Does 500+ AWHP = 615 BHP?
If 271 BHP = 220 AWHP that's 18.9% Divetrain loss. so...

 

I've never put faith in the whole percentage loss theory. I fail to see how drive line loss increases at the same rate as HP gains. I understand there will be more factors, heat for one, but don't see why it should not remain somewhat constant. Let's take a 100 HP car for example that puts 85 to the wheels, which is a 15% loss of 15 HP. If I put my mad tuning powers to good use (now you know this is a hypothetical situation ) and increase that HP to 1,000 and we use the 15% factor then I am now losing 150 HP. That's an extra 135 HP lost through the drive train. Am I the only one that thinks that's wrong?

 

i agree with UFO, i only care about how much it puts to the wheels

 

I'd like to do some engine dyno testing and chassis dyno testing to see someday, but when out road racing, and someone comes up in a 500 BHP Viper and asks what they just got smoked by and what power is that thing making, do you say 500, if that then they think you're trying to lie to them becuase you're smoking em big time especially down every straight. Do you use a 20% rule and say 615 hp. Do you try to spend 10 mins explaining to them the dirve line loss situation plus crank vs wheel hp.. and watch them glaze over and start drooling..

Ahhh. Can you just look at them and go no idea - It feels very down on power though..

 

Remember that the change in the drive line loss is seen when the car is accelerating on the dyno.
A car with more power will accelerate faster ( it better ) than say, a stock evo.
And acceleration is a function of time; actually it's a function of time squared.
(Anyone remember the old 32ft. per second per second rule from school ???)

The mass and friction factors of the drive line are more or less a constant.
But it takes more power to make it go from from 1000rpm to 8000rpm in 6 sec. than it does in 10 sec.

Try it with a bicycle wheel. Take a bike and turn it over a free up the front wheel.
Make it go from 0 to 300 rpms, but do it in 10 seconds.
You can probably do it with one finger.
Now make to go from 0 to 300 in 1 sec.
Better use both hands.

Newton's laws of motion are at work here.
Things at rest (or at a constant speed) want to stay that way, and they resist change very much.

So the line loss changes (increases) because the rate of change has increased.

When the acceleration is over, the drive line loss returns to "normal".
Take a stock evo and a heavily modded one and roll down the freeway side by side in 5th at 70mph.
Would you guess they are putting out about the same power ???
My guess is yes.

Anyways, that's the way I figure it works out.
But as usual I'm probably wrong ...

Mike's Dad

 

I have no doubt that as you increase power you probably continue to consume more power in the drivetrain up to a certain point. However I don't think this is linear and would have to at some point level out. I mean if you are consuming 150hp in you drivetrain I think it would probably melt!

 

High power cars to start to generate a heck of a lot more heat in many places. Engine, Transmission, Diffs, etc. That is why many extra pumps and oil coolers are needed throught the driveline, diffs, tranny, engine, radiator, etc. Maybe 115 HP is being consumed by the driveline in heat, or resistance, etc at 500AWHP. I sure would like to get some temperature readings from like a stock Evo at the diffs, tranny, block, radiator,etc. Maybe we'll try to throw on some thermocouples at the next circuit lapping suspension sort out to see.. Doesn't do much good without some stock temps though.

What is the energy produced by 1HP, and how much temperature increase would that have say on a diff, it's oil and casing. I guess it would get into all the fun stuff, specific weights, moles, joules, etc.

 

Anyone knwo where to find some dyno graphs for some Z06s. Or anyone know what kind of mods a Z06 would need to put down 500 WHP? THis weekemd, we'll be out road raicng this Evo on full slicks and some scared z06 owners aren't going to know what smoked em. We shold weigh less than a Z06 by 100 pounds. so with a pasanger maybe 100 more than a lone driven Z06. So we figure with 2 small passangers in the back if we can coerce the officals into it, we should still be able to smoke em. Now the worked over RUF R that comes out, well hopefully we'll be able to run with him and amybe edge him out. We want to have some numbers handy as to what it would take and cost for those already expensive Z06s to keep up with the 4 door daily driven pick up and drop the kids off at school sedan..

 

z06 won't stand a chance dude

 

We know that. But they don't see it that way... yet.

 

If a stock drivetrain takes 50 HP to spin and accelerate the drivetrain, guess what? It's not going to take any more power to move the drivetrain regardless of whether the engine is putting out 625 horsepower or 271.

Also, if you were loosing 115HP to drivetrain losses, that would be the quivalent of 85,790 watts of power. Assuming the drivetrain losses remain constant at 50 HP or 37,300 watts, another 48,490 watts would have to be used in some fashion... in what form? Heat? I think you'd notice pretty quickly if someone lighted the underside of your car with 49KW of lights. That's 167,286 BTU/hr of heat output. It would get unbearably hot very quickly.

Drivetrain loss can not be measured as a percentage of output.

 

Things do get noticebly hotter under and around a much more powerful car, and at speed on the track 100mph winds an help to dissipate some of that heat, but I sure would like to do some tests to find out if that much energy is being turned to noise, heat, light, mush, whatever. It does seem like an awful lot..

 

May be interesting to see if any of the exotic fluids help things. (differential/transmission) More horsepower used, the higher loading on the gears, increases friction, and heat. This is why losses do not remain a constant xxHP but increase more as a % of output. Maybe some of the exotic fluids have better coefficients of friction under load than the stock fluids. Could be tested, but would take a long time on the dyno. Load vehicle to say 100hp, have thermocouples on various parts of the drivetrain. Run until temperatures stabalize. Replace fluids, repeat test, see if temps are lower. Or, do a dyno pull, replace fluids repeat and see if any HP increase was noticed.

 

We've seen on the dynojet increases in measured HP with certain fluids, so that in my book would mean improved efficiency or lower driveline loss, and more getting to the wheels. But those fluids in the driveline obviously don't generate any more power they just reduce the amount lost, so.. I agree I think the % driveline loss on some of these high hp setups must be much improved and less than some of the stock baseline stock fluid measurements with stock fluids. We've also seen hp increase as some fluids have been run once or twice. They kind of hit a sweet spot. Dyno Check before a weekend of lapping, come back and measure again and we're up 5-6 hp. We didn't start making any more power or change anything... so.. So many things to check..

 

what does it run it the 1/4 mile?