kwrw & kw at fly wheel??

[finnyman]

can someone make help me with workin this out, how do you work the ratio of kwrw to kw at fly wheel? like if i got 200kwrw wat is is at fly wheel? because all the specs on cars that come out on the new XR8's and SS's, actually all production cars are measured at fly wheel aye?

[EFFalcon]

all production cars are measured at the fly wheel, and there is no accurate way to convert between the 2.

[parawolf]

Production cars advertise engine power, correct. However there are different ways of measureing this. One is with just minimal front mount accessories (eg just the alt and starter), and the other is with ALL the front mount accessories (alt, ac, power steering, water pump, etc).

Ford uses the minimal one and Holden use the complete one.

Having said that there is no way to calculate 100% accurately what your fly wheel power is from your rear wheel power. However there is a 'generally accepted method' which is take your rear wheel hp and that is what your engine is making in kW.

So the idea goes that if you are making 200rwkw that is about 270hp.

Which means you are making about 270kw at the fly. Now - this is not scientific, it is an accepted approximation.

[finnyman]

so there isnt any graph or something that compares the 2? all i know is that if you can get good kwrw its more at the fly wheel. Cuz it will be mad to see how much id have 2 spend to race a new XR or SS and beat it, dad just got a new XR8 and i wana be quicker in my EL

[parawolf]

Well you need to know the amount of energy produced by either of the engines at the tractible end (rear wheels). The energy the the area under the curve (mathematically, the integral) of the power graph (mathematically, the function). So a starting point would be to have a rear wheel dyno chart, from the same dyno, done on the same day by the same operator with 3 runs back to back to get a consistant run/average.

So as revs rise you will want to know that your rear wheel kw and Nm are consistantly above that of the XR8.

But there is no way to know exactly the loss through the transmission as it will vary due to input speed, output speed and friction internally to the gearbox (this also applies to the diff).

Then you would need to have a graph of all the gear ratios to make sure that you are consistantly higher in energy output than the XR8.....

So... the short answer, take it to the track if you want to know for sure.

[mcflux]

buy a snort kit :P that'll keep your old man honest!

[finnyman]

what stage snort kit will do that? stage2 or 3? or will i have to spend more like get a stage 4 -5?

[finnyman]

oh and do u have to do any engine work on a stage 2 or 3 kit or can it handle it?