I first dyno'd my car on a Dastek steady-state load dyno and hit about 245 whp. I then dyno'd on the same dyno in "Dynojet simulation" mode (just spinning up the rollers) and hit about 238 whp.

However I wanted some numbers that I could more accurately compare, so I decided to have the car dyno'd on a Mustang dyno (notorious for lower numbers than Dynojets). I data logged a number of engine sensors during the run, and they're plotted below along with the raw dyno data.

Peak numbers on the Mustang: 212 whp @ 6570 RPM and 186 ft*lbf @ 5000 RPM. This is about what I was expecting. Anybody else dyno their stockers on a Mustang with results to compare?

Below are the pretty plots. Note the discrepancy between the wideband on the dyno and that of the left and right bank widebands on the car (converted from voltage to air/fuel using the chart in the 2005 service manual).

 

I dynoed 231.43 hp 213.00 tq stock on a dynojet

 

Sounds about right, a bit high on the torque. '03-'04 by any chance?

 

its a 05

 

Interesting. My peak torque on the "Dynojet simulation" run was only ~195 or so. Again this is why I wanted to go to a more comparable dyno like the Mustang.

Anybody with some Mustang numbers?

 

My stock numbers on a Dynojet were 234 hp and 217 Tq

 

You can't compare between different dynos...

 

Definitely true, but you can start to make some rough comparisons between dynos of the same brand.

 

Not really because there are a number of software trims used to calibrate or miscalibrate [intentionally] the dyno...............also you must maintain exactly the same temperature and barometric pressure for runs to be close to comparable.

Also tire size, brand, mileage and inflation must be EXACTLY equal, as the tire roller interface [coefficient of friction] is the largest friction loss point.

Remember the dyno is only measuring acceleration in 1/100 second increments to derive the torque mathematically. Then that number is massaged to create a imaginary HP number.

 

I disagree that tire size / brand / inflation need to be exactly matched (unless the tires are largely underinflated) to get some decent correlation. Rolling resistances from what I've seen don't vary by that large of an amount in similar setups, but I'm open to any data you have on the subject. I'm not trying to compare runs within 5 whp. But if 10 people dyno'd on Mustangs and also landed in the lower 200-220 whp range and under 200 ft-lbs of torque, I would be able to draw some conclusions.

Now that I have some dyno runs and data logs from the runs, I'm going to switch over to road dynoing completely. With the Cipher I can get vehicle speed to ~0.1 mph at a 20 Hz data rate, and with runs on the same strip of road get repeated calculated power curves within a few whp.

 

Im going to dyno my stock G next week. Was hoping to have my HKS on before but atleast I will get a good baseline to compare to now

 

"compare runs within 5 whp. But if 10 people dyno'd on Mustangs and also landed in the lower 200-220 whp range and under 200 ft-lbs of torque, I would be able to draw some conclusions."

The conclusion is the sample size is too small...........a minimum of 25 different cars with multiple runs each would be necessary based on the 100,000 population.


FOR A DYNOJET TYPE ROLLER DYNO:
Changing the rear toe can cause serious variations as does tire temperature
Tires scrub represent 70%* [10% of the 15-17% total] of the total loss from flywheel to road, next lossy is the differential, then the wheel bearings and half shaft bearings, then the transmission [assuming a manual].......assuming the clutch is not sliping.

* Sum of the intertial and the static and dynamic friction

Simple to determine measure the temperature rise of each component from the flywheel thru to the tire [dyno] road interface...
http://www.keohps.com/imagine/applic...on_Reunalt.pdf

http://www.energy.ca.gov/reports/200...-001CRVOL2.PDF

You will find that tire rolling resistance varies greatly see test graphs in above.

 

I agree Mustang types are much much more repeatable [and accurate] since the tire road interface is removed from the picture.

 

Good stuff, I'll have to read through it. What do you mean by "the tire road interface is removed from the picture" with the Mustang dyno?

 

I think you are refering to a Dynopak dyno, where the hubs mount directly to the dyno. A Mustang Dyno still uses rollers, as does DynoJet and DynoDynamics, and others.