Dyno Test

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Zeca
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Dyno Test

Post by Zeca »

Hey guys,

After a long time, an accident where i damaged the front bumper the headlights and the hood, fortunatly wasn't a front crash, i just drag the front over a rail, so was most of it scratch, but people were asking 2500€ for the headlights, hood and bumper i decided to buy and entire one in the UK just for parts, and i saved like 800€ after paying transport and everything...

The car have one modification, it have a straight exhaust system, no cat.

And after all these years i finally went to a dyno test with my 8.

Me and my friends made our bets, i pointed to 180bhp...

For translation "CV" = "BHP", and this measure was done to the flywheel.

And 171Nm = 126ft-lb

So here is the results...

Image

The question is... this is a normal result? I have no troubles on cold start, no trouble on hotstart, the idle it's fine...

I had one problem, back to 2017 with a coil failure, and i took one coil from the donater, and solve the problem... but i still think the ignition might have something to do with this (at least for me) bad result. If we analyse the graphic, at third stage it collapse right after it enters, and shouldn't be like that, and this is the reason that leads me to the faulty ignition system, eventhough i didn't noticed any misfire until now, it feels smooth :-k

I was kind of disapointed, and with a mix of sadness to know "she's" not in shape, but excited because i already take a lot of fun out of "her", and start thinking what it could be if i can improve this result :lol: :lol:

Well, wait for your opinions! Thank you!

Kind regards! (and sorry for the long post #-o )
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Re: Dyno Test

Post by PeteH »

169bhp would be normal at the rear wheels, but I think those plots show 169bhp at the flywheel, and about 120bhp at the wheels. It's a bit odd though, because the white curve doesn't seem to equal the blue curve plus the green curve, like it should.

And producing peak wheel horse power at only 7000rpm is very unusual for a 231 (It is a 231 I assume, since it revs to over 9000rpm).

So it does look like your car is significantly down on power.
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Zeca
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Re: Dyno Test

Post by Zeca »

PeteH wrote:
Sun Jan 13, 2019 9:15 pm
think those plots show 169bhp at the flywheel, and about 120bhp at the wheels.

And producing peak wheel horse power at only 7000rpm is very unusual for a 231 (It is a 231 I assume, since it revs to over 9000rpm).
Yes you're correct, it is a 231 version and the measures are made to the flywheel aswell.

It's strange isn't it? at the moment the 3rd stage enteres at ~7000rpm, it just looks like it starts stalling immediatly... anyway im going to start looking for someone who can make a compression test, or maybe i'll buy a kit and do it myself the test... to take doubts, hoping it's not compression problems :roll:
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Re: Dyno Test

Post by untakenname »

Was the DSC fully disabled before the run (Button on dash held down for 9 seconds)?

My car made no more power after 7k when there was a group rx8 dyno session back in October, total was 165 bhp at the fly which was around 40 down on the stock RX8's that day even though I have Revi intake, full exhaust and street port so in theory should have been putting down more than stock.
scan0002.jpg
The dyno operators had some issues getting the afr when they put the probe in the exhaust so I think they turned my car on and off on the dyno (my dashcam has a split file 20 seconds in which happens when the ignition is cycled) and then didn't do the DSC disable so the brakes were holding the car back as it tried to accelerate, there was a lot of brake dust on the rears as well I noticed when I next cleaned the car.

My car pulls hard from 7.5k to 9k on the road and I definitely wasn't 40hp down on track when compared to other RX8's a few weeks later as there was quite a few on the day and they didn't pull away on the straights like they would if they had a 40 more hp than myself.
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Zeca (Sun Jan 13, 2019 11:22 pm)
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Re: Dyno Test

Post by Zeca »

untakenname wrote:
Sun Jan 13, 2019 10:27 pm
Was the DSC fully disabled before the run (Button on dash held down for 9 seconds?
Yes, it was off, i disabled it myself right before the test, and the car didnt got shutted down meanwhile... it would be awesome if it was this the problem :o and to be honest i didnt know it could affect that hard :shock: i just deactivated it cause the guy asked to do so :lol: ... nothing more...
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Re: Dyno Test

Post by warpc0il »

It's actually the Traction Control function that kills power on the dyno - which is obvious when you consider what is happening.

Front wheels stationary and rear wheels "spinning". If not fully disabled then the PCM will initially cut power and, when that doesn't stop the wheelspin, it will apply the rear brakes.



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Re: Dyno Test

Post by Zeca »

Well at least both lights were on, the symbol of the car with the tyre marks on the floor, and the dsc off... i assume they were shut down, unless i have some electric problem, but i doubt, cause i drive the car most of the time with both off, and the car spins the wheels freely...

But the front tyres being stop, can interfer? It should consider as if i were doing a burnt out no?

Im searching for dyno tests to compare with other stock cars, and it seems the stages at least until the stage 2 it very identical to all the others, only when the revs go after the 7k it goes wrong...
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Re: Dyno Test

Post by Zeca »

Hey Guys,

Finally i got my dyno results... after the 5,5k rpm the struggle intensifies, the wheel power graphic looks like it have Parkinson. Im sure i disabled the dsc and everything (pressing for 10 secs the button and wait for both lights get on). So admission? ignition? Or somehow it still being strangulated electronicly? It doesnt seem to be compression... or is it?

Image
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Re: Dyno Test

Post by untakenname »

Do you know what your AFR is like at the top end? Could be the fuel pump not supplying enough fuel, there's a youtube video of a guy getting his rx8 dyno'd recently who had a fueling issue above 6k.
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Re: Dyno Test

Post by 13Black »

Just unplug the darn ABS fuse and be done with it methinks.
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Zeca
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Re: Dyno Test

Post by Zeca »

untakenname wrote:
Mon Jan 21, 2019 3:56 pm
Do you know what your AFR is like at the top end? Could be the fuel pump not supplying enough fuel, there's a youtube video of a guy getting his rx8 dyno'd recently who had a fueling issue above 6k.
Is it possible to measure via OBD2, or its not reliable at all?
13Black wrote:
Mon Jan 21, 2019 4:07 pm
Just unplug the darn ABS fuse and be done with it methinks.
Is there any possible way, even bieng everything off, that it is electronicly stangulated?
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Re: Dyno Test

Post by Nerdstrike »

The AFR readings via OBD are fairly good, at least good enough for figuring out if something is wrong. You wouldn't want to tune a car that way, but the estimate has to be good because the ECU trims itself for efficiency that way (efficient for a rotary that is). I believe OBD also reports commanded AFR or am I imagining that?

Aside from fuelling, exhaust restriction is another way to limit peak power. The famous failing catalyst matrix is possible if you've had coil trouble in the past. If you go for a blast to log some AFR readings, have a look underneath immediately after to see if anything is glowing red, or maybe the rails for the driver's seat are crazy hot.
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Re: Dyno Test

Post by Zeca »

Hey guys,

After all this days, i finally could ended a maintenence by myself, i bought the material to lift it up, and working on the garage of my building, near my enviromental friendly yaris hybrid that dies intoxicated everytime i take my baby out ahahhaha.

The objective was to know the cause of that poor dyno test, that made me sad for a while. OFC Im not the greatest mechanic in history but im a very fast learner, the first time is allways the longest, but with persistency i get into this:

1 - Jack it up

Wasn't the easiest task, and taking the wheel out was a bloody strugle... but i was able to do it, and when i take out the wheel and distach the kinda rubber protection to get in the sparkplug are here's what i saw...

Image

yup... the leading wire of the spark plug in the rear rotor was hanging there, i got so mad with that, that i needed to get out and take a breath... start thinking when it happened, and got to the conclusion that it might get back to 2017 when my fist coil died and i went to the mechanic to change it, cause i didnt had the conditions to do it myself, and here's the result... i called myself a bloody idiot for 3 consecutive days, and still calling myself, but now only 3 times a day...

Heres another image for you to see why it was hard to lift it up...

Image

2 - Spark plug conditions

They were all very similar to the one in the photo, and i informed myself from another topic that it's normal that the spark plug get some light brown color, since the previous owner bought and installed new ones, i decided to put them back, maybe you can evaluate better than me, if should i change it, or i can stick with that ones a few more KM?

Image

3 - Compression test

Well, and i recieved some bad news with this one, but i think i was very lucky to get the car in a dyno test and it handled it even with one spark plug out (what a f**king a**hole) and didn't died in there... so it's a warrior i have here!

So, results, front facing rotor 5,51bar; rear rotor 6,05bar (it was the rotor of the hanging cable, kinda got surprised, i was expecting a totaled rotor by that fact)... yup i already start sparing for the rebuild!

4 - Coils

Started by taking out that massive intake box, take a look to the throttle body, it seemed ok for me, and go to the coils... and yup i added the word stupid to the "bloody idiot" so i stand for " bloody stupid idiot"...

Image

3 of the 4 coils were very similar to this one, except the one i substitute back to 2017, i wonder why the hell i didnt take them all out... never will happen again! Replaced it all, and put back everything.


After all this mistakes, and all the corrections, i reset the ecu (20 times brake pedal procedure), i took a calm drive around, and GOD WHAT A DIFFERENCE! So smooth, way less noisy, way less odor (it still smells, with straight pipe lol no wonder, but much better).

Thank you guys for the help, and im waiting for the next dyno test to see the improvements!
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Re: Dyno Test

Post by warpc0il »

Well, at least you now know "why" and have fixed it :D
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Zeca (Sun Feb 03, 2019 9:01 pm)
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Re: Dyno Test

Post by Zeca »

warpc0il wrote:
Sun Feb 03, 2019 1:17 pm
Well, at least you now know "why" and have fixed it :D
Indeed, now the rebuilt, but i think i'll let it to someone that knows how to work with it... im not feeling confortable enought to do it myself, for starters and dont even have the conditions to do it, and also the knowledge isn't enought, not even close... i wish i had kinda R*tary R*vs nearby :roll:
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Re: Dyno Test

Post by RobinPZ72 »

Honestly with the tech doc's available with a membership to this club and the advice you can get, there is not a lot you couldn't do! Go for it and if in any doubt just ask as it will be answered!

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Zeca (Sun Feb 03, 2019 9:00 pm)
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Re: Dyno Test

Post by Zeca »

Hey guys!

After almost 1 year with my car in stand by due to some money struggle, i still managed to keep my car, unfortunatly stayed in the garage, maybe got out 4 times since that last post.

Been thinking for a while in exchanging the coils and cables, since i couldnt remember how were the ones i exchanged, so i went to the garage to take them out, and man, how good it felt put the hands back on the engine bay eheheh.

Anyway, i took it out and got no signs of burn in any of the ignition coils, and it was kinda bitter sweet, cause i really wanted to exchange, but i feel like since theres no potential reason for it, should i invest the money on something else? maybe some coilovers? in the other hand, everywhere i look for this matter people say that the ignition coils is the best investment you can make to your 8. Dont know, any thoughts?