Do not get me wrong. I love chassis dynos.
I like to be able to get my customers to get on them, becuase it isd a wonderful tool to help with a lot of tweeking. You will learn things on a chassis dayno that could take you many months of track testing to learn when it is used as a tool.
I hate chassis dynos when it comes to quickee 3 pulls to get rear wheel horsepower for the sake of bragging rights. I had/hve a customer that has a Mopar RB BB and we got him a little over 670 hp using his Mopar heads when measured on an engiine dyno. He put his car on a chassis dyno and the rear wheels showed a little over 360 hp. He was furious with me at that time. What happened to my 670 hp? He asked screaming at me. The engine hp was still there but not on a chassis dyno it wasn''t showing, becuase he has an old school 5,500 rpm TCI torque convertor in his car.
If you have some extra money and want a little fun, seek out all the chassi dyno in your city, {in mine there are many] and take the same car to all of them. You will think that you were testing with different cars when you see all the results side by side.
If you use a chassis dyno as a tool to check and get a baseline of what the car is now, and then use it to monitor any changes in performance and go to the same chassis dyno ecah time, I love them.
Fact of the matter any dyno, chassis or engine, is still to be used as a worthwhile and valuable tool. Even with engine dynos you will not get repetablity from one dyno to the other.
By all means, I do highly recommend using any dyno you have an opportunity to use and to pay for some real dyno testing. It is money well spent and can save you lots of future grief.
Ed