Q&A Forum
it's great your dyno is working good already!
HI to all!
Lot of new info about my fla!
First of all thanks so so much to all for help and support, especially thanks to walter, i have learned so much talking with you and of course to Jostein, helping me remotely calibrating my dyno and finding problem.
I had problems with wheels slip, my room is under construction yet and floor has lot of dust, so with dirty tyres no good grip...
Jostein advise my to use wd40 for solving slip problem, i was a bit skeptical about it but it works, and trust me it works very very good.
With good grip MOI could be calculated properly, which as tuttur advise me is 11.5.
On the other hand pid setting was set to kp: 1 ki: 0,5 and kd: 0.050.
Power sweep now works like charm.
for to know really HP crank, you have to use an engine dyno, anyway you can get very close Hp readings in a roller/hub dyno. ive tested many cars getting exacts HP that car is supposed to make. also all cars havent the same power that manufacturer says, and people think if a car is supposed to make 225hp for example, many of these doesnt make that power, maybe for years, conditions of engine, or just because these cars never made 225 really. many people dont understand about it.
About MOI, yes, it should be calculate per each car but i think about MOi calcuation , what you calculate too is MOI of your dyno, i thought this conclusion when i calculate MOI, when you are calculating MOi, you measure MOI of the car/dyno in accelerating, you still measure MOI of your car/dyno in steady for seconds, and finally you measure moi of car/dyno going down, ok, when you after that measure, and you have yo adjust, i think you are adjusting the MOI of the dyno, because MOi of the car is a constant value, dyno value doesnt, then that's why you have to adjust it until you get it. maybe with other car could be different? maybe, i never calculated with other car, maybe forwared just for information. maybe im wrong, but im very happy with results on my dyno and after +2years, when first 6 months i was comparing with other dynos like dynojet, dynodinamics, mustand dyno, because you want to have a dyno with good readings as everyone ,all of these dynos has slight different readings but mine reads very close to all of these , and after to tested many cars, looking the results and comparing , i think your dyno is Ok, anyway all dynos are another tuning tool, it worths more to test before and after tune.
another question is, it's the same friction of a gearbox acceleration than accelerating? what happen when you use engine brake? you get the same engine brake in 5 gear than 2 gear at the same speed? it's like when some people use a dyno roller in one way, the load cell is located in compression, what happens when they use in the other way? load cell is working in extension, it will measure same load?
i dont understand, why whp is same but no crank hp, losses should to be the same, and % of friction losses must to be same on 3th than on 4th.
SO it will be imposible to know engine power accurate? as you told, i will need to calculate moi for every car???
found these..attached files, i can't add more files in the same post.
this dynosheet, is the same car, 3th gear and 4th gear, you can see almost identical whp readings, less than 2whp difference in some ares only. you can notice more drivetraing losses in one pull than other one, thats normal. i will upload the other dynosheet for HP crank readings.
Moi incorporates all rotating mass, so wheels, discs, driveshafts, flywheel, crank, rods, pistons all matter.
I dyno various cars and I have not checked it for all of them. The Clio 197 I’ve used is about medium of what I do.
The method Jostein has shared for calculating MOI won’t work with a turbo’ed car, as they are sensitive to load.
try my MOI and see if it’s closer. You’ll always see a difference especially on a turbo’ed car, as when doing inertia you’ll have load compared to a 1st/2nd gear run, while when using the brake with a ramp rate of 300rpm/s it’ll be more likely a 4/5th gear run
it's more like when you want read crank hps (inertial/drivetraing losses reading is needed), you need to run close 1:1 to engine, normally is 4th gear for 5 speed cars and 5ht for 6 speed cars, of course if you try another gear you could see different readings, when you try to see whp readings, it's really close in any gear. ive test some months ago about whp and was almost same whp in 3 or 4 gear for example... im pretty sure i have dynosheets when i did some test about.
Moi incorporates all rotating mass, so wheels, discs, driveshafts, flywheel, crank, rods, pistons all matter.
I dyno various cars and I have not checked it for all of them. The Clio 197 I’ve used is about medium of what I do.
The method Jostein has shared for calculating MOI won’t work with a turbo’ed car, as they are sensitive to load.
try my MOI and see if it’s closer. You’ll always see a difference especially on a turbo’ed car, as when doing inertia you’ll have load compared to a 1st/2nd gear run, while when using the brake with a ramp rate of 300rpm/s it’ll be more likely a 4/5th gear run
Try to calculate again MOI of your own dyno and post dynosheet if you did it correctly.
Great to know it happy to help you with brake!
on the other hand no idea why i am not able to make a good run for testing moi and yes it was a turbo car, 1.8t 225 hp
So you always use moi of 11.5 on your runs? i am using 10,7 and with brake off power look quite accurate, not with brake...
i though moi was independent of engines or wheels, just a dyno value.
thanks
Just to let you know, your pid settings with 15 Hz work great. Thanks for that!
regarding your issue, is it a turbo engine? The difference you see could have lots to do with loading. Also if it has slip on the loaded run the rpms and so torque output will differ aswell. If you want to verify your settings like this it’s best to use a relatively low power n/a car.
what MOI do you have set? Just to rule that out. Think Jostein is at 10,7, but that was tested with a kit car with small wheels and bike engine. I’ve tested it with a Clio 197 on 17” wheels and ended up at 11,5
My guess is load cell calibration or MOI. But if you send me the raw log files plus your saved options then I can take a look. Send to jostein@yourdyno.com
HI thansk for answer, yes the ratio is same i just changed from brake off to power sweep i stopped run before becouse dyno was braking engine too much so rev didnt go high than those, after a few seconds i pushed up foot.
could be problem of pid brake? moi was turn on and load cell calibration shows ok...
There are a few things there. The gear ratio seems different? End RPM and peak come at different locations. Is it the same Noise filtering?
If the gear ratio is really the same and you just stopped the run a bit earlier on one of the runs, then the MOI or load cell calibration is off. We have done exactly the same test in our FLA203 dyno and the curves overlap pretty perfectly.