I really don't know about any of the stuff you guys are talking about, but if you can't strap a 1100 rwhp camaro down effectively to a dj, you are doing something wrong. I watched a 1500++ rwhp camaro make a pull last weekend. Absolutely no drama what so ever.

 

Again, I'm interested in repeatable results. After what I've seen done with high horsepower cars on a Dynojet, I'll pass on that technique.

 

The dyno results I have witnessed at Reckart Performance Tuning using a Dynapack have been very consistent from run-to-run.

Last week, I watched a pair of 2011 Grand Sports being tuned. Both had the A6 transmission and were identical in every way except for the paint color. One had 1300 miles and the other had 2900 miles.

Both delivered dyno results within 1 rwhp at 371 rwhp each bone stock. This is consistent with the 430 factory rating. After tuning, they were within 3 rwhp of each other.

When they are tuning a car, often more than 10 dyno runs are made. The results are very consistent and shows increases or decreases in torque & power during the tuning process. I've never witnessed any runs where the results were wildly different or out of the expected range.

Using the Dynapack, the rate of acceleration is programmable. So you can program it to run at WOT from 3000 rpm to 6500 in 10 seconds. Or you can hold it any rpm under any loads which is handy to build the VE and MAF tables. You can't do that with the Dynojet.

In my experience, there are no better dyno's than the Dynapack and yields very consistent and repeatable numbers.

 

In the end the facts are;

1. Dynos are a tool for measuring deltas and attempting to get as repeatable results as possible.... not an instrument for measuring you manhood
2. Chassis dynos suck, most people have a single control; "Coolant temp is about 200*F...Floor it."
3. All dyno numbers are easily skewed.

 

The Dynapack and DynoJet have nothing in common other than type of tool that it is. Not sure this is the thread to discuss different manufacturers of chassis dynos. I have used my Dynapack for one year and has become a priceless tool. The flexibility that it offers to measure the smallest of gains has allowed me to fine tune with accuracy. There are many features that allow the Dynapack to shine. It has the load bearing features that either holds the test vehicle at a certain rpm or a specific load in ft-lbs. It will hold the rpm to +/- 1 rpm and I can step up once I have acquired enough data for that specific load cell. Next, I can measure the torque at each wheel to test differential issues. No roller can do that.

The test vehicle does not need strapped down and will not have uneven loading due to strap tension. I have tested 1000 rwhp vehicles and it was like dynoing a stock Vette. When I think of accuracy, what is the standard? Each dyno manufacturer has tolerance ranges and measures power differently. The Dynapack measures torque directly and the roller dynos are measuring the drum. Tire slippage can be an issue and can slip throughout the pull. When you are tuning, that can show as a gain/loss and becomes inconsistent. When using the DynoJet, starting the run can be inconsistent since it is due to the operator. With the Dynapack, I set the dyno pull operating parameters and it performs the test. The test is identical from run to run eliminating another variation. I have tuned many of the SAE Certified Engines for GM in Corvettes and all have been spot on with each other. The A6’s are more consistent than people give them credit for. Another example: 3 2009 G8 GT’s with the same mods. They have LT Headers, CAI and Tuning. The spread between these G8’s was 8 rwhp.

I used my 2008 Corvette for a test vehicle using the Dynapack 4000 and DynoJet 248c. The DynoJet was 392 rwhp and the Dynapack was 392 rwhp. To say the Dynapack is inconsistent is not correct. It is the absolute opposite. As far as unbolting the wheels, I can have the test vehicle ready for testing in less time than strapping it down. Another bonus, I received a discount on my insurance since the Dynapack is less dangerous to operate than roller dynos.

 

Correct on point #1. But points 2 and 3, you are wrong.