# dyno dynamics and skylines



## Light-R (Apr 23, 2007)

hi guys.
i wanted to share a thought and a doubt with you guys.

in what comes to tuning cars that are not honda, we are somewhat like 20 years behind most of the countries, so i would like to hear more experienced oppinions.

me and [email protected] that has an r32 gt-r went to measure the car yesterday an got punched in the stomach.

we decided to measure the car on a portuguese dyno to see the difference before and after some modifications we will do. also, we wanted to see the difference between a portuguese dyno dynamics and uk dastek (on my case).
on a dastek my car accused 643ps and [email protected]'s car managed 500ps on a rotronics with the old setup. he now has also 800cc injectors, tomei 264 cams and twin

well, i went to the rollers and came out with..... 473bhp.

i thought, well, must be at the wheels... it wasnt. it was flywheel hp. with 1.3 bar boost. started to go crazy. just wanted to kick the car.

time for [email protected]'s r32 to take his measurements.
2.6 stock block

gt2871r turbos
power fc
800cc injectors
turbo back exhaust
z33afms with apexi intakes
tomei 264 cams with pulleys
etc.

here we go. now this is where i prepared to kick my car. but... his car pulled.... 491bhp. thats odd. tweenierob said that his car, on 1.4bar boost should be doing 600+bhp. so why only 490.
and mine, why only 470 compared to the 643 on dastek.

the dyno is the first portuguese dyno dynamics. when we saw the power to the wheels on both drive shafts, we got... 200bhp on the fronts and 173 on the rears on my car, and 210 on the fronts and 170 on his rears. something like that, i dont have present in my memory.

our conclusion. our measurements were shite... we didnt got no conclusion. maybe the owner didnt configured the dyno to the skyline drivetrain system(partially rwd and partially 4wd). if it was an evo being measured i believe that the values would be accurate. but maybe because it was a skyline with its "unique" torque distribution, the dyno perhaps needed special configuration.
its idiotic to think that the car was 60-40 front to rear torque distribution (as it came on the dyno sheet) when it is supposed to be rwd (varying between 0-100 and 30-70 or something like that).

well, the other 4wd dyno is on vacation so ill have to wait to measure the car in another dyno.

do you know if there is any issues with dyno dynamics and skyline drivetrain?

maybe i should have tried to measure the car with the torque controller all the way to the rears.
=(

its really strange because up to 4750 i do the same power on dyno dynamics and dastek (around 410hp) but from 4750 to 7250 (my present rev limit) the power curve is all stupid going up and down. right in the region where the cars starts to make serious power and the attessa kicks in (on the road i get front torque movement above 4750rpm) nothing like the dastek curve. its almost 170hp difference. and the car certainly doesnt feel like 470hp. it sure feels like a lot more. both mine and [email protected]'s. and another fact. i see 90.1 peak duty in my 660 injectors at 7250rpm. so with a stable afr of 11/12 on the power curve i think its odd to see only 470ps.

let me know your thoughts on this.
is there any special instructions? is there any special configuration that has to be done to the dyno?

also, do you guys (those who have torque splitters) measure your cars with torque split controllers on or off? 4wd or rwd?
can the car be measured in rwd mode? or is this only attainble when the front driveshafts have been removed?

i will post pics of both our dynos today.


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## mifn21 (Mar 19, 2007)

I think you should go back and dyno the car in 2WD mode (not sure if you can just pull a fuse on the R33 like you can on R32s)
If its measuring more power at the front wheels with both cars, its obvious that the dyno is at fault, so don't kick the car just yet 
Maybe the rear wheels are spinning a bit on the rollers? Would explain the curve going up and down


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## Light-R (Apr 23, 2007)

my dastek part 1










my dastek part 2










my dyno dynamics part 1










my dyno dynamics part 2










[email protected]'s dyno dynamics part 1










[email protected]'s dyno dynamics part 2


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## Light-R (Apr 23, 2007)

thanks for the idea mifn.

so if [email protected] removes his fuse and if i turn my splitter off (full rwd mode) there should be no poroblems caused to the drivetrain??

i thought that skylines couldnt be measured with the front wheels "stopped" even with torque set to full rwd.


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## markM3 (Jan 7, 2008)

My dads was mapped on a dyno dynamics and produced 371atw which apparently translated to 442 atf, this was at 1.4 bar boost with N1's.

A few people on the forum suggested something was wrong, but the guys who mapped it said they had done a few with this and similar set ups and that was the power they all made on their dyno dynamics rolling road.

People said it should be 500bhp atf and no doubt on another rr it would be.

You can only really compare similar RR's and even then there will be variances (weather conditions/operators/tyre pressure and even compound of the tyres!), so as long as the car runs well, I wouldn't worry too much.

Cheers,


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## SmigzyGTR (Mar 20, 2006)

Light-R said:


> i thought that skylines couldnt be measured with the front wheels "stopped" even with torque set to full rwd.


Im pretty sure thats correct with R33's, i figured transmittion losses to be around 70-80hp when i was at 365hp, but i cant see it increasing as the power goes up. I reckon the dyno hasn't been set up for 4wd correctly....


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## SmigzyGTR (Mar 20, 2006)

markM3 said:


> My dads was mapped on a dyno dynamics and produced 371atw which apparently translated to 442 atf, this was at 1.4 bar boost with N1's.
> 
> A few people on the forum suggested something was wrong, but the guys who mapped it said they had done a few with this and similar set ups and that was the power they all made on their dyno dynamics rolling road.
> 
> People said it should be 500bhp atf and no doubt on another rr it would be.


I make 480 atf @1.2bar and if the N1's are the R32 variant, you should be getting even more than me at 1.2 IMO


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## mifn21 (Mar 19, 2007)

Light-R said:


> thanks for the idea mifn.
> 
> so if [email protected] removes his fuse and if i turn my splitter off (full rwd mode) there should be no poroblems caused to the drivetrain??
> 
> i thought that skylines couldnt be measured with the front wheels "stopped" even with torque set to full rwd.


Shit, just remembered its only the R32s that can run 100% rwd - later gtrs always have a little bit of power going to the front wheels


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## Light-R (Apr 23, 2007)

i really dont know smigzy.
i believe that the permanent 4wd cars like the evos, get accurate readings.
our 2 skylines were the first to go there, so maybe he doesnt know how to set the dyno.


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## Light-R (Apr 23, 2007)

markM3 said:


> My dads was mapped on a dyno dynamics and produced 371atw which apparently translated to 442 atf, this was at 1.4 bar boost with N1's.
> 
> A few people on the forum suggested something was wrong, but the guys who mapped it said they had done a few with this and similar set ups and that was the power they all made on their dyno dynamics rolling road.
> 
> ...



yes mark, but you had only 30hp difference. i had almost 200hp difference.

if you compare dastek curve and dyno ynamics curve, they are alike until 4750. above that and they are really different. the dd curv starts to jerk a lot.


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## Richard Bell (Jun 29, 2001)

Looks like the dyno is setup in the wrong mode for the GTR to me. The dips are were its shuffling torque between the front and back.


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## tweenierob (Aug 5, 2003)

Light R, ive dynod over 1200 cars on dastek so can safely say chuck the power graph you got there in the bin, totally inaccurate mate. 
Peak power and torque at 7250... Hmmm lol why did your graph stop at 7250?
Ive also had a lot of use recently with a Dyno Dynamics dyno, Strapping on these dyno's is so important for accurate readings. Remove the fuse on Tiago's 32 and unbolt teh G sensor on your car by the handbrake and turn it on its side. 
You should have no problems with power readings then.

Looking at your dastek graph, if dyno'd correctly i would say you are making around 540-550hp peak flywheel. The graph looks like the car has been strapped too hard.

Cheers

Rob


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## Light-R (Apr 23, 2007)

Richard Bell said:


> Looks like the dyno is setup in the wrong mode for the GTR to me. The dips are were its shuffling torque between the front and back.


so, probably, the only solution is not on the dyno but on the car. just like rob said.


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## ru' (Feb 18, 2007)

Remove the front driveshaft for rwd dyno runs with an R33...


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## [email protected] (Jun 16, 2007)

Ok so as my friend light r says its very wierd this power figures, my car was dynoed with the previous owner i think it was on Rising Sun and it was producing 420 bhp at 1 bar.

The spec Then:
-Unknown Cams
-32 Nismo turbos
-Fujitsubo exhaust
-Aftermarket downpipes (unknown brand)
-HKS intake
-HKS hardpipes
-Os Giken Triple plate clutch
-Greddy profec b spec II

A dyno with these mods on a Rotronics dyno its more or less like the Maha dyno but more advanced.












The spec now:

-Sard 800cc inj
-Sard 280lph fuel pump and harness
-Sard fuel rail
-Sard fpr type Rj
-Cometic head gasket(oem replace)
-Greddy 264º 9.15 lift cams(intake and exhaust)
-Tomei cam guears
-Z32 afms
-Apexi super suction kit 80mm
-Twin Garrett GT2871R - 707160 - 10
-Remapp
-Greddy profec b spec II
-Os giken triple plate

The weird thing is that the power and torque cuts are at the same time when turbos beguins to spool up and then the atesa puts power at the front wheels.

More wierd is that both light-r and me had 220 hp to the front wheels and 170 to the rear wheels.:nervous: and my front torque gauge climbs to 30%.


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## tweenierob (Aug 5, 2003)

ru' said:


> Remove the front driveshaft for rwd dyno runs with an R33...


Yup, but no need. Car really needs to be dyno'd in 4wd for accurate readings.

Rob


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## Light-R (Apr 23, 2007)

tweenierob said:


> Light R, ive dynod over 1200 cars on dastek so can safely say chuck the power graph you got there in the bin, totally inaccurate mate.
> Peak power and torque at 7250... Hmmm lol why did your graph stop at 7250?
> Ive also had a lot of use recently with a Dyno Dynamics dyno, Strapping on these dyno's is so important for accurate readings. Remove the fuse on Tiago's 32 and unbolt teh G sensor on your car by the handbrake and turn it on its side.
> You should have no problems with power readings then.
> ...


yes mate, i have absolutely no problem in admiting that the values are innacurate, probably more of a "marketing solution" than anything.
the peak power and torque were on that rpm, because it is the rev limit on my car. it has been lowered due to small injectors. thats why im increasing to 1000cc (took your advice on 800cc ones). i am not saying that it is accurate. only stating thats where my rev limit sits.
our cars were well strapped on the dd. so i believe the only problem should be the g sensor then. cant i just turn the switch that gives me full rwd, on?


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## Light-R (Apr 23, 2007)

mifn21 said:


> Shit, just remembered its only the R32s that can run 100% rwd - later gtrs always have a little bit of power going to the front wheels


sorry.

mifn had already answered my question


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## tweenierob (Aug 5, 2003)

What injectors are you running atm mate?

Rob


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## SmigzyGTR (Mar 20, 2006)

660's Rob.


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## tweenierob (Aug 5, 2003)

OK, not too small then.

Rob


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## Light-R (Apr 23, 2007)

sorry smigzy.
bad spelling from me.

600cc nismo purple tops. 4bar (i believe, not sure) on fpr, and nismo 280(?)lh nismo intank pump. they give me around 90/91 injector duty @ 7250rpm.


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## tweenierob (Aug 5, 2003)

Your car is running way too rich on boost looking at your AFR graph, that would explain the higher IDC. 

No worries, good move with the move away from 800's dude.

Rob


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## Light-R (Apr 23, 2007)

sorry rob, didnt catch that. really dont know what idc is.

you are saying that i am a bit lean and that i should decrease the boost?

if thats it, there is no problem as i usually run my car on minimum boost (0.88bar).

just waiting for the new injectors to do a remap.


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## [email protected] (Jun 16, 2007)

tweenierob said:


> Light R, ive dynod over 1200 cars on dastek so can safely say chuck the power graph you got there in the bin, totally inaccurate mate.
> Peak power and torque at 7250... Hmmm lol why did your graph stop at 7250?
> Ive also had a lot of use recently with a Dyno Dynamics dyno, Strapping on these dyno's is so important for accurate readings. Remove the fuse on Tiago's 32 and unbolt teh G sensor on your car by the handbrake and turn it on its side.
> You should have no problems with power readings then.
> ...


Hy Rob so its safe to do a dyno only on rwd on a R32 ?
Will it be accurate?
All that i want is an accurate dyno ,the hp figures are not the most important feature.

Cheers


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## SmigzyGTR (Mar 20, 2006)

Light-R said:


> sorry rob, didnt catch that. really dont know what idc is.
> 
> you are saying that i am a bit lean and that i should decrease the boost?
> 
> ...


Light - IDC is injector duty cycle, he's saying your running rich so thats why your IDC is 90/91 when it should be lower at that power (I THINK LOL)

i run 700's at 480fwhp and see around 60 - 70% duty on WOT


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## tweenierob (Aug 5, 2003)

It is safe to dyno your R32 in rwd, you may find your flywheel figures slightly higher than actual.
Light R, sorry mate... IDC Injector Duty Cycle. You are running too rich IMPO, hence why your injectors are running at 90-91%. On 600s looking at your power graph and fuel system setup you should be fine to rev to 8000-8250 if mapped correctly.

Rob


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## EvolutionVI (Sep 6, 2005)

Youll just need to look at the "loss" in the dastek dynosheet,nearly 160horses loss between flywheel and wheels 

As Rob wrote,throw that dynosheet in the bin


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## Light-R (Apr 23, 2007)

as i never had a gtr, i dont know if those kinds of values are normal.
if i remember correctly my 380bhp evo got below 300atw. so i dont know if 160 too much.

but as i said, i wouldnt wonder if the value was inflated. nor would i have any kind of shame to say it
=)


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## Conrad (Jul 29, 2004)

Dyno Dynamics are very accurate if done correctly!

As Rob says.... the graphs you have there are nonsense, bin them! The oscillations on the graph are indicative that it was not setup correctly on the dyno.


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## EvolutionVI (Sep 6, 2005)

Light-R said:


> as i never had a gtr, i dont know if those kinds of values are normal.
> if i remember correctly my 380bhp evo got below 300atw. so i dont know if 160 too much.
> 
> but as i said, i wouldnt wonder if the value was inflated. nor would i have any kind of shame to say it
> =)



Yes,thats correct,Evo´s have between 60-100horses loss in the drivetrain,but GTR´s have a lot less,most dynosheets i have seen are under 50 horses loss....


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## chas (Sep 19, 2003)

LOL, questions, questions, questions....

My (Dastek) graph shows roughly 50bhp loss as well, needless to say I'm skeptical about dyno readings of any type now.
I take it that the power is measured at the rollers on the rundown and then "corrected" upwards to give flywheel guesstimate? Do all dyno's do this?
I've seen quite a few cars on the rollers being revved on the rundown, why is that? and why are the torque figures never corrected? Why do the dastek sheets need to go in the bin?, I'll happily throw all mine out but could do with more of an explanation than "they're shite". These are the only way I have of getting the power measured.
Is there any way of working out power on the road using say 3rd gear and engine revs versus speed?


Charlie.


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## Hi5 (Aug 31, 2005)

why do people care about flywheel figures anyway, its what you put down on the tarmac that matters surely?


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## EvolutionVI (Sep 6, 2005)

chas said:


> Why do the dastek sheets need to go in the bin?, I'll happily throw all mine out but could do with more of an explanation than "they're shite".



If yours are correctly,then they dont need to go in th bin,but the ones from this thread,are totally wrong,youll never get 160horses loss on a GTR :thumbsup:


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## chas (Sep 19, 2003)

Hi5 said:


> why do people care about flywheel figures anyway, its what you put down on the tarmac that matters surely?


I care, it's why I f*cking asked!


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## chas (Sep 19, 2003)

I need to add, I care more about the way It's worked out rather than the figures themselves.


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## tweenierob (Aug 5, 2003)

As Alex says, your losses are more realistic Chas.

I personally rev the engine on coastdown to keep the oil and water flow up as the engine has just had a full bore run. The clutch is depressed so actual effect on coastdown losses is nothing.

Rob


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## chas (Sep 19, 2003)

Cheers.


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## Light-R (Apr 23, 2007)

now thats an explanation that everyone can use.


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## [email protected] (Jun 16, 2007)

Ok so tomorrow i will go back do the dyno and i wil make the test only on Rwd.
I will take off the fuse that says 4WD.
-Should i turn the g sensor to the side ?
-Anything else i should do ?
-What guear is better for test ?
If all goes well the chart will not show those cuts on the power and torque lines.

-For those who knows Dyno Dynamics Dynos is there anything i should advice to the person who perfoms the test?

Cheers [email protected]


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## SEGTR (Nov 12, 2005)

See http://www.gtr.co.uk/forum/101221-drivetrain-losses.html#post940765 it may be of some help.


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## Light-R (Apr 23, 2007)

thanks seg.
really nice link.
its going to my fav list.

so the gt-r should be dealed with the rwd formula


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## canman (Jul 7, 2001)

Come on, we know there's only one Dyno to use if you want back to back accurate runs ?? Pesky tyres get in the way of real repeatability and control eh 

Dig Dig....... just winding you up guys........

As others have stated, I'm only interested in what comes out at the axles, but I can understand why others want to know a flywheel figure, but they're only ever going to be an airy fairy made up number, you'll never know if its accurate, but some people like to have stuff to waffle about down the pub............and some are just out driving instead


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## Light-R (Apr 23, 2007)

unfair comment fraser.

i am the kind to go out and driving instead. and i wouldnt mind to get both values. HP and WHP.

its just that everyday supercars, get their numbers in HP. so it would be nice to see an equivalent value. then, adding weights into the math, 2 or 4wd, etc.

i believe that both numbers can be used.


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## canman (Jul 7, 2001)

Not really......... my point was that flywheel figures are just for waffle as they don't mean anything from hardly any makers.

We do a lot of work with OEM's and the figures they quote at the flywheel isn't always, in fact I'd go as far as to say, they are very rarely, real world figures.

There's nothing wrong with following the same process each time they make a change or update, in fact it's a requirement since they need to have a consistent process to make it valuable data, but BMW for instance run their engines without most paracitic devices such as oil pumps, water pumps, alternators etc etc, thats all supplied externally when they get a figure and generally their figures are from an engine dyno, so you're not even comparing the same things...... not even close........so all you can really use that flywheel figure for is pub bragging.

Make sense now ?


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## ru' (Feb 18, 2007)

or pub discussions. I don't really want to spend time discussing how manufacturers give a flywheel figure, but I've just given a wheel figure, and what the difference is.

It's much easier to give the 'calculated' flywheel figure straight away. We all know its rubbish, but then so are the manufacturers figures (see above) so what's the problem?


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## canman (Jul 7, 2001)

No problem, just don't see the point in giving a figure that really has no value in a conversation / discussion when it's all hearsay and non factual.

I'd rather deal with the facts only.........easier, thats all....... I personally don't see the point in introducing "made up" figures..... but I understand that others want to, that's OK, just stating why I felt it wasn't worth it, didn't know if others really understood that the wheel hp figures were just best guess calculations.


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## Light-R (Apr 23, 2007)

i agree with ru.

obviously, i know that WHP will really determine how fast my car will go. and i also know that manufacturers figures, might be off. but then again, chit chatting, what sense would it make, making a discussion, saying that my renault or something that only has 200whp, managed to keep up in a straightline friendly test with someones lambo that has 580fwhp. its nice, but not instantaneous to do the math.

but anyway, i dont want to argue with anyone. just stating the way i see things.


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## Light-R (Apr 23, 2007)

canman said:


> I'd rather deal with the facts only.



i understand what you say. i do.
but for example, do you know an average value for WHP for a murcielago?

if not, you still have the "earsay" value of 580fwhp. its just for easy comparision


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