ManMuchwano93z28

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

englundjd

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

F0x Slaughter

T56 with a 10 bolt and 3.42s has been tested to lose about 12.5% drivetrain, obviously automatic is higher.

So a manual you are looking around 340bhp.

ManMuchwano93z28

I have a automatic and they put my cutout where the cat was cause I cut those off

bowtienut

iTrader: (1)

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.

quik95lt1

iTrader: (7)

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........

bowtienut

iTrader: (1)

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).

quik95lt1

iTrader: (7)

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

Quazz

iTrader: (1)

^dammit, now you have me thinking this.... LOL

bowtienut

iTrader: (1)

It's basic when you break it down to what's going on at every bearing, bushing, etc. in the driveline. Believe it or not, it's a simple static analysis, not even dynamic.
-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.

F0x Slaughter

Correct.

If the friction remains the same and you apply more power to something but the same amount of friction then it is going to lose more power.

speed_demon24

iTrader: (6)

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.

SS RRR

iTrader: (2)

Maintaining RPM is not where there is a loss. It's accelerating from one point to another. Force is applied, more force, more friction, more loss.

1994Z28Lt1

iTrader: (1)

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

quik95lt1

iTrader: (7)

i wasn't thinking of it that way....in a static state it makes sense, I wasn't thinking acceleration....thanks for the explanations

z_speedfreak

iTrader: (3)

Yes thank you master sensi, always curious about that too

Quazz

iTrader: (1)

Then theres the whole business of converter slip in autos. that will foul up a dyno reading. Even though that doesnt decrease power.... But the size and rotational mass of the converter could.