Skyline

Maybe I'm still used to the screaming VTEC of the B18C7, and I know that the 8's power delivery is extremely linear from start to finish, but just seems like as soon as the needle hits 6k, power seems to not drop off, but platteau's to 7k where the motor seems to get its second wind and take off again.

Has anyone experienced this or is there a reasonable explination? Does the latest flash rectify this issue? Any info appreciated.

Cheers
Skyline

takahashi

Agree... although there is another boost low down at around 3500...

Agree the engine does not do much b/n 6500 to 7500 then it gun again until you hear the beep noise.

Gomez

The VDI (Variable Dynamic Effect Intake-Air Solenoid Valve) operates at 7300rpm to increase torque......that explains the relative boost you feel above 7000rpm.

It's normal..........

Gomez.

Skyline

takahashi

dont be alarm... I have pic from the RX-8 book

http://www.step-hen.com/rx8spec.htm#SDAIS

Skyline

Thanks for the info... The dyno graph on Taka's page explains the dip at 6-7k. It just feels more pronounced than the graph illustrates though.

sco

G flash seems to make power delivery more linear across the range, but I don't know if that is because power is cut somewhere rather than boosted where it was low. Would be interesting to compare a before and after dyno plot.

Skyline

Agree SCO, even with the Type R, before the VTEC cut in at around 5800, there was a pronounced drop in power (On dyno anyway) which made the VTEC seem "bigger" than it was.

Hymee

iTrader: (1)

Here are some real dyno plots of mine that show it quite obviously. The first plot on Taka's link is very "low resolution", and it is easy to miss the dips. I have a dyno plot from a DynoLog that looks very similar.

It is when the variable intake tracks (S-DIAS) transitions from one config to another. It would be good to tune it out.


Chassis Dyno


Accelerometer (MRDyno) The "g force" curve is what you feel - the push in the back.

Cheers,
Hymee.

Skyline

Brilliant!! Thanks a lot Hymee...

If anyone knows- With the Ric Shaw piggyback ECU, has there been any favourable results eg tuning out the 2 "humps" in the dyno graph?

Gomez

Hymee, where does the MR Dyno get it's RPM signal from??? It's obviously pretty accurate....

Gomez.

Hymee

iTrader: (1)

Not to my knowledge.



We haven't spent enough time on it.

Cheers,
Hymee.

Hymee

iTrader: (1)

Good question.

It calculates it. How? From the speed. I entered a factor for km/h per RPM. How does it measure speed? It is the first derivative of acceleration.

The MRDyno only measures acceleration and time, rather accurately.

Everything else is physics. Pretty trick really.

Cheers,
Hymee.

(oops - originally edited your sacred words, 'mez . Bad boy, Hymee! )

takahashi

Do you mean this one

Skyline

Thanks Hymee...You have a dyno chart for everything

Hymee

iTrader: (1)

Thanks dude.

I try to understand, and not fall victim to BS. There is plenty of it around. I hope to learn, and let others benefit if they so choose.

Cheers,
Hymee.