Drivetrain efficiency
- Thread starter xring
- Start date
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ramcharger
Dismember
15% to 20%
Ramcharger nailed it preety good. The "%" difference is in which tranny you have as well as torque converter effeciency. (SP?)
Manual tranny's transmit power more effeciently.
Then all the power that goes throgh the driveshaft and rear, axle to tire, whew! All that length eats power.
Alot of people like to know the rear wheel HP because that is what is hitting the ground in reality/actual-ality.
Power at the crank is simpley what the engine makes and is not what is at the ground. Knowing conveter/trans power consumption would be about key to figureing the difference out.
When an engine is on the dynometer, to find out the power it makes, the tunning begins and hopefully you figure out what the engine needs. But that is only on the dyno and real world outdoor use can change this. A dyno is a great tool for tuning every last bit of the engine out.
It is a great tool period. Excellet fror bragging rights. Be it engine on the dyno or vehicle on the rotors.
Burntorange70
Well-Known Member
The weight of the clutch and flywheel in a manual trans can also have a big effect on the power you make at the wheels. The more it weighs the more power you loose. As does the diameter the bigger the clutch the more power you loose.
moper
Well-Known Member
Like Ram. I use 15% for manual, 18% for auto. Also, most chassis dynos have a fairly wide margine of error too...
1wild&crazyguy
Banned
That much? and inertia? + or -?:read2:
Burntorange70
Well-Known Member
WOW! Good read. I like it.
I am having a hard time getting my head around this percent thing. I thought that it took a certian amount of HP to run a tranny or a rearend, not a percent. If you have a 300HP engine and a 700HP engine would it not take the same amount of HP to turn the rest of the drivetrain? If you use 15% then the 300 HP engine would lose 45 HP to the drivetrain while the 700 HP engine would lose 105 HP to the same drivetrain. This just doesn't make sense to me.
Jack
Jack
ramcharger
Dismember
The more torque you have the more is lost in friction and dissipated as heat. Think of a manual transmission. The gears on the shafts are trying to push both shafts away from each other, the more torque there is the harder it's trying to blow the tranny apart. Now add in that higher HP is generally made at higher rpm. The faster the shafts spin, the more rotational friction the engine sees. Then there are bearing and bushing loads, etc.
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