General 3 Cento's spend day at Rolling Road!
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General 3 Cento's spend day at Rolling Road!
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You probably won't see a diffrence on a WOT dyno run. Where you're far more likely to find the difference is with partial throttle openings in the low and mid ranges of the rpm band.
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i do want my ECU professionally setup, but know it's going to cost a few quid. if i could just get the money together to finish of the turbo fab then i wouldn't mind having it mapped then. but considering it would need drastically different mapping to how it is atm, i can't justify spending moolah on the n/a mapping
yeah get it started...i ant your exhaust
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I've looked at the cost per hour for ampping. Not bad. In a few weeks/months I'll have a chat and see about taking it down. Just have to ask him nearer the time if he's ever used meatune, and if he's willing.
At least if i go there, I can like for like the power ratings as it will be on the same RR
Kristian
At least if i go there, I can like for like the power ratings as it will be on the same RR
Kristian
just got to keep my Cinq in one piece longer than you managed to now John
Just stay off the motorway and don't go challenging 7 series BMWs and you should be fine!
LMAO aaron. You've opened the can of "proverbial" worms!!
I have spent a lot of time looking into rolling roads and how figures are calculated etc, and the end of the matter is..... they are pretty much all different. Only thing i would say for consistancy, 1320 told you what the wheel and flywheel was. Obviously they know they have a low loss between flywheel and wheels. The MAHA dynometers have a huge amount, whereas the dastek ones seem similar to the results you guys have seen.
On the whole, flywheel figures seem to be "fairly" accurate from rolling road to rolling road. So, i'd say ignore the wheel hp, and use the 1320 flywheel figures.
I have to say im impressed from the results, and dont see why anyone should be disappointed.
Ross
OP
OP
LMAO aaron. You've opened the can of "proverbial" worms!!
I have spent a lot of time looking into rolling roads and how figures are calculated etc, and the end of the matter is..... they are pretty much all different. Only thing i would say for consistancy, 1320 told you what the wheel and flywheel was. Obviously they know they have a low loss between flywheel and wheels. The MAHA dynometers have a huge amount, whereas the dastek ones seem similar to the results you guys have seen.
On the whole, flywheel figures seem to be "fairly" accurate from rolling road to rolling road. So, i'd say ignore the wheel hp, and use the 1320 flywheel figures.
I have to say im impressed from the results, and dont see why anyone should be disappointed.
Ross
Wheel HP is the only thing a r/r can work out, flywheel HP is ALWAYS going to be a guestimate unless you take engine out and run on dyno. Chris the r/r operator used to work with Emma's Dad at Cosworth in the dyno cells developing engines, so they know there stuff when it comes to engines HP and the guestimate nature of r/r's.
If you read PumaRacing's description of how to get flywheel power and why so many r/r's have very dodgy results. There example of a 100% standard car which makes 118bhp, but in doing coast down results in 3rd, 4th and 5th gears there is over 20bhp differance in results show how easy it is to manipulta eresults to make customers happy. There method for FWD cars is take wheel power +10 divide by 0.9 as being the most accurate way of coming to a flywheel power, the site I listed uses PumaRacings method, it just saves you the hassle of working it out.
What you have to remember is this, the more HP a car makes at the wheels the smaller in percentage terms the lose will be through drive train, the lower the HP output the larger in percentage terms the transmission loss will be, so on the day all Chris did was work out roughly a 18% transmission loss, but PR's method seems a little more accurate as its makes low HP cars have slightly higher % wise loses and higher HP cars lower % wise trans loses. You see unless you get over 100bhp at wheels his dyno does not work out coast down so its not the r/r working it out, just us on day putting thumb rule to it.
Yes.... MAHA r/r's, there is another make I remember being told are high but can't for life of me remember now??? Anyway you are right r/r's can only give an indication of what your car is doing that day, and unless you run your car there standard you will never know, hence why we will run Emma's Dad's 500 1.4 16V to get a bench mark for it to compare against the Sei, same engine and box, so transmission's losses have to be pretty much exactly the same, so whatever it gets down through the wheels will be directly comparable to the Sei and we will know for sure how much its made over standard.
PS no one was disappointed, we all left very happy, was an excellent day.
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OP
OP
Copied from Puma Racings site.
To round off the articles on power and torque, here is a real example of how the coastdown losses from an actual car were measured on a rolling road dyno. Some time ago I asked a colleague to run a series of tests for me on their rollers. What we needed was a car with a reasonably well quantifiable flywheel bhp and one that we could run in any gear without getting wheelspin on the rollers. This ruled out modified cars that had not been on an engine dyno and anything with too much power. Some time later a completely standard cvh engined Fiesta XR2i came into their workshop and this seemed as good a choice as any. The engine was in good condition and absolutely unmodified according to the owner - a good chance therefore of it producing close to the quoted horsepower.
The aim of the test was to see how wheel bhp and coastdown losses change depending on which gear you run the test in. The rolling road in question is a Bosch flywheel system, which means it has a heavy flywheel attached to the rollers and the system works out power according to how quickly the car can accelerate this large mass. It can't take "steady state" power figures which can be a hindrance when setting up fuel and ignition systems but on the other hand there is nothing for the operator to tinker with and distort the readings - you just sit in the car and floor the throttle and wait for the run to reach maximum rpm. At this point you can put the car in neutral while it "coasts back down" and the system measures these coastdown losses. Some dyno systems then add these losses back to the wheel bhp and call the result "flywheel horsepower". Proponents of this method claim that the "flywheel horsepower" figures so produced are more consistent and repeatable than wheel bhp figures. Hopefully this article will show the pitfalls in relying on coastdown losses by means of this real example - anyway on with the plot. Copyright David Baker and Puma Race Engines
Ford quote 110PS (i.e. about 108.5 bhp) as the standard flywheel power for the car in question. Obviously every individual engine will differ slightly and this quoted figure can only be a guide to the spread of power outputs that a selection of engines would produce. To restate my own rules for estimating wheel bhp from flywheel bhp - about 15% transmission losses for front wheel drive cars and 17% for rear wheel drive is a rule of thumb. This tends to overstate the losses for high powered engines and understate them for smaller ones. A more sophisticated guide is to deduct 10% of the flywheel power plus another 10 bhp for FWD and 12% plus another 10bhp for RWD cars. The XR2i is FWD of course so if we apply those two rules to 108.5 flywheel bhp we get either 92 or 88 bhp at the wheels respectively. So that's the sort of level of wheel bhp that one would be expecting if the quoted flywheel bhp is correct.
To run the test, the car was warmed up and given a couple of runs on the rollers to stabilize the temperature of the tyres, gearbox oil and engine. A power run and a coastdown were then done in each of 3rd, 4th and 5th gear with a few minutes for the car to cool down between each run to keep the figures consistent. So first let's look at the how the wheel bhp changed in each gear. The figures are as follows:
3rd gear - 95 bhp at the wheels
4th gear - 92 bhp at the wheels
5th gear - 88 bhp at the wheels
We can add those losses back to the wheel bhp to get the estimated flywheel bhp that so many rolling roads these days quote you.
3rd gear - 95 + 17 = 112 bhp
4th gear - 92 + 27 = 119 bhp
5th gear - 88 + 44 = 132 bhp
Well clearly something isn't working here. The coastdown losses (whatever it is that they are actually measuring) are rising much more in a higher gear than the actual transmission losses are, leading to larger "flywheel" bhp figures in the higher gears. The engine is producing the same power all the time and although we can never know for certain exactly how much power this particular engine had, we can be fairly certain it isn't far away from the factory quoted power. Even the 3rd gear "flywheel" figure is a tad on the high side but it is within the realms of possibility - the figures in the other two gears are obviously not.
The wheel bhp data show a consistent and understandable pattern. Adding back the coastdown losses leads to power figures which vary much more and make less sense. The point to remember is this - if the coastdown losses really were an accurate measurement of the true transmission losses then we would expect to end up with the same estimated flywheel bhp in all 3 gears. The fact that this does not happen means by definition that the coastdown losses are measuring something other than true transmission losses - in turn this means that adding them back to wheel bhp cannot result in true flywheel bhp. The fact that they result in horsepower numbers much larger than the 108.5 bhp claimed for this engine only go to reinforce the message. Copyright David Baker and Puma Race Engines
So the moral, for the last time hopefully, is to look at the wheel bhp as well as (or preferably instead of) the estimated flywheel bhp. It won't be a figure you can take for gospel and it will change from day to day and from rolling road to rolling road. With a modicum of common sense in keeping the test conditions the same and applying reasonable amounts for transmission losses it will get you "in the ball park" of what the true flywheel figure might be. The flywheel figure generated from coastdown losses though, can vary from the sublime to the ridiculous. Every now and then it might come up with a realistic bhp number but it might equally well be a country mile out.
To estimate true flywheel power from wheel power just apply the rules given at the start of this articles in reverse.
To round off the articles on power and torque, here is a real example of how the coastdown losses from an actual car were measured on a rolling road dyno. Some time ago I asked a colleague to run a series of tests for me on their rollers. What we needed was a car with a reasonably well quantifiable flywheel bhp and one that we could run in any gear without getting wheelspin on the rollers. This ruled out modified cars that had not been on an engine dyno and anything with too much power. Some time later a completely standard cvh engined Fiesta XR2i came into their workshop and this seemed as good a choice as any. The engine was in good condition and absolutely unmodified according to the owner - a good chance therefore of it producing close to the quoted horsepower.
The aim of the test was to see how wheel bhp and coastdown losses change depending on which gear you run the test in. The rolling road in question is a Bosch flywheel system, which means it has a heavy flywheel attached to the rollers and the system works out power according to how quickly the car can accelerate this large mass. It can't take "steady state" power figures which can be a hindrance when setting up fuel and ignition systems but on the other hand there is nothing for the operator to tinker with and distort the readings - you just sit in the car and floor the throttle and wait for the run to reach maximum rpm. At this point you can put the car in neutral while it "coasts back down" and the system measures these coastdown losses. Some dyno systems then add these losses back to the wheel bhp and call the result "flywheel horsepower". Proponents of this method claim that the "flywheel horsepower" figures so produced are more consistent and repeatable than wheel bhp figures. Hopefully this article will show the pitfalls in relying on coastdown losses by means of this real example - anyway on with the plot. Copyright David Baker and Puma Race Engines
Ford quote 110PS (i.e. about 108.5 bhp) as the standard flywheel power for the car in question. Obviously every individual engine will differ slightly and this quoted figure can only be a guide to the spread of power outputs that a selection of engines would produce. To restate my own rules for estimating wheel bhp from flywheel bhp - about 15% transmission losses for front wheel drive cars and 17% for rear wheel drive is a rule of thumb. This tends to overstate the losses for high powered engines and understate them for smaller ones. A more sophisticated guide is to deduct 10% of the flywheel power plus another 10 bhp for FWD and 12% plus another 10bhp for RWD cars. The XR2i is FWD of course so if we apply those two rules to 108.5 flywheel bhp we get either 92 or 88 bhp at the wheels respectively. So that's the sort of level of wheel bhp that one would be expecting if the quoted flywheel bhp is correct.
To run the test, the car was warmed up and given a couple of runs on the rollers to stabilize the temperature of the tyres, gearbox oil and engine. A power run and a coastdown were then done in each of 3rd, 4th and 5th gear with a few minutes for the car to cool down between each run to keep the figures consistent. So first let's look at the how the wheel bhp changed in each gear. The figures are as follows:
3rd gear - 95 bhp at the wheels
4th gear - 92 bhp at the wheels
5th gear - 88 bhp at the wheels
We can add those losses back to the wheel bhp to get the estimated flywheel bhp that so many rolling roads these days quote you.
3rd gear - 95 + 17 = 112 bhp
4th gear - 92 + 27 = 119 bhp
5th gear - 88 + 44 = 132 bhp
Well clearly something isn't working here. The coastdown losses (whatever it is that they are actually measuring) are rising much more in a higher gear than the actual transmission losses are, leading to larger "flywheel" bhp figures in the higher gears. The engine is producing the same power all the time and although we can never know for certain exactly how much power this particular engine had, we can be fairly certain it isn't far away from the factory quoted power. Even the 3rd gear "flywheel" figure is a tad on the high side but it is within the realms of possibility - the figures in the other two gears are obviously not.
The wheel bhp data show a consistent and understandable pattern. Adding back the coastdown losses leads to power figures which vary much more and make less sense. The point to remember is this - if the coastdown losses really were an accurate measurement of the true transmission losses then we would expect to end up with the same estimated flywheel bhp in all 3 gears. The fact that this does not happen means by definition that the coastdown losses are measuring something other than true transmission losses - in turn this means that adding them back to wheel bhp cannot result in true flywheel bhp. The fact that they result in horsepower numbers much larger than the 108.5 bhp claimed for this engine only go to reinforce the message. Copyright David Baker and Puma Race Engines
So the moral, for the last time hopefully, is to look at the wheel bhp as well as (or preferably instead of) the estimated flywheel bhp. It won't be a figure you can take for gospel and it will change from day to day and from rolling road to rolling road. With a modicum of common sense in keeping the test conditions the same and applying reasonable amounts for transmission losses it will get you "in the ball park" of what the true flywheel figure might be. The flywheel figure generated from coastdown losses though, can vary from the sublime to the ridiculous. Every now and then it might come up with a realistic bhp number but it might equally well be a country mile out.
To estimate true flywheel power from wheel power just apply the rules given at the start of this articles in reverse.
ermm ... How do they work out these rule of thumb ?? 3 nice car tho thanks for the pic !
thanks for the pic !SO i got 291 whp at the last set of rollers i went to. So how do i work out the flywheel using that calculation?
Ross
p.s. i didnt know that about 100whp and run down.. Explains the change in figures then.
p.s.s better to work it out the other way... i've been told that i have 335 bhp... so deduct 10% and add 10hp? So minus 33.5 bhp and add 10bhp? That gives me 312bhp? But i actually got 291 at the wheels... hmmm.
Lets do it aarons way (reversed calculation). 291 + 10 = 301 / 0.9 = 334.44444
Lol. Pretty damn accurate. Bravo.
Ross
p.s. i didnt know that about 100whp and run down.. Explains the change in figures then.
p.s.s better to work it out the other way... i've been told that i have 335 bhp... so deduct 10% and add 10hp? So minus 33.5 bhp and add 10bhp? That gives me 312bhp? But i actually got 291 at the wheels... hmmm.
Lets do it aarons way (reversed calculation). 291 + 10 = 301 / 0.9 = 334.44444
Lol. Pretty damn accurate. Bravo.
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OP
OP
You see Ross the Puma Racing equation is good as shown by you to within 0.5 of a bhp which at the levels your car was producing is less than 0.2%, impressive.
So FWD car take WHP (wheel horse power) add 10 then divide by 0.9.
RWD car take WHP add 10 then divide by 0.88.
4WD WHP add 10 divide by 0.84
The site I linked to before uses these same equations that Puma Racing came to, so put your figures in there as I did and you get the results that I posted 2nd time, yes slightly higher, we are talking only a few BHP from what we estimated on day.
Heres link again.
showed.http://www.dyno-power-run.com/dynocalc.shtml
Ross's car 291WHP = 334.44bhp flywheel r/r 335bhp which is probably rounded up anyway so you could say they are as near as you will get the same result)
Emma's car 92WHP = 113.33bhp
Jamie's car 74WHP = 93.33bhp
Alex's car 70WHP = 88.89bhp
So FWD car take WHP (wheel horse power) add 10 then divide by 0.9.
RWD car take WHP add 10 then divide by 0.88.
4WD WHP add 10 divide by 0.84
The site I linked to before uses these same equations that Puma Racing came to, so put your figures in there as I did and you get the results that I posted 2nd time, yes slightly higher, we are talking only a few BHP from what we estimated on day.
Heres link again.
showed.http://www.dyno-power-run.com/dynocalc.shtml
Ross's car 291WHP = 334.44bhp flywheel r/r 335bhp which is probably rounded up anyway so you could say they are as near as you will get the same result)
Emma's car 92WHP = 113.33bhp
Jamie's car 74WHP = 93.33bhp
Alex's car 70WHP = 88.89bhp
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I'll defo have to make a trip up there when my 1242 is in
I haven't actually made it to a rolling road yet
would be cool to tag along with some fellow fiaters lol
I haven't actually made it to a rolling road yet
would be cool to tag along with some fellow fiaters lol
OP
OP
I'll defo have to make a trip up there when my 1242 is in
I haven't actually made it to a rolling road yet
would be cool to tag along with some fellow fiaters lol
You may find that the combination of 13" wheels and lowered car means it can't go on r/r, I know Alex had the issue with his car, though sure getting proper size wheels is high on our agenda lol
Although there is a big gap in BHP I can see how the cars would be close considering the torque.
Example, my GF's car gives out 103BHP and mines is 128BHP, not much in it you'd say but driving them shows you the void that is the difference in torque, initially when reading this thread I thought 1.2 Hi Boost low boost only giving out ten more BHP???? but I get the whole idea now.
Cool pics!
Liam
Example, my GF's car gives out 103BHP and mines is 128BHP, not much in it you'd say but driving them shows you the void that is the difference in torque, initially when reading this thread I thought 1.2 Hi Boost low boost only giving out ten more BHP???? but I get the whole idea now.
Cool pics!
Liam
Very interesting.
Im *hopefully* going for a rolling road on a set of dastek rollers 2moz. I have made a few alterations, but i have heard that the wheel loss power is minimal, so should be able to do a comparison again.
Ross
You may find that the combination of 13" wheels and lowered car means it can't go on r/r, I know Alex had the issue with his car, though sure getting proper size wheels is high on our agenda lol
i'm not as low as alex
OP
OP
i'm not as low as alex
Its the actual wheel size added to suspension drop that is issue. If you think of a rolling road as two cylinders a fixed distance apart, then you drop another cylindrically shaped item, ie your wheel between them, the smaller that third cylinder(wheel) is the more its drops in between the other two, hence why it may be an issue as there are so few cars these days that run anything below a 15" wheel as standard.
But only trying it will we know for sure.
OP
OP
333.4! yikes run for the hills!
The WHP would be lower today as I see the air pressure is very low at 973MB, got to be careful of low air pressure in aviation, but that's a different story again to do with transition layers from altitudes to flight levels..........
Though interesting to see that the flywheel power is rising still to its max over 1000rpm higher than wheel power.
I have a r/r print out for my Ignis and its exactly the same, the point where max flywheel power is achieved is different to where WHP's max is all the lines are plotted on the print out and whp is actually dropping away but flywheel power still rising. Makes you wonder what the Sei would make on another r/r as its wheel power is not far off my Ignis wheel power.
The WHP would be lower today as I see the air pressure is very low at 973MB, got to be careful of low air pressure in aviation, but that's a different story again to do with transition layers from altitudes to flight levels..........
Though interesting to see that the flywheel power is rising still to its max over 1000rpm higher than wheel power.
I have a r/r print out for my Ignis and its exactly the same, the point where max flywheel power is achieved is different to where WHP's max is all the lines are plotted on the print out and whp is actually dropping away but flywheel power still rising. Makes you wonder what the Sei would make on another r/r as its wheel power is not far off my Ignis wheel power.
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