Re: 4.8L Performance upgrade options
Posted: 18 Jul 2018 08:35
What wheel?
Flywheel or Rubber?
Flywheel or Rubber?
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Come on Julian - cant throw that out there and not have time?Mystical_Beast wrote: ↑18 Jul 2018 09:21 Guys just for clarification
that I don’t have the time to go into now.
The issue for me is that one car cannot always be compared to another. For starters some people drive 31" and others 33" tyres etc. Then there is weight that affects effective power in any event.CarloG wrote: ↑18 Jul 2018 09:53Come on Julian - cant throw that out there and not have time?Mystical_Beast wrote: ↑18 Jul 2018 09:21 Guys just for clarification
that I don’t have the time to go into now.
Can we assume however that for relatively comparative purposes to asses the changes in setup (supercharger/exhaust etc) that the difference in nm (calculated in whatever manner - as long as the inputs are the same) is enough for the purposes of caparison?
Mystical_Beast wrote: ↑19 Jul 2018 08:49 When a vehicle is set up on the dyno to do your first base run..
In simplistic terms the following should happen.
First ascertain wheels are standard etc.
Same vehicle on same dyno with different wheel sizes will give different result
The Dyno measures the power KW, but within the software there is a conversion to NM, torque.
So what happens is something like this
You do your first run and as long as the car is producing the correct power for that particular model you then have a look at the torque curve.
Then you refer to manufacturer specification which will tell you what the car produces standard and what RPM.
The Torque curve is then manipulated with a correction factor so that it coincides with factory spec.
So the graph resembles factory spec
is this done 'automatically' by the software and, more to the point, why does it need to be matched to the factory curve?
Assuming the car is within spec insofar as producing the correct power, the torque curve will then be an accurate representation of what your motor produces at the flywheel.
1. What happens if the power curve is different to that of the factory at a baseline - i.e. no mods. What torque curve do you match it to
2. What needs to happen if the baseline test is not factory spec - most common would probably be larger wheel. 33" in my case vs 31" OEM.
3. Why conversion to flywheel - Is this because the factory spec is done at the flywheel?
Any reading of torque at the wheels is that particular tuners own calculation and therefor can essentially be whatever he wants it to be.
From my observation at SAC Centurion they printed a print-out for me there and then. I didnt see any input other that finding a clicking on the print button. Could there be a std calc to take into account losses from flywheel to rear wheels (i suppose they would need to be by vehicle model.
So to go back now..
Assuming the core is producing within spec
The dyno software spits out a torque curve.
The Tuner should refer to factory spec and do the calculation factor that mirrors factory figure.
That calculation figure is then unique to that particular vehicle and should be used on all subsequent runs.
Does this normally get disclosed to the customer
If you change tyre size that calculation would have to be redone.
So every single different vehicle type will have its own calculation factor determined from a good one done previously, a database of sorts.
So your Patrol then could possibly be based on the calculation of previous Patrols. Which could all have different tyres, already have exhausts, manifolds or filters, snorkels etc? - this would statistically results in an average somewhere between OEM and the most common mods
Depending on how accurately that original conversion factor was done would then determine the accuracy of your results.
As a before and after sure, the changes will be evident.
If the conversion factor is manipulated the results will be skewered.
Not sure if I managed to explain this properly.
In conclusion, all things being equal, the torque figure should be showed at the flywheel, rather than at the wheels, because the dyno does not measure torque at all.
So how do we know if the figure is done at the wheel or at the flywheel ... (or i suppose somewhere in between!)
And the torque of the motor is derived from the above conversion calculation as mentioned above.