Accuracy of dyno with loss of tach signal
12-29-2007, 09:21 PM
#1
Staging Lane
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Accuracy of dyno with loss of tach signal Ok guys I am just curious what you guys would believe.
There is a thread on another board were the dyno results in question are well lets just say very high.
The car was dynoed on a Mustang dyno and lost the tach signal but the owner of the vehicle keeps saying the #s are real. He has never posted a graph that has not been left unmolested from a crayon and never has shown a full pull graph just a partial graph.
The combo he has is making a additional 200 more rwtq than any other comparable setup but all his friends keep saying the #s are real.
So the question is how valid is a run with the loss of a tach signal and what #s are effected by this loss of signal?
Les
There is a thread on another board were the dyno results in question are well lets just say very high.
The car was dynoed on a Mustang dyno and lost the tach signal but the owner of the vehicle keeps saying the #s are real. He has never posted a graph that has not been left unmolested from a crayon and never has shown a full pull graph just a partial graph.
The combo he has is making a additional 200 more rwtq than any other comparable setup but all his friends keep saying the #s are real.
So the question is how valid is a run with the loss of a tach signal and what #s are effected by this loss of signal?
Les
12-29-2007, 09:34 PM
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FormerVendor
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The rpm(tach) signal is one of the main calculation pts on the mustang dyno. RPM and the strain gauge are big parts in the hp/tq equation, any dips or fallouts can and will cause a odd dyno graph.
Some of the new dyno software from mustang does happen to have a obd2 (autotap) connection to pickup a better way of RPM.
So yes, any changes in rpm pickup will give a false reading, even +200tq.
Some of the new dyno software from mustang does happen to have a obd2 (autotap) connection to pickup a better way of RPM.
So yes, any changes in rpm pickup will give a false reading, even +200tq.
12-29-2007, 09:41 PM
#3
He also never vids the rest of the setup parameters on the MD software screen. I looked closely at the vids to see if the vehicle weight or rpm range of the pull was realistic. I also didn't see the correction factor. I know from building the computer, installing the software, and setting up part of the hardware on my neighbor's MD250 that I can make it read any damn thing I want it to if I were so inclined. Combine that with the totally unrealistic liter-bike race vids and earlier BS dyno half pulls, and I would say that someone is an attention ***** instead of a racer. To answer your original question, a run on a Mustang dyno is completely blown if the tach signal is lost. Also, if running a Smarttach, the rpm can also be fudged by improper setup.
12-29-2007, 09:43 PM
#4
The rpm(tach) signal is one of the main calculation pts on the mustang dyno. RPM and the strain gauge are big parts in the hp/tq equation, any dips or fallouts can and will cause a odd dyno graph.
Some of the new dyno software from mustang does happen to have a obd2 (autotap) connection to pickup a better way of RPM.
So yes, any changes in rpm pickup will give a false reading, even +200tq.
Some of the new dyno software from mustang does happen to have a obd2 (autotap) connection to pickup a better way of RPM.
So yes, any changes in rpm pickup will give a false reading, even +200tq.
12-29-2007, 09:46 PM
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He also never vids the rest of the setup parameters on the MD software screen. I looked closely at the vids to see if the vehicle weight or rpm range of the pull was realistic. I also didn't see the correction factor. I know from building the computer, installing the software, and setting up part of the hardware on my neighbor's MD250 that I can make it read any damn thing I want it to if I were so inclined. Combine that with the totally unrealistic liter-bike race vids and earlier BS dyno half pulls, and I would say that someone is an attention ***** instead of a racer. To answer your original question, a run on a Mustang dyno is completely blown if the tach signal is lost. Also, if running a Smarttach, the rpm can also be fudged by improper setup.
Les
