booch137

Can anyone explain to me how the ZR1 loses 100hp and 100ft lbs of torque on the dyno? Please?
I thought normal loss between flywheel and tires was at max like 50hp on a car...

jrob56

iTrader: (39)

im not for sure but i thought it was like 18% drivetrain loss as a rule of thumb that would be 650x.18=117?

thunderstruck507

iTrader: (18)

yes, drivetrain loss is not a set number it is a percent of the power made

cherryelky305

iTrader: (2)

How is it not a set number. So if I increase the stock power on a 346 ls1, It will lose more power because its making more power?

1994Z28Lt1

iTrader: (1)

yes that is correct to a degree, the more power you make the more you will lose through the driveline, its a percent loss

when you're making more power you're going to be applying more torque to the transmission gears and the rearend, causing losses through friction

when you dyno it especially on an inertia dyno like a dynojet more power will be lost trying to accelerate everything at a quicker rate

think of flywheel, tires, rotors, ring and pinion, transmission etc etc


the loss is always going to be a percent you cannot just say that
T56+aluminum DS+ billet flywheel+10bolt+17inch wheels and tires = 30 hp no matter what

Arc00TA

iTrader: (17)

What he said. It takes more power to accelerate the same pieces more quickly. That is why you can always find it as a %. Google drivetrain loss and you will find lots of articles about it.

fccs

iTrader: (26)

Its the same for ANY car, its usually around a 15% loss from the crank rated power to the wheels, at least for rwd cars its usually that much. So lambos and that **** that have 600+ hp also have a drivetrain loss, a z06 with 505hp is the same.

Pntbll309

iTrader: (33)

You must be kidding.

PowerShift408

iTrader: (44)

Not quite. My car made 514/485 throught my six speed, and 482/439 through a TH350.

SladeX

The percentage power loss through a drivetrain is not determined by RWD or FWD alone, it is the actual type of transmission that says it a lot more.

A manual car will have less drivetrain loss as it is a direct connect, ie all moving parts are mechanically linked. Any automatic type car will lose more power as it uses fluid flow to transfer power which means more power loss. Expect an average of 25% give or take depending on the transmission used and its efficiency. While a manual will be in the 15% range.

NVR_SPDS

iTrader: (39)

It comes down to friction, and the weight of the components like stated above. if you want to bring that percentage down though, you can get lighter driveline components, and for example, with a T56, you can get your internals micropolished, or mikronited(As well as rear gears), and in combination with a good fluid, you can reduce friction.

Our 02 WS.6 made 351rwhp/372rwtq with a built (completely micropolished internally) t56, a lid, catback and 3.73s. The only thing i could think of, that it was makin that much power was the reduced friction in the trans. I at first thought it was a high reading dyno, but our other car, after being tuned, only dyno'd 6hp higher on this dyno than a mustang dyno.

wht01ws6ta

iTrader: (45)

Pretty sure the percent figures are just to help get an estimate and nothing stays "locked" to that percentage. If you have a certain drivetrain it is going to take a certain amount of HP to spin that drivetrain(ie: clutch, tranny, driveshaft, rear-end, wheels). Then, if you increase your engine HP it is not going to magically be harder to spin that same drivetrain just because you have more horsepower. If you truly have a 15% drivetrain loss and have 400HP that is 60HP that it takes to drive the wheels. But if you have 600HP 15% is 90HP, why would it suddenly take 30 more HP to turn the same drivetrain?

SladeX

that's why its an average and never a fixed number or percentage, you can change things within the drivetrain to increase or decrease the load.

thunderstruck507

iTrader: (18)

yes, actually it does become harder to spin those same parts...confusing I know but there is no set number for a t56 transmission to eat up, it depends on the forces being applied, just do some research on it

this is why a high hp racecar gains more power from small things that don't make much difference on street cars (full roller rockers, lightweight gears, and other low friction parts)

on a street car those parts could be worth 2-3hp each, but on a full race car they would be worth much more...making the high cost of those parts worth it

wht01ws6ta

iTrader: (45)

Yeah I've done some research on it and most of what I could find says it is not a fixed percentage. I do believe there is more drivetrain loss with higher power due to friction and the energy loss from friction being expelled in the form of heat, but it is not a set percentage. It is not going to stay at say 15% no matter how much power you are making, even if the drivetrain all stays the same. This has been debated over many times though. We need to find an example where someone tested an engine on an engine dyno and then a wheel dyno, and then did some major power upgrades and tested the engine both ways again. And then sticky it! lol

thunderstruck507

iTrader: (18)

I agree its not a fixed percentage, and there will be many other variables too, but its def. not a set hp number like some people in the thread wanted to imply.

Counted Out

iTrader: (6)

That's a good point, I've never thought about it that way. I'm looking forward to seeing what people have to say.

Sunset'01Z

iTrader: (10)

its fairly simple physics really. you know that HP is a rate of how fast acceleration takes place. so it can be understood that it takes more hp to spin the items in the drivetrain as well as more hp to propel the car forward at increased rates of acceleration.

it's using 30 more hp to spin the same components because it's spinning them FASTER.

Sunset'01Z

iTrader: (10)

just read over that again.. and damn i'm a genius LOL

the_merv

iTrader: (88)

Right around a 100hp loss the way I figure it with the Drive Train Loss.