Rolling Road on 24/11/2007

[Andiroo]

It is exactly what he said mate, and with the logic as above, who could disagree?

Now I hate to be picky, but as I remembered what Mihnea actually wrote was:

We're at crossed purposes here Graham - your post indicated that the RR guy at G-Force didn't say what he said, to which my reply was directed. No probs

And Minhea did say in that post that he could 'buy' a 30% trans loss for power, not torque. Just shows that if Minhea could 'buy' a 30% loss, then the FWHP corrections are just finger in the air. In 2002/3 I was in the position of 'buying' a 30% loss too, as the predominate tuners of the day in the UK, AMD said it was so. The 30% loss was scoffed a bit by G-Force, they reckoned only 26%, which Mitch who was mapping my car agreed with was a realistic figure.

Cheers,

Andiroo

[Andiroo]

[quote="GrahamS4

The G-Force dyno, now run by DS Automotives, was run by the operator in SHOOT_6 mode. I now know that while this was correct for a 6 cylinder car, it was not even correct for a forced induction 6 cylinder car and it certainly wasn't right for any 4wd car. Therefore the transmission losses "calculated" were far too low.

The DS Automotives dyno in SHOOT_6 gave 249.2 BHp @ wheels and 302 BHP flywheel.

The Thorney dyno in Shoot_44 gave 249.1 @ wheels and 334 BHP flywheel.

I had an other car run at G-Force (when it was G-Force) and the power at wheels seemed good but the flywheel power seemed over, I cant find the plots but I do wonder if that was run in a suitable mode.

Even just talking about the one type of dyno (the SHOOT modes specific to DD dynos), I have noted B7 RS4s run in SHOOT_8, SHOOT44 and B5 S/RS4s run in SHOOT_6, SHOOT_6F and SHOOT_44. No wonder we see variations and people question numbers. As common with good machines I think the operators can let the equioment down!

Another problem where the numbers go all wrong is if people who have run on inertia style dynos whos flywheel figure is probably also roughly correct, but from what I have seen before have really high (low loss) wheel power figures compared to a DD HP (wheel) figure try and comparing the two. Or worse still adding ~22-25% to that and coming up with nonesense. Which of the wheel BHP measures is correct, who knows? This is where we see variation of opinion of losses being anything from 16% to 25%![/quote]

Couldn't agree more

Cheers,

Andiroo

[S4TAN]

Dyno for pissing contests, seat dyno for real world & track for head to head fun.

2nd that. Leathering other cars on the road is what really counts.

[Andiroo]

Dyno for pissing contests, seat dyno for real world & track for head to head fun.

2nd that. Leathering other cars on the road is what really counts.

Or even better on the track

Cheers,

Andiroo

[Andiroo]

For me Paz's car was testament to the accuracy, if a stock car can read stock power, then what's the problem? (general question not you Andi).

That is a very good point Graham, probably the best point of this whole thread IMHO.

How can I bang on about predicted trans losses being finger in the air, like I have done for years, when you can get result like this?

Cheers,

Andiroo

[martinhans]

the fact that RR results for the same car vary so wildy is testemant to the fact they are not accurate measures of mfrs stated power. The reason why Porsche, BMW, Audi et al come so close to generating the same sort of BHP per litre is because they use ISO type standard measures in their testing, it seems RR companies cannot even agree on a standard setup to measure with let alone come upw ith a de facto ISO type certified standard so in this regard trying to disprove flywheel figures taken under benchmarked conditions in such a vague way is like trying to guess the weight of a fat bloke at the fair.

The only usable place for RR figures imho is measuring "comparative" gains whent uning a car, i.e you take the measure before you tune it then after and compare the difference, but since this thread proves its very easy to "massage" the figures you would have to wonder how accurate even such measures are, since its in the tuning co's own interests to talk up the gains.

[P_G]

That comes down to how much you trust the facility you are dyno'ing your car with to give you true and independent advice rather than what you want to hear.

[S4TAN]

Which version of "hp" do UK rolling-roads use as their measure: metric or imperial? (see link below)

http://www.statman.info/conversions/power.html

[alex_123_fra]

Which version of "hp" do UK rolling-roads use as their measure: metric or imperial? (see link below)

http://www.statman.info/conversions/power.html

Satan, I think we use imperial here. Metric tends to be used elsewhere in Europe, hence the germans quote 420 PS (or metric HP) vs our 414 bhp (or imperial HP).