1000, has a 1.2 liter engine, that produces 56hp.

-Error

zyounker

Well, i believe AUS dynos are not comparable to US Dynos. So 56RWHP would be close to 70RWHP on a US dyno. Which seems about right..


That also means the ones making 72&75RWHP are pretty strong engines.


-Zach

MosesX605

What are the factory stats for drivetrain loss anyhow?

Matt
1979 SA22C

David88vert

I doubt that the Aussie dynos are setup to read exactly like US dynos. What brand/model of dyno where you on?

I've also always heard that drivetrain loss should be 15-20%, depending on drivetrain configuration.

Wankelguy

As the knights rally to defend the 12A's honor...

Seriously, those numbers DO seem a little lower than one would expect.
Maybe they just build lousy motors in So. Australia. (j/k!)

Don't the pre-'76 12As have larger stock ports than the RX7 12As? -WG

error402

I thought they had smaller ones. *scratches head*

btw: 12a o\/\/n$ u$ @77!!

-Error

smnc

Here's where I came up with 101 rwhp...
I really should read things more carefully...

At least it all makes sense now...

https://www.rx7club.com/forum/showth...ock+horsepower

Defprun

I say its 101rwhp, so it is.

smnc

sweetege

I say its 111, so it is'nt.

PaulFitzwarryne

The data given by Nota V6 was that a stock gsl-se gave 101rwhp, but that is a 13b not a 12a. Using his results against the factory flywheel data gives a powertrain loss of some 26%.

According to Revhed in another thread, there is a slight difference in dyno calibration with the USA ones giving a higher reading.

I originally started this thread because it was the first set of figures I have seen for over 20 rotaries made at the same time. My surpise was the wide variation between similar set up cars. Absolute hp was of seondary interest as was powetrain loss [22-28%???]

In my case I am trying to get the best spread of torque rather than peak horsepower, as this is what gives you performance on the road. Its the view of a person brought up on European rally cars rather than on American 1/4 mile drag cars.

Sterling

Ehhh- What's the difference? While everyone's busy measuring thier ****** in inches, I'll measure mine in centimeters.

Everyone wants a number to quantify the power of their rocket, but like Paul said, the # means nothing unless it's compared to something. And that # means nothing unless you've drivin it and can know the difference, right?

I also agree with Error- I really enjoy telling my passenger that my engine is only 70 cubic inches after taking him on a white knuckle ride!

I could say the thing has 200 HP, and what the hell would they know? It drives just like the car they were in that did have 200 HP, but wieghed 700 lbs more.

S'all relative, guys.

680RWHP12A

here is the real output of a 12a turbo!!!@www.roraryshack.com/dyno

maybe more real soon , i hope

MIKE-P-28

iTrader: (1)

Yeah this is like saying my car will do 0-60

Sure it will get to 60 mph, but not specifying a time in which to do so , is simply clueless

I think car HP ratings fall into the same criterea as lies, damn lies and specs

680RWHP12A

well if you want to hear something really sad.... my white bone stock automatic 85 only made 47 rwhp!!!! thats bad! i think the tranny eats some of the power....a few tranny guys told me its the same tranny as the nissan