S2Power.com RR meeting 2009

[Bram]

What turbo is that? looks like a 3071r from the graph

Indeed. It's the S2 from Smartie with a complete rebuild and optimized engine and painting!

Fully Wagnerized with tubular EM, short route IM and big IC from Carsten. Car is running high-boost 034MS chipset, ABY cams and Joe clutch. I was also surprized this 034MS generic chipset produces that high torque as it's made for OEM internals....
We need to figure out why the graph is showing some wiggeling lines. Seems like the car should be capable of running smoother.

Here is a vid of Smartie's run @ JD:

http://youtube.com/watch?v=SxQOc5mEx-8

[EspenW]

Lots of nice cars there but I hope you guys didn't pay real money for the testing:
266whp is 298hp at the flywheel?
That would mean a record shattering Quattro drivetrain loss of only 10.5%.
Heck, that is just a few more hp than the loss to just unloaded rolling resistance at peak power in 4th gear. If the whp numbers can't be trusted, neither can the guesstimated flywheel numbers.
The Superflow is an excellent dyno, so this is probably due to operator error, as is often the case when European operators try to guess flywheel numbers from a USA made dyno.
Were any bone stock cars in good condition dynoed?

[quattro84]

I made the same comment on the Dutch forum after seeing some graphs.
Especially this one had my interest:http://www.s2power.com/forum/downloa...2081&mode=view
A lot of high numbers.. like some over 300crankhp's with the standard K24-7000.
Poorly running chipped S2 with 1.1 bar passing the 230crankhp barrier.

The company that did the runs is well known in the business for it's high-end graphs.. Most people prefer numbers on paper in stead of performance.. this way everybody leaves happy.

[quattrostyle]

@q84 you are right, I don't think my S2 is fast enough but it certainly is nice to have those numbers on the RR paper

[Henkjan]

here is the plot from my run

I'll go and check yr comments with an expert, I know that the translation/calculation from wheel HP to crank HP is the most difficult part, and also among the RR pro's (=the guys building the things) there is no consensus on which method is best

[Henkjan]

just to compare: results from a few years ago, on a different RR, also a different exhaust on my S2

[Henkjan]

A lot of high numbers..

I'll have to disagree with that mate.. maybe some are high, but also many left looking sad e.g. when finding 260HP i.s.o. the 290HP that their tuner promissed...

The company that did the runs is well known in the business for it's high-end graphs..

??? can you state this with facts?

[Henkjan]

Ok, a few notes on rolling roads & reported HPs
(my translation of the words from a manager of one of the leading RR manufacturers)

• a RR cannot measure crank HP, only calculate it
• there are 2 ways to calculate CHP from WHP:
  1. use a loss %
  2. use the TÜV approved method of letting the car spin out on the rolls and calc loss from that

Both can be shown to have their own errors:

• a fixed % is not right, take the example of a car that had 200CHP, measure the WHP and that is 182HP, so a tranny loss of 10%. now do some serious tuning to the engine and rerun, now we measure 364WHP, so using the % we expect a CHP of 400HP. this means that the losses in the drivetrain should have doubled, which (provided it is not outside its operating region) not true in real life
• applying the method #2 looks at first sight better, but a drivetrain under load behaves different than a drivetrain under no-load. take the above example again, where we measured a 18HP loss (200CHP vs 182WHP), so the tuned motor will not have an effect on that so when 364WHP are measured, the calculated CHP would be 382HP.

truth will be in the middle....

some manufacturers (and Superflow is one that does this) will collect all run data from their RRs, and from there make better estimates on the losses for both methods of calculation, and in that way improve the accuacy of the calculation.

sum-up: we should start talking wheel-HP only.. CHP can only be measured by taking the engine out of the car and putting it on a testbank. any tuner who claims his CHP are correct without that the engine has been on a motor testbank is a liar

[Bram]

That's why I have my WHP number already for some time in my signature I got lost in all crank HP discussions.....

[A80Avant]

as it has been said millions of times, because of all of the above reasons RR meets are useless. Meets for grub and spins and beer, go for it.

The only meaningfull measurements that can be done IMO are the ones on the road.No fans immitating air coming into the car, no rollers with different load specs or double rollers which have larger surface areas, OR hubs which have no wheels at all.

Dyno machines are only usefull for tuning the spark tables or tuning sessions in gereneral.

This is why i bought the perfomance box which is GPS data aquisition of acceleration. EVEN when i do the excel files and make out numbers, these numbers are based on specific acceleration. SO if the same road is used and the same weight is inputed, you can log differences in the car.Otherwise,lots of things may differ on a dyno.

[EspenW]

Yep, whp is the only thing that is actually measured.
The funny thing, though, is that different types of dynos will produce wildly varying whp numbers, with the Maha dyno producing ridiculously low numbers, for example 65whp on a 163hp 1.8T, all the way to dynos that give a whp number that is way too high, like Dynojet and Dastek.

If the crank numbers from these tests are OK, the whp numbers are too high (there is no way to get 10% loss on a moderately powerful Quattro), and if the whp numbers are wrong, everything is based on wrong data

[EspenW]

The only meaningfull measurements that can be done IMO are the ones on the road.No fans immitating air coming into the car, no rollers with different load specs or double rollers which have larger surface areas, OR hubs which have no wheels at all.

Yep, testing on the road, under real life conditions is invaluable. As with any rolling road, I can't measure what the cars I'm testing actually produce at the flywheel, but I can measure what they put down on the ground in the conditions they will be used in.
Just tested a Stage 5 Hohenester RS2 that is listed at 400ps/550nm.
In third gear, it put down a SAE corrected (for temp/pressure and aero drag) 313ps and 405nm to the wheels. My own alcoholic blue wagon put down 401ps and 530nm to the wheels in the same temps right before that, so I know that it has a lot more power and torque than the tuner car, but I have no way to accurately say what that means at the flywheel, but who cares. As with RR numbers, they are baseline numbers for evaluating mods and tweaks.

[quattro84]

I'll have to disagree with that mate.. maybe some are high, but also many left looking sad e.g. when finding 260HP i.s.o. the 290HP that their tuner promissed...

??? can you state this with facts?

BTDT, I'm in the same business and have seen his mapped & dynoplotted cars on other dyno's.

As for the % of loss, there are several factors that come into play while guesstimating dissipated power. For instance the inertia of the rollers themselves, friction in bearings and seals, ...

Some brakes like remotely powered Eddy Currents can be used to calculate inertia loss. They power the car mounted on the rollers and measure the amount of power needed to get to a certain rpm.

But then, cooling on the dyno is everything but realistic. I've seen 25hp drops on 450hp cars by switching of the external fans.
Same goes for the rollers. Small double rollers suck. Big single rollers give a more accurate surface to run on.
But, the straps that hold the car onto the rollers can cause a preload in the tires and bearings. Therefore the dynamic radius of the tire reduces, friction factors of the rubber onto the roller causes extra high hysteresis readings and thereby loss, and give a different wheelslip.

Endless discussion for some, quite obvious to me.
If you want an accurate reading of engine power you have to mount it on an engine brake.
If you want to check for power gains/losses a rolling road is just fine as long as the circumstances stay the same.