There is some value in a butt dyno, but placebo is also a strong force. When I had my 2000 SS Camaro it was fast. I test drove one of the supercharged Mustangs and it had some a smooth power curve that it didn’t feel as fast as my Camaro but was proven to be superior. The Mustang held a constant rate of acceleration while my Camaro increased the rate of acceleration all the way to the fuel cutoff. The butt dyno was wrong in this case.
While I agree that impressions felt by a driver can be wrong, they can also be profoundly different and more accurate in feeling performance gains on the track that the incredibly accurate engine dyno data could not produce. Ask Ted at engnbldr about his experience with engine dyno data and then with that same engine driven in a NASCAR Sprint Car and the driver’s “butt-dyno” comments… or the results on the clock.
There is an incredible amount of accurate data collected and reported by the technology installed in a NASCAR vehicle, but if Kyle Bush, Martin Truex Jr., or Brad Keselowski tells their Crew Chief to make a change to their car based on their “butt-dyno”, what do you think will happen?
You compared your Camaro to a blown Mustang. How was the Mustang “proven to be superior”?
My comment was simply to say that while testing and tuning, and in the absence of a chassis dyno or engine dyno to test the actual changes, most of us go by our gut feeling and physical senses.
Would you argue that andykrow’s recent experience with his valve lash setting is a placebo effect?
Or how about H8PVMNT’s ongoing and lengthy butt-dyno testing… are his experiences a placebo effect or does his experience have a degree of accuracy and real change?
Most of the changes and results I have done to my engines, dating back to my 5 years of racing go-karts, with engines that were built and dyno tested by my good friend and competitor, and one of the best McCulloch go-kart engine builders of his time, and he had a room full of 1st Place Trophies to prove it, has been because of what I felt after making a change.
Since my 1964 283 CU Chevy Malibu, thru two 327-powered Corvettes, 8 years and 3 sand rails, while hang’n with some the best engine builders around, including a few racing legends, most of the changes I personally experienced with my own vehicles can be easily proven by a huge library of data and history by every automotive expert on the planet…. that backs up my butt-dyno.
That’s just my opinion – it may be worthless.