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Location:
Canberra
Registered:
July 2003
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Drivetrain Loss
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Mon, 04 August 2003 15:30
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How much drivetrain loss would be expected in an AE86.
Mine has a close ratio box and a Cusco 2-way LSD if it makes any difference.
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Location:
c'town, NSW
Registered:
May 2002
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Re: Drivetrain Loss
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Mon, 04 August 2003 22:16
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id also be interested in finding out how long is a piece of string.
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Location:
Canberra
Registered:
December 2002
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Re: Drivetrain Loss
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Mon, 04 August 2003 22:30
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Thats easy from one end to the other of course 
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Location:
near chris and murray vic
Registered:
July 2002
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Re: Drivetrain Loss
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Mon, 04 August 2003 23:12
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easy to work out
1: take engine out of car, run on engine dyno, note power figures
2: put engine in car, run on chassis dyno, note power figures
3: do some simple maths and you know the difference
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Location:
Brisbane
Registered:
November 2002
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Re: Drivetrain Loss
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Mon, 04 August 2003 23:28
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It is very hard to say, but don't listen to anyone who says it's 25% or 30%, because that's a load of rot.
Maybe this would be accurate if you have a V8 with a big sloppy auto and a massive diff/tailshaft/wheels.
I'd be surprised if it was more than 15% on a Sprinter.
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Drivetrain Loss
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Tue, 05 August 2003 00:27
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As much as what 7m-brisbane says, for a manual front engine/rear drive car, budget on around 21% loss. This will vary a little but should be close.
Take my car. Running essentially a standard 1G with 2.5in exhaust and pod airfilter. The standard engine is supposed to put out around 200hp.
Less 21% gives 158 hp at the wheels.
This is about 117kw.
Running standard boost, it put down 111kw on the dyno.
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Location:
Canberra
Registered:
July 2003
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Re: Drivetrain Loss
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Tue, 05 August 2003 01:40
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Ok, cheers 
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Location:
Perth
Registered:
October 2002
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Re: Drivetrain Loss
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Tue, 05 August 2003 05:48
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On a similar thread (ie, I'm not hijacking, honest!),
Anyone want to hazard a guess at the difference in drivetrain loss between a stock manual and stock auto 1JZ Soarer or Chaser?
Ta muchly,
Justin
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Location:
Madrid - Spain
Registered:
August 2002
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Re: Drivetrain Loss
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Tue, 05 August 2003 06:39
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It depends on the type and condition of the auto. I am not aware of any exact figure.
It has been a long day at the office, so this is likely to be nothing more than dribble BUT....................I would think that you would get a percentage due to the mechanical side of the drive (probably similar to a manual) plus a specific figure for the slip in the torque converter.
My logic for this is as follows and is just my guess at how it would work. Being a viscus coupling, the power required to slip a torque converter would be exponential against RPM. This means that after a certain RPM, you could reasonably assume that it is locked and absorbing a fixed amount of power.
Not having any interest in automatics, I have never looked into this, but I wouldn't be surprised if the manufacturer could supply you with a curve like this for a particular torque converter.
Some auto's have a locking type top gear meaning that they don't slip at all. The drive losses will be silimar to a manual for these boxes, which is why they use diff ratio's similar the manual cars.
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Re: Drivetrain Loss
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Tue, 05 August 2003 07:24
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Celicamad has exact proven figures for all these queries.
try his website or maybe he will fill us all in.
Matt
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: Drivetrain Loss
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Tue, 05 August 2003 07:56
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just remember, what the factory quotes as power figures at the engine and what the engine will actually put out are 2 entirely different things. that's where most people get figures of 25+% from... but if you actually run them on an engine dyno then a chassis dyno, it's quite a bit less
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Location:
On your mum!
Registered:
May 2002
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 Re: Drivetrain Loss
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Tue, 05 August 2003 08:05
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Most engines indeed put out more power than the factory quoted figure, this would mean that the drivetrain losses being calculated using this as the base, will in fact be higher than they were worked out to be.
rob_RA40 and shteeve will be pretty close on the money. Dyno dynamics dynos have a calculated flywheel output based on transmission vs diff ratio. This means that you may ask your dyno operator to tell you what the dyno reckons (and that opens a whole new argument).
Best off not worrying too much about the flywheel figure, the only ponies that matter are those that hit the deck.
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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 Re: Drivetrain Loss
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Tue, 05 August 2003 13:09
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7M-Brisbane,
Generally I avoid these arguement but I can't this time. What line of reasoning are you basing your 15% on... Its a small car ? Small engine ?? the engine size (ie V8 or 1600) has sweet FA to do with it !
Its called drivetrain loss because thats what causes it. There are alot of theories and calculations out there and I'm not going to add more dribble to the thread. Fact is the ONLY way to know it to have the engine on an engine Dyno and then the same engine on an accurate Chassis dyno. Then you will have an answer. (For that car on those two Dyno's on those two days !)
-Mark-,
There are rules of thumb out there for a reason, these are "Industry standards" if you wanna play with imaginary figures use em they are the best guides out there. As jason has already pointed out tho. The only important figure is what you actually transfer to the road. Anything else is pretty much pointless. The ONLY comparison i know of was for a TA22. Its drive train loss was 35% from Engine Dyno to Chassis Dyno. (199kw - 130kw) And what do you know... Rule of thumb for a RWD is 30 - 35% !!!!!
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: Drivetrain Loss
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Tue, 05 August 2003 15:03
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Toymans on the money here, but gotta add a bit more dribble.
i remember reading in a few different books (like carroll smith and philip smith) that drivetrain loss is not proportional to engine power. they stated that the drivetrian loss is just that, drivetrain loss, and for a specific box and diff, wether you put 50kw or 500kw thru it, the actual drivetrain loss will not increase by that much. with reasoning, the oil friction and bearing loss will remain pretty constant, and the only thing that increases with power is the geartooth to tooth friction.
if you go by the 30% rule, that means that V8 supercars are losing about 180hp thru their boxes, i can't imagine how a gearbox and diff could absorb 180hp worth of energy and not melt!
so basically, you can't just take a percentage and mutiply by engine power as it's not linear. as the members of the smart party said, the only way to tell is run back to back engine and chassis dyno tests (and even do both at half throttle and see if the loss is linear  )
dribble dribble..... 
Cya, Stewart
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Location:
Sydney
Registered:
June 2002
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Re: Drivetrain Loss
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Wed, 06 August 2003 00:15
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In Julian Edgar's book 21st Century Performance.
He has some very interesting Dyno power comparisons recorded on the same chassis dyno..
-------------------------------------------------- -
Standard Ford V8 5 speed manual RWD
Factory Flywheel power = 185kw
Chassis Dyno result = 143kw @ the wheels
Drivetrain loss = 42kw or 23 per cent.
-------------------------------------------------- --
Standard Holden 5.0L V8 RWD
Factory Flywheel power = 195kw
Chassis Dyno result = 154kw @ the wheels
Drivetrain loss = 41kw or 21 per cent.
-------------------------------------------------- --
Standard FWD 1.3L 4cyl.
Factory Flywheel power = 55kw
Chassis Dyno result = 52kw @ the wheels
Drivetrain loss = 3kw or 5 per cent
-------------------------------------------------- --
Standard Subaru Impreza WRX AWD
Factory Flywheel power = 155kw
Chassis Dyno result = 95kw @ the wheels
Drivetrain loss = 60kw or 39 per cent.
-------------------------------------------------- -----
Modified Nissan S12 Gazelle FJ20ET RWD
Engine Dyno Result = 358kw
Chassis Dyno result = 235kw @ the wheels(some wheelspin)
Drivetrain loss = 123kw or 34 percent.
-------------------------------------------------- -------
-Regards Mike
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