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Old 12-10-2002, 12:29 AM   #1
CupertinoSteve
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Default Dyno Comparison - Dynojet & DynoDynamics (Apples to Apples)

Here's a repost of my original post (at that OTHER place) ... I can't post attachments so you'll have to follow this link:

http://www.nasioc.com/forums/showthr...&threadid=2553 -- (looks like there is a filter ... replace the nasioc with that other place I-something)

try this one - http://64.191.37.124/forums/showthre...&threadid=2553

*************
Hi Everyone,
I'm a curious person (just like the most of you), but I found it increasingly difficult to understand who's products makes how much power. But from all the posts and dyno plots, it seems that everyone had slightly different scenarios (so no apples-to-apples comparison). So I'd figure I'd try and help out our community by ponying up the $$$ and getting some real-world answers.

So what was the plan for the today? Let's take the exact same car and go to two different dynos to see the differences (keeping as many variables the same).

Who are the gineau pigs? ATP (Fremont, CA) using their in-ground Dynojet and Vishnu Performance Systems (Pleasanton, CA) using their DynoDynamics. They are approximately 20 miles from each other (25 minutes). And finally my car ... 2002 WRX (silver - its the fastest color) with 25,910 miles on it ... the mods are a full Vishnu Stage 2.

What was the test setup? Of course with my luck, the fan ATP used to cool the TMIC broke. Oh well, to be consistent NO fan was used to cool the TMIC at Vishnu's either. I've also seen some posts about the fans used to cool the radiators ... let me tell you that the one at Vishnu's was massively stronger that the one at ATP (so we pulled it a lot farther away that the one used at ATP). I don't think this makes too much of a difference, since the engine coolant temps stayed the same. For those anal people ... ATP was 60deg.F and Vishnu was 61deg.F and I don't think there is more than a 100' of elevation change. I did forget to measure the temperature of the intercoolers (but oh well). The car were driven to their each location, sat around for 20 minutes, driven onto the dyno, sat around for another 10 minutes and then first two runs were pulled and printed. That's all folks ... we don't want to make this more complicated that it needs to be.

The Results:
ATP (Dynojet) - 275.8whp and 232.2 torque
Vishnu (DynoDynamics) - 224.7whp and 192.2 torque

So depending on how you look at it ... Dynojet runs 22.74% higher than a DynoDynamic or DynoDynamic runs 18.53% lower than a Dynojet (with regards to whp). Check out these graphs ... (oops ... I can't figure out how to get multiple attachments with a single post)

Interesting observations ...
Setup on the Dynojet vs. DynoDynamics ... all I got to say is that it was a lot harder getting my car on the Dynojet ... first thing was that we didn't get the tracks pulled apart far enough until we rolled the car on to it (so we had to back off the car, stretch the dyno and put the car back on). The second thing, was that it was tough getting the car balanced on top of both rollers ... so about 20 minutes elapsed from getting into the garage to the first pull. The DynoDynamics was really simple ... drive car onto ramp and fall into the first set of rollers (in case you didn't know they have 8 rollers - two for each wheel) and use a simple control to slide the rear rollers into place, strap it down and you're ready to go (5-6 minutes tops). The other thing I noticed was that you had to bring the car to a complete stop on the Dynojet ... the DynoDynamics could run back-to-back pulls really quickly - you don't have to bring the car back to 1st gear.

The important thing I've learned is that when you want to know the differences between modifications, you need to have testing tools that repeatable (ie. stick to the same dyno and record the environments - so you have the same correction factors in play).

Conclusion
So what have I accomplished with all this ... nothing, my car still make the same power it did going to both dynos. So, I wanted to help put some of those concern people at ease ... I'm sure you're making the power you made (since you have dyno plots), just know there is a significant difference between dynos. All I'd like to see are vendors advertising the % differences they have measured (and world peace).

/getting off soap box/

Have a great and safe Christmas and New Years ...

Steve

In a couple of weeks, I'll hopefully have the reflashed ECUTEC ECU from Vishnu ... I'll run this test again on the Dynojet and DynoDynamics and and not shutdown the motor before dyno'ing (retaining what it has learned since startup) and post up the results.

Lastly, for those Vishnu Stage 2 customers who are concerned with my "low" results ... just a week ago I dyno'd 255.2whp on the DynoDynamics ... I didn't stick any correction factor (since that can vary between dynos), I just took the raw readings as is. (i'll attach the dyno plot on a different post if anyone is interested).

****************
I'll call BS anytime someone says the stock ECU doesn't learn. I've got proof that car learns even between shutdown and startup and even larger differences between ECU resets. So I wished that more dyno places based their prices on rental-time vs. runs ... Check out this graph, NO ECU reset, only the difference between starting the car and the 11th pull ... this includes the first two pulls at Vishnu (graph posted above). Each pull gave me a little more power and of stablized by the last pull.
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Old 12-10-2002, 12:46 AM   #2
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Old 12-10-2002, 09:05 AM   #3
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Wow, thanks for sharing. I had no idea they were that different from each other. That's a big difference.

So, WRX owners with mods should be quoting "HP past baseline" from now on and never an absolute figure. Yeah, that'll happen

I wonder how many people just went, "Wow, I got my car tuned at Vishnu, but I can theoretically add 22% more HP to my quoted figure and still say it was from a dyno!"
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Old 12-10-2002, 09:29 AM   #4
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Im bored:

vishnu subzero is advertised at 185hp, that * 22.74% = 227hp on a dynojet.

Turboxs stage2, full turboback and utec, dynos at 227hp on their dynapack.

Pretty huge difference in dynos!

We all know that an upipe and a fancy little emi adapter isnt going to come close to touching a full turboback and a tuned utec.

Id guess that a stock wrx would dyno at 202whp on a dynojet?
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Old 12-10-2002, 12:20 PM   #5
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Never seen a stock WRX break 200 whp on an AWD dynojet. But I've seen them come close make anywhere from 190-197 after typical ECU learning.

FWIW, we recently tuned a modded WRX to made a repeatible ~210 wheel hp on Apexi's Dynapacks. Later, it re-dyno'd in on our Dyno Dynamics unit to make ~190 wheel hp. The conditions (temp, humidity, cooling fans, etc,.) were a bit different so don't jump to any firm conclusions. Although it is reasonable to conclude (as expected) that different brands of dynos will read quite a bit differently as far as raw #s go.

Thanks to Steve for taking the time to conduct such testing.

Cheers,
shiv
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Old 12-10-2002, 12:30 PM   #6
2000vfr800
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Being in the dyno business, this is a very interesting thread. I find it very amusing that even after people prove that the dynos have different numbers from each other, it is just accepted.

This would NEVER fly with my customers. I usually have a tolerance of 1% before acceptance.
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Old 12-10-2002, 12:40 PM   #7
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Quote:
Originally posted by 2000vfr800
Being in the dyno business, this is a very interesting thread. I find it very amusing that even after people prove that the dynos have different numbers from each other, it is just accepted.

This would NEVER fly with my customers. I usually have a tolerance of 1% before acceptance.
huh? why wouldnt it be accepted? its pure plain fact.
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Old 12-10-2002, 02:10 PM   #8
2000vfr800
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Quote:
its pure plain fact.
Can you explain this fact? Just curious.

Does torque vary from place to place?

Speaking in the most fundamental way possible, a dyno load cell measures the torque applied to it. This torque is used to calculate HP.

So, the only way for a car to make drastically different numbers at two different locations (disregarding the affect of altitude and weather), the torque number measured (or calculated) would have to be drastically different.

This difference could be due to the fact that different dynos used different methods of measuring that torque. It might calculate the torque based on how fast a specific, known inertia mass is accelerated. Or it might have an actual load cell.

In any case, any time I install a new dyno in a facility, the customer always has several mule engines that are used for data correlation. Specific tests are run on the new dyno with all of these engines and they have to have results within a certain percentage of the known results, or the new system isn't accepted.

So, in my mind, if you have two different dynos producing drastically different numbers (like we do in this case), results from both dynos are questionable.

edit: since we are talking about HP here, the error could also come from the RPM measurement.

Last edited by 2000vfr800; 12-10-2002 at 02:17 PM.
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Old 12-10-2002, 02:20 PM   #9
CupertinoSteve
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From what I can see, i don't believe that the difference are linearly related. I think there is a sliding % difference as you move up and down the power ranges ... for example, I saw 23% difference at 200-300 whp, but this may not hold true for cars at the 400-500whp range. Likewise for lower power numbers could be different. So what do we know ...

Power Range --- If Dynodynamics is ---> Dynojet Equals
< 219 1.00 ---> ????
219 to 225 1.00 ---> 1.23
225 to 225+X 1.00 ---> ????
225+x to 225+2X 1.00 ---> ????
...

So as I vary my mods, I'll try and fill in the blanks ... but then we'll have to add another variable, "Correction Factor" since temps and humidity will vary (maybe I'll stick with a single correction factor forumula for all the dynos and then make the same extrapolation for each scenario). Time to save up the pennies for the dyno runs ...

As far as vendor advertising, i think dyno plots are good, but they should always include where they started from (baselines). As far as numbers advertising, they can do what ever they want ... but for myself, I'll always end up calculating % difference from their stock baselines (that's the number I'll value the most).

Last comment ... I forgot to mention the people at both shops. I was extremely happy to see such professional people in this industry. I've seen enough shops (in the past), where they have one guy who thinks he can wrench and they build a whole business on that ... boooo and not here. Vishnu and ATP have excellent and professional personel ... at NO time did I ever worry about my safety, or more importantly my car's safety. Thanks again guys!
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Old 12-10-2002, 02:21 PM   #10
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Is their an atomic clock of dynos?

What I mean is their a dyno of all dynos that is dead on with hp and torque that all other dynos and calculations based off of.

Also if their is a formula to figure out hp and torque should not all dynos read the same theoretically?
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Old 12-10-2002, 02:28 PM   #11
CupertinoSteve
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2000vfr800 - Since it seems like your a dyno installer (please correct me if i'm wrong), I have a question. I had the "unfortunate" experience of converting my car to 2WD to dyno on a 2WD Dynojet, since no AWD Dynos were in my area. I noticed that if I didn't do a WOT run on the DynoJet I would get different measurements. The shop owner told me that if I slowly accelerated from 2000 rpm to redline, that if the changes were small and slow ... the dyno wouldn't read ZERO whp. This does seem a little odd to me, since I know my car is making X whp at Y rpm.

Vishnu - I thought I saw a screen on your dyno that showed me how much whp I was generating when you were holding the throttle at a constant position ... I may have been wrong, since there a lot of "stuff" on the screen ... but could you explain how you can measure whp with no delta in rpm?

Thanks ...
"Curious" Steve
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Old 12-10-2002, 02:30 PM   #12
2000vfr800
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Quote:
Is their an atomic clock of dynos?
Not exactly, but that is what the fleet of mule engine/vehicles are for. These have known torque numbers and are used to verify a calibration on a dyno. The dyno load cell and speed encoder are manually calibrated. But the mule engines/vehicles are usually used every 6 months or every year for validation.

Quote:
Also if their is a formula to figure out hp and torque should not all dynos read the same theoretically?
That's what I'm saying. HP is a calculation based on torque and RPM. So, if you get two different HP numbers on two different dynos, then either the measurement of RPM is different, or the measurement of torque is.
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Old 12-10-2002, 02:36 PM   #13
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Quote:
The shop owner told me that if I slowly accelerated from 2000 rpm to redline, that if the changes were small and slow ... the dyno wouldn't read ZERO whp. This does seem a little odd to me, since I know my car is making X whp at Y rpm.
Yes, it is odd. I have never heard of this before.

To get a power curve for an engine, you go from idle to redline (or where torque goes negative) at WOT. You can go from above idle to below redline if you want, but you need to be a WOT (wide open throttle).
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Old 12-10-2002, 02:40 PM   #14
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2000vfr800
Thanks for the info.
I think you should get the title of dyno guru under your name.


I noticed you are in michigan, do you know of any awd dyno close to cleveland Ohio?
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Old 12-10-2002, 02:44 PM   #15
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Not any that are open to the public.
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Old 12-10-2002, 02:48 PM   #16
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what I meant by fact is that the 3 types of dynos used to compair staged upgrades for our cars have WILD variance. thats a fact. dynojets read higher than dynapacks which read higher than dyno dynamics. This information hasnt been kept secret from the various tuning circles around the world. Steves car dyno'd with a 40lb/ft of torque different on the same day.

Now if you want to stand by and say that both dyno's are miscalibrated or whatever, thats fine by me as I cant argue that.
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Old 12-10-2002, 02:56 PM   #17
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And that's all I'm saying. I can't believe that it is just accepted.

I'd really be curious to go and see a calibration and see what each system is doing. Unfortunately, I don't have much hands-on experience with the types of dynos listed.
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Old 12-10-2002, 04:00 PM   #18
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Quote:
Originally posted by 2000vfr800
And that's all I'm saying. I can't believe that it is just accepted.

I'd really be curious to go and see a calibration and see what each system is doing. Unfortunately, I don't have much hands-on experience with the types of dynos listed.
Find old Dynojet tech papers explaining how wheel torque is calculated from the rate of accel. of the big roller. They used to mention a ~15% positive correction for "unrealistic load conditions". Not sure if it's still there. The reason Dyno Dynamics dynos read lower than Dynopacks is simple... one measures at the tire/roller interface, the other measures at the axles. Taking away 150-200lbs of rotational mass (4 wheels and 4 tires) will, and rightfully so, raise hp readings.

Just my 2c,
shiv
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Old 12-10-2002, 04:13 PM   #19
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I agree. And the method of reading HP at the tire/roller interference is a more accurate "real world" number. You just can't compare the two numbers at all (which is what this whole thread is about). It's like comparing crank hp vs. wheel hp.

As long as you are using the same dyno to measure your hp gains from new mods, you will get valid results.

I'm guessing this has all been hashed out in other threads like the PB (where person A says they make x hp, while person B says they make y hp and they are on different dynos) bragging forum.

So, I can see how this is accepted here. Sorry for hijacking the thread.
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Old 03-01-2007, 08:59 AM   #20
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Here's a blast from the past.

The folks over on LS1tech wrote up some more information on Dyno Camparisons pertaining to the Dynojet and DynoDynamics dyno's.

http://www.ls1tech.com/forums/showth...2&page=1&pp=20
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