Chevy Corvette Forum banner
1 - 17 of 17 Posts

·
Registered
Joined
·
452 Posts
That is variable depending on thickness of fluid and outside temperature.I've heard as much as 16% when cold out .To only 14% once warmed up
Good point with the temp difference
 

·
Smokin Vendor
Joined
·
220 Posts
Anywhere between 14-18% for a RWD

FWD tend to loose alittle less; 12-15%

And AWD car loose a whole bunch lol; I've seen as high as 24%

That being said, these are VERY rough numbers and shouldn't be taken too seriously. The only real way to see how much power your car is making is to check the trap speed at the drag strip because there are still significant differences from one dyno to another.
 

·
Agent
Joined
·
2,233 Posts
In which Corvette driveline (LS2/T56 or LS3/T6060)?

Unless you can come up with a frictionless system you are always going to strapped with some loss to your driveline. The LS3 and T6060 equipped C6 fro 2008/2009 is arguably the lowest driveline loss in a Corvette. The actual loss in the newest C6 driveline is down several horsepower to the previous generations.

Frankly, use of the "percent loss" is a bit of a misnomer. Percentages have come about for comparison and bench racing. Because of manufacturing tolerances and wear The only valid way to determine the driveline loss of a particular car is to remove the engine best test the crank horsepower and then re-assemble it and rear wheel dyno it. Each car is going to be slightly different but with in a given range.

The LS2/T56 combination in use in the 2005 to 2007 C6 looses about 60 horsepower to the driveline in a manual transmission. This is where the "15%" figure comes in to play. I don't believe that a "15%" assumption is correct for the LS3. I believe that the LS3 is closer to 10 or 11% (if expressed in percentages, which I don't believe in that either). It appears that the LS3 drivetrain is loosing between 40 and 45 hp to the wheels.

The problem always comes down to the tolerances and differences vehicle to vehicle. There is no way to accurately predict crank horse power from rear wheel horse power. The only legitimate means of approximating driveline loss is if you have a baseline number for the crank on that vehicle and then can get an accurate rear wheel measurement on a dyno.

Driveline loss should not change on a given vehicle once established. What I mean by that is the same components should keep the same loss (allowing for wear) over the entire horsepower curve as modifications are made. If you use a divisor such as .85 (15% loss) you are taking more from the drivetrain as horsepower increases and that just shouldn't happen. For example:

baseline
400-60 (15%) = 340 on a stock C6 manual.

add intake and exhaust (gross about 15hp)
415-60 = 355 as the driveline didn't change so all the same friction and slop is present.

but using the conventional 15% it would show:

415-62.25(15%)= 352.75

Not too significant at lower hp ratings but think about as you begin to add a supercharger (150hp)

550-82.5 (15%)= 467.5 Why would the very same driveline now all of a sudden create a 82.5hp loss? No increased friction, so it should not.
 

·
Registered
Joined
·
334 Posts
Anywhere between 14-18% for a RWD

FWD tend to loose alittle less; 12-15%

And AWD car loose a whole bunch lol; I've seen as high as 24%

That being said, these are VERY rough numbers and shouldn't be taken too seriously. The only real way to see how much power your car is making is to check the trap speed at the drag strip because there are still significant differences from one dyno to another.
Really front wheel drives loss less? I mean the motor is closer to the rubber/road. But would guess that would make much difference. :coffeetime: Good information.

In which Corvette driveline (LS2/T56 or LS3/T6060)?

Unless you can come up with a frictionless system you are always going to strapped with some loss to your driveline. The LS3 and T6060 equipped C6 fro 2008/2009 is arguably the lowest driveline loss in a Corvette. The actual loss in the newest C6 driveline is down several horsepower to the previous generations.

Frankly, use of the "percent loss" is a bit of a misnomer. Percentages have come about for comparison and bench racing. Because of manufacturing tolerances and wear The only valid way to determine the driveline loss of a particular car is to remove the engine best test the crank horsepower and then re-assemble it and rear wheel dyno it. Each car is going to be slightly different but with in a given range.

The LS2/T56 combination in use in the 2005 to 2007 C6 looses about 60 horsepower to the driveline in a manual transmission. This is where the "15%" figure comes in to play. I don't believe that a "15%" assumption is correct for the LS3. I believe that the LS3 is closer to 10 or 11% (if expressed in percentages, which I don't believe in that either). It appears that the LS3 drivetrain is loosing between 40 and 45 hp to the wheels.

The problem always comes down to the tolerances and differences vehicle to vehicle. There is no way to accurately predict crank horse power from rear wheel horse power. The only legitimate means of approximating driveline loss is if you have a baseline number for the crank on that vehicle and then can get an accurate rear wheel measurement on a dyno.

Driveline loss should not change on a given vehicle once established. What I mean by that is the same components should keep the same loss (allowing for wear) over the entire horsepower curve as modifications are made. If you use a divisor such as .85 (15% loss) you are taking more from the drivetrain as horsepower increases and that just shouldn't happen. For example:

baseline
400-60 (15%) = 340 on a stock C6 manual.

add intake and exhaust (gross about 15hp)
415-60 = 355 as the driveline didn't change so all the same friction and slop is present.

but using the conventional 15% it would show:

415-62.25(15%)= 352.75

Not too significant at lower hp ratings but think about as you begin to add a supercharger (150hp)

550-82.5 (15%)= 467.5 Why would the very same driveline now all of a sudden create a 82.5hp loss? No increased friction, so it should not.
Great info :patriot:
 

·
Registered
Joined
·
2,690 Posts
Well said, Talon.
This:
"percent loss" is a bit of a misnomer.
Is one of my biggest pet peeves... Tons of ""800HP" / "900HP" / "1000HP"" cars out that that, if you were to believe their owners, must be losing 200+ horsepower at the driveline... Which, if true, would have the transmission oil boiling over in no time :coffeetime:
 

·
Registered
Joined
·
59 Posts
In which Corvette driveline (LS2/T56 or LS3/T6060)?

Unless you can come up with a frictionless system you are always going to strapped with some loss to your driveline. The LS3 and T6060 equipped C6 fro 2008/2009 is arguably the lowest driveline loss in a Corvette. The actual loss in the newest C6 driveline is down several horsepower to the previous generations.

Frankly, use of the "percent loss" is a bit of a misnomer. Percentages have come about for comparison and bench racing. Because of manufacturing tolerances and wear The only valid way to determine the driveline loss of a particular car is to remove the engine best test the crank horsepower and then re-assemble it and rear wheel dyno it. Each car is going to be slightly different but with in a given range.

The LS2/T56 combination in use in the 2005 to 2007 C6 looses about 60 horsepower to the driveline in a manual transmission. This is where the "15%" figure comes in to play. I don't believe that a "15%" assumption is correct for the LS3. I believe that the LS3 is closer to 10 or 11% (if expressed in percentages, which I don't believe in that either). It appears that the LS3 drivetrain is loosing between 40 and 45 hp to the wheels.

The problem always comes down to the tolerances and differences vehicle to vehicle. There is no way to accurately predict crank horse power from rear wheel horse power. The only legitimate means of approximating driveline loss is if you have a baseline number for the crank on that vehicle and then can get an accurate rear wheel measurement on a dyno.

Driveline loss should not change on a given vehicle once established. What I mean by that is the same components should keep the same loss (allowing for wear) over the entire horsepower curve as modifications are made. If you use a divisor such as .85 (15% loss) you are taking more from the drivetrain as horsepower increases and that just shouldn't happen. For example:

baseline
400-60 (15%) = 340 on a stock C6 manual.

add intake and exhaust (gross about 15hp)
415-60 = 355 as the driveline didn't change so all the same friction and slop is present.

but using the conventional 15% it would show:

415-62.25(15%)= 352.75

Not too significant at lower hp ratings but think about as you begin to add a supercharger (150hp)

550-82.5 (15%)= 467.5 Why would the very same driveline now all of a sudden create a 82.5hp loss? No increased friction, so it should not.
Good stuff Talon!:rockon6rk:
 

·
Registered
Joined
·
1,564 Posts
but using the conventional 15% it would show:

415-62.25(15%)= 352.75

Not too significant at lower hp ratings but think about as you begin to add a supercharger (150hp)

550-82.5 (15%)= 467.5 Why would the very same driveline now all of a sudden create a 82.5hp loss? No increased friction, so it should not.
Powerlabs said:
Is one of my biggest pet peeves... Tons of ""800HP" / "900HP" / "1000HP"" cars out that that, if you were to believe their owners, must be losing 200+ horsepower at the driveline... Which, if true, would have the transmission oil boiling over in no time :coffeetime:
I agree that it is mostly fixed, but it is not entirely fixed. The faster the tranny and differential accelerate, it seems like it takes more power to push the fluids. Also, is there some heat through the friction in the gears that is generated?

Take C6s, one stock, one stock with a SC, and make a couple passes down the track. I think you'll find the tranny temps in the SC car are higher. I bet the differential temps are higher too, but I've never measured differential temps.
 

·
Registered
Joined
·
2,690 Posts
I agree that it is mostly fixed, but it is not entirely fixed. The faster the tranny and differential accelerate, it seems like it takes more power to push the fluids. Also, is there some heat through the friction in the gears that is generated?

Take C6s, one stock, one stock with a SC, and make a couple passes down the track. I think you'll find the tranny temps in the SC car are higher. I bet the differential temps are higher too, but I've never measured differential temps.
Absolutely... You have a couple different things as the power goes up:
1- More power = more force between all the drivetrain components = more deformation = more power wasted.

2- More power = higher acceleration rate (as you pointed out) = higher inertial losses. This is extremely obvious on a DynoJet; the same car on a Dynojet will show less power to the wheels when fitted with a higher final drive because of that. This does not hold true for brake dynos (Mustang, Dynapack, DynoMite, engine dynos).

3- More power is USUALLY made higher up in the RPM range. The faster you spin the driveline, the more power it consumes. An LS3 makes peak power at 5900RPM and it is dissipating about 45HP in the driveline at that RPM. At redline (6500RPM), the drivetrain losses are probably close to 60HP. If you cam the car, and it now makes peak power at 6500RPM, the new flywheel power is not RWHP + 45.

But I think the real point is that driveline losses are closer to a fixed number than to a fixed percentange.
 

·
Agent
Joined
·
2,233 Posts
I agree that it is mostly fixed, but it is not entirely fixed. The faster the tranny and differential accelerate, it seems like it takes more power to push the fluids. Also, is there some heat through the friction in the gears that is generated?

Take C6s, one stock, one stock with a SC, and make a couple passes down the track. I think you'll find the tranny temps in the SC car are higher. I bet the differential temps are higher too, but I've never measured differential temps.
I agree wholeheartedy but for purposes of this thread I simply generalized my point. Anyone that has ever spoken to me (or suffered through some of my forum replies) knows that I can "go on." :lol:

The topics that you touched on would certainly fill more than a paragraph on a forum thread and likely bore many to tears so for simplicity sake, the point I was trying to get across is that the "percent loss" is less than accurate and a lot more goes in to the equation than that.
 

·
Registered
Joined
·
939 Posts
I agree wholeheartedy but for purposes of this thread I simply generalized my point. Anyone that has ever spoken to me (or suffered through some of my forum replies) knows that I can "go on." :lol:

The topics that you touched on would certainly fill more than a paragraph on a forum thread and likely bore many to tears so for simplicity sake, the point I was trying to get across is that the "percent loss" is less than accurate and a lot more goes in to the equation than that.
You, "go on"??? Never :smilielol5:

Whenever you post something like this Talon, no matter how long it may be, I read it from start to finish. They are always very informative and I usually come away with something new that I have learned.

Keep up the awesome a$$ posts and thanks for all of the help you have given all of us.
 

·
Registered
Joined
·
1,564 Posts
I agree wholeheartedy but for purposes of this thread I simply generalized my point. Anyone that has ever spoken to me (or suffered through some of my forum replies) knows that I can "go on." :lol:
I enjoy your reading your posts and they don't seem too long. :sm_party:

I tend to think of it in terms of y=mx+b but I know that if wrote that, PL would have to write a half dozen paragraphs explaining that it is non-linear and I didn't have not enough variables. :yoda: :friday:
 
1 - 17 of 17 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top