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Comparable Dyno Tests for owners


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#1 EK9turbo

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Posted 01 December 2010 - 12:39 AM

After reading a lot of post where people compare dyno numbers I felt the need to make this topic for everyone.

You have to take into account the Make/Model dyno and control conditions by which the dyno tests are carried out.

Why everyones using estimated 'bhp' figures instead of measure WHP figures I dont know!
Basic template for everyone to use! ASK for some of the info from your tester and it makes it more comparable to other owners graphs on the forum. If your dyno operator doesnt know what your talking about then steer well clear. these are basic control conditions (example)

Car make & Model: Honda DC5
Mods:
XYZ
XYZ
XYZ
Dyno make/model: Dynojet 244xLC
Test mode: Inertia only
Test Standard: SAE
MEASURED run time: 9seconds (strapping tension can affect this if theres a lot of tension difference)
Amb Air Temp: 12*C
humidity: 25%
Correction factor applied: 1.01 (this is becuase of the SAE/DIN/etc standard applied
peak WHP: XXX
peak Torque: XXX

Key points for comparative dyno testing:
1.You should always have your car baseline tested on the same dyno before tuning with the vehicle up to temperature so you know what your starting with. The coolant temperature that the engine was at when the run started should be a key piece of data for when the final dyno run after all the tuning is performed. This is because you want the cooling jacket at the same temp when starting.

2.if on a roller dyno, an experienced tuner will always check tyre pressures and wheel nut torque along with doing a general safety inspection before commencing the dyno-run. These factors ARE important in maintaining consistent testing

3.When strapping a vehicle securely on a roller dyno, I had graduated marks on the straps and would note down the locations and tensions on each of the six to eight straps I used so the tension is repeatable

4.Run time matters! More-so on turbo cars. Make sure that the run time is the same as on the baseline run when final testing the vehicle. going from 6-8 seconds on a turbo car can be 20+hp difference because the turbo has more time to build pressure

5.Always have the car tested in inertia only mode if on a roller dyno and look at the WHP only... Dynojet, Mustang and Superflow have been proven to read within 1% of each other on SAE testing standard

6.Always use SAE correction standard. The correction is for weather conditions including Barometric pressure, humidity and air temperature, this makes the testing on one dyno at sea level consistent with another dyno at say 1000ft elevation above sea level.

7.HP and torque will always vary in different gears since your gearbox is a torque multiplier so make sure the tuner tests the baseline and the final measurement in the same gear

8.If you want a real-world hp/torque output measurement in a certain gear, time the car in a controlled environment from X rpm start point to redline in X gear and then at the dyno ask the tuner to also test the vehicle in said X gear with said X run-time!

9.Always look at WHP/HHP only. There is many varying methods to engine HP estimation from WHP measurement.
Roller dynos measure whp and then calculate torque from it via measured/calculated engine RPM
Hub dynos that are hydraulic based system Directly measure the torque as a pressure (force) out of the pump-head outlet then the dyno, divides this hub-torque by the overall gear ratio to give arguably the most accurate engine-torque measurements possible, they are directly measure and not affected by type slippage/flex/strapping tension etc. Then the HP is calculated from this.


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#2 F6HAD

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Posted 01 December 2010 - 12:44 AM

Will, that's a great guide - many thanks.

The only comment I would make is that WHP is not the industry standard, and most people who are not hardcore power nuts, just want some sort of a comparison to what gains they are getting from stock manufacturer figures, and manufacturer figures are not WHP either.

Not saying I agree with it.
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#3 EK9turbo

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Posted 01 December 2010 - 10:34 AM

Which industry standard do you speak of? OEMs that measure on engine dynos ? Because without knowing the make and variables its not comparable data and it woudl be naeive to try compare the two. best way is always a before and after on a dyno in whp. And the operater shouldnt be making blatant mistakes like in the graph above

In the aftermarket tuning industry including motorsport clients, wheel hp is the most widely used comparison basis before and after with proffesionals. If you just want a correction applying to give estimated engine hp thats alot higher than what you put to the road then 'quote me happy' by all means.

The fact is that theres so many different BHP calculation methods by all the dyno manufacturers that do-it they are not comparable between each other! Some use run-down tests (negative drag testing), some use a set percentage for various drivetrain layouts, some just let you specify a correction factor too.

Interestingly Honda in Japan invested in a Dynapack system for their chassis and NVH testing!

But this thread is all about MAKING peoples graphs comparable, see point 5. in my topic especially.

Edited by EK9turbo, 01 December 2010 - 10:39 AM.


#4 luvmyaccord

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Posted 01 December 2010 - 09:45 PM

That some serious info!! Cheers dude, lots i didn't know ;)

Got a question though, whn i get the final drive mod in my car does that mean that i won't be able to get my car on a dyno cuase the revs will be wrong? As far am i'm aware the final drive mod changes the ratio of the gears in the box so if doing a dyno run in say 3rd, then gettting the final drive mod installed, the same run same variables etc i would get a different result in FHP and WHP cause the ratios are differnent? How will i then overcome this when i do an new mod to the car?

Sorry for all the questions.

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#5 luvmyaccord

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Posted 01 December 2010 - 10:34 PM

Okay, after doing some reading i've found that apparently the dyno tester can alter the input measurements. So when setting up the dyno for the run you can input that the new Final Dri ve is 4.64. Is this correct?

Again i have to say sorry for all the questions.
2001 Milano Red, Eibach springs, VtecDirect Mani, downpipe, decat and zorst, ported and polished head, K+N panel filter, VtecDirect oil cooler, lightweight pullies, XTD lightweight flywheel, Full new set of valves retainers and springs, DS250 pads, Bremtech disks, throttle body coolant bypass, New standard ATR cams and a re-built head, balance belt removed, Volk TE37 - resprayed in Anthracite. Light Tints, K+N Long Ram Typhoon.
1997 Impreza 555 RA - New Cosworth forged pistons and matching piston rings *.50 oversize.**Rebore block to suit New Crankshaft. New race quality crank bearing set. APi uprated oil pump.STi 2003 year model con rods.STi gasket and seal set, baffeled sump.* Stage 2 organic clutch, lightweight competition spec. Flywheel and balance, TD05G20 Turbo, Standalone ECU, 650cc injectors. HDi Hybrid racing front mount intercooler.

#6 chrismc

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Posted 28 September 2011 - 02:10 PM

From my experience-it's all a dyno-lottery tbh...

The only real comparisons are achieved with back to back runs on the same day/same dyno & between similar cars. What is considered a "genuine" figure by person A could be interpreted as vastly "optimistic" by person B too....

I used to own an integra r that made 185fwhp on 1 dyno yet 216fwhp on another...no mods between runs

I don't think it is possible to compare results from different days/makes of dyno etc etc with any degree of accuracy as there are SO many variables

#7 F6HAD

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Posted 29 September 2011 - 12:13 AM

Agree with you entirely mate.
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#8 EckMcMann

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Posted 18 February 2014 - 06:41 PM

The mapper I used on my Civic doesn't have pub figures, only whp. Iirc its a dyno dynamics set up but its usually called the heartbreaker with it reading lower than other RR's!

#9 F6HAD

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Posted 18 February 2014 - 06:48 PM

thanks for your input.


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