Taking my '03 to the dyno for the first time..

[79KTs03]

I'm taking my stock 03 to be dyno'd tomorrow before I add the mods. This will be the first time I've ever had a vehicle dyno'd or even seen it done. Are there any questions I should ask of the guys in the shop or anything I should look out for while it's being done? Any advice that can be offered would be greatly appreciated. Thanks.

"Blessed lady of acceleration don't fail us now!"

 

[PhillyCobra]

Make sure the Traction Control is turned off.

Think it's helpful to have an A/F performed-- worth the money.

Ask for SAE correction (it's more commonly accepted than STD correction).

Make sure car is cooled off some from driving it in, but not stone cold (Coolant temp should be over 160 to allow optimum power).

Let us know your results!!!

 

[Jon Massaro]

SVT ,nice should have a great reading even stock, i'm guessing 300hp but i dont kno I've nevered owned one

 

[Cobra-Master]

Get her into 4th gear and punch it...

 

[soniccobra 03]

SVT ,nice should have a great reading even stock, i'm guessing 300hp but i dont kno I've nevered owned one

Yea, she should be a little over 300 hp........lol..........

 

[JamesT]

Originally posted by PhillyCobra
Think it's helpful to have an A/F performed-- worth the money.

Can you explain this please?

 

[PhillyCobra]

Air to Fuel ratio. Tends to be lean at low RPM's and pig rich at high RPM's with stock computer.

As this is a baseline run, it would be very interesting to see if A/F changes as car is modded, usually first with CAI and catback exhaust. Many of us have found the stock program is less rich after these mods, especially on late run 2003 cars. Aftermarket chips or computer reflashes change A/F ratio as well as timing.

 

[79KTs03]

Dyno Results

Here are the dyno results for my stock 03 cobra:

As you can see it started off really lean and then went pig rich at about 5500 rpm. I expected it to start lean and end rich but not that lean and that rich. I also expected the torque numbers to be higher. I'll post the Post-Mod results once they're complete. Maybe in a month or two.

 

[Chris_H]

Pictures don't seem to show up for me... does it for everybody else? Maybe its my firewall here at work. Whats your #'s from the dyno?

Chris

 

[79KTs03]

Results

Crap, that figures.. Here are the numbers:

Max Power = 376.03 Max Torque = 354.71

A/F started lean w/ 15 @ 3000 RPM and then steadily decreased until it went to about 10 @ 5000 RPM and dropped off the chart at about 5500.

If anyone wants the chart, let me know and I'll email it to them.

"Blessed Lady of acceleration don't fail us now!"

 

[Chris_H]

Nice numbers. We finally got a dyno here in town, so I am hoping to go get a dyno before too long. Need to take my LX and get it tuned in too. I hope to see some decent numbers when I go too, but I have a feeling this elevation is going to hurt me.

Chris

 

[JamesT]

Thanks for the information.
I, for some reason, alway thought that since these cars are closed loop systems it would have tried to keep the output gases the same (by messing with the input ratio). At least, I would have thought the airflow sensor would have adjust the ratio respectively.

Maybe I have had too many "theory" controls classes, time to go to the real world. I guess the other explaination is error, but that seems pretty high for error.

Thanks again.

 

[PhillyCobra]

JamesT,

All cars go open loop when at Wide Open Throttle. They still read the air flow from the Mass Air Sensor but follow a programmed A/F ratio that transitions from lean at low revs (for lower emissions) to very rich at high revs, to prevent detonation and engine damage. Our cars don't have knock sensors, so the stock computer program at WOT is super rich to try to prevent detonation and engine damage.

The other reason A/F is real lean at low revs is often a misreading, since A/F is usually measured with an O2 sensor in the tail pipe, which is also exposed to ambient air with a high O2 content. At high revs and high exhaust gas flow, the ambient air is all pushed out and you get an accurate reading, but at low revs you probably get a false lean reading (higher O2 content) in the tail pipe until things really get moving. Using an O2 sensor placed in the rear O2 sensor bung (after the cats) or one welded in before the cats prevents this misreading, but few dyno operators do this.