Do dynos lie?

[guybo]

Dynos need to be calibrated and there are several variables that need to be calculated into the final numbers. Meet an average dyno tech and judge for yourself if he even knows what a calibration is, much less how its done. It is a precision instrument and when done right it can be very accurate but few techs or shops have the attention to detail to do it right IMHO.

[Tcoat]

Originally Posted by guybo

Dynos need to be calibrated and there are several variables that need to be calculated into the final numbers. Meet an average dyno tech and judge for yourself if he even knows what a calibration is, much less how its done. It is a precision instrument and when done right it can be very accurate but few techs or shops have the attention to detail to do it right IMHO.

Even the best calibrated dyno will give different readings with different pulls. The very nature of the testing being done leaves it open to minor discrepancies which can be multiplied to major differences in the results.
Things can be made better by a truly great operator but there will still be variables.

[wparsons]

Originally Posted by Poodles

3) The new cars have 5 more HP than the older cars, so no, dynos aren't going to be showing that much difference without some bs going on.

Dynos of bone stock 2017's show more like 10-15whp over bone stock 2013-2016's, same dyno and similar conditions. They were slightly overrated on earlier models and 2017's seem to be more accurate.

[nikitopo]

If real difference is 10-15 whp, then I cannot explain why the '17 bone stock cars had so bad times in the mentioned race. I agree that human factor is an important thing, but this was a proffessional class, the track is large, the conditions same and there were more than 20-25 drivers. In fact, the lap times are suprising close comparing to last year. I mentioned already that some drivers were complaining about issues in acceleration. Probably, they were told the same thing (10-15 whp difference) and they could not see it in reality.


Here are the cars of last year:




Here are the cars of this year:

[D_Thissen]

Different gearing, the 13-16 had 4.1 gears and the new cars have 4.3. The newer cars would probably out accelerate the older cars at the sacrifice of top speed. There is so many variables. Tire compound, track temperature, humidity. Heck, maybe all the drivers put on 10lbs this season.

A half second is still a healthy margin when you work out how much ground is covered at a given speed.
For example:
- 50km/h = 13.9m/s = 6.9m ahead
- 100km/h = 27.8m/s = 13.9m ahead
- 150km/h = 41.7m/s = 23.6m ahead

[nico_rsx]

Are those cars modified in any way? Especially headers and tune?
If yes, then the 2017 are not faster because most of the gain is better header and tune in the stock 2017 vs stock 2016.

[mav1178]

Originally Posted by nikitopo

How can we explain it and what about all these dynos that give a 10-15 hp difference in favor of the new cars? Do dynos lie?

Large track = more emphasis on speed/top speed.

Given the revised, more aggressive final drive on the 2017 cars, it's not unexpected to have a lower overall top speed given the roughly same peak power output. That would more than make up for the difference...

Plus, do you even know what tire compound they are running? They make the biggest difference and often are subject to series sponsorship.

-alex

[nikitopo]

Originally Posted by nico_rsx

Are those cars modified in any way? Especially headers and tune?
If yes, then the 2017 are not faster because most of the gain is better header and tune in the stock 2017 vs stock 2016.

Nope. They are bone stock because of regulations. In fact the engine and the ECU are sealed and no-one can touch it. Same for the exhaust.

Originally Posted by mav1178

Large track = more emphasis on speed/top speed.

Given the revised, more aggressive final drive on the 2017 cars, it's not unexpected to have a lower overall top speed given the roughly same peak power output. That would more than make up for the difference...

Plus, do you even know what tire compound they are running? They make the biggest difference and often are subject to series sponsorship.

-alex

I would agree with you if there wasn't a limit on top speed. In Japan these cars are limited to 180km/h (112 mph) by a speed limiter.


There wasn't any serious change on tires.