How much drivetrain loss is there..??
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Launching!
Joined: May 2012
Posts: 235
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From: Gurnee IL
How much drivetrain loss is there..?? Hi I always wondered how much drivetrain loss is there in a automatic vs a manual my car is making 302 rwhp and 310 touqre but I heard that a cut out adds 10rwhp but how much power am I making to the block..? I wanna get my car to 400 block hp
TECH Regular
Joined: Dec 2011
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From: Hastings, Nebraska
sooo your right about an auto loosing more power but are you an auto or a manual? lol
a cutout will prolly gain you about 12-15 hp if put in the y-pipe of immediatly after it
to get to around 400 flywheel hp you'll prolly need a small cam and 1.6rr
a cutout will prolly gain you about 12-15 hp if put in the y-pipe of immediatly after it
to get to around 400 flywheel hp you'll prolly need a small cam and 1.6rr
Thread Starter
Launching!
Joined: May 2012
Posts: 235
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From: Gurnee IL
I have a automatic and they put my cutout where the cat was cause I cut those off
For autos with stock or moderately-stalled efficient converters like Yank or Vig, about 18% with typical NA setups.
For power adder setups where there's much more torque at a given rpm, the loss increases.
For power adder setups where there's much more torque at a given rpm, the loss increases.
ok im gonna complicate this one lol......IMO parasitic drivetrain loss is not relative to hp via %, I can see it being relative to rpm due to friction coefficients increasing as heat increases at higher drive train rpm but not due to the amount of power applied to it..........ie. if a car has x drivetrain weight it will take y power to spin it at a certain rpm with no load at the end of the drive train.......lets say it takes 30hp just for argument sake to spin a stock drive train at 5000rpm.........well in that case a 300hp stocker should make 270 at the hub.....and a 1000hp turbo motor should make 970.....the more power applied should have no effect on the loss.........thusly I don't buy the percentage thing........
If you assume the OP was referring to hp numbers on an inertia dyno, where there is always a load applied during the run, then % DOES apply.
The two main differences in auto vs manual are:
1. the trans front pump (independent of load, dependent on rpm)
2. the torque converter (highly dependent on load).
The two main differences in auto vs manual are:
1. the trans front pump (independent of load, dependent on rpm)
2. the torque converter (highly dependent on load).
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ii know what your saying pat but I still have a tough time wrapping my head around the percentage thing, just doesn't seem right from a physics standpoint to me......why would a 600hp motor loose 120hp and a 300hp motor loose 60hp spinning the EXACT same drivetrain at the same rpm.......just doesn't make sense
btw not arguing just talking about a thing ive always wondered about
btw not arguing just talking about a thing ive always wondered about
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ii know what your saying pat but I still have a tough time wrapping my head around the percentage thing, just doesn't seem right from a physics standpoint to me......why would a 600hp motor loose 120hp and a 300hp motor loose 60hp spinning the EXACT same drivetrain at the same rpm.......just doesn't make sense
btw not arguing just talking about a thing ive always wondered about
btw not arguing just talking about a thing ive always wondered about
-The coefficient of friction stays constant (at least for our talking purposes here).
-Frictional force (seen as torque or hp loss on the dyno) is reaction load (normal load, ie. load perpendicular to direction of motion) x coefficient.
-Reaction load in each bearing/bushing is linearly proportional to the load being transmitted (torque) through the driveline, therefore frictional force (torque loss) is also linearly proportional (that's that percentage thing
) to the transmitted torque. 
ok im gonna complicate this one lol......IMO parasitic drivetrain loss is not relative to hp via %, I can see it being relative to rpm due to friction coefficients increasing as heat increases at higher drive train rpm but not due to the amount of power applied to it..........ie. if a car has x drivetrain weight it will take y power to spin it at a certain rpm with no load at the end of the drive train.......lets say it takes 30hp just for argument sake to spin a stock drive train at 5000rpm.........well in that case a 300hp stocker should make 270 at the hub.....and a 1000hp turbo motor should make 970.....the more power applied should have no effect on the loss.........thusly I don't buy the percentage thing........
ii know what your saying pat but I still have a tough time wrapping my head around the percentage thing, just doesn't seem right from a physics standpoint to me......why would a 600hp motor loose 120hp and a 300hp motor loose 60hp spinning the EXACT same drivetrain at the same rpm.......just doesn't make sense
So gears and bearings aren't going to have any increased frictional losses when it's loaded up with over 3x the force? Not to mention inertia losses from spinning up faster. If that was true it wouldn't matter if you pressed on the brake pedal with 5lbs or 50lbs of force, the car would slow down at the same speed.
Exactly the point I was going to make but was beaten to it. Another way to look at it... There is a reason that when you start making some serious power you need to think about cooling things like differentials and transmissions. The extra heat generated in your transmission, differential, and bearings is simply horsepower/BTU's/Fuel/power not making it to the pavement
