Big 'D'

Yes my turbo does spool late, probably due to me using a flat boost duty cycle the headers I am using, the size of my intake bore and the volume of my intercooler, but despite the late spool on the dyno the setup seems to work very well on the road as my Pod runs have proven.

Cheers Iain

Big 'D'

The spool times for both graphs are actually very similar just the scale is different and very hard to make an accurate comparison plot, the duty may have been slightly higher on the S4U dyno run too by about 4-5% (was a flat 45% at DSA today).

Cheers Iain

Big 'D'

Thanks Shaun, it seems that there is alot of R+D to be done here to understand exactly what is a correct setup for the RR and how it all comes together, I cant wait to see how the TN figure acts with the correction.

Cheers Iain

MartynJ

The ratio of a given gear or box has no bearing on the TN, to be perfectly honest I have never seen anything that does affect it. Ours is always 3.531 on every car we have ever ran regardless of all the other parameters.
I am of course as interested as the rest of you so I will put the question to the DD rep on Monday.

Big 'D'

After doing more searching of DD RR graphs the TN figures mostly all seem to be set at somewhere between 3.5 and 3.6, it will be interesting to see what if any the effects are of changing the TN figure.

Cheers Iain

dynamix

iTrader: (3)

DSA always seem to be 4.512

Lewak

iTrader: (1)

Well done Iain. Excelletn results there mate.

Still it does leave brown marks on the seats from passengers lol.

Question tho what does the BP mean at the bottom of the graphs?

Big 'D'

Yes but why, that is all I am asking.

From the outset all I have been looking for is a fairly accurate dyno run, up to now my IT and corrected power output have been in question which is fair enough, the IT is now bang on AT but now there is this TN figure issue? If the meanings of all these figures/settings were layed out somewhere for all to see I would not have to ask the question but it is not clear and all my dyno runs up to this last run have been with a TN of 3.536 so the 4.512 TN caught my eye and I would like to know what it means and how it is related to the displayed figures.



Cheers Iain

Big 'D'

Barometric pressure which is affected by air temp and altitude so will be different from location to location and even day to day depending on the weather.

Cheers Iain

Big 'D'

Well it looks like I should have been a little braver with the boost duty on the last run, with a 45% duty cycle the apexi was indicating 1.5 peak and on the DD RR it was only peaking at 1.35 Bar.



The torque and power curves follow the same trace just further down the scale.



Cheers Iain

Shaun

If the Apexi was showing the same peak boost of 1.5bar on your S4U dyno run then it is irrevelant imo, as you are remaining apples and apples on your boost targets from a constant source..... regardless of what one RR reports the peak over another RR.

The Apexi is a constant.... using different RR's isn't.

Big 'D'

The apexi did show the same boost at S4U (1.45 on the dyno graph) but I had about 4-5% more duty than when at DSA to achieve the same boost, probably due to the high intake temp. The best thing I can see to do now is leave the car as it is, run it at S4U again with the IT sorted, have a play and see how the TN figures affect the correction then if it all ties in then up the boost back to 1.45 and see what the differences are if any

Cheers Iain

typeRv4

If the boost was slightly down it would explain some of the difference in power figures.

Different dynos can put different loads on the car effecting spool - vf turbos pushed hard can be quite sensitive.

Shaun

Iain has stated the boost recorded on the Apexi was the same on both dyno runs, so according to that constant, peak boost remained unaltered..... what has altered is the Rolling Road venue.

Also both dyno runs used the same Ramp Rate.

typeRv4

Probably more scientific to ask them to check their boost sensor for accuracy.

If it is under reading they would like to know im sure + help anyone who uses their dyno in the future

Big 'D'

I am booked in to S4U for another run tomorrow morning 09:00.


Cheers Iain

Terminator X

iTrader: (7)

Why not SRR? IMHO give S4U a miss.

TX.

Tidgy

i hope S4u arn't charging you for all these runs D, the fact that people are questioning there results should warrent investigating by S4U to find out if there doing it right or wrong

JohnHey

TN will be the roller inertia/retarder, quoted in kgm2. 4.5 sounds a lot, however if the dyno is calculating that its having to overcome 4.5kgm2 and its only having to overcome 3.5kgm2 it would inflate your figures (I think) so I dont think you need worry that the TN is reduced your result in this case.

The TN would be same on every run for a specific set of rollers, its a roller calculation not a car calculation and most likely calibrated by the dyno installers.

Hope this helps

Big 'D'

I think that it is very unfair to assume that just because they have not had the Dyno in for long that they are in any way at fault here, I am sure that with the figures I have from DSA and the settings I have kept on my Apexi the runs tomorrow should be a fair comparison. I am interested to see what effect if any the sorted IT has on the runs and if the TN figure has any bearing on the correction factor.

Again I will post the results as soon as I can.

TX, I feel it is quite important and only fair to run at S4U again to compare figures etc, especially as that is where this all spawned from.

As my IT is now sorted and I have boost and TN figures to compare tomorrow so it should make for an interesting run.

A run will be done at SRR later on in the month so dont panic

Cheers Iain

Big 'D'

I am not worried about the figures being inflated/deflated, like I said I am not looking for free power, but it is very odd that the TN is 1.0 higher at DSA than pretty much any other DD RR I can find printouts for. So I just wanted to find out why that was and what effect it would have on the correction.

Cheers Iain

Tidgy

think you miss understood what i mean. I'm not assuming its right or wrong. If it was my dyno and there were some questions about the validaty of the results i'd ask the person back to run again without charging them to find out if i have done something wrong or if theres a fault with the dyno or if it was a correct reading, at least get to the bottom of it either way

Maybe even try a few different cars with result from other well established dyno's to try to figure out if your doing things right or wrong as a comparison.

Or possibly run your car, then ask a local dyno to run it as well as a comparison on same day. It does happen, was at a dyno a few weeks ago and a car was being sent up due to results being alot lower than expected elsewhere.

in the grand scheme doing a few power runs ain't much at all for a compay with £100k dyno, so if they keep charging you to put it on then sounds like there trying to get you to pay for testing it and there learning.

but hey thast just if it was my dyno

JohnHey

Like I say, the TN will depend on the type of roller, weight, circumference, bearing differences etc will all effect the resistence of the rollers, and the TN figure quoted is merely a dyno correction figure dependant on the type/model of rollers being used. As MartynJ says, their TN never changes regardless of car etc. My guess would be that DSA use heavy duty rollers.

(Just looked, DSA and S4U both use DynoDynamics, but thats not to say they may be different)

Big 'D'

I understand that it is dyno specific but as the output on the S4U rollers is in question I just want to make sure that I am covering everything thats all.

Nobody has said anything towards the DSA printout, going off that printout I am running 11.80 at santa pod with only 330ft/lbs torque and 1.35 Bar of boost on a VF35, seems almost insane to me but thats not to say it cant be done.

Cheers Iain

Terminator X

iTrader: (7)

Makes sense as DSA have a reputation for conservative (read accurate!) figures ...

TX.

JohnHey

Ah, yes I get you. Well I would guess (quick mental physics) that if the TN at S4U was meant to be 4.5 (ish) kgm2, and your 'real' bhp was 360 (as per DSA), then S4U would have given about 425bhp, so think you're safe on that front too! LOL

Tidgy

after a bit of digging,

Dyno dynamics do two different version of the same dyno,

AWD 450 DS Quad retarder Chassis Dynamometer

and

AWD450DS Chassis Dynamometer

the latter has this in the tech information regarding intertia

Inertias (Per axle)
Roller inertia and retarder (combined) --- Standard Aux Retarder/PAU*
2.590 kgm2 (61.5 lbft2) --- 3.566 kgm2 (84.6 lbft2)
Bed equivalent inertia (typical) 219 kg --- (483 lb) 302 kg (665 lb)

so there's 2 different intertia settings.

the difference visualy between the two dyno's is the blue roller covers at the side,

http://www.dyno.com.au/dyno/modules/...AWD450DSQR.jpg

http://www.dyno.com.au/dyno/modules/...s/AWD450DS.jpg


Later being the one thats got the two differnt settings, my guess is thats the difference, although it is a pure guess and may be way way off the mark

Big 'D'

So do you mean that all the dynos with a TN of around 3.5 are over reading then? Because if they are that covers just about everyone else including SRR? ( I guess not as was mentioned before that the TN should be part of the calibration of the dyno )

I am just interested to see what my output is tomorrow at S4U, who knows perhaps with the IT sorted it may run bang on what it did at DSA.

Anyway we shall see what tomorrow brings, I get the feeling that no matter what I post up or where the figures come from some of you will still have something to say.


Cheers Iain

Big 'D'

I did notice that the IT sensor at DSA was like a tube unlike the wire/probe sensor used at S4U.

So the 2 dynos may well be of different spec/type

Cheers Iain

MartynJ

Quite right Tidgy, the DSA dyno has twin retarders on one axle. This shouldn't affect the figures at all as the dyno will compensate for it anyway.

Martyn