Why do people talk about power loss in a percentage? The Miata makes say 116 hp, and about 90 at the wheels, I hear. That's about 22 percent, or 26 hp. Now, say the care has a turbo installed, and now makes 200 at the wheels. Now, 22 percent is alot more hp. But it's the same trans and differential. I can't understand why it would suddenly draw a great amount of hp. But people always say "figure 25 percent for drivetrain loss"...
Joey
I made this same thread some months ago. Basically some fancy engineering maths says that a percentage is right.
Where it gets dumb is that it's pretty hard for us to find out exactly what that percentqge actually is.
92CelicaHalfTrac wrote: I made this same thread some months ago. Basically some fancy engineering maths says that a percentage is right. Where it gets dumb is that it's pretty hard for us to find out exactly what that percentqge actually is.
I don't get it! How could a t5 and a (I'm not exactly sure) ford 9 inch behind a tired old 200k mile 5.0 mustang drag down the engine less than the same drivetrain behind a fresh 5.0 with a blower? It's the same gears!
Joey
I always thought it was more like 15% for front-engine, rear drive cars.
But either way.............what does it change?
http://grassrootsmotorsports.com/forum/grm/one-of-those-discussions-driveline-loss/40778/page1/
joey48442 wrote:92CelicaHalfTrac wrote: I made this same thread some months ago. Basically some fancy engineering maths says that a percentage is right. Where it gets dumb is that it's pretty hard for us to find out exactly what that percentqge actually is.I don't get it! How could a t5 and a (I'm not exactly sure) ford 9 inch behind a tired old 200k mile 5.0 mustang drag down the engine less than the same drivetrain behind a fresh 5.0 with a blower? It's the same gears! Joey
some scientifical nonsense about actions and equal and opposite reactions.. the harder you push it, the harder it pushes back.
or something like that..
Press your hand against the top of a table then push it sideways. That's friction. Now press twice as hard and repeat. It's a lot harder to push because the friction's worse. Same thing in the tranny. Running more torque through it is going to make it get hotter - and lose more power.
In reply to kb58:
Exactly. More power means more load which means more friction and heat.
In reply to kb58:
Now that make sense to me!
Thanks!
Joey
Good read...
http://www.modified.com/tech/modp-1005-drivetrain-power-loss/index.html
All in all... there really is no satisfactory way to relate flywheel to drive wheel
oldeskewltoy wrote: Good read... http://www.modified.com/tech/modp-1005-drivetrain-power-loss/index.html All in all... there really is no satisfactory way to relate flywheel to drive wheel
Pretty much. The only way is to dyno the engine and then dyno it in the car. That will get you close. But you need to use all the accessories and exhaust that is in the car to get it right. Even then it will never be 100% correct, just too many variables to deal with.
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