How to calculate percentage of power lost to the driveline?
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Car: 1986 IROC-Z
How to calculate percentage of power lost to the driveline?
I've been playing around with Desktop Dyno, but the program only supplies power estimates from the flywheel. Is there some sort of calculation that I can perform to compensate for driveline loss in my car?
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Car: 1989 TransAm GTA
Engine: One sweet modified 355 TPI.
Transmission: The kind that shifts....
I've read that;
Manuals usually lose 15%
Auto's usually lose 20%
I've heard varying estimates from 17% to 24% for auto's and again different opinions on manuals as well.
So, take it with a grain of salt.
Flywheel HP * (expected loss in decimal form (20% loss = .80)) = Estmated RWHP
Manuals usually lose 15%
Auto's usually lose 20%
I've heard varying estimates from 17% to 24% for auto's and again different opinions on manuals as well.
So, take it with a grain of salt.
Flywheel HP * (expected loss in decimal form (20% loss = .80)) = Estmated RWHP
#3
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I've always figured around 12% for a manual and 15% minimum for an automatic- significantly higher if it's got a high-stall converter.
My Mailibu lays 390 to the rollers through an automatic trans with stock coverter. Add 15% driveline loss and that's about 450 at the flywheel. That's what I built the motor to make so the numbers pass a basic sanity test.
My Mailibu lays 390 to the rollers through an automatic trans with stock coverter. Add 15% driveline loss and that's about 450 at the flywheel. That's what I built the motor to make so the numbers pass a basic sanity test.
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Car: 1986 IROC-Z
Thanks for the numbers, guys. I'm just trying to compensate for everything in the somewhat-innacurate Desktop Dyno. 275 hp on a 9.0:1 motor with 882 heads... . Oh well. I guess I'm supposed to look for change, versus absolute statistics.
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Car: 2005 BMW 545i
Engine: 4.4L N62B44
Transmission: 6spd auto
Axle/Gears: Rotating
Originally posted by Damon
I've always figured around 12% for a manual and 15% minimum for an automatic- significantly higher if it's got a high-stall converter.
My Mailibu lays 390 to the rollers through an automatic trans with stock coverter. Add 15% driveline loss and that's about 450 at the flywheel. That's what I built the motor to make so the numbers pass a basic sanity test.
I've always figured around 12% for a manual and 15% minimum for an automatic- significantly higher if it's got a high-stall converter.
My Mailibu lays 390 to the rollers through an automatic trans with stock coverter. Add 15% driveline loss and that's about 450 at the flywheel. That's what I built the motor to make so the numbers pass a basic sanity test.
I really have no clue how you gained 150hp at the flywheel due to a tranny and stall
sorry but your math comes out to a 33.333 percent loss
also another thing to think about drivetrain loss can never be a exact thing
rpms spun, wieght,oil thickness and type, tires, rims, how the gears are cut, and many other factors make a difference as to how much you lose through your car before it hits the wheels
and another thing to me percentage of loss is kinda a stupid idea
lets say you take a full drivetrain from a v8 making 500hp at the crank
take 15% from that and you have a loss of 75hp
now take that whole drivetrain from that car and put it behind a v6 making 145hp and it only has a loss of 21.75hp
something seem wrong with this?
#6
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Originally posted by rx7speed
I really have no clue how you gained 150hp at the flywheel due to a tranny and stall
sorry but your math comes out to a 33.333 percent loss
I really have no clue how you gained 150hp at the flywheel due to a tranny and stall
sorry but your math comes out to a 33.333 percent loss
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Car: '89 Formula 350 & '86 Z28
Engine: L98 & 355ci
Transmission: 700r4 in both
Originally posted by blue86iroc
Thanks for the numbers, guys. I'm just trying to compensate for everything in the somewhat-innacurate Desktop Dyno. 275 hp on a 9.0:1 motor with 882 heads... . Oh well. I guess I'm supposed to look for change, versus absolute statistics.
Thanks for the numbers, guys. I'm just trying to compensate for everything in the somewhat-innacurate Desktop Dyno. 275 hp on a 9.0:1 motor with 882 heads... . Oh well. I guess I'm supposed to look for change, versus absolute statistics.
Do you have the actuall flow numbers on the 882 heads in there? or are you using one of their generic heads?
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Car: '89 Formula 350 & '86 Z28
Engine: L98 & 355ci
Transmission: 700r4 in both
I took the flow numbers out of Chevy Hi-performance's article and got the actaul flow numbers for the more popular sets..
Edit: forgot pic, my bad
Edit: forgot pic, my bad
Last edited by SweetS10v8; 11-13-2003 at 10:09 AM.
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Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
Originally posted by blue86iroc
Thanks for the numbers, guys. I'm just trying to compensate for everything in the somewhat-innacurate Desktop Dyno. 275 hp on a 9.0:1 motor with 882 heads... . Oh well. I guess I'm supposed to look for change, versus absolute statistics.
Thanks for the numbers, guys. I'm just trying to compensate for everything in the somewhat-innacurate Desktop Dyno. 275 hp on a 9.0:1 motor with 882 heads... . Oh well. I guess I'm supposed to look for change, versus absolute statistics.
i hate thoes heads. i had a bad experiance.
if i ever have a friend that has thoes.. im going to crack them... that way, he HAS to get new heads.... he might hate me for awhile, but he'll thank me later.
right now desktop dyno is showing me around 500hp for the motor im building.... i think thats wayy high... i really wonder about the accuracy of the head files i find online....
right now i have 3 head files for my Dart Iron Eagle heads.... all 3 are pretty diffrent.
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Car: 1986 IROC-Z
I'm using DD's included 882 head file. Those numbers coincide with numbers that I've seen from other sources, too.
I don't actually intend on building a motor with these heads (though, my 882 heads are the better version), but I wanted to see roughly how much power this 350 I have will produce. I set up the DD file for an L48, which is what I have -- motor from a 1974 Corvette, 195 hp. Desktop Dyno said that it puts out 250 hp... which is why I thought about driveline loss. But, I guess that GM always quotes raw engine power, not rear-wheel power. The discrepancies lie with the computer, I think.
Anyway, no need to have a "Desktop Dyno inaccuracies" thread -- I've read all of those already . Just checking on driveline loss.
I don't actually intend on building a motor with these heads (though, my 882 heads are the better version), but I wanted to see roughly how much power this 350 I have will produce. I set up the DD file for an L48, which is what I have -- motor from a 1974 Corvette, 195 hp. Desktop Dyno said that it puts out 250 hp... which is why I thought about driveline loss. But, I guess that GM always quotes raw engine power, not rear-wheel power. The discrepancies lie with the computer, I think.
Anyway, no need to have a "Desktop Dyno inaccuracies" thread -- I've read all of those already . Just checking on driveline loss.
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Car: 1987 Camaro Z-28
Engine: 6.3L Victor EFI
Transmission: Tremec TKO 600
Axle/Gears: Moser 9"/4.11 Trac-Lok
Originally posted by SweetS10v8
Ive found that when playing with DD2000, it is more realistic to put on "HP manifolds and mufflers" when you are using headers. It simply adds way too much when you use "small tube headers"
Do you have the actuall flow numbers on the 882 heads in there? or are you using one of their generic heads?
Ive found that when playing with DD2000, it is more realistic to put on "HP manifolds and mufflers" when you are using headers. It simply adds way too much when you use "small tube headers"
Do you have the actuall flow numbers on the 882 heads in there? or are you using one of their generic heads?
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Car: 2005 BMW 545i
Engine: 4.4L N62B44
Transmission: 6spd auto
Axle/Gears: Rotating
Originally posted by 25THRSS
Where did you come up with 150?
Where did you come up with 150?
thought he said 300
not 390
oops
#14
There are some excellent discussions of drive train loss, rotational inertia, chassis dynos, etc. in the tech notes here:
http://www.pumaracing.co.uk/mainmenu.htm
http://www.pumaracing.co.uk/mainmenu.htm
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