it made 225 atw with a stage one chip.

265 with a 4x4 cooler t34 and greens

added a pro alloy 500 style cooler and it made 287.

dont really think they are unbelieveable figs.

good power but not unreasonable....

what do you think it should make??

 

i am reckoning at 250-260 ish atw on 21.9 psi

i am impressed you got a 25bhpATW increase by just bolting on an intercooler

 

the inlet temps were staring to become an issue with the 4x4 cooler. the pro alloy more than halfed the inlet temps.

they were only 25-30 deg c if my memory is correct...

the boost was raised from 20 to 22 when fitting the big cooler

 

so occording to your graph what bhp at the flywheel did your car make??
and what was the torque figure and at what revs was maximum for both?

 

AVA never quote flywheel figs but when forced on the issue say add around 40 bhp

never had a torque print out before.

peak power was made at 6k

 

you cant just say add 40bhp.......because add 40 bhp at what revs as frictional transmission losses increase pro-rata with revs

 

stop bitching you two :P

 

oooooooooops sorry

 

A 0.63 T3/4 makes peak power at 6500rpm, so 320bhp at 6000rpm isn't out of the way surely?

 

im surprised at 320 - to be honest with a T34, greys and a live map it defo should be more.

 

Karl do you like planes?

 

For the hard of reading (Ran ).

 

what was that Mike?

I actually do have a hearing impairment as i get a constant buzzing sound in my right ear - been like this for months only i cant be bothered to go to the docs

 

Didn't realise that hearing loss affected your eyesight .

 

its the constant wanking thats affecting my sight - guess its true then ...wanking does make you go blind

 

Who said that?

 

Pugo,

Different rolling roads give u different wheel figures compared to fly figures.

THus a car on ava pulling 200 at the wheels if 2wd rwd cossie for instance might be about 240 bhp. A 200 at the wheels figure on nobles due to smaller radius rollers and therefore higher rpm rollers might be akin to 260-270 at the flywheels.

My evo made 277 at the wheels on AVA and was estimated at 315-320 at the flywheel. Similar Evos make about 245 at the wheels on G-foreces rollers and are making about 315 to 320 flywheel. Again due to roller diameter

The above figures are only indicative to help explain " The rapid ones " wheel to flyhweel figures.

RW

 

my brother made 275@wheels at ava with stg3 t3,greens,3 bar,mongoose,unknown chip and genuine 500 cooler,peakin at 24 and holdin 22,made 240@wheels before 500 cooler on same boost,so its possible,this was 4wd

 

the calculation for converting flywheel power from wheel power cannot alter from rollers to rollers

if i make 300 bhp at the wheels on dyno A then i will always make 300bhp at the wheels whether i go on dyno b,c,d,or e if i then calculate my frictional transmission loses, it will be lets say 400bhp at the fly wheel it doesn't then matter where i go in the world my engine should always make 400bhp at the flwheel even if i remove the engine and bolt it on an engine dyno

all this proves is how easy it is to frig a dyno reading

 

Pugo,

I don’t think you know what your talking about. (though I only know what I have gleaned from people who make rolling roads, so my position isnt much better)

Rolling roads measure the amount of energy required by the retarders to stop an engine accelerating.

Natural losses occur through the system of the rolling road. A rolling road with large diameter rollers turns at less rpm and therefore have less losses than a smaller roller diameter rolling road which turn faster.

The effect is the same as an electrical fan. At 1000 rpm it may draw 2 kilowatts of power to turn. If you up the revs to 2000 rpm it draws 5 kilowatts not 4 kilowatts as expected. This analogy can be aligned with the difference in roller diameter. Smaller rollers = more rpm = lower wheel figure.

The random calculation used by most rolling roads, with run down losses and so on is used to try and estimate the flywheel figure. It may state that certain cars have a wheel horsepower of 500 and a estimated flywheel of 700. That would be a 200 bhp loss thru the transmission according to this system. Where has this 200 bhp gone? Into the gearbox? What has it turned into? Heat? So the gearbox is glowing red is it? I don’t think so.

The calculation is there to estimate the difference between the figure read by the rolling road which is a calculation based on the torque required by the retarders to stop the car accelerating and the actual bhp produced by the engine.

Ask yourself why a car run up in 2nd gear makes more power at the wheels on the rollers than it does in 3rd which makes more than it does in 4th which makes more than it does in fifth?

Therefore from experience. Taking say a new M3 bmw. It is known to make 340 bhp or whatever factory figure is. It may make 300 at the wheels in 3rd on a rolling road and therefore we could add 40 bhp to make the flywheel figure. When the car makes 320 at the wheels in similar conditions, same gear etc and ambient temp we could guess it now makes 360bhp. It is not a direct calculation based on actual losses through the gearbox as you suggest.

An example of this was my old rst. It made 195 at the wheels at ava in 3rd gear. This equates to circa 220 bhp according to ava's estimates at the flywheel. It then went down to Nobels the next couple of days and put out 175 at the wheels, and with nobels estimate/calculation made 220-225 flywheel bhp. The exact figure is floating about here on this site somewhere. Both are correct. Both rolling roads run different size rollers. This wouldn't be the same as your example which is wrong and only would work in an ideal world where all rollers were the same size, peoiple used the same gear to run the car up, used the same tyres and many other contributing factors that effect "wheel bhp"

I, unfortunately am clearly not an expert on rolling roads and have just taken information I have learned from people who make rolling roads and tried to relay it to you in a second hand fashion.

I hope this helps clear this up

Steven RW

ps as for your tears.. confusion often results in crying.. its natural... so no need to be embarrased.

 

a quick question for you

do you know the formula for calculating torque????on an inertia dyno or rollers

just in case you don't know the calcs

The formula for determining the torque is:

Torque = JM * rpm per second / 9.551

where JM represents the Polar Moment of Inertia of our inertia dyno's flywheel.

If we don't know the Polar moment of Inertia for the flywheel (and our flywheel has a constant thickness cross-section) we can calculate it with the formula:

JM = (W * r ^2) / 32.16 / 2

where W represents the flywheel weight in pounds and r is its radius in feet.

Once you have the torque, it is easy to calculate the horsepower with the standard formula:

Hp = Torque * rpm / 5252

Keep in mind that the rpm in the last formula must be the average rpm during the sampling period.

so from this you can see that the radius should not affect our result

i have tried to keep it simple for you to understand

Pugo

 

Pugo,

Okay, sounds like you are the specialist here and the information I have, sampled from the real world, doesn't relate to your mathematical calcs.

So, if I have managed to keep up with your theory, the dyno works out the torque by the level of acceleration during the sample period? As that looks like it can be the only variable due to flywheel of the dyno being a constant weight and radius.

If so, please furnish me with the mathematical theory behind a rolling road that is a loaded figure that holds an RPM and measures the load rather than an accelerated figure?

This is all quite interesting.

PS I may not be a scientist or a mathematical theorist however do not try and play on an assumption of my lack of inteligence.

RW

 

you cant argue with an expert stevie!

Alan (owner of AVA and person steve has learned alot from) doesnt know what he's talikng about, he only designed and built the rollers and has operated them for years seeing thousands of different cars...

wonder how many power runs pugo has done on his rollers??

 

Euan,

As much as I agree withyou on Alan's understanding of rolling roads. With AVA having built the rollers, and programmed the software that runs one of the most sophisticated rolling roads in the country with 30 years experience. I also want to understand where Pugo is coming from.

On another note. How close are you to having some decent BHP on your current engine?

Cheers

RW

 

i have done about 1500 -2000 runs on an eddy brake dyno with 2 stroke race engines working for dieter konig at konig race engines( one of my engines still holds the 750cc water speed record across windermere as well as numerous 2 stroke proddy bikes and kart engines, possibly 5000 runs on roller dyno's working for mobil oil when they were testing developing mobil1 and other oils at there research and technical services labs at coryton oil refinery (now BP)


as for your assumption that i know nothing, thats down to you

as for your loading up an engine to a constant rpm, that is a braked dyno as you cannot do this on a inertia dyno unless its dual facility...but you obviously already know this and most rolling roads in this country are inertia only!

so enlighten me as you designed and built a dyno what calculations does your software use to calculate the torque from acceleration of a given mass??????????

the div is waiting

 

This is getting good.

 

ooooh this is getting interesting


with that last comment I make Pugo 2:1 favourite

 

Pugo,

no need to be 'quite' so much of a drama queen.

I think you said “the calculation for converting flywheel power from wheel power cannot alter from rollers to rollers “ I think I said depends on the figure measured at the wheel and how they are calculated.

Does that not still stand?

Its always good to have people with so much experience on the site. Also please don’t assume you are talking to one person in your reply when clearly Euan and I are looking at this from slightly different angles.

Why would someone with a loaded roller rolling road and a Dyno believe that Inertia run ups are a pile of pap? There must be a reason. Could be something to do with the car wheelspinning during the sampling period making your calculation suddenly inaccurate.

What do you think of the calculations that state a car running “500” at the wheels is actually “700” at the flywheel due to a % loss. Is the loss through the transmission or how the chasis dyno registers the torque and its own integral losses?

Another question would be. If changing the type of tyre on a motorbike can massively change the registered wheel BHP on a rolling road as proven. Does this mean that the flyhweel bhp of the bike has also gone down? Would using a set method of rundown flywheel bhp calculation take that into account?

Steven RW

 

I apoligise if i came across as a drama queen, however i read the responce by rapidcossie as sarcastic and demeaning and answered occordingly, it wasn't directed at you
the first thing to understand is that in the real world all the figure that are being bandied around by the pub figure boys are purely based on theories and that all dyno's are only really good as a comparison tool i.e today my car made xlbft of torque on the dyno at yrpm, now i have turned the boost up and it makes x+10lbft of torque on the dyno at yrpm!
however all the rolling road dyno's are inertia based otherwise there would be no point in accelerating through the test, if you use a traditional brake dyno you would set the engine revs to say 5000rpm with a small load then you would start increasing the load as you increase the throttle until you got to maximum throttle then when the load is holding the engine rpm to 5000rpm it will show in lbft of torque what the engine is developing, as you increase the load slightly the revs will start to fall showing that the engine is not producing sufficiant torque to overcome the loading required
most engine dyno's are traditional brake dyno's i.e eddy current or fluid
The reason traditionalists don't like inertia dyno's is that the results can be frigged very easily to achieve the desired result , on the usual inputs you run in 4th gear as its 1:1, you then input the diff ratio, you then input the rolling diameter of the wheel and tyre and it calculates expected acceleration times of the known mass, if the operator alters one of these figures in his software, he can make the customer see exactly what he wants him to see! just as he can when he is correcting the figures with barometric pressures( you have noticed most dyno sheets show a corrected figure). The down side to this is you take your car to have a set up, the guy does it honestly and you come away 50 bhp down from your last dyno run on somebody else's rollers and have got the hump

The loss is from the car itself and is calculated in reverse from a power run, ie you run the car upto say 6000rpm and thentake dip the clutch and allow the dyno to monitor deceleration times, because that will show the true drag on the known mass!

the type of tyre should have absolutly no impact on the figures, only the size affects this or unless grip is an issue, however pressure can alter the rolling radius of the wheel as can a soft compound this is mainly due to excessive heat production of the tyre which will increase the tyre pressure again altering the rolling radius of the wheel!

HTH

Pugo

 

Pugo,

thanks for the reply.

The only thing I can go with is what I have seen with my own eyes or what has been relayed to me by a trusted source.

AVA use a brake dyno and this takes away from the risk of wheelspin making overly high figures.

I recall a conversation saying that the difference between a bike running one type of tyre and the next can be massive to the recorded figures. It was never stated that the rolling radius changed. It sounds to me like he softer compound tyre was either changing shape or creating drag somehow.

If you are purely measuring the amount of effort the retarder on the braked r/r has to effect to stop a car raising its revs then if the retarder is turning at higher rpm ( as, from what I understand the roller turning is like the roller is the motor of an electrical fan and the higher the rpm of the roller the higher the losses ) thus the losses and the final effort the retarder has to effect to stop the car revving is less.

Therefore a smaller roller results in a smaller effort being required by the retarder to stop the car revving and therefore a smaller figure is recorded. This is then taken into a account with the loss theory.

SO, if you do a run down test to gain the transmission loss through drag, why would cars produce a bigger loss depending on th amount of horsepower they have? Surely once you press in the clutch on the run down the drag would be the same if the car had 200 or 400 bhp aslong as the transmission stayed the same? if so where do al these estimates ot 28% loss come from?

As for a r/r purely being for comparison same day on same day. Couldn't agree more. I'm not a fan of adjusted figures in anyway as it just clouds reality. However with a decent rolling road booth and operator i believe it is possible to closely replicate the environment to have a good comparison even tho runs are on different days. I saw this with my own rst producing near identical graphs time after time.

"however all the rolling road dyno's are inertia based otherwise there would be no point in accelerating through the test"

im confused by that part as i didnt think a braked r/r was inertia based?

Cheers

Steven RW

 

as far as i have ever seen all rolling roads are inertia or dual inertia and brake, i have never seen a purely braked automobile rolling road....engine dyno yes, axle dyno yes, rolling road no
although i am not saying it can't be, just that i have never seen one

I personnaly would have thought a braked rolling road would cause excessive loading on the tyres to the point of destruction on initial acceleration unless you increased the load as the rpm raised, but that wouldn't give you a true figure i wouldn't think

Pugo

 

wel i got lost, all i will say is that even though stephen trusts his tuner ect dosent mean you understand it totally ( dont take offence as im sure you understand what i mean)

but certaint rollers DO vary from place to place,,,,,,,,, why i dont know though

 

Euan bring your graph around and I'll scan it in


Above quote from Allan @ AVA originaly posted on MLR a few months ago.

More here:-
http://www.lancerregister.com/showth...&pagenumber=19

 

what the hell is all that about

 

sorry pugo if i offended you but it was meant as a light hearted comment!

 

about one month til blast off mate!

 

no i haven't a clue what your on about, are you saying i do not understand it or stephen doesn't????

pugo

 

Pugo,

I rarely understand a word B19 Bal says. He always seems good at heart but his posts confuse me utterly.

Have you read the other link that B8 put up? It will put you onto an explanation of rolling roads directly from Alan who i was attempting to quote/re-state.

B19 Bal: No offence taken or meant on my behalf.

Cheers

Steven RW

 

right i have just read it through 3 times and either i have read it wrong (please correct me if i have, with a quote from it)

but he is saying the run down times i.e the losses would still be 24%( hypothetically) no matter what gear you are in its the torque that has reduced by changing gear, however i do not think he is compensating for the change in gearing in his calcs, its like undo'ing a nut with a 6inch long spanner, if you put a 6ft pole over the spanner then the torque required to undo the same nut will be reduced but then you still need to work out what torque would be needed to undo the nut without the pole by calc'ing backwards, it would actually still be the same except that you would have worked less to achieve the result ,and as to the losses , you bang your box down from 4th to 1st and tell me what happens? the engine braking is massive, however you change down to 3rd from 4th and the braking will be a lot less vigorous, so therefore the losses have to increase dramatically by changing the gears in which we run (also we shorten the acceleration time and that will reduce the accuracy of the test)

also he does state his dyno is a dual inertia and brake dyno!

Pugo

 

Wow, what an interesting read. Taken me 20 mins to read this page but that was really interesting and didnt turn to a bitch fight. Well done guys.