Driveline HP Loss
Thread Starter
Racer
Joined: Nov 2013
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From: tampa fl
Driveline HP Loss
It is generally agreed that there is about a 15% HP loss between the crankshaft and the rear wheels. The 436HP LS3 makes about 380HP at the wheels, or a loss of 56HP. Lets assume that the engine is then modded and dyno'd at 490HP at the rear wheels. Does the 15% horsepower loss rule still apply which would mean approximately 563HP at the crank or, since no other changes were made in the driveline the original loss of 56HP would still be the rule which would mean 546HP at the crank.
Safety Car
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From: Baton Rouge LA
St. Jude Donor '14, '16
It's hard to say because I think the number of people who have their engine dyno'd alone after doing a few mods is quite low.
My gut feeling is that you'd "lose" the percentage.
My gut feeling is that you'd "lose" the percentage.
Race Director
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It is generally agreed that there is about a 15% HP loss between the crankshaft and the rear wheels. The 436HP LS3 makes about 380HP at the wheels, or a loss of 56HP. Lets assume that the engine is then modded and dyno'd at 490HP at the rear wheels. Does the 15% horsepower loss rule still apply which would mean approximately 563HP at the crank or, since no other changes were made in the driveline the original loss of 56HP would still be the rule which would mean 546HP at the crank.
No, the drive line power lose is a constant, and the % amounts are based on stock power lose alone.
So on a say a manual trans C6, you have about a 61HP lose through the drive line. As the HP it increased through mods and no changes to the drive line, the drive line lose stays at the same 61Hp lose.
Pro
Joined: May 2009
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From: Milwaukee WI
St. Jude Donor '13
Driveline HP Loss
Originally Posted by Dano523
So on a say a manual trans C6, you have about a 61HP lose through the drive line. As the HP it increased through mods and no changes to the drive line, the drive line lose stays at the same 61Hp lose.
Thread Starter
Racer
Joined: Nov 2013
Posts: 317
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From: tampa fl
I would assume that for a 1000hp car, there were substantial changes made to the driveline to support that power that may change the 61hp constant. In my example, the drive line would stay as stock. It makes sense (at least in my head) that if nothing in the drive line changes that the HP loss would remain the same after the engine was modded.
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Racer
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From: tampa fl
Safety Car
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From: Bay Area CA
Even adding horsepower using a supercharger will not affect powertrain loss. Adding a supercharger will increase the loss of HP at the flywheel, but the loss will be more than compensated by the overall gain in HP.
Last edited by Mike's LS3; Jul 21, 2015 at 05:38 PM.
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Team Owner
Joined: Jun 2005
Posts: 46,295
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From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
I don't know if you can go by "conventional wisdom" or anything that is not factual, based on a particular car/engine, and then backed up by proof of many examples. After all, unless I'm very wrong, I've not heard of a <5% loss from an entire drivetrain, but look at these two posts over on C7Z06:
Post 39 and 40
"Tripleblk6spd
I have dyno'd a half a dozen stock c6 Z's, and they all make 480ish to the wheels with the average at about 483. I am talking on the same dyno to my c7 z."
"Realistic dyno? The only dyno I trust is the one that is consistent and agrees with the trap speed at the track, and that is a dynojet. Doesn't matter which dyno you use, the delta is the same! My c7 made 531whp on hot pulls stock. The c6 Z's I have dyno'd make 480's stock. BOTH cars trap 126 to 127 in the AZ heat... Do the math, my c7 scaled 3550 without driver, the c6 Z's scale about 3150 without driver. It all agrees. I have used every dyno out there on numerous occasions tuning cars all over the country, and only one will NAIL the trap speeds consistently, and that is a Dynojet."
That was in answer to my question to what he stated as fact that a stock C7 Z06 making 650 crank horsepower (chp) LOSES 130 chp and would dyno on a hot lapping road course at 530 rwhp---which is about a 20% loss from 650. But, the most important part is that he said he regularly sees C6 Z06s dyno at 480 rwhp for a car that has chp of 505---and that is less than a 5% drivetrain loss. If anyone else has seen that number/figure, please advise because I haven't yet.
Long way of saying, there are many answers to the question of drivetrain loss, loss factor, rules of thumb, etc.
From this thread: https://www.corvetteforum.com/forums...ped-for-2.html
Post 39 and 40
"Tripleblk6spd
I have dyno'd a half a dozen stock c6 Z's, and they all make 480ish to the wheels with the average at about 483. I am talking on the same dyno to my c7 z."
"Realistic dyno? The only dyno I trust is the one that is consistent and agrees with the trap speed at the track, and that is a dynojet. Doesn't matter which dyno you use, the delta is the same! My c7 made 531whp on hot pulls stock. The c6 Z's I have dyno'd make 480's stock. BOTH cars trap 126 to 127 in the AZ heat... Do the math, my c7 scaled 3550 without driver, the c6 Z's scale about 3150 without driver. It all agrees. I have used every dyno out there on numerous occasions tuning cars all over the country, and only one will NAIL the trap speeds consistently, and that is a Dynojet."
That was in answer to my question to what he stated as fact that a stock C7 Z06 making 650 crank horsepower (chp) LOSES 130 chp and would dyno on a hot lapping road course at 530 rwhp---which is about a 20% loss from 650. But, the most important part is that he said he regularly sees C6 Z06s dyno at 480 rwhp for a car that has chp of 505---and that is less than a 5% drivetrain loss. If anyone else has seen that number/figure, please advise because I haven't yet.
Long way of saying, there are many answers to the question of drivetrain loss, loss factor, rules of thumb, etc.
From this thread: https://www.corvetteforum.com/forums...ped-for-2.html
Safety Car
Joined: Nov 2007
Posts: 4,436
Likes: 875
From: Bay Area CA
I don't know if you can go by "conventional wisdom" or anything that is not factual, based on a particular car/engine, and then backed up by proof of many examples. After all, unless I'm very wrong, I've not heard of a <5% loss from an entire drivetrain, but look at these two posts over on C7Z06:
Post 39 and 40
"Tripleblk6spd
I have dyno'd a half a dozen stock c6 Z's, and they all make 480ish to the wheels with the average at about 483. I am talking on the same dyno to my c7 z."
"Realistic dyno? The only dyno I trust is the one that is consistent and agrees with the trap speed at the track, and that is a dynojet. Doesn't matter which dyno you use, the delta is the same! My c7 made 531whp on hot pulls stock. The c6 Z's I have dyno'd make 480's stock. BOTH cars trap 126 to 127 in the AZ heat... Do the math, my c7 scaled 3550 without driver, the c6 Z's scale about 3150 without driver. It all agrees. I have used every dyno out there on numerous occasions tuning cars all over the country, and only one will NAIL the trap speeds consistently, and that is a Dynojet."
That was in answer to my question to what he stated as fact that a stock C7 Z06 making 650 crank horsepower (chp) LOSES 130 chp and would dyno on a hot lapping road course at 530 rwhp---which is about a 20% loss from 650. But, the most important part is that he said he regularly sees C6 Z06s dyno at 480 rwhp for a car that has chp of 505---and that is less than a 5% drivetrain loss. If anyone else has seen that number/figure, please advise because I haven't yet.
Long way of saying, there are many answers to the question of drivetrain loss, loss factor, rules of thumb, etc.
From this thread: https://www.corvetteforum.com/forums...ped-for-2.html
Post 39 and 40
"Tripleblk6spd
I have dyno'd a half a dozen stock c6 Z's, and they all make 480ish to the wheels with the average at about 483. I am talking on the same dyno to my c7 z."
"Realistic dyno? The only dyno I trust is the one that is consistent and agrees with the trap speed at the track, and that is a dynojet. Doesn't matter which dyno you use, the delta is the same! My c7 made 531whp on hot pulls stock. The c6 Z's I have dyno'd make 480's stock. BOTH cars trap 126 to 127 in the AZ heat... Do the math, my c7 scaled 3550 without driver, the c6 Z's scale about 3150 without driver. It all agrees. I have used every dyno out there on numerous occasions tuning cars all over the country, and only one will NAIL the trap speeds consistently, and that is a Dynojet."
That was in answer to my question to what he stated as fact that a stock C7 Z06 making 650 crank horsepower (chp) LOSES 130 chp and would dyno on a hot lapping road course at 530 rwhp---which is about a 20% loss from 650. But, the most important part is that he said he regularly sees C6 Z06s dyno at 480 rwhp for a car that has chp of 505---and that is less than a 5% drivetrain loss. If anyone else has seen that number/figure, please advise because I haven't yet.
Long way of saying, there are many answers to the question of drivetrain loss, loss factor, rules of thumb, etc.
From this thread: https://www.corvetteforum.com/forums...ped-for-2.html
The C6 ZR1 has dyno'd 550 -560 rwhp and with 638 hp at the crank. That is a 78-88 hp loss at the wheels which in line with a 12% loss with a manual transmission.
There are You Tube videos with stock C6 Z06's pulling around 440 rwhp which is in line with a 12% rwhp loss.
480 rwhp on a stock C6 Z06 seems high.
There are documented dynos on C7 Z06's with 572 rwhp also in line with a 12% loss. A heat soaked C7 z06 engine can easily drop to 531 rwhp.
Dyno readings have to be compared with conditions being equal.
Last edited by Mike's LS3; Jul 21, 2015 at 11:40 PM.
Team Owner
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From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
With a heat soaked supercharger, the flywheel horsepower could easily be down 50 hp which would translate into lower rwhp #'s.
The C6 ZR1 has dyno'd 550 -560 rwhp and with 638 hp at the crank. That is a 78-88 hp loss at the wheels which in line with a 12% loss with a manual transmission.
There are You Tube videos with stock C6 Z06's pulling around 440 rwhp which is in line with a 12% rwhp loss.
480 rwhp on a stock C6 Z06 seems high.
There are documented dynos on C7 Z06's with 572 rwhp also in line with a 12% loss. A heat soaked C7 z06 engine can easily drop to 531 rwhp.
Dyno readings have to be compared with conditions being equal.
The C6 ZR1 has dyno'd 550 -560 rwhp and with 638 hp at the crank. That is a 78-88 hp loss at the wheels which in line with a 12% loss with a manual transmission.
There are You Tube videos with stock C6 Z06's pulling around 440 rwhp which is in line with a 12% rwhp loss.
480 rwhp on a stock C6 Z06 seems high.
There are documented dynos on C7 Z06's with 572 rwhp also in line with a 12% loss. A heat soaked C7 z06 engine can easily drop to 531 rwhp.
Dyno readings have to be compared with conditions being equal.
Burning Brakes
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