Drivetrain loss in 4wd's

[crankycruiser]

does anyone have a rough idea what the power loss is from motor to rear treads though a cruiser / patrol drivetrain?? in percentage of course

[-Scott-]

does anyone have a rough idea what the power loss is from motor to rear treads though a cruiser / patrol drivetrain?? in percentage of course

Factory configuration, or aftermarket/larger wheels & tyres?

[crankycruiser]

does anyone have a rough idea what the power loss is from motor to rear treads though a cruiser / patrol drivetrain?? in percentage of course

Factory configuration, or aftermarket/larger wheels & tyres?

im only after a rough guesstimate...

so lets say factory manual gbox and std diff's and 33's, so basically std.

[Red Dog 4x4]

When i was working with dynos, i was told the power loss to the rear was 33% on avareage and a feather 20% to the front. Thats just what i was told at the time how true it is i don't know.

[ferrit]

I was told 30-40% for a part time 4wd system- turning a gearbox, transfer case and big heavy diffs and axles takes its toll.

[dumbdunce]

there is only one way to work it out accurately, which is to test on a chassis dyno then test the engine on a flywheel dyno.

people can throw around percentages all they like, the facts are that there is no magic % and no easy way of working it out - the % loss changes across the rpm range, and with load, and with gear selection, and with the temperature of the drivetrain components, and the lubricants selected, the transmission type, ambient conditions, condition of gearbox, diff and wheel bearings and the lubricants used - larger wheels and tyres can have an apparent power loss effect when testing on a chassis dyno however this falls into two categories - rotational inertia and slip - and is once again difficult to quantify.

if you're trying to work backwards from a chassis dyno figure to a flywheel figure, it's more or less guesswork. it could be anywhere within 15 - 50%.

[PGS 4WD]

Our dyno does accurate calculations of drivetrain loss, it is not a static number as it increases with speed due to tyre windage and friction. To give you some examples, a 3.0L GU series one with 117 engine kW makes about 80 kW to the rear wheels in 2wd. If you run the vehicle in 4wd theat may drop to 65 kW into 4 wheels. If you are near to Mornington we can do a dyno run and apply the drivtrain calculator. It takes a little longer as we have to do 3 pre runs under certain conditions for the software to gather enough information to calculate the losses.
I have tested a few stock vehicles just recently as we have had a software update to digital, a new D40 Navara, rated at 127 engine kW, calculated 124.7 or something very close with 40 k klms on it. A series 1 GU 3.0L rated at 117 with 100 k klms made about 114 calculated and a brand new LS2 rated at 400 HP made 399.4 HP calculated at the engine.

Joel

[-Scott-]

Top Gear very briefly described that the driveline loss calculator looks at how the dyno slows after the power run, and derives losses from that.

I got the impression that they use inertia in the rollers to drive the drivetrain, and look at deceleration?

It's probably a lot more complicated than that, and I'd love to know more about the theory behind it. Anybody know of any links?

[PGS 4WD]

Like I said 2 million dollars in software developemt in our dyno, I can't see anyone handing that sort of information out.

Joel

[KiwiBacon]

I have tested a few stock vehicles just recently as we have had a software update to digital, a new D40 Navara, rated at 127 engine kW, calculated 124.7 or something very close with 40 k klms on it. A series 1 GU 3.0L rated at 117 with 100 k klms made about 114 calculated and a brand new LS2 rated at 400 HP made 399.4 HP calculated at the engine.

Joel

So for the vehicles you've mentioned above (D40, GU, LS2) what power did they put to the ground?

Because flywheel figures are actually useless. It's power to the ground that moves the vehicle.

[dumbdunce]

I have tested a few stock vehicles just recently as we have had a software update to digital, a new D40 Navara, rated at 127 engine kW, calculated 124.7 or something very close with 40 k klms on it. A series 1 GU 3.0L rated at 117 with 100 k klms made about 114 calculated and a brand new LS2 rated at 400 HP made 399.4 HP calculated at the engine.

Joel

So for the vehicles you've mentioned above (D40, GU, LS2) what power did they put to the ground?

Because flywheel figures are actually useless. It's power to the ground that moves the vehicle.

you're forgetting wank value?

[KiwiBacon]

you're forgetting wank value?

The ultimate in wank value is getting the gear ratios wrong and telling everyone you've got over 1000Nm of torque.

[gouldy]

try this site
http://frozenmist.co.uk/cars/conversion/

Cheers
gouldy

[BryanGUIV]

you're forgetting wank value?

The ultimate in wank value is getting the gear ratios wrong and telling everyone you've got over 1000Nm of torque.

ha ha ha so true!

[Bush65]

does anyone have a rough idea what the power loss is from motor to rear treads though a cruiser / patrol drivetrain?? in percentage of course

WOW!!! who cares what makes what and who has the biggest best shit on earth!
Can anyone answer " crankycruiser" question????

Re-read the first posts by dumbdunce and PGS 4wd.

Joel gave results for GU patrol, you need to calculate percentages. But how much can you rely on Nissan's quoted power?

[BEEPJEEP]

does anyone have a rough idea what the power loss is from motor to rear treads though a cruiser / patrol drivetrain?? in percentage of course

WOW!!! who cares what makes what and who has the biggest best shit on earth!
Can anyone answer " crankycruiser" question????

Re-read the first posts by dumbdunce and PGS 4wd.

Joel gave results for GU patrol, you need to calculate percentages. But how much can you rely on Nissan's quoted power?

QUOTE by RUFF-:THIS IS GENERAL TECH NOT TOYOTA OR NISSAN
Didn't RUFF make it a sticky or i'm i wrong here?

[-Scott-]

does anyone have a rough idea what the power loss is from motor to rear treads though a cruiser / patrol drivetrain?? in percentage of course

WOW!!! who cares what makes what and who has the biggest best shit on earth!
Can anyone answer " crankycruiser" question????

Re-read the first posts by dumbdunce and PGS 4wd.

Joel gave results for GU patrol, you need to calculate percentages. But how much can you rely on Nissan's quoted power?

QUOTE by RUFF-:THIS IS GENERAL TECH NOT TOYOTA OR NISSAN
Didn't RUFF make it a sticky or i'm i wrong here?

What's your point? The question was about offroad 4wd vehicles, and he used Cruiser / Patrol as an example.

Which forum do you propose he post in?

[BEEPJEEP]

does anyone have a rough idea what the power loss is from motor to rear treads though a cruiser / patrol drivetrain?? in percentage of course

WOW!!! who cares what makes what and who has the biggest best shit on earth!
Can anyone answer " crankycruiser" question????

Re-read the first posts by dumbdunce and PGS 4wd.

Joel gave results for GU patrol, you need to calculate percentages. But how much can you rely on Nissan's quoted power?

QUOTE by RUFF-:THIS IS GENERAL TECH NOT TOYOTA OR NISSAN
Didn't RUFF make it a sticky or i'm i wrong here?

What's your point? The question was about offroad 4wd vehicles, and he used Cruiser / Patrol as an example.

Which forum do you propose he post in?

Oh sorry dont worry about me i've been mislead!
Carry on

[Dzltec]

Instead of % loss it should be power loss. A 100 series fact turbo engine makes 105-115 rwkw on our dyno, my info tells me they make 150 at the flywheel. Thats a loss of 35-40%. Now if we power it up to make 135 rwkw, it still doesn't lose that % total it only looses 35-45rwkw.

I hope that is easy enough to understand.


Andy

[Struth]

Instead of % loss it should be power loss. A 100 series fact turbo engine makes 105-115 rwkw on our dyno, my info tells me they make 150 at the flywheel. Thats a loss of 35-40%. Now if we power it up to make 135 rwkw, it still doesn't lose that % total it only looses 35-45rwkw.

I hope that is easy enough to understand.


Andy

Yes so you are saying it will take a certain amount of power to put drive to the wheels via the drivetrain and that is all it will take, regardless of engine power.

Therefore if you added 20kw to your engine power you should also add 20kw to your rw power.

Changes the discussion a bit really, is this something you have/is proven?

Cheers

[Dzltec]

I have no physical proof, like what was said, it would need to go from engine dyno to chassis dyno to prove. But why would it go up in percentage terms if nothing was changed in the driveline.

If we went from 100 to 200 flywheel kilowatts and the driveline consumed 20kw or 20%. That means that for the change in engine power figures, the same driveline is now consuming 40kw, yet nothing has changed in it.


Andy

[Auto-Craft]

for an AWD cruiser you would work on 35% as a guide.

[BEEPJEEP]

Our dyno does accurate calculations of drivetrain loss, it is not a static number as it increases with speed due to tyre windage and friction. To give you some examples, a 3.0L GU series one with 117 engine kW makes about 80 kW to the rear wheels in 2wd. If you run the vehicle in 4wd theat may drop to 65 kW into 4 wheels. If you are near to Mornington we can do a dyno run and apply the drivtrain calculator. It takes a little longer as we have to do 3 pre runs under certain conditions for the software to gather enough information to calculate the losses.
I have tested a few stock vehicles just recently as we have had a software update to digital, a new D40 Navara, rated at 127 engine kW, calculated 124.7 or something very close with 40 k klms on it. A series 1 GU 3.0L rated at 117 with 100 k klms made about 114 calculated and a brand new LS2 rated at 400 HP made 399.4 HP calculated at the engine.
Hi Joel, you say here there's a drop in power in 4wd,does this mean its been on a dyno in 4wd? Is it a rule of thumb in 4wd you'll always loose power to rear diff once front diff is employed,BUT it then becames very high torque because you all most have full traction?

Joel

[BEEPJEEP]

Sorry the last post didnt work, meant to ask can a 4wd be dyno tested in 4wd cause you say there's a loose in power once front diff is employed which this is correct, But dose this mean the engine then becames high torque cause you all most have full traction?

[Dzltec]

Traction won't alter if its strapped down correctly. You are just adding another item that is consuming power to make it turn. Hence the loss of power.


Andy

[bazzle]

Sorry the last post didnt work, meant to ask can a 4wd be dyno tested in 4wd cause you say there's a loose in power once front diff is employed which this is correct, But dose this mean the engine then becames high torque cause you all most have full traction?

The overall torque will still be the same (negating friction losses) but shared to all points with traction.

Bazzle

[PGS 4WD]

Ours displays the drive train loss real time as you ramp the vehicle. I put a stock twin turbo V8 200 series on today which we are doing an exhaust and chip on. There are two sets of figures on these stock engines, gross and nett. We meausure the nett figure which is the remainder when all ancilliary devices are turning, water pumps, power steer pumps fans etc. The gross figure is if you were to take all the drive belts off which is one of the slightly dodgy ways most manufacturers do their press releases as it is a higher figure. Chrysler Australia were so dodgy in the 70's their Hemi 6 was rated with the oil pump being driven externally.

The Nett engine kW rating is 173 engine kW and the gross 194 engine kW.
For interests sake we did 3 runs and got 174, 171 and 166 as the engine got hotter power dropped off. For interests sake that is 151 kW at the wheels so the drive train loss percentage is not as high as what some people may have you believe.

Last week we did a Lexus 4.7 V8 rated at 174 kW, we got 204 engine kW with an exhaust and extractors, and 224 kW with the exhaust, extractors and chip.

Joel

[PGS 4WD]

The 200 series now with exactly the same measured EGT's is up from 173 to 196 engine kW, the gain being through the whole rev range means blistering torque. There is more in it but being it tows horse floats we are being conservative retaining stock EGT's.

Joel

[Auto-Craft]

The Nett engine kW rating is 173 engine kW and the gross 194 engine kW.
For interests sake we did 3 runs and got 174, 171 and 166 as the engine got hotter power dropped off. For interests sake that is 151 kW at the wheels so the drive train loss percentage is not as high as what some people may have you believe.

Joel

So 220kw [200 claimed power] minus 35% = 143kw, and your saying 151kw at the wheels.

Thats a 5% difference, in real terms.

Work it back the other way, 151kw + 35% =203kw vs 194 engine KW on your data = < 5% difference, in real terms.

As you say, there is no "precise" method, and to estimate, without getting out the slide rule, 24% for 2wd, and 35% for AWD/4WD models has worked out pretty close normally for us, for interests sake, on the 2 annually calibrated dyno dynamics dyno's we use, which read within 4 kw of each other when weather station and intake temps are the same, on the same cars, we use the % not as a claimed figure, but to be an estimate of flywheel to wheels, or vice versa.

Just running the same car on different days, or changing tyre pressures can make +/- <5%.