I thought about posting this in Advanced Tech, but we'll see how this goes.

What sort of dyno, in your opinion, is "the best"?

It is my understanding that Dynojets give the highest horsepower readings, and that most people prefer them for that reason. From a technical standpoint, I believe this to be that the rollers carry inertia which is not compensated for within the dyno itself. A buddy of mine says it's like testing your acceleration downhill.

There are also issues with Dynojets -- for instance, running on rollers gives an unrealistic tire contact patch, which may provide a different rolling resistance than running on the street.

A Dynapack removes the tire issue by connecting directly to the hubs. This, again, is unrealistic because the tire acts as a moment arm, and going to a smaller tire will yield more torque at the ground. Since you test on a Dynapack with the wheels and tires are removed, you cannot measure the difference you get from one wheel/tire size to another. Also, you have eliminated rolling resistance from the equation.

A Mustang dyno seems to be the most technically accurate. It can apply a load to the rollers and simulate a real quarter mile run, or any other run you feel like programming into the thing. There is still the unrealistic contact patch issue, but it is my understanding that no other issues exist.

I know a lot of people like to compare their dyno results with others' results, and that in order to do that, you really need to run on the same kind of dyno. So if everyone has tested on a Dynojet, it doesn't matter how unrealistic those numbers are. If you want to compare, you need to test your own car on a Dynojet too.

I also know that Mustang dynos yield the lowest numbers of the group, which doesn't do any good in terms of bragging rights, which is what we're all here for anyway, right?

Seems to me that if real world performance is your primary concern, you should get your horsepower tested on a Mustang dyno. If getting the highest numbers is your primary concern, you should get your horsepower tested on a Dynojet.

Dynapack's marketing focuses mostly on explaining how it's better than Dynojet, but they have very little to say about the Mustang dyno, which tells me that even Dynapack knows they have nothing on the Mustang system.

Comments, corrections, criticisms, opinions, etc are welcome. Anyone with experience with multiple dyno types? I'd love to hear your impressions and opinions.

-Jake

 

There was an interesting article in Hot Rod magazine about a year ago, comparing the operating features, advantages and disadvantages of each type of chassis dyno. They took a typically "HP-challenged" stock late-model Mustang GT and ran it on 5 different setups. The results showed significant HP and torque differences. Worth reading.

 

Having a hard time finding that Hot Rod article. I'll keep looking, but if anyone knows where I can read it online, I'd appreciate a link.

 

I think both are good measuring tools. Running the car at the track measures much more than just power and torque, though (traction, driver skill, etc). Sometimes one might want to focus on measuring power... (just playing devil's advocate)

Someday, I'll drop $50,000 on a dyno to install in my garage. You can all come use it, for a price of course.

Good article -- thanks.