Dyno Dynamics - Shoot out modes
Discussion
Is there anyone familiar with the various "shoot out" modes on Dyno Dynamics rollers?
Recently had my 135i on for a power run but had disappointing figures. Noticed later that the chart is showing "Shoot 2R" which is for a twin-rotor rotary engine. I understand it should have been on 6F for 6-Cyl forced induction, but unsure what difference this really made.
All I can find is that the modes affect the ramp rate but not to what degree or what overall effect this would have on results.
I'm not even hung up about the figures, even though I'm aware that's what it probably comes across like, just genuinely interested / curious.
Recently had my 135i on for a power run but had disappointing figures. Noticed later that the chart is showing "Shoot 2R" which is for a twin-rotor rotary engine. I understand it should have been on 6F for 6-Cyl forced induction, but unsure what difference this really made.
All I can find is that the modes affect the ramp rate but not to what degree or what overall effect this would have on results.
I'm not even hung up about the figures, even though I'm aware that's what it probably comes across like, just genuinely interested / curious.
Hi .. although I run my DD pretty much every day, I've never run a rotary so don't have any answers for you as regards how that might affect the recorded power. The ShootF modes use a faster ramp rate than the normally aspirated equivalent rate to try and reduce the thermal effects of a long slow dyno pull, but the modelling used to get back to the power figure should give you the same end number assuming the thermal changes are adequately accounted for, it's just a faster rate to reduce the effect of temperature build up in a forced induction engine.
I'm more than prepared to be proved wrong, but I suspect if your car recorded disappointing numbers in the rotary setting it would also have also given disappointing numbers in the correct setting, but as i say I don't *know* for sure having never done the test (and I've learned over the years to not make any hard and fast assumptions as they often turn out to be incorrect and you just end up looking stupid - much better to admit you don't know! as mignon says : "things you know you don't know"). How disappointed are you ? 5hp? 10hp? 50hp?
But, I would say that if the test wasn't done in the correct mode they should be running your car again for free, it's their mistake not yours.
If that does happen, please share the results, we might all learn something here
I'm more than prepared to be proved wrong, but I suspect if your car recorded disappointing numbers in the rotary setting it would also have also given disappointing numbers in the correct setting, but as i say I don't *know* for sure having never done the test (and I've learned over the years to not make any hard and fast assumptions as they often turn out to be incorrect and you just end up looking stupid - much better to admit you don't know! as mignon says : "things you know you don't know"). How disappointed are you ? 5hp? 10hp? 50hp?
But, I would say that if the test wasn't done in the correct mode they should be running your car again for free, it's their mistake not yours.
If that does happen, please share the results, we might all learn something here
- all dynos vary from each other .. but running it in the correct test mode as suggested by the dyno manufacturer is at least a good first step to ensuring some degree of believability, though why there should be any need really to have different modes for different engine configurations is another argument entirely, which is why I like seeing the same kinds of cars, run in the same modes .. I can build up a mental database of trends so I can tell if something doesn't look right.
Thanks for the input so far, i'm about 30bhp disappointed, I ran the same dyno bone stock months before at 326BHP on Shoot 6F and now with a downpipe and map 333. But there was a number of issues that could have led to this other than the shoot out mode used. I feel the fan used initially was too small, a bigger one was eventually used. Also the operator was struggling with wheel spin so there were many aborted / failed runs (not sure if related to the mode) and calibrating the speed of the dyno with the car seemed a struggle, holding it for several seconds at 5K RPM multiple times (is this normal?) all of which combined I feel just heatsoaked the standard intercooler.
Apologies for the poor quality pic, I didn't bother getting a printout.
Apologies for the poor quality pic, I didn't bother getting a printout.
spitfire4v8 said:
Hi .. although I run my DD pretty much every day, I've never run a rotary so don't have any answers for you as regards how that might affect the recorded power.
Perhaps next time you run a car up you could try a couple of different modes and see if it corrects back to similar bhp figures.Shootout class controls 3 things :
Ramp rate : more powerful classes tend to get higher ramp rates.
Driveline Inertia : we assume a rotating inertia based on class.
Losses : the flywheel -> roller loss algorithm uses different parameters for different classes.
It's all a bit of a juggling act - we could do better with more classes (or vehicle info), but then where do you stop? 25 classes? 50?
What gen software are you using? It's under help->about IIRC
Ramp rate : more powerful classes tend to get higher ramp rates.
Driveline Inertia : we assume a rotating inertia based on class.
Losses : the flywheel -> roller loss algorithm uses different parameters for different classes.
It's all a bit of a juggling act - we could do better with more classes (or vehicle info), but then where do you stop? 25 classes? 50?
What gen software are you using? It's under help->about IIRC
Edited by AW111 on Monday 12th November 09:35
Vixpy1 said:
Yes all of those things can be a factor, you should be looking at 370 plus with those mods, standard intercooler is crap and at best you get 2 runs out of these before they start to pull 20bhp plus when mapped. So its really a one shot or give up car.
Yes that's what I thought, but couldn't even get the one clean run. I asked what the IAT was but it wasn't being monitored so they had to get something to hook up to the OBD port, could see IAT was high, it was left to cool down for maybe 15mins IAT was dropping v slowly the whole time, this gave the best run of 333 but still down on expectation. GregK2 said:
Yes that's what I thought, but couldn't even get the one clean run. I asked what the IAT was but it wasn't being monitored so they had to get something to hook up to the OBD port, could see IAT was high, it was left to cool down for maybe 15mins IAT was dropping v slowly the whole time, this gave the best run of 333 but still down on expectation.
Where was the dyno inlet temp probe?The graph shows inlet temp of 19 degrees (18 ambient).
Also ramp rate 100, which seems slow for a 300+ hp car. Driveline inertia is probably too low too.
I'm not at work, so I can't look up what it should be until tomorrow.
AW111 said:
GregK2 said:
Yes that's what I thought, but couldn't even get the one clean run. I asked what the IAT was but it wasn't being monitored so they had to get something to hook up to the OBD port, could see IAT was high, it was left to cool down for maybe 15mins IAT was dropping v slowly the whole time, this gave the best run of 333 but still down on expectation.
Where was the dyno inlet temp probe?The graph shows inlet temp of 19 degrees (18 ambient).
Also ramp rate 100, which seems slow for a 300+ hp car. Driveline inertia is probably too low too.
I'm not at work, so I can't look up what it should be until tomorrow.
Cant help with the version either unfortunately, the picture was a few weeks back when I was there.
Thanks for looking into it, I'll be keen to hear what settings should be used when you get a chance to look it up.
GregK2 said:
Thanks for the input so far, i'm about 30bhp disappointed, I ran the same dyno bone stock months before at 326BHP on Shoot 6F and now with a downpipe and map 333. But there was a number of issues that could have led to this other than the shoot out mode used. I feel the fan used initially was too small, a bigger one was eventually used. Also the operator was struggling with wheel spin so there were many aborted / failed runs (not sure if related to the mode) and calibrating the speed of the dyno with the car seemed a struggle, holding it for several seconds at 5K RPM multiple times (is this normal?) all of which combined I feel just heatsoaked the standard intercooler.
A chassis dyno is a tuning tool, it isn't a good comparator. On top of the intercooler being heat soaked it sounds like they may have tightened down the car to get it to grip, this will have shown as a power loss.I remember we needed an engine to do 500bhp in a FWD car so I could wave my cock around on Facebook, but it stopped just short of that on the dyno at maybe 496 or something, in order to get it to break the magic 500 the operator put another shootout mode on and it gave it a little bit more. This is only by memory as it was a while ago, i'd have to look at the paperwork to see if it shows exactly what happened.
It wasn't cheating as such as It also shows some weird peaks and troughs on the dyno which look like huge flat spots that you would feel, but out on the open road you wouldn't know they were there. It could have been wheel spin and I remember Maxtorque making some comment about the dyno not being able to keep up with the very steep climb in power/torque as it came on cam and the turbo spooled hard accordingly. It's quite normal for a car to make more power on the road than it did on the dyno due to temp, airflow, grip, different gear etc.
If you want more accurate results over a long interrupted period of time then find a hub dyno.
Edited by Evoluzione on Monday 12th November 10:10
Turbos can always be difficult to get the right temperature. I only book one dyno a day so we can let things cool if necessary whilst getting on with other work. Turbo power graph tends to be a textbook 1% up or down for each 3 degrees C.
Dave, I don't want to spark off a war but we are getting some interesting stuff, I hadn't realised Dynodynamics has in built factors changing what it 'thinks' should be power losses. I have never run our Dynocom in ramp test, I have always run inertia on it's own, % load for big F Off engines, turbos and SC engines. I use the pau for holding loads for testing pinking, specific fuelling at differing throttles etc.
Some of our customers have lost engines to incorrect ramp tests when the operator should have manually overridden the test.
I, like you and probably many others, have always been fascinated with what does it make at the engine. I can understand why you like the purity of engine dyno figures with no baggage attached. Most folk use rolling roads though. Like you I have searched the net for 'definitive' power losses for each component but to no avail. Either folk don't really know or they do not 'tell' us Earthlings.
I did find this article about Roush Nascar engines where it mentions 900 fly and 850 at wheels, well it says to the wheels which could be ambiguous? I did say in a previous thread I had read 850 to 800 whp but I remembered wrong,I should have written 900 to 850.
https://www.roadandtrack.com/motorsports/news/a802...
The nearest I get to seeing some pattern is with humble Minis and VW aircooled with std engines ( especially the Minis as a lot are still on original engine) The Factory figure seems very close if around 2000 rpm and low mph to be same as we get for torque, so we get wheel torque = fly torque. The max wheel figure we get, when coastdown added is very close to factory bhp. This may only work on low speed low rpm engines, I don't know but there is a pattern.
I agree with you Dave that it would be interesting to see the same car tested in the different modes to see what differences there are.
EDIT....I hadn't seen your post Evoluzione, did you get to wave your dick on facebook?
Dave, I don't want to spark off a war but we are getting some interesting stuff, I hadn't realised Dynodynamics has in built factors changing what it 'thinks' should be power losses. I have never run our Dynocom in ramp test, I have always run inertia on it's own, % load for big F Off engines, turbos and SC engines. I use the pau for holding loads for testing pinking, specific fuelling at differing throttles etc.
Some of our customers have lost engines to incorrect ramp tests when the operator should have manually overridden the test.
I, like you and probably many others, have always been fascinated with what does it make at the engine. I can understand why you like the purity of engine dyno figures with no baggage attached. Most folk use rolling roads though. Like you I have searched the net for 'definitive' power losses for each component but to no avail. Either folk don't really know or they do not 'tell' us Earthlings.
I did find this article about Roush Nascar engines where it mentions 900 fly and 850 at wheels, well it says to the wheels which could be ambiguous? I did say in a previous thread I had read 850 to 800 whp but I remembered wrong,I should have written 900 to 850.
https://www.roadandtrack.com/motorsports/news/a802...
The nearest I get to seeing some pattern is with humble Minis and VW aircooled with std engines ( especially the Minis as a lot are still on original engine) The Factory figure seems very close if around 2000 rpm and low mph to be same as we get for torque, so we get wheel torque = fly torque. The max wheel figure we get, when coastdown added is very close to factory bhp. This may only work on low speed low rpm engines, I don't know but there is a pattern.
I agree with you Dave that it would be interesting to see the same car tested in the different modes to see what differences there are.
EDIT....I hadn't seen your post Evoluzione, did you get to wave your dick on facebook?
Shootout mode has it's origin in the early days of dyno competitions.
Until then, tuners were happy to work with the measured (roller) figures, with correction for atmospheric conditions.
Once people wanted "flywheel" power, and it became a number to brag about, we did a lot of correlation testing and came up with the original 6? classes.
Driveline inertia has an effect in that it takes power to accelerate the gearbox, diff, axles, wheels etc.
You can enter it manually, but of course that means you can use it to "cheat" to get a bigger power figure.
Ditto with ramp rate, correction method, etc.
So the idea of shootout is to lock down most of the variables so you're comparing like to like.
I can look at the shootout chart and know exactly what the variables are.
And that they're set for a n/a twin rotor rotary, with gearbox and tyres to match.
Until then, tuners were happy to work with the measured (roller) figures, with correction for atmospheric conditions.
Once people wanted "flywheel" power, and it became a number to brag about, we did a lot of correlation testing and came up with the original 6? classes.
Driveline inertia has an effect in that it takes power to accelerate the gearbox, diff, axles, wheels etc.
You can enter it manually, but of course that means you can use it to "cheat" to get a bigger power figure.
Ditto with ramp rate, correction method, etc.
So the idea of shootout is to lock down most of the variables so you're comparing like to like.
I can look at the shootout chart and know exactly what the variables are.
And that they're set for a n/a twin rotor rotary, with gearbox and tyres to match.
AW111 said:
Shootout mode has it's origin in the early days of dyno competitions.
Until then, tuners were happy to work with the measured (roller) figures, with correction for atmospheric conditions.
Once people wanted "flywheel" power, and it became a number to brag about, we did a lot of correlation testing and came up with the original 6? classes.
Do I deduce from this that shootout mode goes straight from wheel bhp to flywheel bhp via transmission and tyre loss equations rather than using any sort of coastdown procedure?Until then, tuners were happy to work with the measured (roller) figures, with correction for atmospheric conditions.
Once people wanted "flywheel" power, and it became a number to brag about, we did a lot of correlation testing and came up with the original 6? classes.
That is what I understand to be the case from Karl next door Dave. I think there are quite a few modes to choose from. For instance a Cossie 4wd would come under 4F/4WD ( 4 cyl, forced induction, 4WD) the software then adds what are considered to be transmission losses as deemed fit by the developers, there is no measurement of transmission losses. I am not sure if the dyno can be run like old fashioned Sun eddy current brakes where a coastdown approximation could be made.
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