I am quite confused (and worried)! Surely someone here can educate me on the way to read a Dyno report.

I wanted to know the current state of my 2000 A4 coupe, before installing the TPIS headers, so I asked for a Dyno before and after the installation. It was a busy day at the shop, so I was quite reserved in asking “stupid” questions when I was done.

DYNORUN.002 is before the headers and DYNORUN.003 after.



What is the HP at the wheels?
What is the HP of the engine?
What is the Torque at the wheels?
What is the Torque at the engine?

Are these results “normal”?


[Modified by Hex29A, 11:58 PM 4/18/2002]

 

Looking at Webtv it is hard for me to see your numbers, but I will take a guess. It looks like your rwtq is 336.8 and your rwhp is 320. To find flywheel hp for an A4 divide by .8, which means a 20% loss in transfer of power to wheels. 320/.8 = 400hp at the fly!

I can not see your number before headers, but it looks like maybe 15hp gain, which is normal.


[Modified by wallstAL, 11:35 PM 4/12/2002]

 

Thanks for the reply wallstAL

On the top left corner of the chart the numbers are as follows:
DYNORUN.003 Max POWER = 323.5 Max TORQUE = 444.6 (After headers)
DYNORUN.002 Max POWER = 306.7 Max TORQUE = 360.5 (Before headers)

On the top right corner: RPM = 4.02

On the actual graphs, from top to bottom the numbers are:
Top Graph – Torque (after headers) = 330.8
2nd from top – Torque (before headers) = 318.5
3rd from top – HP (after headers) = 252.9
Last from top – HP (before headers) = 243.5

The Graph axes are:
Left - SAE Horsepower
Bottom - RPM (x1000)
Right - SAE Torque (ft-lbs)

I guess that the numbers on the actual graph represent HP and TORQUE values at RPM=4.02 where the Torque AFTER headers was the highest.

Are the numbers to the right of DYNORUN.003 and 004 the flywheel values? If that’s so, then the car is bellow the 345 HP that is advertised as stock, even after all the mods I did. That’s why I am worried.

If the numbers are RW then…
DYNORUN.003 Max POWER = 323.5 / 0.8 => 404.4 (After Headers)
DYNORUN.003 Max TORQUE = 444.6 / 0.8 => 555.8 (After Headers)
DYNORUN.002 Max POWER = 306.7 / 0.8 => 383.4 (Before Headers)
DYNORUN.002 Max TORQUE = 360.5 / 0.8 => 450.6 (Before headers)
… at the flywheel. Aren’t the TORQUE numbers too height?

Thanks in advance

 

336.8 and your rwhp is 320 :yesnod: :cool:

 

I have serious doubts about that dyno graph's torque readings. I've never seen a pair of headers add 84 ft/lbs of torque to an LS1.

 

I have serious doubts about that dyno graph's torque readings

His TQ went up approx 12 lbs over first line
His Hp went up approx. 9-12 rhp over first line

the spike at first is not a reading its a spike and not to be used.
Second the lower #s are when the user is moving the cursor on the graph to look at what the engine is putting out at a given RPM.

 

Most dynos really need a GOOD & EXPERIENCED operator who know how to set up the parameters for A4 cars.

There is a MAJOR difference in the #'s depending on inputs & adjustment factors. Spikes are measured, & it sucks.

 

With your help, I believe I now understand how to read the Dyno chart.

The two sets of numbers on the top left are the rear wheel max HP and max Torque for each pull (DYNORUN.002 and 003). Because of the “spike” in the 3700 to 3800 RPM range, the Torque Max numbers reported on the top left are incorrect. The torque graph after 3800 RPM never went above the spike value, so the computer is reporting the wrong max. To find the max torque, I need to find the highest point in each torque curve and follow a horizontal line from that point to the right side to get the SAE Torque value from the scale.

In my case:
RW Max Torque before headers = 320
RW Max Torque after headers = 330

The Max HP values reported on the top left for each pull are valid, because after 3800 RPM, the HP curves go above the spikes shown in the 3700 to 3800 RPM range.

Again in my case:
RW Max HP before headers = 306.7
RW Max HP after headers = 323.5

Now, if I want to find the flywheel numbers, I need to divide the RW numbers by 0.8 (20% loss for the automatic). So ...

Before TPIS Headers:
306.7 RWHP or 383.4 HP at the flywheel
320.0 RWTQ or 400.0 TQ at the flywheel

After TPIS Headers:
323.5 RWHP or 404.4 HP at the flywheel
330.0 RWTQ or 412.5 TQ at the flywheel

Finally, the numbers appearing next to each curve are the operator’s cursor showing the specific values at the chosen RPM point.

I have no ideal if these results are to be trusted or not, based on the comments from Iboomalot and 2thDr.

I feel better now that I know the car made more HP that the 345 advertised by GM, even before I put the TPIS (the money for the intake / x-pine / corsa where well spend).

Thank you wallstAL, Iboomalot and 2thDr for taking the time to educate me.


[Modified by Hex29A, 4:31 PM 4/13/2002]

 

Ah, that's much better, thanks!