520 BHP on dyno

[SteveN]

Originally Posted by R33_GTS-t

Some people over do it with the corrections but 60-80bhp maybe a decent estimate for losses on a hub dyno but not a wheel dyno.

So you reckon there is more than 60KW per min in heat lost from flywheel to wheels? Do you realise how much heat that is!? Most decent space heaters (i mean 500quid+ jobs) cant create that amount of heat in a bloody hour.

Maybe its me, but I cant see it at all.

[mifn21]

On 1000cc motorcycles you tend to lose 15-20hp through the chain and I've seen dyno graphs to prove it (engine dyno'd then put in the bike and dynoed again)
So does 60hp really seem excessive in a heavy 4wd car?

[SteveN]

No. Read what I said.

Its the 150bhp+ people often see that I find hard to believe.

[R32 Combat]

SteveN, losses are not just heat.

[mifn21]

Steve, from the post above it sounded like you thought 80hp (60kw) is excessive - apologies if I misunderstood

[R33_GTS-t]

Originally Posted by borat52

Am I correct in thinking the top speed of the GTR at 19x mph coincides with 7k rpm in 6th?

Roughly, yes.

I'm sure the tuners will just add a new valvetrain and raise the rev limit anyway.

[borat52]

Originally Posted by R32 Combat

SteveN, losses are not just heat.

It's pretty hard to lose a lot of energy to anything other than heat, realistically what else could the energy be lost to (friction/resistance ends up as heat)?

[SteveN]

Originally Posted by R32 Combat

SteveN, losses are not just heat.

What losses are there that equate to anything else but heat?
Friction Losses = Heat, Hydrodynamic Losses = Heat.

I cant think of anything else TBH

[R32 Combat]

Indeed, let us not forget that this gearbox is perticually noisey. And this is a form of energy loss too.

[SteveN]

Sound energy? Massive losses there, lol...

[kismetcapitan]

15-20bhp loss in a bike drivetrain, I've been looking for that number for quite awhile!! Means I'm making 95~100bhp at the crank on my bike (80-ish wheel), so it's unclear whether I hit my goal of 100bhp, up from 85 stock.

[borat52]

Originally Posted by R32 Combat

Indeed, let us not forget that this gearbox is perticually noisey. And this is a form of energy loss too.

Even 1Kw would make a huge noise (way louder than gearbox whine). my hifi amp is 110W and I never have that turned up past half way, unless I really want to annoy the neighbours

Its not just this gearbox though, even a 'normal' one which is not noisey will lose a lot of energy. Very good point SteveN, when you think of it in heat terms its enourmous.

Having said that, that figure is at full power which will rarely happen on the road for sustained periods.

[R33_GTS-t]

Originally Posted by SteveN

So you reckon there is more than 60KW per min in heat lost from flywheel to wheels? Do you realise how much heat that is!? Most decent space heaters (i mean 500quid+ jobs) cant create that amount of heat in a bloody hour.

Maybe its me, but I cant see it at all.

What's the specific heat capacity of air? What temperature does a space heater get it to?

What's the specific heat capacity of synthetic motor oil? What temperature does this oil reach during hard driving without any oil coolers? What would happen to the metal if it wasn't there?

[borat52]

Originally Posted by SteveN

So you reckon there is more than 60KW per min in heat lost from flywheel to wheels? Do you realise how much heat that is!? Most decent space heaters (i mean 500quid+ jobs) cant create that amount of heat in a bloody hour.

Maybe its me, but I cant see it at all.

Thats not stricty true either, I have a 2Kw £10 B&Q convection heater next to me. If I leave that on for one 30 mins thats the same amount of energy as 60kw for one minute. Remember KW is a measure of power and power is work done/unit time, so its not 60kw per minute, but rather 3600Kj per minute. Either way its a lot, but its not unbelievable.

[FiLi]

Nice results. Congrats

Just a bit off-topic, anyone know the CO2 emissions per km?