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Originally Posted by Stan
Ahhh the joys of a decent datalogger...your dyno in a little box. Do your correction factors and the numbers jive with chassis dynos just fine...
A nice thing about them as far as turbo cars go is that the airflow over the car is...the actual airflow that matters. So cooling issues, intercooler factors, and on and on are 100% real world.
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I agree with you Stan, there is merit to data loggers for sure and I do in fact use them as additional data.
The one thing the dyno does offer is the ability to fine tune and steady state load the car at various rpm and tp points to target problem areas.
Basically, picture holding the car at 4500rpm, 30% throttle with say a 25% load, while watching one laptop monitoring the stock ECU for fuel trims and timing advance while the second laptop has the Emanage software open with all the maps out with a map trace going on along with the superflow dyno display outside the window with a/f being shown, oil temp, boost pressure, (And just about any variable we wish to monitor) etc
Now take that one sample rpm and load and multiply that into various points along the way. That really allows us to not focus on hitting a tree while we are trying to monitor these things on the street.
On the street, we pretty much log and then review afterwards to be sure all lines up accordingly.
The dyno we use is a Superflow unit housed in a location that has a 36,000cfm 3 foot diameter "wind pipe" that pretty much buffets the car like it's on the highway and will cool a 200* car down below the digital coolant display in a couple minutes if you shut the car off and leave it on.
As the owner says "if it aint bolted down, it's out the door once that fan starts". LOL
As for comparison and correction factors - I'm very very suspect of correction factors as most are centered on naturally aspirated cars and can't take "created atmosphere" and all the variables that go along with it into account in a forced induction vehicle. I normally watch the correction factor and if it's anything outside of a .9 or 1.1 max, I use uncorrected numbers and report the conditions at the time of the test.
The correction factor I was talking about in this particular instance was the *calibration* of the dyno and not a correction. Basically it takes a real world twisting force or torque and then uses a reference arm to calibrate. I guess the best way *I* can explain it is like taking a bathroom scale and adjusting it minus 10lbs. It says you are lighter even though you know better but you can still diet and see that you lost 5 lbs - it would just be off relatively speaking from the true weight. That was the situation here. The dyno was and always is incredibly consistent from run to run.
Hope that explains things better.
Oh and for reference we use the Nology Laptop Dyno for street testing and have found it within 5hp of the dyno 99% of the time.
