Q&A Forum
@Walter, I will measure a EP3 in the next few days. the 90HP car was a Honda D14Z2, S20 trans, in a EG chasis.
@Admin, I do not use constatnt power correction because the correction factor is showed up in the final result and the customer asking why I use that f*g big correction. ofcos I can't proven those # is real.
Already I did a linearity test over 240kg range, I have 1.5Kg bump around at the middle range. I use a 300Kg weight scale to check the whole range for linearity.
the loadcells is 300Kg/each with 29.4 cm Tq arm.
BTW the shocking of the retarders can cause big differences on the #s ?
YourDyno v3.2.55 is available now. It removes information about horsepower correction/calibration in the results table and in the print out.
HondaRulesz, can you send me your MOI testing log file plus your settings file by mail? I will take a look.
@Walter, I will measure a EP3 in the next few days. the 90HP car was a Honda D14Z2, S20 trans, in a EG chasis.
@Admin, I do not use constatnt power correction because the correction factor is showed up in the final result and the customer asking why I use that f*g big correction. ofcos I can't proven those # is real.
Already I did a linearity test over 240kg range, I have 1.5Kg bump around at the middle range. I use a 300Kg weight scale to check the whole range for linearity.
the loadcells is 300Kg/each with 29.4 cm Tq arm.
BTW the shocking of the retarders can cause big differences on the #s ?
ok, let me know and we can compare numbers. i see photo of your dyno, is the center of the brake sitting in the chassis?
@Walter you mean the brake's front bearing ?
@Admin I just send a Audi A3 Vr6 datalog by email. The car is around 250 HP and we got 223.
Some tought about the MOI.
About 20-30% of the car what I measured the retarders have different RPM if not is in PID control include idling in a gear and also the coasting run.
sometime the RPM difference is really high. I guess in this case need a different MOI settings to the retardes. the app is allows different MOI values but no way to determine the right MOI for each retarder also the MOI finding is a little time consuming.
I guess a dedicated brake setup (like ramp test) needed for auto MOI setup.
this doing a ramp test and at end of the run would calculate the MOI for each retarder.
Thanks for the files. A few things to note here.
First, you shall not have RPM differences. The RPM is a digital signal, if you have differences then something is wrong. Your RPM sensor data looks super clean, no noise issues. However, RPM1 and RPM2 follow exactly the same RPM. Were they really measuring two different wheels? This looks strange since the load cells read quite different numbers during the power run. How can the RPMs be exactly the same? (unless the diff is locked)
Your system has low noise. But you use very high noise reduction. Your curves look good at Noise reduction of 2, while you use 6. This will dull out the results and mask problems.
You turn off the brake early. The engine accelerates abruptly after the brake turns off at 6300RPM. If you have an issue with the retardation curve, try using the "stored retardation run".
Your PIDs are not set up ideally. RPM does not follow a straight line. If you turn off MOI compensation then you see what the load cells measure, it varies quite a lot because the brakes vary. My guess is you should reduce Ki and Kd, but you need to test.
You really should add a power correction factor. The losses are higher at full load than at coasting, so a power correction is necessary. With 15% you get about 245hp. But first fix the RPM issue!
@Admin
The RPM differeces caused by the car's trans/drive line. the retarders rotating at different RPM which is visible by eyes. like 100/300 RPM.. so I can't to do anything with this .. If the PID control comes on (start a run) the RPMs become same..
with this car we have NO rpm issues.
The noise reduction comes from the previous install of my HW, I already redoing the whole wiring/connectors etc, shielded wires on the Fan's VFDs etc.., so we got very good signals finaly. I will reduce the smoothing factor.
with this car we finishing the run early because the ECU forcing the trans switch from gear5 to gear6 at 6500 RPM in manual mode too 🙁 so we can't stay in same gear on the whole run. also the coasting run is hard to achieve becaus need alot of time to go to N from gear 5 or 6 (ECU delaying...)
sure, the PID was not ideal for this car always over runs, also at constant RPM load we see a little oscillation on the brake force curve. with other cars we do not experienced this.
hmm, with my pluging I displayed the 2 Loadcell values and I see they are different, always..., so at a constant RPM load they MUST be same ? or the difference may come from the drive line ? maybe this is my real problem ?
OK, so RPM differences are because of an auto trans, there is nothing you can do with that. You should plot the results vs speed instead of vs RPM in those cases.
What I meant was that the load cells look normal, they are giving two different results as you would expect when they measure two different brakes. But the RPM sensors give the exact same values. This does not look right. There will always be small differences between the wheels, due to different loads (as we can see from the load cells) and individual PID control.
Are you feeding the same RPM signal to both RPM inputs?
wow, this is suprising ! I have 2 sensor and I always displaying both retarder speed on the session display. They showing right speed for each retarder ! when moving by hand the speed displayed on their gauge independently from the other one. Maybe SW bug ? The car waht U see have speer diff so the RPM can be very close to each other. also when I doing static RPM test while the PID is active the 2 retarder speed always seems to be same (within 1-2 RPM).
the weird to me with same RPM the load cells have sligtly high difference.
@radics1 the real issue I have low reading mostly on all measured cars and we can't find the error source 😀
BTW 70-80% of the car have same RPM on both retarders even at the coasting independently the PID is on or not. Some car have big difference if the brakes is not controlled. As I see on these cars the HP/Tq reading is more low..
@radics1, on some cars I can setup perfect MOI because have paralell lines 🙂 but your 9+ seems very high, the bigest MOI what I used is 4.2/each retarder. what retarders you have any pics of it ? do U have HUB dyno ?
Guys,
I wondered if something was wrong with the setup here since the two RPMs were SO similar. I really zoomed in and saw only tiny almost undetectable differences along the complete run between the two RPMs. Surprising since the load was quite different on the two load cells, and the PID was not setup well. But if you have an LSD I guess that can explain it.
So we are down to adding a power correction, plus the small tips I gave earlier on PID params, etc.
I never had problems on my hub dyno.
Im looking that yourdyno is going up with many corrections, etc, i means, maybe a software with too much adjustments will be maybe difficult to configure a dyno?
Ive been scaried sometimes when i have test a new version.. my dyno works really great, just some easy improvements, maybe a assistance for to get the best PID control, or to put a countdown clock for to start ramp or when finish, some small changes will make very easy and intuitive for using. Im pretty sure PID of my dyno can be improve but idk how to see, how graphs to diagnostic etc.
@Walter, if you seeing HUB's RPM and brake force as a graph you perfectly see how the PID control oscillating and reaching the target RPM.