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Is my dyno graph messed up?

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Old Jan 29, 2013 | 12:20 PM
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Default Is my dyno graph messed up?

Hey Everyone,

I recently got my 2002 Z28 A4 dyno tuned and have posted the corresponding dyno graph. Why are my lines so wavy/bumpy?

Is that normal or a sign of something wrong? Thanks!

This is on smoothing 5 btw.
Attached Thumbnails Is my dyno graph messed up?-run-4-max-power.jpg  

Last edited by redlineshifter; Jan 29, 2013 at 12:26 PM.
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Old Jan 30, 2013 | 07:00 AM
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anyone?
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Old Jan 30, 2013 | 08:06 AM
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Looks like a dyno pickup problem to the spark plug wire. Nothing wrong with the car.
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Old Jan 30, 2013 | 08:22 AM
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Not that anything is wrong with the car, but the Torque and HP should cross at 5250 rpm, yours does not, so something was not right with the data. You also want it to be on SAE, not STD. STD will typically have higher numbers than SAE which is the typical standard.

Seen a lot of people posting STD lately, thinking they are fooling someone.
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Old Jan 30, 2013 | 09:40 AM
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Originally Posted by Slowhawk
Looks like a dyno pickup problem to the spark plug wire. Nothing wrong with the car.
Thanks for the info! Could that affect the numbers?
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Old Jan 30, 2013 | 12:05 PM
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Still curious that the hp vs tq intersects at 4750, not 5250 like it is supposed too.
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Old Jan 30, 2013 | 01:26 PM
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Originally Posted by RAMPANT
Still curious that the hp vs tq intersects at 4750, not 5250 like it is supposed too.
Youve got two different scales going on. Mathematically they can only cross at 5250 if hp and torque are on the same scaling.
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Old Jan 30, 2013 | 02:35 PM
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Originally Posted by therabidweasel
Youve got two different scales going on. Mathematically they can only cross at 5250 if hp and torque are on the same scaling.
You are 100% correct, I missed that.

Equal scales and SAE will give you a better visualization of your power/torque curve as well.
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Old Jan 30, 2013 | 02:46 PM
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Originally Posted by RAMPANT
Not that anything is wrong with the car, but the Torque and HP should cross at 5250 rpm, yours does not, so something was not right with the data. You also want it to be on SAE, not STD. STD will typically have higher numbers than SAE which is the typical standard.

Seen a lot of people posting STD lately, thinking they are fooling someone.
Thanks for making me feel welcome, Rampant.

1) If you'll look at the scale on the right and left sides of the graph, you'll notice that they are different to reflect hp vs torque. The actual hp/tq numbers are equal at 5250 if you read the graph
2) STD is what my tuner gave me: I wasn't trying to "fool" anyone as you say. I didn't post this in the dyno #'s section and start bragging or anything. I just came here seeking help. With all the highly modified cars on this site, the 5hp difference between my SAE and STD numbers probably wouldn't impress to many people, anyway.
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Old Jan 30, 2013 | 03:15 PM
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Originally Posted by redlineshifter
Thanks for making me feel welcome, Rampant.

1) If you'll look at the scale on the right and left sides of the graph, you'll notice that they are different to reflect hp vs torque. The actual hp/tq numbers are equal at 5250 if you read the graph
2) STD is what my tuner gave me: I wasn't trying to "fool" anyone as you say. I didn't post this in the dyno #'s section and start bragging or anything. I just came here seeking help. With all the highly modified cars on this site, the 5hp difference between my SAE and STD numbers probably wouldn't impress to many people, anyway.
Not meant as a slam. I see tuners doing STD to inflate the number a little more. Not the owners doing it, but the owner should be aware.

As an example, one of my 560ish hp graphs goes up by 14hp with a switch from SAE to STD.

I personally ask for the dyno files now and download the free Winpep software so I can see what all the numbers are. Nothing is hidden in the file with the software.

I already mentioned that the other guy was 100% correct and I was incorrect on the scale issue. I just find it a good idea to follow the standard industry practises if you really want to have an idea how you are doing. Your car looks like it is doing very well.
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