Dunno about a scientific argument but here's a mathematical one.

Standard Falcon 5.0L, Ford quoted what, about 165kw at the flywheel. Let's take that at face value, we all know there are smoke and mirrors around quote kw figures - but for arguments sake, lets say its within 10% of that figure.

Now, put that standard car on a dyno and you're looking at about 110kw - 120kw at the wheels. This is a fairly average obsevation on most dynos, certainly agrees with all the standard 5.0L e-series ive seen on dynos over the past couple of years.

So let's say we're talking about a 45kw - 50kw difference between quoted flywheel kilowatts and measured rear wheel kilowatts. That's a 27% - 33% reduction from the quoted factory figure for a standard 5.0L e series.

Pretty easy to see where the old "30% rule" comes from.

I agree that when you start talking about high powered motors, this ratio is blown out the door. I mean for a driveline to be absorbing a couple of hundred kilowatts, that energy has to be going somewhere... that kind of energy loss would probably see the car set on fire.... so it doesnt seem phyically possible to lose 30% of an engine's power when the engine is creating, say 600kw.

But for ppl who are doing exhausts, cams, air intake mods etc etc and are looking to add 10kw - 20kw to the engine's power - then the 30% rule (albeit very very very rough) is perfectly acceptable. For minor upgrades to engine power, i dont see the need to make things more complicated than need be.

you just said the engine make more power at the wheel then it does at the flywheel.......

and you can't guess or put a % loss on it.. the power needed to turn the mass of the driveline never changes. friction how ever does.. if one part it never changes you can't put a % loss on it.

i've seen you argument to this befor, and at best it's dodgy... because you asume to much...

that was exactly my point. you can't use 1/4 mile times a judge of power

ok

i give up LOL

cheers

Still ,,,, how can you judge how much volumetric efficiency the engine has, due to better flowing portwork ,cam lift- duration, max rpm available,
I feel that there is no formula to accuratly measure HP/KW exept in real time driving conditions- A G force measuring device, this gives you real power figures that the vehicle can & does use, taking into account wind resistance the power figures may be lower than a chassis dyno but it is real usable power.

at least we wont have to read you dribble on about it

u make larf , my dribble PMSFL sorry we not all experts like you and on this note since your such a expert what rear wheel kwatts will a BA GT rated at 290 kwatts at the engine ( SO FORD MOTOR COMPANY QUOTE ) will produces on a dyno dynamics chassis dyno and when u have work this out please give me the % differences ????

and remember " i've seen you argument to this befor, and at best it's dodgy... because you asume to much..." i'm not assuming anything here how u have suggested previuously or has ford motor company got here kwatts wrong also maybe there assuming this figure to


LOL


I'm going to have a great larf on this answer PMSFL


cheers

Last edited by FPV_GTp on Sat Feb 11, 2006 4:41 pm, edited 2 times in total.

wow some people realy went to some effort for this

who realy cares!
whoever passes the finnish line first has the"quicker" car/pass! at the time
but as for the 260kw boss, the RWKW in standard trim is 206rwkw@ 5800rpm
you guys do the math, i'm too drunk! but it looks like about 25-30% less than flywheel kw's

The following is just a theortical question in all its aspects:

Does the driveline always lose about the same percentage no matter how powerful the engine? Or does the driveline percentage of loss increase once the engine output approaches, say, 500kw to 1000kw, i.e: 35%, 40%, 45%, 50% loss through the driveline.

And following on from that, does the same engine always lose the same percentage of power through the driveline? For example, does air or engine temp effect driveline efficiency?? What about if you only apply 50% throttle? Do you lose the same percentage?

There is no accurate way to compare rear wheel figures to flywheel IMO. A dyno is a tuning tool, usefull for setting up timing curves and fuel delivery, so that you can get the maximum out of an engine without hurting it. Dyno comps have prompted people to build cars with one thing in mind, peak horsepower. This means bugger all on the street, but heaps at the pub! Average horsepower over the usaeble rev range is more critical than peak horsepower on the street AND on the track.

you are assuming that every GT rolls of the floor with exatcly 290kw...

they dont, so go pick one. rip the engine out put it on an engine dyno, run it in a controlled atmosphere shed, then put it back in the car put it on a chassis dyno from the same maker and run it in the same conditions..

go do that with a few hundred engines from different cars if you get between %28 and %32 for all of them i will bow down to your god like ability come up a a %loss for drivelines


when something as simple a tyre pressures can change the reading
% LOSSES ARE ALL s**t

LOL

again im assuming ford motor company has quoted 290kwatts ok ( i'm merely quoting Ford )

my test is complete

i could type more here i will leave it at that

and remember guys i haven't said its gospel that its 30% drive tran losses

Someone asked the question how to convert tyre horse power to flywheel horse power , it is a guideline maybe not a exact guideline other dyno makes quote different losses so who do we believe ???

Tickford again u said im assuming the kwatts of a ba_gt i'm merely quoting from a known figure which i would have to say ford is a reputable company and wouldn't over quote nor under quote there horse power figures. so in this case we have a baseline to work with and make a calculation of some sort

But judging from all the cars that i have run on the dyno and known factory engine horsepower readings i can make a educated calculation on the drivetrian losses from one car to another and it always comes up to approximately 30% on a dyno dynamics chassis dyno.

as far as testing 100 engines on a engine dyno and then doing back to back tests on a chassis dyno i would undertake such a exercise cause the motor companies supply that information

So i will have my engine dyno running soon and a controlled dyno room , which i will do back to back tests on my EA falcon and compare engine dyno and chassis dyno results and the at the drag strip.

drag strip is a interesting topic , i have seen so many guys thinking cause there car produces 500Bhp there going to run 11 seconds , it probably is capable of it depending on a lot of variables

it takes a lot of time just making the right adjustments at the race track not just engine horse power thats another topic to discuss another day

If one has a know horse power figure and a known weigh you have to exsirt the force on it u can make a mathematical calculation how quick in elapsed time and speed you should be able to run down the quarter mile in a ideal world ???

like i said my car will be the test ginny pig engine dyno , chassis dynos and drag strip

This a open forum for discussion and we can talk civilized or we can scream and carry on, I'm better than you and your better than me.

Tickford i have nothing against you and some of your ideas are fine but lets be open minded as well.

And if you ever get a chance to run a BA_gt on a dyno dynamics dyno let me know the results from flywheel horse power that ford quotes us and your actual chassis dyno results you have measured.

Have a look at bretts XR6 in one of the threads i have posted just from a simple air box and air filter change he gained some extra kwatts so my questions is now and i don't know the answer does ford quote engine dyno figures with or without dyno accessories on or off the engine
cause as far as im concerned that factory air filter and air box is a restriction or a drivetrain losses which of the two ???

i don't claim to know all the answers to everything but insults i will not tolerate

cheers guys

here you go again assuming that every BOSS290s leave the floor with exactly 290kw.. news budy they don't. production tolerences ever heard of them????


as far as bretts car, you know as well i do that dynos can be fudged to produce just about any result you want it to. you spent days leading up to it going on about power losses and asking people guess, then you come out and "well %30 is 124rwkw," supries supries what do we get 124rwkw, dynos can be made to poduce numbers, any numbers regardless of actual power