My S6 work in progress with dyno figs and pics

[Greg_S]

@Greg - I'll drop you a PM about something I'd like to try out with Aquamist on your ABY.

Sound interesting...

[EspenW]

yes but my peak power is not at 7000rpm,but lower,around 6000rpm.On 4th gear im doing about 180kms around that area(i think so,cant be sure)

At 6K, you are going at approx 168km/h. Power loss to aero drag at that speed is approx 50hp

[A80Avant]

so should i add to that the driveterrain losses ?

[EspenW]

You need to establish power produced at the wheels, in this case approx 365whp.
Then you can start guesstimating drivetrain loss. I one assumes 20% loss, you will be at 456hp at the crank, 15% loss would mean 429hp, 25% loss would mean 486hp at the crank.
I think somewhere between 15 and 20% is correct at this power level, so somewhere around 440-450 at the flywheel. Should rhyme pretty well with the 3071 and the rest of the setup.
However, I'm pretty confident that peak power is well above 6K on your setup. If not, something is off.

[S2central.net]

I concurr - my somewhat trusty turbo calculator estimates ~440bhp at 7000rpm (at the flywheel) with a GT3071 so thats in the zone alright

[EspenW]

Stock RS2 (that peaked at 1.5 bar) produced around 250whp in 2nd gear on my Mr. Dyno), it produced 283whp with a "360hp" chip).
The V8 S6+ with claimed/BS 400hp pulled 255whp in 2nd gear.
My RS2 pulls 340whp in 2nd and approx. 360whp in 3rd with dodgy A/F ratio.
The Turbonetics E50 in that one should be able to deliver air for 470-480hp at the flywheel on gasoline. It will be most exiting to see what I can pull on E85. Stock bottom end and all

[A80Avant]

EspenW i have pmed you

[JP]

OK been a little quiet due to work commitments and kids half term.

However I've still got a little update. The Gtech unit arrived in the post yesterday and I spend the evening reading the 100+ pages of the manual after i had a random play with it to see how it all worked. I definatelly like the way the analysis software allows the overlay of multiple runs which will proof usefull later on.
So far I've got most parameters set to how I would like it however there is 2 issues I'd like to make better.

1) I need to get the car on a weighbridge to get the most accurate reading I can possibly have. I've found a couple open tomorrow morning in Hertfordshire within 30min from me. So I'll get a baseline weight with half a tank of petrol and add/subtract accordingly on the day of testing.

2) Also before gathering accurate road analysis I'd like to take the car to the strip to set the pitch callibration up as accuratelly as possible. So if the weather holds out I'll head up there this sunday which is apparently a RWYB.

I also had a missed delivery from UPS today as I had to attend a speed awareness course however I can only assume that these are my awaited RS2 cams for future testing as this is the only UPS delivery I'm expecting.

If all goes well over the weekend I'll post up the progress on Mon/Tue when i get a moment.

Once the baselines are sorted I'm going to sort out a wideband and EGT probe to hook my Zeitronix unit up with which will also be monitering boost and hopefully rpm (can't remember if it allows 5cyl calibration as it's been a while since I used it).

By datalogging with the Zeitronix unit I should then be able to overlay the graphs of the two units based on rpm scaling. Giving a good range of comparable parameters.

In having a hunt around the web I also came across this little gem which I will be looking into with greater depth than I have had time to do so far but for those interested here's a link to some very comprehensive hp/weight vs 1/4 mile ET/MPH calculators. If you have a hunt from the homepage there is loads more including turbo temp calculators, air fuel calculators etc... http://www.stealth316.com/2-calc-hp-et-mph.htm

[Acidburn]

Which weigh bridges you planning on using in herts?

Drove past the one in st albans today

[UrS4boy]

Just remember that when you change camshafts, e.g. to RS2, the RS2 ADU intake is the same as the AAN intake. Both are PN 034 109 021 AN.

Dave F.

[JP]

Well went to weighbridge in Tring, Hertfordshire today. The car with everything in it as I would run it, spare tire, protective mat, mobile phone, chargers and the Gtech unit came in at 1640kg with approx 20ltrs of fuel in it (based on average mpg vs range left on the MFA) as I couldn't find a shell petrol station en route. As literature on the net states 1700kg unladen I will assume that the figure represents the car with a full tank of fuel which is 80 litres.

So From now on I will take the base weight of the car prior to any testing as follows

1) Base weight of 1620kg
2) +1kg for every litre of fuel calculated from mpg and range on the MFA - (values will be zero'd then a short drive to take a reading)
3) +88kg for myself driving, if passengers are to be included these will be added accordingly.


I've subsequently pulled a couple of base runs near to where I live on a nice stretch of road from which I appear to be getting relativelly consistant results in 2nd. I will make an attempt at a third gear pass to see how much difference this will make on the accuracy of the results, however I'm not sure if the straight is long enough.

At the moment the Pod isn't looking positive for tomorrow so I may have a play with the pitch factor on the same road section to see if it varies peak hp/tq vs rpm as at the moment they are coming in at a slightly lower rpm (and a bit more enthusiastic)than on the dyno as can be seen from the attached jpeg below.



I haven't quite decided how I'm going to implement the roadrace feature of the Gtech I may end up not using it and instead do part and full throttle pulls in drag race mode whilst in motion on a private track ignoring hp/tq figures but concentrating on time to accelerate between key mph milestones. However I'll confirm this as I make the final decision as how to visually get across the driving feel of each chip. Alternativelly I may book a track day at one of the local circuits and record some lap statistics and run a similar test to that of the pod.

Out of curiousity once I'm happy with all the settings I will make some calculated guestimates on actual flywheel power using the following factors and the following formulae:-

HP loss due to Aerodynamic Drag is approximately equal to:

Cd * A * V3
------------
150,000

Drag Co-Efficient - Cd = 0.35 (based on book value)
Frontal area - A = 26.80ft² (based on a book width of 1.804m and actual lowered height of 1.380m)
Speed - V3 = will be altered according to Gtech info of speed at the same point in the timeline as the peak hp fig's.

Once a wheel hp has been calculated transmission loss will be worked out based on WHP+10/0.84 = Approximate Flyweel for a 4WD setup.

For those that don't wish to do the maths if you take the 202hp Gtech run as a conservative example the calculated flywheel is 266hp just over 8hp up from the AAN cam calculated figures of the dyno and around 18hp up from previously calculated figures of AAN cam WHP from the above transmission loss formulae.

Some of this discrepency will be down to the fact that on the day at the dyno ambient temperatures where 17degrees celsius whereas today the runs where recorded at 5.5degrees celsius. Obviously the denser air charge giving inflated figures. The second cause will be down to the requirement of some final tweaking of the parameters re weight and pitch. Obviously I'll never expect it to be perfect but it would be nice to get a pretty good baseline to work from.

[Rusty]

To get results from my GTech that were consistent with BHP ATW from a rollign road session the weight of my S2 Coupe was 1700kg. This is an older GTech though. I was after 240bhp ATW and got it over 8 results. Rough check, 210bhp*100/80=262 so that ties in with your previous RR sessions. Good work.

[knobstar]

It may sound pedantic; but isn't your "power loss due to aero drag" going to be off by 20% straight away because of neglecting rho i.e. air density?

Power = Force * Velocity

= (1/2 * rho * Cd * A * V(squared)) * V

= 1/2 * 1.2 * Cd * A * V(cubed)

[urquattro-island]

chips

on the way...

[JP]

^^^^^(knobstar) lol yes it is a very basic assumption I'm working to. Keeping in mind though that theoretical hp loss to aero drag is limited to approx sub 15hp in the case of the example around 12 without going back to my calculations I figured 3-4hp errors on a fictitiously calculated figure would be considered a neglible error as ultimatelly we're using the Gtech unit as a baseline reference for the roadruns. Using the formulaes only to set the unit up with reference to earlier dyno pulls. As opposed to actual end hp calculations.

I have been playing about with it a little more and managed to get almost a like for like power curve to that of the dyno results by changing the pitch to 3 within the settings of the unit, giving power peaks in the same rpm ranges. So any further comparisons will now be solely the actual figures given by the Gtech as opposed to calculated variables of them. Same with the dyno runs they will all be WHP only.

^^^ URQuattro Island, great to hear. I'll be starting the testing towards the back end of Nov. giving me the opportunity to sort a couple of things such as:-
Extra Lambda boss for wideband, EGT probe and boost sensor for the Zeitronix unit. I'll also be changing the clutch next week as it is starting to slip quite badly on any launch over 2500/2800rpm. That way I'll get a chance to bed it in before actual testing starts as I feel it would be unfair if the clutch lets go during the testing of one of the chips resulting in either the later ones being better or worse due to a different setup.

I'll let you know when the chip arrives.