Wilko said:
Surely due to torque being read at the wheels then whp figures should be more accurate than fwhp figures?
If the inaccuracy starts at the wheels then it has to get wider by the time the calculation has been made for fwhp?
Surely due to torque being read at the wheels then whp figures should be more accurate than fwhp figures?
If the inaccuracy starts at the wheels then it has to get wider by the time the calculation has been made for fwhp?
As Wilko said: "in other words whp figures are just as meaningless as fw figures. \don't try to compare one dyno of one manufacturer to one from another. Pointless. Most dynos give a realistic fwhp figure plus or minus 10% or so. They are a tuning tool. Not a power measure."
We can all argue about dyno types, numbers, losses, etc. until we are blue in the face but in the real world on the road they mean absolutely nothing, so it's pointless getting worked up about them - it's not nice to see someone stick some numbers up (Vortex!) then all the keyboard jockeys who think they know it all rip into them and tear them apart - if you're happy with your numbers and your car feels strong on the road, that's all that matters - it's not a competition after all.
Too many people are far too quick to jump in and have a go - can't we all be a bit more friendly about it - there are far worse things happening in the world that are of greater concern.
We can all argue about dyno types, numbers, losses, etc. until we are blue in the face but in the real world on the road they mean absolutely nothing, so it's pointless getting worked up about them - it's not nice to see someone stick some numbers up (Vortex!) then all the keyboard jockeys who think they know it all rip into them and tear them apart - if you're happy with your numbers and your car feels strong on the road, that's all that matters - it's not a competition after all.
Too many people are far too quick to jump in and have a go - can't we all be a bit more friendly about it - there are far worse things happening in the world that are of greater concern.
Nobody is having a go Rob, they are merely questions regarding results that are posted on a public forum.
Maybe the OP shouldn't get so defensive about them and just answer to the best of his knowledge.
Im no rolling road expert (easy to tell) but always wondered why whp and fwhp varied so much.
We all have to agree that its the real road that does count
Maybe the OP shouldn't get so defensive about them and just answer to the best of his knowledge.
Im no rolling road expert (easy to tell) but always wondered why whp and fwhp varied so much.
We all have to agree that its the real road that does count
I agree Gary - but the same stuff is asked, argued and debated by the same people ALL the time, surely by now the answers are clear ... there is no correct answer, dynos are a very large grey area with no clearcut answers! Yes people will defend their tuner and their numbers, of course they will, it's human nature because they want to believe that whoever they have invested their faith and money in is doing the best job.
Anyhoo ... Baz got great results, the new mods are working well and he is happy, good for you fella!
Yes people will defend their tuner and their numbers, of course they will, it's human nature because they want to believe that whoever they have invested their faith and money in is doing the best job.Anyhoo ... Baz got great results, the new mods are working well and he is happy, good for you fella!
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GaryM said:We all have to agree that its the real road that does count
I think we would, but if we ever compared cars against each other on the (private) road we would argue more about driver error, getting bogged down, being off boost, being in the wrong gear
I agree though if your happy with your own car then that should be enough.
Ok guys i shouldn't have said the dynojet rollers where crap as i've had no experience of them myself and the information i have on them isn't set in stone(from forums, not that reliable then really!!! )
I'm really pleased with the results I got yesterday due to the fact the car still has the silly little side mount on and it's only running 1.1Bar, unlike most ko3s guys running 1.3+.
Once the FMIC, IC water spray and water injection are on i think Jim will be able to get some even better figures out of it.
)I'm really pleased with the results I got yesterday due to the fact the car still has the silly little side mount on and it's only running 1.1Bar, unlike most ko3s guys running 1.3+.
Once the FMIC, IC water spray and water injection are on i think Jim will be able to get some even better figures out of it.
cuprabaz said:
knew you'd see sense
Seriously, if you and some lads wanna come down to dyno meet @ Awesome Gti, more than welcome, i think in spring maybe rob should organise a star RR day, i'll come, and if i have a decent car by then i'll stick it on dyno
maybe talk jim cotton into fetching up the awesome lcr, so we can see what's what eh? ![[B)]](/forums/styles/seatcupra/oldforumsmileys/shades.gif "Cool [B)]")
I was under the impression than sun and maha dynos are basically the same thing?
I'll try and explain it as simply as I can. All a dyno does is measures how fast the car can accelerate a known inertia load.
Inertia is the rotational equivalent of mass so instead of force=mass x acceleration, we have torque=inertia x angular acceleration.
Now the dyno does the rotational equivalent of f=ma for the roller and by knowing engine speed can convert that to a torque equivalent at the engines rotational speed.
Now what the dyno doesn't know is the inertia of the rotating bits of the drive train. On coast down, the dyno brakes the roller, and it knows how it should decelerate on its own (known inertia), it can calculate the inertia of the drive train by comparing the deceleration of the roller compared to how it would decelerate on its own.
Now this figure is in no way shape or form a drive train loss. It is the extra inertia that needs to be added to the rollers inertia to get a power figure at the roller.
In other words you get torque =(roller inertia+drivetrain inertia) x angular acceleration.
or as dynos wrongly put it torque=(wheel torque + losses) x angular acceleration.
Now depending on what the roller inertia:drivetrain inertia is, the larger or smaller a dynos drivetrain losses will be.
If the ratio was 3:1, the dyno would claim 25% losses.
If it was 4:1, the dyno would claim 20% losses
If it was 9:1, the dyno would claim 10% losses.
If you take a car and take the wheels off, and attach it to a dynapack you will see higher whp figures, as the wheels are a large part of the drive train inertia, plus it removes the inefficient tyre to roller interface. Think about the wheel. a bit like a flywheel?, a bit like the roller? Is it starting to make any sense yet.
There is no way that by brakeing a drivetrain you can in any way measure it's mechanical losses that would be there when power is applied. To do this you need to have known power going in one end of the drivetrain, measure power coming out the other end, and then take one from the other to get the loss.
The dyno would need to be able to hook up to the input shaft of the gearbox to do this.
Any gearbox or transmission designer that loses more than 5% of input power through noise and heat would be sacked and told to go do something he was good at. The tyres lose a little as well, as they're flexible, and make a little noise and heat, but its a few hp at most.
Let me say it again. A DYNO CANNOT MEASURE THESE LOSSES!
They are measuring the drivetrain inertia to add it to the roller inertia that's all.
I'll try and explain it as simply as I can. All a dyno does is measures how fast the car can accelerate a known inertia load.
Inertia is the rotational equivalent of mass so instead of force=mass x acceleration, we have torque=inertia x angular acceleration.
Now the dyno does the rotational equivalent of f=ma for the roller and by knowing engine speed can convert that to a torque equivalent at the engines rotational speed.
Now what the dyno doesn't know is the inertia of the rotating bits of the drive train. On coast down, the dyno brakes the roller, and it knows how it should decelerate on its own (known inertia), it can calculate the inertia of the drive train by comparing the deceleration of the roller compared to how it would decelerate on its own.
Now this figure is in no way shape or form a drive train loss. It is the extra inertia that needs to be added to the rollers inertia to get a power figure at the roller.
In other words you get torque =(roller inertia+drivetrain inertia) x angular acceleration.
or as dynos wrongly put it torque=(wheel torque + losses) x angular acceleration.
Now depending on what the roller inertia:drivetrain inertia is, the larger or smaller a dynos drivetrain losses will be.
If the ratio was 3:1, the dyno would claim 25% losses.
If it was 4:1, the dyno would claim 20% losses
If it was 9:1, the dyno would claim 10% losses.
If you take a car and take the wheels off, and attach it to a dynapack you will see higher whp figures, as the wheels are a large part of the drive train inertia, plus it removes the inefficient tyre to roller interface. Think about the wheel. a bit like a flywheel?, a bit like the roller? Is it starting to make any sense yet.
There is no way that by brakeing a drivetrain you can in any way measure it's mechanical losses that would be there when power is applied. To do this you need to have known power going in one end of the drivetrain, measure power coming out the other end, and then take one from the other to get the loss.
The dyno would need to be able to hook up to the input shaft of the gearbox to do this.
Any gearbox or transmission designer that loses more than 5% of input power through noise and heat would be sacked and told to go do something he was good at. The tyres lose a little as well, as they're flexible, and make a little noise and heat, but its a few hp at most.
Let me say it again. A DYNO CANNOT MEASURE THESE LOSSES!
They are measuring the drivetrain inertia to add it to the roller inertia that's all.
Wilko said:
and the braked portion and application???????????????
applied on the up and down, equally?
ibizacupra said:
Yes bill thats why I called it inertia load. The brake load has exactly the same effect as straight inertia. I'm trying to simplify it to make explanation easier.
ibizacupra said:
As I said a couple of posts ago my impression is that sun and maha are basicaly the same thing from different times.
Wilko said:
other than jabba's old dyno, who's is inertia..
they all have inertia content obviously, but application of load on the up... compared to the coastdown..
I think my caption sums it up nicely.
Dyno Lottery(TM)
Unless I've missed something, the aim of "tuning" is to make the car faster? Somehow that intention almost always ends up turning into a "Shat your marf an look at mah plot" affair. You can wave printouts around all you want but if your car's no faster than it was before, you've wasted your money - period.
So for those who want to engage in c0ck-waving contests , how about putting your heads together and coming up with an agreed standard that everyone can use & understand and that takes the emphasis away from "Who's got the biggest plot" and puts it back where it should be : on performance.
That way, people who've undergone weight-reduction programs or made changes to wheel size or gearing can go toe-to-toe with those who've just thrown money at the engine.
An example might be in-gear acceleration times : 30-70mph in 3rd/4th/5th gears. Just a suggestion, so no need for "Yeah, but no but..."
There are enough of you here with seemingly nothing better to do than argue over RR plots, you must be able to come up with something better and more meaningful?
So for those who want to engage in c0ck-waving contests , how about putting your heads together and coming up with an agreed standard that everyone can use & understand and that takes the emphasis away from "Who's got the biggest plot" and puts it back where it should be : on performance.
That way, people who've undergone weight-reduction programs or made changes to wheel size or gearing can go toe-to-toe with those who've just thrown money at the engine.
An example might be in-gear acceleration times : 30-70mph in 3rd/4th/5th gears. Just a suggestion, so no need for "Yeah, but no but..."
There are enough of you here with seemingly nothing better to do than argue over RR plots, you must be able to come up with something better and more meaningful?
hehe....
it would'nt be the same if there were'nt the odd flame battle going on..
I think I have just detuned mine in real terms.. only gear which grips & accelerates now is 5th. Woops!
it would'nt be the same if there were'nt the odd flame battle going on..
I think I have just detuned mine in real terms.. only gear which grips & accelerates now is 5th. Woops!
Impressive figures. Need to get a wee race with you at Crail at some point - times are pretty close (you - 14.1, me - 14.2).
Awesome jimbo
Guest
Just been following this thread and obviously people take things like this ultra seriously ! Awesome only want a fair playing field so the only winner is the customer ! Some people say you should ignore RR results but if you do then the 'claimed' figures listed in compaies adverts are also useless ! This is where my personal quest starts as higher published power figures sell products!So why should we publish 'lower' clutch figures than others? Sales provention or the truth? We are always going to argue over 'clutch' figures but unfortunatly these make the best'PUB TALK'! If the back to back figures are substantiated then great, but if they are not then who loses out? I am not out to discredit any other rolling roads as they all should offer uses over 'seat of your pants' tuning!The one factor that seems to be quite consistant is wheel horsepower-why not all quote this and quote WHP found on the virgin car?Glenn said:
Better still why don't all the tuners front a line up of their modded cars(customer or tuner owned) and run them on a number of tuners rollers over a period of 1 week? All can publish wheel and clutch figures and everyone to watch and judge the roller runs for impartial operation ? The public must ask WHY if a tuner does not front its product for scrutiny!
As has also been stated 'the higher the horsepower' does not mean the best driving car.This will be a matter of opinion as all drivers have differing needs for their cars and max power is not always whats required.
Maybe the old saying about the subjects of religion and politics should now include rolling roads!
In conclusion all rolling roads have their uses to the tuner operating the equipment ,as long as we know the different scales they correct to !
many moons ago.. on an infant SCN, I organised a RR (SCN 1st ever) at a local Chelt RR outfit. I invited formally a bunch of tuners (UK) to the day to show off their wares to an expectant customer base, on the same dyno same day.
Several of the tuners declined on the grounds of I quote: "rr dyno's can be run in such a way to give misleading figures etc"
Make of that what you will.
One thing from that day did become very apparent however, is that the way the cars were run, the loads were applied, the available cooling available (for SMIC's for example), all made for very different (lower) figures than expected by the majority of chipped cars.
We've seen from an earlier abortive RR event with SCN, that these RR variables, in the hands of the inexperienced, can also make a mockery of the hardware, contradicting the power figures claimed from the software they sell.
Rollers? Operator? Software? Hardware?
Dyno Lottery(TM)
double edged sword tho Jim maybe? Everything you ever sold previously which is'nt going to be proven on the dyno?
I look forward to making the trip up to your place sometime soon with my ibiza.. I am intrigued to see how the figures run on the Dynojet.
cheers m8
Several of the tuners declined on the grounds of I quote: "rr dyno's can be run in such a way to give misleading figures etc"
Make of that what you will.
One thing from that day did become very apparent however, is that the way the cars were run, the loads were applied, the available cooling available (for SMIC's for example), all made for very different (lower) figures than expected by the majority of chipped cars.
We've seen from an earlier abortive RR event with SCN, that these RR variables, in the hands of the inexperienced, can also make a mockery of the hardware, contradicting the power figures claimed from the software they sell.
Rollers? Operator? Software? Hardware?
Dyno Lottery(TM)
double edged sword tho Jim maybe? Everything you ever sold previously which is'nt going to be proven on the dyno?
I look forward to making the trip up to your place sometime soon with my ibiza.. I am intrigued to see how the figures run on the Dynojet.
cheers m8
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