the results do not differ from shootout to non shoot out!!!
the at the wheels figure is no different but you dont get pressure and temp corrections
you cant run a flywheel figure if you dont run in correct shootout mode
Pro's & Cons of Dyno's
Gary, the results definitely should differ between shootout and non shootout for a number of reasons.
One is that for shootout you pump the tyres up to 50psi and the compensation for this is an estimate.
Another is that the compensations in shootout mode are based on an measurement taken from a number of vehicle and transmission types and which the operator has pre-selected from the list. In shootout mode the dyno calculates the gear ratio based on the speed/rpm and uses the compensation table for the transmission type to guess what fudge factor to use. As you at APT have said in the past "it doesn't seem to matter what gear we run in, the results work out about the same. We're not sure why it works but it does" - well the compensation table and gear ratio calculation is why that works but it's only really a carefully calculated guestimate. In dyno mode the rollers can calculate everything properly so the results should be more accurate.
It is worth noting that compensations are used even in "at the wheels" results whether in shootout or dyno modes which may not be what some people expect. Of course the full raft of compensations only kicks in when you choose "flywheel" figures, which is where the differences between the two major modes of operation are most apparent.
If you are not seeing improved accuracy between shootout and dyno modes then that is somewhat odd. I could digress into a discussion about accuracy versus resolution versus repeatability and how all three differ but I think that is perhaps a bit too far off topic and perhaps worthy of another topic in its own right.
One is that for shootout you pump the tyres up to 50psi and the compensation for this is an estimate.
Another is that the compensations in shootout mode are based on an measurement taken from a number of vehicle and transmission types and which the operator has pre-selected from the list. In shootout mode the dyno calculates the gear ratio based on the speed/rpm and uses the compensation table for the transmission type to guess what fudge factor to use. As you at APT have said in the past "it doesn't seem to matter what gear we run in, the results work out about the same. We're not sure why it works but it does" - well the compensation table and gear ratio calculation is why that works but it's only really a carefully calculated guestimate. In dyno mode the rollers can calculate everything properly so the results should be more accurate.
It is worth noting that compensations are used even in "at the wheels" results whether in shootout or dyno modes which may not be what some people expect. Of course the full raft of compensations only kicks in when you choose "flywheel" figures, which is where the differences between the two major modes of operation are most apparent.
If you are not seeing improved accuracy between shootout and dyno modes then that is somewhat odd. I could digress into a discussion about accuracy versus resolution versus repeatability and how all three differ but I think that is perhaps a bit too far off topic and perhaps worthy of another topic in its own right.
Westfield zei370 - GPS confirmed 167mph flying brick.
Cosworth YB - GT2871 - 8-injectors - Swedish plenum - ported head - pace chargecooler - water injection
Cosworth YB - GT2871 - 8-injectors - Swedish plenum - ported head - pace chargecooler - water injection
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ScoobieWRX
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Quite possibly yes. Obviously if your vehicle perfectly matches the default metrics for shootout mode and your tyre pressure/characteristics match then the results may be the same but in general no it won't quite match up but it should be reasonably close. Oh and no cheating by adjusting tyre pressures or overriding the compensation tables, you need the proscribed 50psi for shootout and we expect the same gear selection for both runs - 3rd is your usual I believe but 4th would be fine too.gary@apt wrote:so chris if i do a power run in shoot out and the in normal dyno mode you saying it will be different??
We know that DDs are repeatable to 1% so it's accuracy that we're interested in here. For these purposes the interesting things for a back to back run are the two "at the wheels" figures on a graph and the two calculated "flywheel" plots on a graph. Note: this test only demonstrates accuracy for a single car between the two modes, it doesn't demonstrate absolute accuracy (ie calibration) or accuracy for all power outputs and vehicle types.
Westfield zei370 - GPS confirmed 167mph flying brick.
Cosworth YB - GT2871 - 8-injectors - Swedish plenum - ported head - pace chargecooler - water injection
Cosworth YB - GT2871 - 8-injectors - Swedish plenum - ported head - pace chargecooler - water injection
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Bladerider
- Posts: 1597
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I have to say,
You sound like a world class stroker !!!
Sorry to be all blatant and childish like, but even though I consider myself a stickler for accuracy and lack of BS, and ironically agree with alot of the sentiments of what you are talking about, if you feel the need to get this worked up about whether you think Dyno A or Dyno B is better by 1 or 2% then you need to stop spanking your monkey so often and get another hobby.
The PRINCIPLE consideration for a dyno is the operator. And even then the main concern isnt whether he's going to tell you a jackanory about your souped up tincan that does B2G in 8minutes, its whether he's gonna blow the fukka up in the process.
When you consider the real world significance of your labtest lifestyle you can have Bod A with a 370bhp car that would have about 7bhp variance for a "massive" 2% error, or Bod B with his new Veyron who would see a mighty 20bhp difference for the same 2% error. If you can actually feel that difference in either vehicle when the weather conditions alone could easily make a similar discrepency depending on when the dyno test was done whilst hanging it out to dry round the ring then your second name is obviously Vermuelen, Walker or maybe Atkinson (although he's a bit of a ponce IMHO).
Why not your use vast intellect and superior spreadsheet to learn us all how to match your prowess round the ring ??
J.
You sound like a world class stroker !!!
Sorry to be all blatant and childish like, but even though I consider myself a stickler for accuracy and lack of BS, and ironically agree with alot of the sentiments of what you are talking about, if you feel the need to get this worked up about whether you think Dyno A or Dyno B is better by 1 or 2% then you need to stop spanking your monkey so often and get another hobby.
The PRINCIPLE consideration for a dyno is the operator. And even then the main concern isnt whether he's going to tell you a jackanory about your souped up tincan that does B2G in 8minutes, its whether he's gonna blow the fukka up in the process.
When you consider the real world significance of your labtest lifestyle you can have Bod A with a 370bhp car that would have about 7bhp variance for a "massive" 2% error, or Bod B with his new Veyron who would see a mighty 20bhp difference for the same 2% error. If you can actually feel that difference in either vehicle when the weather conditions alone could easily make a similar discrepency depending on when the dyno test was done whilst hanging it out to dry round the ring then your second name is obviously Vermuelen, Walker or maybe Atkinson (although he's a bit of a ponce IMHO).
Why not your use vast intellect and superior spreadsheet to learn us all how to match your prowess round the ring ??
J.
I have issues !!! 
....I used to be average, now I reminisce !!!
....I used to be average, now I reminisce !!!Bladerider, We are all here to learn more and in this forum we are talking about dynos, dyno runs and related topipcs, if that's not your thing then there are plenty of other discussions going on that you may be more interested in.
Since you are interested in the ring take a look at http://uk.youtube.com/watch?v=_InrLEU4cyo# that is my car doing a pretty tidy 8:10 B2G back with 120KG of ballast in the passenger seat and without the 50% power hike that it has had since that video was taken.
Since you are interested in the ring take a look at http://uk.youtube.com/watch?v=_InrLEU4cyo# that is my car doing a pretty tidy 8:10 B2G back with 120KG of ballast in the passenger seat and without the 50% power hike that it has had since that video was taken.
Westfield zei370 - GPS confirmed 167mph flying brick.
Cosworth YB - GT2871 - 8-injectors - Swedish plenum - ported head - pace chargecooler - water injection
Cosworth YB - GT2871 - 8-injectors - Swedish plenum - ported head - pace chargecooler - water injection
i dont normally get in to arguements with dynos as some other people always seem to have the answers so heres the test you asked for
i dont use 50psi in tyres unless i have probs with grip or its a big car or its a dyno day
i think graphs explain themselves,the lats one is all runs together so you can see bugger all difference!!
i dont use 50psi in tyres unless i have probs with grip or its a big car or its a dyno day
i think graphs explain themselves,the lats one is all runs together so you can see bugger all difference!!
EVO 7 with 2300cc,GT35,HKS 272's,1000cc,MOTEC...the list goes on..