Poor dyno results?

[300CUL8R]

I got back from the Dyno today for the first time and my numbers are nowhere near JMatt's or cbutlers'. Is it the fact that I only have 4k on the new motor? What gives? Question for the gearheads: What causes the dispersion from one car to the next? Here are the #s:

Best pull: 347.59 HP 351.18 ft/lb Torque
(Sorry, I'd post the file but can't figure out how to get it small enough to upload)

Granted I only dyno'd it to get a baseline for when I add the MF and CAI to see what gains to expect.

Should I be bummed?

[XCITsNU]

I've been wondering when this was going to happen, cause I knew it would. There are always subtle differences from car to car. I'm hoping that with some better pulls, weather, etc. your numbers will go up...

What type of Dyno was it?

[300CUL8R]

A dynojet. What model I have no idea. It was at a local shop that strictly works on WRXs and Evos so it was an All Wheel dyno but they ran it in 2WD. They definately knew what they were doing and even followed John Hennessey's advice on how to best run it. I'm not too freaked out and I'm sure the motor will get better with some curing and right foot exercise.

[need4speed]

Hmmm ... typically a dynojet reads higher than a mustang dyno ....

The numbers aren't that bad ... it could be as simple as crappy gas .. not getting enough ignition advance ... too hot .......

Did you guys ever let the car cool down almost cool to the touch, or at least room temp before doing another run ?

[bigslim]

Take into consideration the weather. How hot was it? Was it humid? What kind of dyno was it compared to the others.

[DanRealtor]

Originally Posted by 300CUL8R

I got back from the Dyno today for the first time and my numbers are nowhere near JMatt's or cbutlers'. Is it the fact that I only have 4k on the new motor? What gives? Question for the gearheads: What causes the dispersion from one car to the next? Here are the #s:

Best pull: 347.59 HP 351.18 ft/lb Torque
(Sorry, I'd post the file but can't figure out how to get it small enough to upload)

Granted I only dyno'd it to get a baseline for when I add the MF and CAI to see what gains to expect.

Should I be bummed?

I would not give it a second thought. Depending on fuel, temperature, elevation, humidity, mileage, dyno machine etc... Your results will vary. Also, 425 HP at the crank will always be less at the rear wheels.

As you said, you did it for a baseline. Now, try and dyno your car on the same machine under the same conditions to measure the percentage increase after your mods.

Don't get hung up on the numbers.

If your SRT-8 feels underpowered (which I doubt) have the dealer pull the codes. (probably unnecessary).

Gotta Go, the open road beckons...

[Johnny G]

I'd like to see what it would be on a completely different dyno?!

[glhs837]

Best guess is "bad" gas. We see this on SRT-4s. Even though the car is rated for 91, it does run better on a higher octane. 93 seems to be optimum pump gas. Which I know is no help to you, trapped in Communfornia.

[btlfed1500]

Looking at your curves it looks like ECT was not maintained. The engine is definately seeing different ignition advance and fueling. Looking at the worst curve I see much more PCM intervention as seen by the more jagged curve.

Were these all done in 4th gear? Look @ the Gear Ratio number provided by the Dynojet and see if they are the same. The smoother (and higher) curve numbers look more like a 3rd gear pass not 4th. See automatic shifting graph below (2nd-3rd-4th gear):

Under normal operating conditions (ECT 180-190) your numbers should be stable and repeatable within 3-4 HP on a 400 HP application. Did they actually have to make 8 passes to get those numbers?

Richard

[Jeff's SRT]

All dyno's read very very different. My cobra dyno'd 594 on one dyno and 575 on another with similar temp and humidity conditions. Its really hard to compair dyon #'s when they are not done on the same dyno.