hi blacky

just give u a example most place that run dyno dynamics dynos use this method of calculations from flywheel back to rear wheel horsepower

we wont get into a debate whether im right or wrong because the proper way would be run the same engine on a engine dyno and then on a chassis dyno.

the horsepower ( Kwatt ) u quote 164kwatts at the flywheel

164 kw at flywheel = 164 times 33 % = 54.12

164 - 54.12 = 109.88 rear wheel kwatts

to get back to flywheel if u have a rear wheel reading only is the reverse

109.8 divided by 2 = 54.94
109.8 + 54.94 = 164 Kwatts give or take a few LOL

see how u go with this a estamate

this is general accepted with in the dyno industry but some others may debate my results but its a ball park figure


have fun

cheers

So you are telling me that with 210rwkw I am loosing over 100kw through the drive train... I think not...

no by dividing it by 2 is equivalent to 33% losses if u wanna work backwards to flywheel kwatts


so 210rwkwatts is = flywheel kwatts 210 divided by 2 = 105

then u get 210 + 105 = 315 at the flywheel kwatts

cheers

hi

let me pose a question here ??? not meaning to steer the thread or hyjack it ???

how many kwatts does it take to drive ur airconditiion in the car say in a EF ford ????

i have done a before and after run on the dyno with air off and aircon on


and remember the engine is connected to a say convertor and or clutch flywheel setup which is connectted to a tailshaft and 2 universals which is connected to a differential center and two axles and bearings and rims and tyres dependin on the rims and tyre size and weight losses can be discieving but just curious here ???


corrected on the 10th/11/2005 , i made a error here guys and i applogize for the error so i stand corrected here and have looked up my dyno results and confirm the Kwatts of a standard VL commadore , thank you to the gentleman who pickup the error cheers

Quoted from my electrspec software - VL commadore

normally aspirated kilowatts 114 DIN @ 5200 rpm ( 9.2:1 comp/ratio )
Torque 247 DIN @ 3600 rpm

turbocharged ....... kilowatts 150 DIN @ 5200 rpm ( 7.8:1 comp/ratio )
torque 296 DIN @ 3200

the figures i had looked up of the dyno database and i over quoted it , but have corrected it now and ask the same question as i did before

if a commadore turbo stock stand from the factory on 7 psi produces 102.7 kwatts at the rare wheels which is approx 154 kwatts at the flywheel
the losses are approximatelty 50 kwattts drive tran losses

now lets boost the car higher say 14psi and the tune is done and now the car produces 220 kwatts at the rear wheels !!!! follow !!!!! why have the lossses increased ????

same car same engine , gearbox diff tyres and so on ????

why have the losses increased ???????
if a commadore turbo stock stand from the factory on 7 psi produces 120kwatts at the rare wheels which is approx 180 kwatts at the flywheel
the losses are approximatelty 60kwattts drive tran losses

now lets boost the car higher say 14psi and the tune is done and now the car produces 220 kwatts at the rear wheels !!!! follow !!!!! why have the lossses increased ????

same car same engine , gearbox diff tyres and so on ????

why have the losses increased ???????


cheers

Last edited by FPV_GTp on Wed Nov 09, 2005 10:10 am, edited 6 times in total.

the figures that ford quoted originally (ie. 157kw) was without ancilleries.
even the load that headlights put on the alt effect overall power. (by tenths of a kw)
greater power through drive train = more heat = more losses. same applies with other types of drive train losses

thanks FTP_GTp ... is that method for automatic or manual?

oh what fun debateable topics we all talk about.

There are so many things that affect your drivetrain losses.

Diff gears, tyre dia , let alone auto or manual.
converter plays a big part even.


All I can say is go to one dyno, and stick to that dyno, whether it reads 2 kw or 200 kw don't worry about the kw race.
Make a mod and go back to that dyno and see if you increase or decrease, that is the only way to get a true repsonse.

That is what is good about dyno days, everyone runs the same dyno at the same day, so you are comparing your car to the next guys on an equal playing field, not comparing, bob's dyno to jim's dyno.

hi


LOL seems u have lost wot the original question is ????


lets have a look at ur car ur stating
'Other car 580 hp @ wheels now 624.7 hp !! '


am i to assume its 580 hp @ the wheels or 624.7 hp ????

which of the two ?

then when u tell me i pose another question to u ??

just wanna confirm this first !!!!

how much horse power does ur car produce ??? and what is the car in detail ?????


plz

cheers


PS ; bear in mind this is not a dyno debate as u stated ???!!! lol

whether we use joe blows dyno or sillybillys dyno !!!!!

well the old engine made 580 hp @ wheels in shootout mode on a brand new dydno dynamics dyno.
Then I built a new engine and it made 624 hp on a brand new dyno dynamics dyno.
I am not going to give specifics of the engine combo, but lets just say, it's not stock !
I also do believe that the 20% rule or 30% rule does not apply.
I never thought it did.
After all some of these dyno queens that push 1500 rwhp with say 20% losses, means they must be pushing 1800-1900 fw hp.
Now you know as well as I do the Holden block is not capable of supporting that power,
Also lets face it why would drag racers build Keith Blacks, when u can just twin turbo a holden engine !

I personally believe in the kw losses more than the % of losses.
and by changining things in the driveline you can up and down the kw losses in the driveline.

hi

I'm not concerned with the internals of ur engine combo but thats another issue as to power losses

the magic number in % losses i have no idea what it is for each car combination , but remember it all relates to numbers ??? HOW MUCH ???? all varies , i dont want to cause another dyno debate here , this is just to show even from one dyno manufacturer to another there all quoting different losses so who do we believe i dont make the dam things i use one thats all


just wanted know gear box , diff tyres etc ???

the gentleman who started this thread want to know how to convert from rear wheel horsepower to flywheel horsepower , had nothing do with whos dyno you use to measure horsepower !!!!


now V8capri my car is no secret its a standard ford GTp , which is rated at 290 Kwatts at the flywheel , have u ever run a standard GT 290 kwatter on a dyno dynamics dyno ???? and if so how many Kwatts did it produce on the dyno ???? and can u please calculate the LOSSES for me ??? and remember this is not a dyno debate !!!

I didnt say its the correct 20% or 30% losses but this is what generally is used to make a calculation from flywheel to rear wheels.

lets get back to ur car now , lets get back to ur car that produces 624 hp at the back wheels , how much horsepower does it produce at the flywheel???

cheers

Last edited by FPV_GTp on Tue Nov 08, 2005 9:21 am, edited 2 times in total.

HEadlights, with high beams draws about 40A. This actuallt atranslates in kW losses from the alternator, not 10ths of kW losses. An alternator probably sucks up to 5kW when it's putting out its full 80A.

With the info you've posted, you can not assume anything about losses with 14psi boost.... you might want to include the new FW power figure @ 14 psi boost and not just the rear wheel figure

hi

yes it probably does concume up kwatts.

remember all moving parts need power to move them to what extent each part consumes i dont know , would have to play fun and games to work it all out for the DIFFFERENT parts .

cheers

30% Drive train losses is a rule of thumb that was out dated 20 years ago. It probably worked then, but not now.

In the last 20 years, the power output per litre of engine capacity has increased. A 4.0L engine 20 years ago might have put out 120kW.

Also, drive trains have become more efficient in the last 20 years aswell, so less losses through the drive train. 20 years ago, that 4.0L engine might have lost, for the sake of example, 40kW through the drive train giving you a 33% loss and 80kW @ the rear wheels.

Now, with a more modern Falcon, you're producing approx 160kW but you might only lose 30kW through the drive train. So you lose 18.75% and get 130kW @ the wheels.

If you want more info, read this link Of particular interest is this paragraph

"The worst scenario case for a rear drive setup is on the order of 12.5% in 4th gear, not the 20 -25% often published. If 25% was being lost in the drive train, the oil would boil in the differential housing in short order and aluminum transmission cases would fatigue and break from the temperatures generated. On a 200 hp engine, something on the order of 37,000 watts would have to be dissipated out of the transmission and differential housings. Obviously, this is not the case."

The main reason why the 30% loss calculation is so commonly used is because men have C**k. And to calculate your engine power by dividing rear wheel power by 0.7, you get a calculated power output that is higher than reality which makes all our C**k feel bigger and more masculine. I hate to say it, but it's the truth.

Also, the power output of 157kW that Ford quote us is wrong. It's different now, but for decades, car companies have been quoting power figures higher than what the typical engine actually puts out. If you get over 150kW out of a brand new, stock standard I6, you're doing good. Tack on 250,000km onto that engine and you'll get nowhere near that 157kW that you think you have. This is another reason why people calculate larger that actual power train losses. If your XR6 puts out 130kW @ the wheels, then based on a 12.5% power loss, you've only got 149kW @ the flywheel. It'd be nice to factor in a 33% loss which gives you 194kW, but the reality is, no factory EF/EL XR6 has EVER put out 194 FWKW!

So boys and girls, (well, not really girls) it's time to look down at your penis' and realise that it's not responsible for 15kW more fly wheel power than you actually have. Instead of talking up your engine for more than it is, put your money where your mouth is so that when you say "I have 200 flywheel kW" you actually mean it.

i know a standard version of my model makes 145 rw kw, that car is rated at 210 kw so that is 70 kw loss
so i beleieve my driveline is 70 kw loss
the driveline i have is
zf 6 speed, heavier than standard flywheel
b/warner 3.45 gears
235/45/17's on alloy wheels.

FYI the ba 220 kw engine auto made 175 rw kw on a brand new DD dyno