Dyno Variances

[djvoodoo]

Hi Sau.

I am fully aware that different dyno's = different power output, and generally you will not get the same result twice, even on the same dyno and same conditions.

My question is this.

I had my 34R tuned (power FC, front pipe/metal cat/3.5 inch exhaust and boost restrictor removed)

On this dyno, it netted me 263 atw on a 4 wheel dyno

I am now getting Garret - 7 turbos, hks evc 5 and a retune at a different workshop.

They have put the car on the dyno for the "Before tune" run, and this came up with only 213awkw on a 4 wheel dyno.

I was expecting a variance of about 10-15kw give or take, but 50kw seems to be huge.

Reading the RB26 dyno thread, the 263awkw power range for my mods seem to be in line with the average 34R owner.

Is it more likely that the new workshop the car is at is a very low reading dyno?

I guess I'll find out once i get the car back :-)

[Ben C34]

Thread should get good so I'm in!

The track doesn't lie.

[djvoodoo]

Thread should get good so I'm in!

The track doesn't lie.

Care to elaborate. Good in what way mate...

As i said in my original post, I am aware of dyno variances, and that dyno operators can change load etc to make a "happy" dyno. That said, as per RB26 dyno thread, with my mods, the majority of GTR owners achieve between 240-260 atw.

For a dyno to throw 213kw is very low.

I guess you're right. Track will separate the men from the boys ey.

[Dose Pipe Sutututu]

^ dyno wars lol.. that's what he meant

Maybe the previous operator ran it in 4th and maybe this one ran it in 5th (being a R34 GT-R, 5th gear is 1:1 as it's a 6 speed).

[Ben C34]

I meant good sarcastically.

Missed the smiley

Remember that it's not just inflated high figures, a low initial run is also beneficial for the shop for impressive printouts.

Of course there could have been a reason for your car putting out lower power. Boost leak etc.

[scotty nm35]

The largest variations I have seen relate to not strapping the car down hard enough, roller dynos require down force to stop wheel slip on the rollers.

[levinboy]

Also some workshops like to make a reading lower to make you believe a previous workshop did a shit job and show how they made "big" gains

1/4 mile mph will give you a good indication of power

[scotty nm35]

^ dyno wars lol.. that's what he meant

Maybe the previous operator ran it in 4th and maybe this one ran it in 5th (being a R34 GT-R, 5th gear is 1:1 as it's a 6 speed).

Mine didn't change power much between different gears, only the torque went through the roof.

[djvoodoo]

Cool. I missed the sarcasm there Ben, sorry bout that :-)

I won't name the workshops as it's not fair to them.

Car is def running in tip top shape, but I was just quite surprised at the results.

[GTSBoy]

I concur with the strapping & wheelspin point.

Face it......losses in the drivetrain are not as large as the difference between flywheel power and wheel power would have you believe. If they were, then the oil would boil in gearboxes and diffs in a single dyno pull (just based on the massive number of kW of energy dumped into those oils). Therefore, the power must be going somewhere. And the tyre/roller interface is the single best candidate. Face it - those things are spinning around really fast, so they are well cooled. They definitely have slip at the interface, and we all can see that the harder you strap the car down the more power it makes, so therefore power is definitely being lost in slip.

And that's before you get to the paranoid android stuff involving workshops doing low reading initial runs to make any mods they do look better.

[Lithium]

It's a tad frustrating that there seems to be a culture of automatically assuming that a workshop/dyno/tuner who produces dyno results which read a bit higher than what you are used to the results/tuner are potentially misleading or dishonest and sometimes the info is taken less seriously.

50kw sounds like a LOT to lose, dyno variance or otherwise - you'll certainly be able to tell if the car is as much quicker after the retune as the numbers would indicate.

[Jazzadub]

I was told my car had 330wkw, it was retuned to 260wkw and feels faster, so explain that one!

I think the first run might have been done in RWD, and the second in AWD, but even so, it seems like a huge difference!

[Cassbo]

I was told my car had 330wkw, it was retuned to 260wkw and feels faster, so explain that one!

Power delivery. What you lost in peak power you may have gained everywhere else

[Super Drager]

Power delivery. What you lost in peak power you may have gained everywhere else

So you think he lost 70rwkw and gained what in the midrange? Makes no sense. Yes power delivery and area under the curve are what counts but come on.

[zebra]

I was told my car had 330wkw, it was retuned to 260wkw and feels faster, so explain that one!

I think the first run might have been done in RWD, and the second in AWD, but even so, it seems like a huge difference!

Feels faster or is faster?

[ARTZ]

The largest variations I have seen relate to not strapping the car down hard enough, roller dynos require down force to stop wheel slip on the rollers.

Still crying about RTR dyno day mate

[Sinista32]

Ramp Rate ?

50kws between 6 and 8

Edited July 18, 2014 by Sinista32

[hypergear]

The term of 1HP, is defined by people and more specifically to the people whom builds dyno meters.

There are no obvious concepts proves one's terminology is at mistake, so there will not be an matching dyno reading between two branded dyno meters.

On top of it, there are configurations determined by operator that could alter an precise output, as well as the extend of vehicle setup on particular dyno meters.

Seeking psychological balance as well as for the sake of promoting successful businesses. Owners whom bought a lower reading dyno will likely to argue that their reading stand for the absolute accuracy while others are inflated, While operator with an higher reading dyno might argue the lower reading dynos are poorly calibrated, On the end every one is there to defend for their own investment, While the true focus of a car can only produce so much "HP" with given fuel and given supporting mods at optimum calibration is lost.

Dyno is just a tool. so the quotation of what a specific setup is capable of doing is more accurately served based on past experiences of an likely setup. As I quote the capacity of my turbochargers to relatively common turbochargers which past collection of data is plentiful. Alternatively quote based on a percentage gain based on factory output. That way it is more meaningful then just a number.

Besides, for people whom value the safety of their own and others on road, the maximum potential of a engine is rarely used. It might be worth while for some tuners advertising drive ability and fuel consumption rather then just peek power. Which I prefer if tuners might be able to put some explanations into their work and spend some time educate people how a car should be tuned based on Torque, AFR, Timing, and Fuel maps. That way not only ensures the vehicle is tuned to their maximum potential, and most importantly let customers understand what their maximum potential is, in reference to supporting mods installed.

[Missileman]

Who are you quoting there Stao?

[Dose Pipe Sutututu]

long story short, dyno a tuning tool to safely determine max torque and load up the motor without snapping out sideways and getting pulled over by cops.

Want to test power? go do a quarter mile.. that never lies (technical constraints apply, such as: tyres, weather, surface temperature, driver ability, not getting kicked off the track because you ran a 10, etc.)