Someone said recently that the ZF losses about 100 HP, is that correct? 25% seems about right if talking about a 400 hp motor
Original Post
Replies sorted oldest to newest
The HP lost through drivetrain friction is not a set figure, but is of course proportional to the flywheel horsepower.
From my experience, a generally agreed figure of roughly a 22% loss of horsepower is used by many owners.
400 FWHP becomes 312 RWHP.
Larry
From my experience, a generally agreed figure of roughly a 22% loss of horsepower is used by many owners.
400 FWHP becomes 312 RWHP.
Larry
Agreed with Larry. The difference between a Pantera's horsepower measured on an engine dyno and measured on a chassis dyno is usually about 20%.
Though the numbers have been documented often enough to generate this rule of thumb value of 20%, I still have a hard time wrapping my my around just where the lost horsepower goes.
Put another way, if I take a 100 horsepower engine and consume all of its power in an engine brake, doing no work except converting it to heat, I'm going to have a rather hot tank of water pretty fast. Considering a ZF doesn't have any heat exchanging ability other than some pretty skimpy fins, where does it go?
Put another way, if I take a 100 horsepower engine and consume all of its power in an engine brake, doing no work except converting it to heat, I'm going to have a rather hot tank of water pretty fast. Considering a ZF doesn't have any heat exchanging ability other than some pretty skimpy fins, where does it go?
Two words..."Parasitic Loss".
Look at the horsepower loss in driving/spinning a supercharger...
OCT
12
Efficiency of Dodge Hellcat supercharger slaps 2015 Corvette C7 Z06 LT4 supercharger silly and makes it look obsolete
The parasitic losses caused by the compressor drag on the crankshaft is a given. Just like with any mechanically powered device, certain power is required to produce power. However, that parasitic loss is not a set number, and like with everything else, the lower the loss, the higher the efficiency of the supercharging system.
A quick comparison between the efficiency of the supercharging system used on Dodge Hellcat motor versus its +General Motors counterpart used on LT4 engine quickly reveonal a truly embarrassing lack of thought and development coming from +Tadge Juechter and his team of geniuses who apparently remain under mistaken impression they accomplished something meaningful.
The parasitic loss caused by a supercharger typically ranges between 15-20 percent for a typical supercharger installed on a large displacement push rod engine, resulting in about 120-140 hp lost to run the compressor. In addition to drag on the crankshaft, efficiency is lost to air leakage and subsequent pressure loss. Other factors affecting this efficiency is the ability of the heat exchangers to cool the air rapidly and again, minimizing the pressure losses while doing so. Of course, the maximum boost level affects the efficiency as well, with higher allowable boost resulting in less losses-due to the physics laws that govern the basics of forced air induction.
Interestingly enough, GM approach is completely different from the previous design, 2.3l positive displacement, with 9:1 compression ratio and 10.5 psi maximum boost. This time around, the compressor size has been reduced to 1.7l, engine compression ratio upped to 10:1 with the maximum boost reduced to 9.5 psi. Clearly, this an attempt to increase the responsiveness of the 3600 lbs car.
However, there is a price to pay here and it is directly related to the size of the supercharger. Due to those pesky laws of physics, the faster the compressor spins and lower the boost pressure, the lower the efficiency of the resulting system is. The loss of efficiency is pretty obvious. 430 hp rated LS3 vs 638 hp LS9 means 208 hp. How about LT1 and LT4? The difference between 460 and 650 is exactly 190 hp or 18 hp loss from the previous generation. Not a significant loss but nevertheless, it is a loss and with such a porker like new Z06, every little bit helps. What makes this loss such a failure is the presence of so called performance enhancing technologies such as VVT and DI. Apparently they do not add up to performance oriented improvements? Certainly, the price to pay for improvements in off idle response is a heavy one. The low boost ceiling clearly indicates that longevity of the current design overshadowed any potential performance gains.
But... how does the efficiency of the LT4 supercharger compare to the Dodge Hellcat supercharger efficiency?
Unlike the GM fast spinning small diameter supercharger, Chrysler decided to go with the design that is not that much different than the LS9 used, with slightly larger supercharger and very impressive maximum boost at 11.5 psi. The engine compression stands at 9.5:1 which is low enough to support the maximum boost. Between larger compressor spinning at lower speed, both cooler and more efficient and superior supercharger cooling, the 707 hp output is actually a very conservative figure while providing consistent performance for much longer than strained LT4 design.
Unlike GM who took the Eaton route, Chrysler SRT team picked something considerably more technologically advanced and well established in the super high performance circles: IHI who happened to supply AMG superchargers which currently are firmly at the top of high performance game, with no other superchargers coming even close.
Its twin-screw rotors are specially coated with a proprietary formula of polyimide and other resins; nanometer-sized, wear-resistant particles; and solid lubricants, such as PTFE (Teflon). The coating accommodates tighter tolerances, cutting air leakage for higher efficiency.
So what is the result of using this outstanding supercharger? The parasitic loss from the supercharger is only 80 hp!!! This figure is very impressive by any standard but especially impressive when compared to both LS9 and LT4 systems. Ironically enough, the LT4 system is considerably less efficient than the old LS9 supercharger. While the LS9 parasitic losses resulted in 120 hp loss, the LT4 parasitic losses came in at 140 hp.
Of course Tadge Juechter is not worried about these small details but the ultimate outcome does not look very good for horsepower increase for Z06 car while the Hellcat potential is virtually still untapped. Oh and it shows especially well at the strip, quickly exposing inferior GM design philosophy and technologies
Look at the horsepower loss in driving/spinning a supercharger...
OCT
12
Efficiency of Dodge Hellcat supercharger slaps 2015 Corvette C7 Z06 LT4 supercharger silly and makes it look obsolete
The parasitic losses caused by the compressor drag on the crankshaft is a given. Just like with any mechanically powered device, certain power is required to produce power. However, that parasitic loss is not a set number, and like with everything else, the lower the loss, the higher the efficiency of the supercharging system.
A quick comparison between the efficiency of the supercharging system used on Dodge Hellcat motor versus its +General Motors counterpart used on LT4 engine quickly reveonal a truly embarrassing lack of thought and development coming from +Tadge Juechter and his team of geniuses who apparently remain under mistaken impression they accomplished something meaningful.
The parasitic loss caused by a supercharger typically ranges between 15-20 percent for a typical supercharger installed on a large displacement push rod engine, resulting in about 120-140 hp lost to run the compressor. In addition to drag on the crankshaft, efficiency is lost to air leakage and subsequent pressure loss. Other factors affecting this efficiency is the ability of the heat exchangers to cool the air rapidly and again, minimizing the pressure losses while doing so. Of course, the maximum boost level affects the efficiency as well, with higher allowable boost resulting in less losses-due to the physics laws that govern the basics of forced air induction.
Interestingly enough, GM approach is completely different from the previous design, 2.3l positive displacement, with 9:1 compression ratio and 10.5 psi maximum boost. This time around, the compressor size has been reduced to 1.7l, engine compression ratio upped to 10:1 with the maximum boost reduced to 9.5 psi. Clearly, this an attempt to increase the responsiveness of the 3600 lbs car.
However, there is a price to pay here and it is directly related to the size of the supercharger. Due to those pesky laws of physics, the faster the compressor spins and lower the boost pressure, the lower the efficiency of the resulting system is. The loss of efficiency is pretty obvious. 430 hp rated LS3 vs 638 hp LS9 means 208 hp. How about LT1 and LT4? The difference between 460 and 650 is exactly 190 hp or 18 hp loss from the previous generation. Not a significant loss but nevertheless, it is a loss and with such a porker like new Z06, every little bit helps. What makes this loss such a failure is the presence of so called performance enhancing technologies such as VVT and DI. Apparently they do not add up to performance oriented improvements? Certainly, the price to pay for improvements in off idle response is a heavy one. The low boost ceiling clearly indicates that longevity of the current design overshadowed any potential performance gains.
But... how does the efficiency of the LT4 supercharger compare to the Dodge Hellcat supercharger efficiency?
Unlike the GM fast spinning small diameter supercharger, Chrysler decided to go with the design that is not that much different than the LS9 used, with slightly larger supercharger and very impressive maximum boost at 11.5 psi. The engine compression stands at 9.5:1 which is low enough to support the maximum boost. Between larger compressor spinning at lower speed, both cooler and more efficient and superior supercharger cooling, the 707 hp output is actually a very conservative figure while providing consistent performance for much longer than strained LT4 design.
Unlike GM who took the Eaton route, Chrysler SRT team picked something considerably more technologically advanced and well established in the super high performance circles: IHI who happened to supply AMG superchargers which currently are firmly at the top of high performance game, with no other superchargers coming even close.
Its twin-screw rotors are specially coated with a proprietary formula of polyimide and other resins; nanometer-sized, wear-resistant particles; and solid lubricants, such as PTFE (Teflon). The coating accommodates tighter tolerances, cutting air leakage for higher efficiency.
So what is the result of using this outstanding supercharger? The parasitic loss from the supercharger is only 80 hp!!! This figure is very impressive by any standard but especially impressive when compared to both LS9 and LT4 systems. Ironically enough, the LT4 system is considerably less efficient than the old LS9 supercharger. While the LS9 parasitic losses resulted in 120 hp loss, the LT4 parasitic losses came in at 140 hp.
Of course Tadge Juechter is not worried about these small details but the ultimate outcome does not look very good for horsepower increase for Z06 car while the Hellcat potential is virtually still untapped. Oh and it shows especially well at the strip, quickly exposing inferior GM design philosophy and technologies
Two Words..."Parasitic Loss"
Here's a very interesting article in my opinion about parasitic loss in driving/spinning a supercharger in the New Dodge Hellcat & Corvette engines.
http://corvettec7fiasco.blogsp...f-dodge-hellcat.html
Can you imagine loosing OVER 140 HP driving/spinning a supercharger???!!!...Mark
Here's a very interesting article in my opinion about parasitic loss in driving/spinning a supercharger in the New Dodge Hellcat & Corvette engines.
http://corvettec7fiasco.blogsp...f-dodge-hellcat.html
Can you imagine loosing OVER 140 HP driving/spinning a supercharger???!!!...Mark
quote:Originally posted by LF - TP 2511:
The HP lost through drivetrain friction is not a set figure, but is of course proportional to the flywheel horsepower.
From my experience, a generally agreed figure of roughly a 22% loss of horsepower is used by many owners.
400 FWHP becomes 312 RWHP.
Larry
I have been told by a very well know Pantera builder that the ZF horse power loss is somewhere between 80 and 90. What I have never understood about the use of a percentage is that how putting more power into the ZF would create more horse power loss if nothing is done to the transaxle or any other part of the drive train. I am sure we have some mechanical engineers on this forum that can explain this.
If by the term "power" you are referring to "RPMS" then yes, a "Greater" power loss is the direct result of having to spin/turn the ZF transmission at higher RPMS.quote:Originally posted by JFFR:quote:Originally posted by LF - TP 2511:
The HP lost through drivetrain friction is not a set figure, but is of course proportional to the flywheel horsepower.
From my experience, a generally agreed figure of roughly a 22% loss of horsepower is used by many owners.
400 FWHP becomes 312 RWHP.
Larry
I have been told by a very well know Pantera builder that the ZF horse power loss is somewhere between 80 and 90. What I have never understood about the use of a percentage is that how putting more power into the ZF would create more horse power loss if nothing is done to the transaxle or any other part of the drive train. I am sure we have some mechanical engineers on this forum that can explain this.
If you had a 300 Hp engine turning the ZF transmission at 4,000 RPMS & a 500 HP engine turning the ZF at 4,000 RPMS the percentage of power loss for both engines would be the same as a specific amount of HP would be required to turn the ZF at 4,000 RPMS whether it is being turned by a 300 HP engine or a 500 HP engine...Mark
quote:Originally posted by 1Rocketship:If by the term "power" you are referring to "RPMS" then yes, a "Greater" power loss is the direct result of having to spin/turn the ZF transmission at higher RPMS.quote:Originally posted by JFFR:quote:Originally posted by LF - TP 2511:
The HP lost through drivetrain friction is not a set figure, but is of course proportional to the flywheel horsepower.
From my experience, a generally agreed figure of roughly a 22% loss of horsepower is used by many owners.
400 FWHP becomes 312 RWHP.
Larry
I have been told by a very well know Pantera builder that the ZF horse power loss is somewhere between 80 and 90. What I have never understood about the use of a percentage is that how putting more power into the ZF would create more horse power loss if nothing is done to the transaxle or any other part of the drive train. I am sure we have some mechanical engineers on this forum that can explain this.
If you had a 300 Hp engine turning the ZF transmission at 4,000 RPMS & a 500 HP engine turning the ZF at 4,000 RPMS the percentage of power loss for both engines would be the same as a specific amount of HP would be required to turn the ZF at 4,000 RPMS whether it is being turned by a 300 HP engine or a 500 HP engine...Mark
Thank you for that explanation. It is exactly what I was trying to say. It also confirms that my engine did lose 90 horse power through the drive train when it was tuned on the chassis dyno. I already had the engine dyno horse power number and the figures are correct.
Glad to be of assistance!...Markquote:Originally posted by JFFR:quote:Originally posted by 1Rocketship:If by the term "power" you are referring to "RPMS" then yes, a "Greater" power loss is the direct result of having to spin/turn the ZF transmission at higher RPMS.quote:Originally posted by JFFR:quote:Originally posted by LF - TP 2511:
The HP lost through drivetrain friction is not a set figure, but is of course proportional to the flywheel horsepower.
From my experience, a generally agreed figure of roughly a 22% loss of horsepower is used by many owners.
400 FWHP becomes 312 RWHP.
Larry
I have been told by a very well know Pantera builder that the ZF horse power loss is somewhere between 80 and 90. What I have never understood about the use of a percentage is that how putting more power into the ZF would create more horse power loss if nothing is done to the transaxle or any other part of the drive train. I am sure we have some mechanical engineers on this forum that can explain this.
If you had a 300 Hp engine turning the ZF transmission at 4,000 RPMS & a 500 HP engine turning the ZF at 4,000 RPMS the percentage of power loss for both engines would be the same as a specific amount of HP would be required to turn the ZF at 4,000 RPMS whether it is being turned by a 300 HP engine or a 500 HP engine...Mark
Thank you for that explanation. It is exactly what I was trying to say. It also confirms that my engine did lose 90 horse power through the drive train when it was tuned on the chassis dyno. I already had the engine dyno horse power number and the figures are correct.
Remember also that the higher the torque the harder the gears are pressing together therefore the higher the friction. This is why there is a percentage rather than an solid figure.
JFFR I'm interested in seeing the two dyno sheets. I don't know if most people are lucky enough to get both, I only have the chassis dyno numbers and was curious through drivetrain loss and ansa mufflers what my engine may be making for power.
I had heard before thatost automatic transmissions loose around 20 - 25 % and manuals were around 15%. Is there a reason that the ZF may loose a larger percentage?
I had heard before thatost automatic transmissions loose around 20 - 25 % and manuals were around 15%. Is there a reason that the ZF may loose a larger percentage?
IIRC, my Ansa mufflers cost me 35 RWHP.
First keep in mind the ZF duplicates the functions of BOTH a transmission and a rear axle. Comparison of a transmission's losses to a "transaxle's" losses is possibly not an apples to apples comparison. It depends upon how those losses were determined.
What we're referring to is horsepower differences between what is measured with an engine dyno and what is measured with a chassis dyno. That encompasses more than just the losses via the transaxle alone. The 20% loss (or 22% as per Larry) is the sum of several factors; the transaxle is not the lone source of horsepower loss. Besides the friction and weight of the rotating parts of the transmission and rear axle, or of the transaxle in the Pantera's case, other contributors to power loss include:
What we're referring to is horsepower differences between what is measured with an engine dyno and what is measured with a chassis dyno. That encompasses more than just the losses via the transaxle alone. The 20% loss (or 22% as per Larry) is the sum of several factors; the transaxle is not the lone source of horsepower loss. Besides the friction and weight of the rotating parts of the transmission and rear axle, or of the transaxle in the Pantera's case, other contributors to power loss include:
- air temperature differences, the air in the Pantera engine bay is quite hot (horsepower decreases 1% for every 10 degrees F the air temperature goes up)
- exhaust system differences, for instance the ANSA mufflers are most likely not used on the engine dyno
- weight of all rotating parts downstream of the flywheel besides the parts within the transaxle, such as those big heavy 335 section tires.
- friction in all the drivetrain besides the friction within the transaxle, such as that possibly contributed by the u-joints
- clutch slippage, if any
Tajonquote:I had heard before that most automatic transmissions lose around 20 - 25 % and manuals were around 15%. Is there a reason that the ZF may lose a larger percentage?
The hp loss thru any manual transmission is (among other things) a function of the gear design and the meshing efficiency. A Ford/ZF factory memo circa 1970 mentioned ZF's own number was 1.3 for their 'friction coefficient'. I take that to mean a 30% loss from input to outputs for trans model 5DS-25/2. It should be obvious that 30% of 300 hp will be less numerically than 30% of 500....
Second: dyno operators sell you time and can give you any figure you tell them you expect. There are so many fudge-factors available in any dyno software. A dyno is a comparative tuning tool for successive runs, not a quantitative one for a single-run amount.
With chassis dynos it also depends on what gear the trans is in. A 1:1 gear ratio is the most accurate but the ZF has no such ratio. Judy's auto-trans Z-28 gave 240 bhp in 'Drive' and 250 bhp in '2' on one chassis dyno. That only tells me the auto trans & fluid coupling system is a little more efficient in ratio '2' than in 'D'. The engine made the same power; it just didn't deliver all of it to the wheels in 'D'.
Modern dynos do not require a 1:1 gear ratio. Most are eddy current brake units and have a lever arm and load cell to instantaneously measure torque which is then compared to road speed and engine rpm to calculate a power number rather than the old inertia dynos which simply measured how fast you could ramp up the speed on a gigantic drum filled with concrete. That being said every different brand of dyno will produce a different number. Sometimes this is by as much as 15-20 percent. Comparing an engine dyno number to a chassis dyno number would IMHO be useless in telling you drive train loss as the variance is too great. As was said before dynos are a tuning tool only to be used to test successive runs.
When I asked Lloyd Butfoy about the loss several years ago for my 550 HP rated motor he said expect to lose 100 horsepower. I too have wondered about the strict percent rule and where does the heat go if that is true for all horsepower levels. I could understand RPM and a curved figure for x horsepower per RPM but not the flat rate per horsepower.
quote:
Originally posted by GTPowered:
... 550 HP rated motor he said expect to lose 100 horsepower ...
That's 18%.
The point is nobody has an "exacting" figure. Speaking for myself all I am trying to do is offer a ballpark way to calculate "about" what to expect.
If I recall correctly, there is a dyno housed in the shop on the NE corner of Hayden and Raintree in Scottsdale Arizona that can measure drive train loss. Any Phoenix area guys been there and can verify?