2 Dyno Graphs and the Engine Dyno Graph Compared
 

Compare shapes only - not actual numbers

Mazda Claimed Engine (Flywheel) Graph
http://mysite.verizon.net/romano.michael/3.jpg

2 Graphs from RX-8 owners - rear wheel dyno
http://mysite.verizon.net/romano.michael/2.jpg
http://mysite.verizon.net/romano.michael/1.jpg

Any one with expertise see anything here?

I don't:D

Call me pigheaded, but I think this tends to support my theory that the engine is not fully recovering after each intake tract change, when run up in a single continuous pull on a constant-load dyno.

Look closely at the engine dyno sheet and you'll see that it's not a single pull, but a series of discrete measurements at 1000rpm increments, joined by an interpolation line.

I strongly suspect that a similar series of measurements on a variable-load chassis dyno will indicate a similar curve.

when comparing these curves, keep in mind that our experimental data is taken from the wheels, which is why there is a discrepency between the ~132lbft reading at 2500 from the Mazda data, and the ~113lbft reading on the protechnik (i'm not sure why, but the dynojet starts at ~3200).

...i'll see if i can find some time to generate the three curves on one graph in excel or something today... that might be fun.

"Look closely at the engine dyno sheet and you'll see that it's not a single pull, but a series of discrete measurements at 1000rpm increments, joined by an interpolation line." - ecc

come to think of it, i recall someone saying something about doing SOMETHING in 1000rpm or per 1000rpm or somethign like that on the dyno in regards to results, might have been 1rx8er or whatever is name is, who did i think it was the second pull

either way, i dont know what your talking about, maybe i have to look closer, though i dont really know what im looking for lol

and when your talkigna bout a similar curve, are you talking about the original mazda numbers or the other pulls?

im assuming the mazda numbers
________
Shaved Pussy Webcams

The first graph is a theoretical extrapolation of crank hp and torque based on gearing and power numbers as advertised by Mazda. It has nothing to do with real world wheel hp numbers.

Even though one graph shows flywheel hp & torque and the other shows rear wheel hp & torque, would it still be acceptable to compare the shape of the curves?

Looking at the torque curve from 6000rpm - 8000rpm notice that the flywheel graph from mazda shows a slight increase in torque for this range, but the rear wheel dyno shows a continual decline in torque for this range. By the time you hit 8000 rpm the actual dyno show a significant reduction in torque as compared to 6000 rpm.

Either the drive train loss is increasing significantly during the above rpm range or the engine is not producing the same torque curve presented by mazda. It's hard to say which it is without an actual production engine flywheel dyno to compare to.

Now if you look at the air/fuel ratio you'll notice that the ratio becomes richer at the same point. It is too bad that the Mazda graph does not include the A/F ratio. It would be interesting to see if that was different.

RomanoM,
It appears that the Japanese hi-power graph matches the shape of the actual dynos better than the original Mazda graph posted in this thread (i.e. torque starts declining around 6k).

...actually, that was surmised to have been altered so that the peak torque came at a lower RPM... that's just another diagram from Mazda Corp...

anyways, i've got the spreadsheet and graph: who the hell can put a picture of this marvelous graph i've made (in 10 mins or so) up here?? email me, and i'll mail it to you: andrew_keech@hotmail.com

Go here- free picture hosting:

imagestation.com

But you can only link directly to the smaller 'preview' images on the site- so keep it small and it will be fine- like this size:
http://www.imagestation.com/picture/...c/fc920d30.jpg

...the problem isn't hosting the picture, the problem is MAKING the picture from the spreadsheet... sorry, i should have been more clear.

Here's the spreadsheet (i'm not sure what the different curves are)

http://filebox.vt.edu/users/dstreile/tqhp.jpg

wak,

Will this help?

http://www.webtree.ca/newlife/printkey_info.htm

...sadly, this is a work computer, i dont' think that's a good idea. :(

but thanks for taking care of it for me Dave!! :D

**GO HOKIES!!**

dang, should append a little explination

TRQ 1 and HP1 are derived from the Mazda dynoplot that Romano posted first, TRQ 2 and HP2 are derived from the dynotechnik plot, and TRQ 3 and HP3 are derived from the dynojet picture: all in the order they appear here :).

hmmm, i was looking at these, i added (hope you don't mind:D) tq/hp4, which is the mazda theoretical tq * .8

http://filebox.vt.edu/users/dstreile/tqhp2.jpg

nice one. :)

...bumpage, mostly so i can claim i did it before Brian :p

wait a min... can someone explain to me why the the A/F graph is pretty steady... like it gets richer but it gets steadily richer and is almost maximally rich at like 4-5krpm. I thought people were getting sudden richness at 6,7krpm?

thanks for the bumps on this guys i almost missed this thread. so to me it looks like the dynojet is showing substantially lower numbers than the dynotechnik. so is this a problem with the dyno not being "compatible" with the car? also it does appear to not recover right away when the ports open, it doesn't just keep going but rather plateaus for about 500 or so rpm.

We can go through these power/dyno/ECU/fuel stuff for months without any real resolution. Until Mazda USA gets its acts together and start spilling some answers and solutions, all we are doing is blind guessing and speculations.

DO YOU HEAR THAT MAZDA!! WE WANT ANSWERS!!!

can someone explain to me why the japanese graph is TQ / HP vs rpm

but all the graphs from dynos are TQ vs rpm and HP vs rpm

the japanese graph is just analysied interpretation of the actual figures, no?
hence the "max power" is at the end of a negative slope

also, japan runs 96 RON min (i think)
wouldn't that gives the car more HP? probably not 40 but it should increase for sure

time for use to brew some xylene enhanced fuel for the dynos huh? probably 2 tanks before getting on the roller? giving the ecu to adjust?

I'm pretty sure that Japan and Europe rates gasoline octane differently than the US does. So their 96RON isn't the same as if you had 96 octane here. I think 98RON in Japan is equivalent to 94 in the US. So their 96 is probably closer to our ~91-92.

don't quote my octane rating... i wasn't sure
but the point is they have "better gasoline" than some of us does in the states