Dyno theory . . .
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Dyno theory . . .
to possibly explain some "mysteries" showing up here.
In the case of my "Trollmobile-Under-the-bridge-GT" there is always talk about resetting the computer after mods - or waiting for the beast to "re-learn" the situation. I know from testing that after a mod (and even "re-setting") that performance continues to improve after several runs.
So: Are you changing chips and things between runs? Is the dyno environment different from real life? (air flow might be a big factor) Does the TT computer continue to adjust with changing imputs?
To tell the honest to God truth, I would be amazed if tests showed closer results. (Mfg. variances, chip changes?, intercooler temps could all influence results.)
Very interesting stuff. smallTT, comments please?
In the case of my "Trollmobile-Under-the-bridge-GT" there is always talk about resetting the computer after mods - or waiting for the beast to "re-learn" the situation. I know from testing that after a mod (and even "re-setting") that performance continues to improve after several runs.
So: Are you changing chips and things between runs? Is the dyno environment different from real life? (air flow might be a big factor) Does the TT computer continue to adjust with changing imputs?
To tell the honest to God truth, I would be amazed if tests showed closer results. (Mfg. variances, chip changes?, intercooler temps could all influence results.)
Very interesting stuff. smallTT, comments please?
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Few answers...
All cars except two did not change set ups..if came in with chip and exhaust tested same. The two exceptions...Ellen (aka 225TTR) has the APR set up so she dyno performance and stock mode (can program ECU via cruise control button) and Bill (02BNME) TT we pulled the MTM ECU and installed OEM ECU...by doing this we verified that the spiking of the hp and torque curves that showed up on the readouts of the MTM ECU continued with the OEM ECU (but to a lesser degree but still there) and thus concluded problem was not with MTM ECU but a fault in the engine and in particular the boost control solenoid.
No to 'real life'...although large fan was pushing air over front of car (for cooling purposes) it did not duplicate a car going 75+ mph...thus less ram and cooling effect in the dyno.
Yes ECUs do adjust to environmental factors and the dyno computer adjusts readings to SAE.
As I posted earlier this morning I found the one example that I showed to be IMHO well within appropriate %age deviation.
No to 'real life'...although large fan was pushing air over front of car (for cooling purposes) it did not duplicate a car going 75+ mph...thus less ram and cooling effect in the dyno.
Yes ECUs do adjust to environmental factors and the dyno computer adjusts readings to SAE.
As I posted earlier this morning I found the one example that I showed to be IMHO well within appropriate %age deviation.
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I wish I could have been there!
I've been reading the results and comments.
So far not much is surprising.
I'm quite interested in how Dynojet does the 4 wheel attachment. Their website is a tad vague.
I'd guess it's another inertia wheel not physically connected (chains, belts, etc) to the main roller and measurements are added to main to get total. 4wd has always been a big problem for chassis dynos.
I'm positive a lot of discussion, figuring and conjecture will come from the results of these tests. Having hard data makes it worthwhile.
I'll keep reading and thinking.
So far not much is surprising.
I'm quite interested in how Dynojet does the 4 wheel attachment. Their website is a tad vague.
I'd guess it's another inertia wheel not physically connected (chains, belts, etc) to the main roller and measurements are added to main to get total. 4wd has always been a big problem for chassis dynos.
I'm positive a lot of discussion, figuring and conjecture will come from the results of these tests. Having hard data makes it worthwhile.
I'll keep reading and thinking.
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I am certainly not an expert on dynos...but what I have heard...
that 4 wheel dynos are actully like two two wheel dynos, with adjust feature for wheelbase length (they measured our wheelbases and then electronically adjust the distance between the 'rollers') and that the computer receives inputs from the two dynos and does computations.
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I think that's correct. It works for inertia type dynos...
I can see some chance for car-to-car variation here. Tires and tire pressure come to mind first.
If you haven't included it, wheel and tire combinations for each TT would be interesting to know. So would tire pressures.
Still thinking.
If you haven't included it, wheel and tire combinations for each TT would be interesting to know. So would tire pressures.
Still thinking.
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