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Differences in Dynos

684 Views 6 Replies 6 Participants Last post by  WAR
Well i just got my Turbo Magazine in the mail and i was looking through it. Found an article where they took the same car to 6 different dynos in the same day to see what the differences were. Its alot bigger then i thought it would be...about 37 horsies between the highest and the lowest....heres the details for ya to splurge through:

The car tested was a stock 350Z.

DynaPack 5500 - Hydraulic - Dynapack Series 4.5.3 - 249.4 hp - 247.8 tq

DTS - Eddy Current - DTS B18.3.5 - 257.6 hp - 556.3 tq ( no account for gear reduction )

Dynojet 248 - Inertia - WinPeP 6.03 - 235.8 hp - 227.8 tq

Dynojet 248 - Inertia - Pep 4.94 ( DOS v7.8 ) - 243.7 hp - 237.2 tq

Clayton VTT - Eddy Current - VVT 6.1 - 265.7 hp - 240.6tq

Super Flow SF 1853 - Eddy Current - WinDyn - 228.9 hp - 226.6 tq

The first item in the dyno itself..the second is the type of dyno..the third is the software used and then u have the hp and tq averages out of 3 pulls at each.

The Dynapack 5500 dyno is attached by removing the wheels and then using like a hub adapter to attach it to the machine.

All the other dynos just seems to use the rollers.

As you can see there is a pretty big difference in the numbers from place to place. This all took place during one day with the same car. Just thought this was kind of interesting so i would post it here so you all could see it too. :D
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did they include temperature while doing dyno? also humidity? Because in the morning it is cold tend to get better numbers, while afternoon would get not as good numbers because air is hotter than mornings. On a turbo car it would not make as much difference (because air gets hot by turbo anyways) but on N.A. applications in this case it may play a factor.
The ones at the top were done in the morning and then the one at the bottom was done the latest. They were all indoor facilities as far as i could tell and the time range was from about 10am to 5pm.
Do they list correction factors and ambients? Maybe it's just here in the North but my dyno was done indoors and the temp was 62, outside temp was in the 20s. Even indoor facilities can vary widely in temperature. The biggest thing in all this is the correction factor used. I know that the 248 and the WinPep software that was used on my car can be set to use different correction factors, fairly easy to make a dyno read higher or lower by up to 10% by mucking with the correction factor used on the report. Looks like more evidence that dyno runs meaning jack diddly unless they are at the same facility, on the same dyno, on the same day. Tell me how much an exhaust (intake, header, pulley, etc) did on the same car, same dyno same day or don't bother to tell me.
I've said this a million times: it is so easy to dramatically vary dyno results. I take all dyno results with a big grain of salt.
The dyno results don't suprise me.

cool2miketlu, you got it around backwards in regards to power outputs for Na/Turbo in high humity/temp conditions. NA cars are more consistent, yes heat soak is a factor. But on turbo car high humidity, high temp will play more of a factor in boost pressure, therefore influcing dyno results even more. Cold night, car runs naturally higher boost level. Hot day, runs less boost. All to do with oxygen density in the atmosphere.

If peolpe get worried about peak hp figures on different dyno's they have issues. It's a tuning tool, not a di*k/ego measuring contest like some people treat it.

If i had to question anything, when was the last time each machine was re-calibrated?

As long as I have a good tuner, I don't mind what type of dyno he uses. Because I know the results are always going to be good. That's the bottom line.
this is why they say always use the same dyno at the same shop in order to find out what the real gains or losses are in any mod.
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