Bhp at the wheels??????

[AARON77]

Does anybody know how to work out the bhp at the wheels!!!
I had my s3 on amd's road on sat but couldn't pick it up till after they had closed so there was no 1 to explain the graph to me !!!!!
The stats are - 294 bhp and 304 lb/ft of torque can some1 pls help

 

[gez]

I think roughly its minus 15% of the flywheel power. Unsure though. What setup do you have to make that power?

 

[paul20v]

Hi
you should be given wheel readings as there accurate
the flywheel reading are a guess to a point as different transmissions and configurations give different losses also oils used can alter the readings
there are many factors to be taken into configuration there is no hard and fast rule to working out flywheel BHP
Power at the wheels is the only accurate reading that should be taken , after all thats were the rollers take there readings .

 

[AARON77]

MMMmmm that's wot I thought Paul but jus wasn't expecting it to be that high it seems quite impressive for an old banger with high mile???

 

[paul20v]

Is it standard then ?

 

[Padtwo]

Bit of a lottery as each car will be different even the same model due to wear and tear on different parts but for a 4wd car I'm guessing between a 15 and 25% reduction in the figures you have, 2wd will be less. I believe the figures you have will have been reached by doing the opposite, taking the figures off the rollers then adding in a factor for transmission losses, the factor being between 15 and 25% by my estimation. Each tuner will have their own ideas about what the factor should be, and different rollers will give slighlty different results, which is why it's good to return to the same place for repeat runs in the future. That's just to give you an idea, best to speak to amd themselves and see what they say. Nice figures, I'm sure it goes very nicely

 

[AARON77]

Stage 1 map, 007 diverter, updated clutch( wouldn't make a difference would it) k&n that's all of the engine mods that I have done changed the rear diff and haldex??? But nothing to major ???

 

[paul20v]

Mmm now we have had 2 replies stating a percentage
now dont attack me but i have a problem with percentages

For example a car giving 200bhp at the flywheel. Now knock off say 22% transmission loss - that's 44bhp lost in the transmisison. So at the road wheels you get 156bhp.

Lets mod that car, remap it etc., so its now giving 300bhp at the flywheel. Now put it back on the dyno. Knock off 22% transmission loss - that's now gone up to 66bhp. So at the road wheels you have 234bhp.

BUT - you have not touched the transmission, however the transmission loss has gone from 44bhp to 66bhp !!

So percentages really dont work

Paul

 

[AARON77]

She's done over 170000 miles I've had had it for 4 years and got it with 99000 on the clock

 

[AARON77]

When I showed the graph to a few mates they had mixed comments most of them being "that's not the actual bhp" ????
I must admit I'm not totally convinced myself Its the 1s time I've ever put it on a road and I was thinking it might have been around the 250bhp at best!!!
It gets driven every day within an inch of it's life

 

[AARON77]

Good comment Paul

 

[badger5]

Power at the wheels is the only accurate reading that should be taken , after all thats were the rollers take there readings .

Erm, Nope.. I have to disagree - and here's why:

atw makes no allowance of transmission/tyre temps, viscosity of oils in transmission etc etc..

run on a DD for type roller set for example, and run one wil be lower than run 2 which will be higher, and run 3 higher again... Why? cos the tyres are higher temp, more pressure, less rollign losses, the transmission oil is warming up and thinner, less draggy... Power @ flywheel has;nt changed one jot, yet the "apparent whp" has risen..

Sorry dude..

coastdowns and fly figures on repeatable rollers is for me far better

 

[badger5]

Does anybody know how to work out the bhp at the wheels!!!
I had my s3 on amd's road on sat but couldn't pick it up till after they had closed so there was no 1 to explain the graph to me !!!!!
The stats are - 294 bhp and 304 lb/ft of torque can some1 pls help

those will be quoted @ fly figures. but of course subject to dyno lottery

 

[AARON77]

Also a very good comment am I right in thinking that the graph shows the power at the wheels????
Is all this power at the engine a load of ole guff to make the car seem more impressive than it really is???
You have excuse My ignorance but I'm still none the wiser!!'
I would but a copy of the print out on here but I'm using my ifone

 

[AARON77]

Bill do you mind if I email the graph over to see if u can make sense of it I would wow appreciate it

 

[AARON77]

Dyno lottery I like it!!
so its a load of ole crap I'm guessing

 

[paul20v]

Erm, Nope.. I have to disagree - and here's why:

atw makes no allowance of transmission/tyre temps, viscosity of oils in transmission etc etc..

run on a DD for type roller set for example, and run one wil be lower than run 2 which will be higher, and run 3 higher again... Why? cos the tyres are higher temp, more pressure, less rollign losses, the transmission oil is warming up and thinner, less draggy... Power @ flywheel has;nt changed one jot, yet the "apparent whp" has risen..

Sorry dude..

coastdowns and fly figures on repeatable rollers is for me far better

No dont be sorry ,
i agree with your comment on the viscosity of oils etc
but your flywheel readings are still calculated via the wheels which also will alter with temps allthou as you rightly say the flywheel figures shouldnt actually alter but they will with the calculations taken from the wheels due to transmission loses and heat differences etc .
The car should be tested at full working temprature so all components and oils should have a reading that will be pretty consistent
readings then should be at a good average
the only true flywheel power readings you will get is with an engine on a test bench with the readings taken straight off the flywheel
and i still stand by what i have said that there is no definate way of working out the losses of the transmission and other items as every car is different ,
at the end of the day flywheel power has no place in the real world when its the power at the wheels the makes us travel forwards .

I await the barrage of abuse especially for the last line

 

[AARON77]

Test 1
Power 292.2 hp
Torque 297.8 lp/ft @ 3922 rpm

Test 2
Power 282 hp
Torque 303.3 lp/ft@3922rpm

Test 3
Power 270.9 hp
Torque 304.6 lp/ft@3922rpm

 

[badger5]

No dont be sorry ,
i agree with your comment on the viscosity of oils etc
but your flywheel readings are still calculated via the wheels which also will alter with temps allthou as you rightly say the flywheel figures shouldnt actually alter but they will with the calculations taken from the wheels due to transmission loses and heat differences etc .
The car should be tested at full working temprature so all components and oils should have a reading that will be pretty consistent
readings then should be at a good average
the only true flywheel power readings you will get is with an engine on a test bench with the readings taken straight off the flywheel
and i still stand by what i have said that there is no definate way of working out the losses of the transmission and other items as every car is different ,
at the end of the day flywheel power has no place in the real world when its the power at the wheels the makes us travel forwards .

I await the barrage of abuse especially for the last line

Well, I have a dyno, use it alot.. Do you?
coastdown is where you aquire the rolling losses, and once warmed up you see them reduce, but the atw figure "apparently" rise... BUT the overall measured figures remain consistent once the cars up to operating temps..
How it works on my dyno anyhows..

ATW figures are american way of doing things of people who have been suckered into Dyno Dynamics sales patter of why theirs is so accurate, when I know its not and adds a % calc factor the atw figures.

every car is indeed different, which is why measure coastdown takes such things into account, which atw figure simply cannot do

 

[badger5]

Test 1
Power 292.2 hp
Torque 297.8 lp/ft @ 3922 rpm

Test 2
Power 282 hp
Torque 303.3 lp/ft@3922rpm

Test 3
Power 270.9 hp
Torque 304.6 lp/ft@3922rpm

Hi

This will be AmD Essex's rollers I presume?
I see similar numbers reported by LCR's off SCN forum from there.

Dyno Lottery (TM)

 

[AARON77]

It sure is amd Essex
I would be interested to use a different road to see jus how different it is ???
Do they differ quite a lot???? Is the margin quite large ????

 

[AARON77]

Badger where are u based it seems I'm gonna have to see wot u can do for my car as I t seems your a bit if an s3 guru on ASN

 

[s3dave]

hes in gloucester area

 

[jojo]

hes in gloucester area

The home of the S3! lol

 

[AARON77]

Does he have a website ??? How do I get hold of him ???

 

[s3dave]

Address :
Badger5 Ltd
Unit 2b
Queen Annes Gate
Oldends Lane
Stonehouse
Glos
GL10 2DG

Tel: 07976 800775 or 01453 827936
email: sales@badger5.co.uk

 

[badger5]

It sure is amd Essex
I would be interested to use a different road to see jus how different it is ???
Do they differ quite a lot???? Is the margin quite large ????

i have'nt had a car which has run there run here yet to my knowledge
dynos do vary in their measurements yes, so getting hung up with one set of rollers numbers is'nt worth the brain ache.

i have run a few audi's from guys on here, as a comparitive number. the only k04 cars which break into 300bhp numbers are hybrid k04 cars. highest k04 car power achieved on my dyno thus far is 278bhp, most of them being in the range of 245-260bhp

the dyno lottery is a whymsical pop at assorted dyno numbers.
unless you have a car consumming 240g/s of mass airflow on pump fuel, you do not have a 300bhp car imho.

 

[AARON77]

I honestly didnt think that it was as powerfull as the graph shows I'll call Shaun at amd 2moz and see wot he has to say on the matter ??? And if he can explain the figures that his Dyno has produced ????

 

[badger5]

dyno's differ in how they do their measurements.
whats more relevant is using same dyno and tracking mods, keeping the dyno checking at the same place. numbers are relative then and gains achieved over time with assorted mods can be seen.

dont get hung up on the figures - you will waste yours and others time (eg shaun)

go to some dyno days and compare numbers on the day, "relative" to each other...

you will find you will get as many figures as dynos you visit..

hence this fave logo below

 

[<tuffty/>]

I'll sort a dyno day out at Bill's subject to his (and the mods) approval of course... last one went really well especially the buttie van ;P

<tuffty/>

 

[AARON77]

Plan

 

[Dane]

Mmm bacon and sausage AND egg! Cant go wrong. Be pretty good to do it in ooh I don't know a month... it would be interesting to see how far my standard k04 will go.

 

[paul20v]

Well, I have a dyno, use it alot.. Do you?

Sorry is this comment and question put to undermine my posts ? if not then i apologise but thats the way it comes across ,and in answer to your question No i dont have a dyno
which obviously means as i suspect that you feel i have no right to comment or have an opinion about anything on this subject ,
i still ask what is wrong with ATW figures that remain constant once everything is up to temprature surely this requires no guess work on a well operated and fully calibrated road, of course the ATW figures will rise when everything is warming up and losses will decrease so im asking and genuinely intrested as to the problem with the ATW figures as both ATW and Flywheel reading require calculations yes so what makes either in your opinion any better than each other on the same road with the same user .

 

[badger5]

Sorry is this comment and question put to undermine my posts ? .

No I have'nt posted that to undermine your post, but enquire as to your experience to have the belief you do..?

I refer you to your original post

er at the wheels is the only accurate reading that should be taken , after all thats were the rollers take there readings .

...and the reasons I have already given why this is not the case or defacto the "only way it is".

atw - from single roller? - one contact point
atw - from twin roller? - two contact points
atw - from inertia only dyno? - load and ramp rates effect readings significantly
atw - from braked dyno? - load and ramp rates effect readings significantly
atw - tyre pressures consistent?
atw - tyre size/width/stickyness consistent across cars?
atw - transmission std or competition dogbox?

looking at the above, a lot of other influences are not taken into account is the point I was trying to make, that atw figure is'nt the be all and end all, defacto "the most accurate" measurement.

All of the above can give "different" atw figures - how consistent do you think that is? I can tell you they will vary as much as the make of dyno and how its used.
@Fly figures is a comparison to manufacturers quoted fly figures, but no manufacturer quotes atw figures.

and it measures torque at the wheels, as tractive effort, and calculations are made from that figure.. to turn it into power @ wheels.. RPM is required to calc this, and this RPM is determined by different means depending on the dynos as well. (impulse detector hooked to cars electrics and all lights on, tach wire feed for pickup, teaching the rollers a known rpm.... etc etc)

Dyno lottery applies overall tho... lol

 

[Welly]

Mmm bacon and sausage AND egg! Cant go wrong. Be pretty good to do it in ooh I don't know a month... it would be interesting to see how far my standard k04 will go.

Put me down for 3.

 

[Dane]

haha standard.