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Percentage should not be used. Majority of loss is rotating wheels and discs and that stays constant for the same car if you triple it's power
 

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Discussion Starter · #6 ·
Wheels was removed Tim I have a wheel power and torque just wanted to know what it would be at the fly I was told around 15% ????
 

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Its 18% loss, beware on dyno dynamics as none of the shootout modes match this, make sure you get the very accurate and important wheels figures. There is a very long standing debate over the fixed or percentage method, both sides have valid points. If at all unsure I always just give the wheels figures as at the end of the day, that's what's being laid down to the tarmac.
 

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Discussion Starter · #12 ·
Its 18% loss, beware on dyno dynamics as none of the shootout modes match this, make sure you get the very accurate and important wheels figures. There is a very long standing debate over the fixed or percentage method, both sides have valid points. If at all unsure I always just give the wheels figures as at the end of the day, that's what's being laid down to the tarmac.
Thanks For that mine was on a hub dyno and only gave me power/torque ATW.
Was just wondering what sort of drive loss from wheels to fly.
 

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About 30lbft and 50HP IMHO which is as good as anyone else's as this is a hugely complex topic with Neanderthal thinking, incorrectly received wisdom and marketing contamination in most of the claims. At least I am not giving you a fake percentage which misrepresents the physics as Tim Ridley points out. Most of the losses are SPEED related.
 

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Thanks For that mine was on a hub dyno and only gave me power/torque ATW.
Was just wondering what sort of drive loss from wheels to fly.
Hub dyno is at the hubs with wheels/tyres removed. You should be very close to the flywheel figure on a hub dyno.

Imagine a car with a transmission with a 200bhp loss on an 1000bhp engine through friction. This transmission has no water cooling circuit. Now imagine a 200bhp engine on the dyno and remove the cooling circuit. You have 200bhp of energy whatever way you want to look at it for both applications. If you do 5 pulls on both scenario's, how hot is the uncooled engine and how hot is the transmission? If both are generating 200bhp then surely the transmission would be hotter due to less mass in its casings. Answer - its not. You can put your hand on it.

The physics are quite simple and transmissions DO NOT GLOW IN THE DARK hence the validity of some methods. Calculate the inertia of 4 wheels and 4 tyres rotating at a given speed. Therein lies one's answer.

FWHP is an ego massager on a chassis dyno, nothing more.
 
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R35GTR we have calculated that you loss around 75bhp from all 4 hubs to the flywheel on a Dynapack dyno.

Just on my way back from a tuning trip to Croatia will post some stock GTR Runs on our Dynapack when I am back in the office.
 

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Ive been on a fair few dynos over the years and have always found hub dynos very close to the flywheel figures ive seen on a dyno dynamics, before i went crazy with the power my supra made 902bhp flywheel at SRR and the next day did 915 atw's on a dynapack hub dyno.
 

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Ive been on a fair few dynos over the years and have always found hub dynos very close to the flywheel figures ive seen on a dyno dynamics, before i went crazy with the power my supra made 902bhp flywheel at SRR and the next day did 915 atw's on a dynapack hub dyno.
Jamie, 902 Flywheel on Dyno Dynamics is CALCULATED what was the Dyno Dynamics ATW figure which is measured ?(assuming no slip logged on dyno)
 

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Jamie, 902 Flywheel on Dyno Dynamics is CALCULATED what was the Dyno Dynamics ATW figure which is measured ?(assuming no slip logged on dyno)
A lot of chassis dyno's use an assumed inertia value. If you put lightweight wheels and tyres on vs heavy ones the flywheel figure should not change but it does. Wheel should change in this scenario
 
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