% of power lost in drivetrain

[71dustar]

What is an approximate % of power lost due to the drivetrain in a-bodys and does the 727 vs 904 vs 833 have a big difference?

 

[two_70darts]

not sure but im thinking the 727 draws 20 plus horse and the 4 speed is half that but the guys that are up to date will chime in for sure:happy10:l

 

[rmchrgr]

Generally, there's a 20% loss of HP through the drive line regardless of the car but there is not set number. So let's say you have a 450HP engine, you'd likely end up with around 360 at the wheels. % would probably be lower with a correctly-geared manual since there's less getting in the way of a direct connection.

 

[70aarcuda]

an old car craft magazine said...

904 requires 18 hp
727 requires 45 hp..

dont know about the 833

 

[FISHBREATH]

I read somewhere that all automatics "draw" more power than manuals. "Draw" is probably not the correct term, lose is probably more realistic because of inherent slippage in the auto trans.

 

[Boxer]

Can we really use a set % for all engines? If we use the 20% on a 450HP motor with a 727, that gives the approximate rear wheel HP of 360. So, if we had a 600HP motor, this equates to 480HP to the rear wheels. It seams that there should be more of a set number required to run the drive system. If we use the 20% rule, why does the 600hp scenario require 120hp vs 90hp from the 450hp scenario. Just wondering what the thoughts are on this, thanks.

 

[Burntorange70]

Can we really use a set % for all engines? If we use the 20% on a 450HP motor with a 727, that gives the approximate rear wheel HP of 360. So, if we had a 600HP motor, this equates to 480HP to the rear wheels. It seams that there should be more of a set number required to run the drive system. If we use the 20% rule, why does the 600hp scenario require 120hp vs 90hp from the 450hp scenario. Just wondering what the thoughts are on this, thanks.

Sucks don't it? But that is just the way it is. It has nothing to do with the motor at all. It is the parts you put after the motor that determin how much loss you will have. Even your tires play into it.


So it is unique to every set up.

 

[abodyhotrod]

rearend and unsprung weight will add to it as well, say a dana 60 vs a 8 3/4 the lighter of the two will move easier. same with rims and tires.
i believe a high stall is responsible for sum % loss as well.
if you lose 100 hp thats a drag. you need to go lighter and tighter.

 

[player1up]

Wicked complicated subject, but it's not exactly as easy as putting a horsepower number on it or even a percentage. Now I'm only guessing but I would start with how much the internals weigh and how much drag the trans fluid puts on the components at every rpm ( drag goes up as speed increases )..... ok so it would be easier to dyno the motor then slang it in a car and dyno again to see.... at least it would make my head hurt less
All I know is that a non-lockup converter will always be slipping and thus always be gobbling up power, and after swapping to a 4-speed, the slant "feels" much more peppy
SO.. does anyone have engine dyno vs chassis dyno results??

 

[71dustar]

so basically the type of trans with different internals and oil weight plus drive shaft, rearend gears, rearend oil, and wheels/tire contribute to power loss.

Has anyone found a good combo of drivetrain parts to decrease the amount of power loss?