generally because of the effort associated with finding dynos in the local area and operators that can be trusted. In addition, the fact that dynos as much as error should not be a factor is, and numbers are easily skewed.
Time associated with a non local dyno and for some people the cost associated as you need to spend anywhere from another 150-400 just to have before and after dyno numbers.
__________________ Im in the highspeed aluminum business
Many will benefit from finding out that their car is missing horsepower, consuming too much fuel or at least know if their money spent on
modifications was worthwhile. No one is posting results?
I would note that mottati's full-boat Dinan setup was dynoed recently, he posted the results, and I'd bet they're about as far as you can reasonably go with a normally-aspirated S62 on 91-octane California pump gas.
I'm a big fan of 'trust but verify"... UOAs, ISO5011 testing, etc... and a dyno seems a great way to cut through the marketing hyperbole.
But I've seen big variations in dyno numbers based on where a fan is placed on the engine bay, and other factors... getting a 'true number' and then replicating the test at a later date seem challenging. Plus the $200 a decent dyno should cost is better spent on....
Finally, once I've modded the car what does the dyno number do for ME? There are plenty of posts of people who add mods, dyno and post differential numbers far less than you would expect from the manufacturers' claims. Those posts help the reader, but not the guy who paid for the dyno.
For me... trying to schedule some pulls, the "dyno guy" never calling me back, traveling to much, dyno is closed on random days, etc. We only have one dyno in west Michigan.....that I know of.
But I've seen big variations in dyno numbers based on where a fan is placed on the engine bay, and other factors... getting a 'true number' and then replicating the test at a later date seem challenging. Plus the $200 a decent dyno should cost is better spent on....
a) Tests taken on the same dyno under similar weather conditions with the same fuel should produce results repeatable to within a couple percent (of course, at 350whp 2% is 7HP.)
b) Tests taken on different dynos under different conditions or with different fuel could be all over the place. Note that in some localities fuel formulations change seasonally. I'd swear in some cases they change because some bureaucrat wakes up with crab lice and wants to spread his misery around.
c) Because of airflow and temperature issues what you get on the road may vary from what you see on the dyno anyway.
I'm a big fan of 'trust but verify"... UOAs, ISO5011 testing, etc... and a dyno seems a great way to cut through the marketing hyperbole.
But I've seen big variations in dyno numbers based on where a fan is placed on the engine bay, and other factors... getting a 'true number' and then replicating the test at a later date seem challenging. Plus the $200 a decent dyno should cost is better spent on....
Finally, once I've modded the car what does the dyno number do for ME? There are plenty of posts of people who add mods, dyno and post differential numbers far less than you would expect from the manufacturers' claims. Those posts help the reader, but not the guy who paid for the dyno.
A
Excuses Excuses
A good dyno shop should not charge more than $85 for 3 runs (that is what 3 local dynos here charge)
Also if you stay with the same brand Dyno say Dynojet the variance in numbers is very small. Just make sure you have a large fan blowing sufficient air to replicate a driving environment.
The point you are forgetting is that when you Dyno your car the big area to focus on is not only your RWHP but the AIR/Fuel ratio which indicates if your car is running at optimum level. Wouldn't you agree that if you discovered from a dyno than your O2 sensors is causing your cause to run very rich your $85 would help produce say 20HP... DYNO's are a great "checkup" and tuning tool.
Would there be any sort of difference between a dynos A/F reading verses having a wide band reading? I don't see how there would be... but just checking.
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