Michael Yount said:
....and you don't have to be a professional grade driver to get meaningful data on changes at the drag strip or the road course. You simply have to be able to drive the car in a similar fashion during the runs. At the strip you can idle it out and short shift into second and run hard from there. That eliminates most traction and driving variables. Also, when you're looking to check whether you've added HP or not, you're looking at mph, not ET. Traction/driver/launch issues impact ET much more than they impact mph.
Michael that would not work and isn't close enough to be repeatable. If you think about it, how are you going to idle out the same, or shift out of 1st at the same exact rpm and distance, or go WOT at the same rpm in 2nd gear? It simply would be nearly just as accurate of info as a "normal" drag race.
I am very aware of mph and e.t. and if you have ever paid attention I am a big proponent of pushing mph and not e.t.
Michael Yount said:
Even simpler than that are tests anyone can run on the street. All that's needed is an open, lightly traveled section of road. You simply do timed wot acceleration runs in one gear -- second or third gear from say 2000 rpm to 5500 rpm. You do 4 to 6 runs, be sure everything (tranny, rearend too) is up to operating temp, and you do the runs in BOTH directions and average them. This takes wind and elevation changes out of the picture. Of course you want to try and test in similar ambient temps and when it's dry. It's a VERY effective way to measure changes and much cheaper than track time or dyno time.
That could work as well...I agree. Stay on the same road and start at close to the same location as possible to keep grade levels the same. Then you just have to rely on how quick/accurate your fingers are on the stop watch or when you look at it.
Michael Yount said:
While there are track variables, they can be accomodated and adjusted for and you don't have to be a world class driver to do so. The challenge with dynos are multiple 1) you don't know when or how the unit has been calibrated; 2) you don't know when new operating software updates have been done or what impacts they have; 3) you don't know how or if the dyno operator is impacting outputs through changes in software or inputs; 4) strap down techniques - both belt tension and HOW the straps attach to the car can have significant impacts on readings; 5) all the environmental elements at work at the track also impact dyno runs; 6) most vehicle elements that can impact consistency from run to run aren't monitored at all - tire pressure, tranny and rear end fluid temps, oil temps, etc.
Well 1-3 of those variables you listed can be answered by
asking the dyno[/B] operator
Dyno runs are more in an enclosed area in most cases (besides those portable ones at the track and events). They are mostly inside in a working environment. The ones I have seen and witnessed in person and thru media.
The operating temps and tire pressure also effect the track as well.
The dyno simply has less impactive scenarios to degrade mod information gathered as compared to the track.
Michael Yount said:
I've watched (and participated in) a lot of dyno runs. I'm amazed at the number of times that the results of the runs end up really close to the owner's expectations (funny how the operator will ask 'what do you think it will do?'). Coincidence? I think not - it happens too much. Or the results end up FAR short of expectations only to find out after an 'adjustment' by the operator that the dyno brake was dragging....well, how often has that happened? And all of that is for Dynojet dynos -- the Mustang dynos (any of the eddy-current dynos) have WAY more variables than that in the way the dyno is loaded with current.
I don't see to much of that...and anyone that is serious enough about their car should realize what is accurate and what is not. How could a dyno operator give you the exact or close to rwhp numbers that the owner thinks he will get? How can he do those type of calculations because as you know much information has to be entered and taken into consideration to get "real numbers". I bet I could guess within 10rwhp what I'm putting out...but I'm sure it would be because the dyno operator rigged it
Lol...not.
Michael Yount said:
The chassis dynos are simply not as accurate or repeatable as you think they are. That's why people are pointing to using both track and dyno - neither are perfect, one isn't better than another. They're different and have different reasons for being fallible.
I never said they were up to any standard. Just that they are more reliable than a track times/mph. Never said one was perfect or the answer would be obvious and no debate would exist.
Again to go back to the question: If you added a horsepower enhancing modification what would be better to tell what kind of power you got (more accurate?). I'm not sure how someone can say how the track has less variables to control or can be more accurate with a power enhancing mod.
What if you have traction problems at the track and due to that aren't aware of where to shift and end up in a low mph stage. The dyno can show you the potential that there is more to it...just a simple example.
), would the dyno or track be more suitable to see what gains you actually received.
