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r3meyer

% of loss through different transmissions

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4 minutes ago, 2011BFD said:

But that's if it gets hot or something has changed. If it takes x amount of HP to spin gears AND nothing changes in gears, than adding more HP to the system turning gears does not deduct output of HP. 

Again all being the same at 3000 rpms it takes X hp or energy to spin transaxle

So friction never changes with load? 

Your differential always spins at road speed. What you’re proposing means there should be zero difference in temperature towing or not. Hell, not towing should make it hotter since we almost always drive faster when not towing. 

Edited by Rockwood

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57 minutes ago, tjZ06 said:

Yes, yes it does.  Remember HP is just a mathematical derivation based on Torque.  Torque is is simply the vector cross-product of the Force and Radius vectors.  All of that to say, the more HP you have the more Force is acting on everything and/or the more RPM.  Take two surfaces and rub them together with just their static weight, say, pushing a brick across your driveway at a given speed.  Now have a buddy stand on that brick (if you're unable to come up with a buddy just stack a few paver stones on it) and try to push it across your driveway at the same speed.  You have the same two surfaces (analogous to having the same gears, CVs, etc. in a drivetrain) but suddenly it takes WAY more Force to move the brick at the same speed.  So now way more Force (and therefore Energy) creating the same outcome... so where is all that extra Energy going?  It's going into parasitic loss (friction... which creates heat).   That's akin to having more HP acting on the drivetrain.  If you want to simulate more RPM just move the brick back and forth faster... again it will take way more Energy and create way more heat. 

 

31 minutes ago, 2011BFD said:

But that's if it gets hot or something has changed. If it takes x amount of HP to spin gears AND nothing changes in gears, than adding more HP to the system turning gears does not deduct output of HP. 

Again all being the same at 3000 rpms it takes X hp or energy to spin transaxle

See my scenario above.  If you press two things together harder, it takes more Energy (HP) to slide them against each other.  Maybe you're picturing gears as "pushing" against one another with no relative movement between them?  That's not the case, they slide into, and out of mesh.  Again, think about the brick... with just the weight of the brick it's pretty easy to slide it along the concrete.  If my fat ass stands on it, it's going to take a LOT more Energy to slide it (and produce more heat in the process).  

We're not talking about free-spinning things at a given RPM with the drive-wheels in the air... in which case yes the amount of HP needed to sustain 3000 RPM will be the same independent of what HP the engine can produce (assuming it's at least sufficient to spin the entire drivetrain with the wheels in the air and maintain 3k RPM).  We're talking, in this case, about exerting force in the form of Torque through the drivetrain and into the Dyno's rollers (or hub adapters if it's that style). 

-TJ

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How about you just drive your shit and see how it feels. 

 

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16 minutes ago, RIDERED said:

How about you just drive your shit and see how it feels. 

 

It feels like a 500hp LS1 and a 2D

But I know its a 750hp Stroked LS3 and an Ablins by using internet HP gainers.

 

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19 hours ago, cali kid said:

Depends on what CV grease you use.

Here we go!!! LOL  :popcorn:

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2 hours ago, r3meyer said:

It feels like a 500hp LS1 and a 2D

But I know its a 750hp Stroked LS3 and an Ablins by using internet HP gainers.

 

That is because the Albins takes so much more power to turn 😂 

 

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If someone has access to one of these:

maxresdefault.jpg&sp=fca960de517990a7a86

Transaxle dynomometer, this issue could be 'put to bed' at least for the transaxle itself. Several of the most popular transaxles should be tested and compared showing the relationships between load/speed (RPM)/loss/heat (lubricant heat build up and also case temps)

CV's really should be tested separately both to simplify testing and also to go more in depth in understanding the effects of polishing, greases, etc.

 

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well someone should put that tesla sand truck on a dyno im sure the software would be able to tell you the power out put of the motor at the same time the wheel dyno is calculating the load

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5 hours ago, diesel-e said:

well someone should put that tesla sand truck on a dyno im sure the software would be able to tell you the power out put of the motor at the same time the wheel dyno is calculating the load

Despite the name, IIRC he's not actually running Tesla controllers and software, so IDK if he can actually see actual motor output. 

 

-TJ

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21 hours ago, tjZ06 said:

Yes, yes it does.  Remember HP is just a mathematical derivation based on Torque.  Torque is is simply the vector cross-product of the Force and Radius vectors.  All of that to say, the more HP you have the more Force is acting on everything and/or the more RPM.  Take two surfaces and rub them together with just their static weight, say, pushing a brick across your driveway at a given speed.  Now have a buddy stand on that brick (if you're unable to come up with a buddy just stack a few paver stones on it) and try to push it across your driveway at the same speed.  You have the same two surfaces (analogous to having the same gears, CVs, etc. in a drivetrain) but suddenly it takes WAY more Force to move the brick at the same speed.  So now way more Force (and therefore Energy) creating the same outcome... so where is all that extra Energy going?  It's going into parasitic loss (friction... which creates heat).   That's akin to having more HP acting on the drivetrain.  If you want to simulate more RPM just move the brick back and forth faster... again it will take way more Energy and create way more heat. 

  

How can you pretend to talk about these things like an expert and not know that all power/torque ratings in the US since the early '70s have been SAE NET?  Regardless, unless you personally took YOUR motor out and had it on an engine dyno, your little anecdote is entirely meaningless.  Is it not possible GM underrated it?  It was actually pretty common through the 2000s for GM to grossly underrate power numbers, and the C8 is showing it's still a common practice.  If you want another vignette take my '99 Z/28 Camaro.  It was a LS1, T56 car which GM rated at 305 HP.  I dynoed mine bone stock (right down to the paper filter and OE spark plugs) on 3 different dynos.  It made 298, 306 and 314 RWHP on the various dynos, and was actually a low-producer for most stock LS1 Fbodies (I was in a LT/LS club at the time, and we'd often hold dyno days where we dynoed dozens of cars).  I've seen several 2001-2002 LS1 Fbodies rated at 310 HP dyno 320-330 RWHP. 

So am I meant to believe 4th Gen Fbodies have negative drivetrain loss? 

-TJ

 

Some days I have a man crush on a fella I've never met....straight dude...BTW...LOL

Edited by Kraut_n_Rice

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On 12/12/2019 at 3:56 PM, 1HasBeen said:

I think everyone that doesn't agree HP impacts drivetrain losses has just been ignoring this ^^^^^

 

-TJ
 

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27 minutes ago, Kraut_n_Rice said:

Some days I have a man crush on a fella I've never met....straight dude...BTW...LOL

I know, that Rockwood is dreamy right?  ;)

 

-TJ

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Those that know, know.  Right?

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14 minutes ago, tjZ06 said:

I think everyone that doesn't agree HP impacts drivetrain losses has just been ignoring this ^^^^^

 

-TJ
 

Why’d that article use efficiency numbers rather than static numbers... 🤔

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In all the discussion that is running, what most have missed is how power is measured.

On most dynos, Power is measured as/at a rate of acceleration.   How fast does it go from 0-100?...for example

It takes power to move things. Want to move it faster?  Takes more power...duh.. You want to make more power,?  Its going to take more power to measure it.  Exponent factor (that I do not know) will come in.

It "takes" power to measure the power..  As  a few  may know, I used to work as a wrench for Honda/Acura.  I now work in the waterblasting field building equipment.  I have to calculate torque ratingns of side mount PTOs, output shafts speeds for split shaft box speeds, ect

If I try to take 250HP off of a 2018 Powerstoke, it overheats.

330HP isn't 330HP....

Edited by Kraut_n_Rice

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22 hours ago, RIDERED said:

How about you just drive your shit and see how it feels. 

 

this.

So much win in this thread, I have an opinion, and a background in high perform...…….. you know what nevermind……...

just drive it. and btw, I know guys with shit for power that beat guys through the dunes with waaaaay more power. so I will end with this thought, none of it matters if you cant fuggin drive it.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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I'm so confused, all what I know is I love horsepower..

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On 12/13/2019 at 2:56 AM, 1HasBeen said:

This is quite an informative article.

It separates out the transmission, the differential and also the CV's.

 

Since our use of CV's is quite a bit different than a road vehicle (angles, etc), we should look first at the transmission and differential.   Then numbers given estimate out to about 88% getting through the transmission and differential (.941 x .931 ≈ 88%, meaning about a 12% loss BEFORE you get to the CV's). That would mean that the loss in the transaxle of a 300 H.P. sand rail should be expected to be in the 37 HP range, or just under 28Kw of heat. That is still a lot of heat, but remember that is only being generated at maximum power.

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7 minutes ago, journeyman said:

This is quite an informative article.

It separates out the transmission, the differential and also the CV's.

 

Since our use of CV's is quite a bit different than a road vehicle (angles, etc), we should look first at the transmission and differential.   Then numbers given estimate out to about 88% getting through the transmission and differential (.941 x .931 ≈ 88%, meaning about a 12% loss BEFORE you get to the CV's). That would mean that the loss in the transaxle of a 300 H.P. sand rail should be expected to be in the 37 HP range, or just under 28Kw of heat. That is still a lot of heat, but remember that is only being generated at maximum power.

Yep, but the parts are continuously being cooled by the metal housings they’re in. The hotter it gets, the faster the cooling. You also have to heat the entire mass up, gears, case, bearings, all of it. Specific heat of gear oil is ~0.6ish (could only find motor oil on a quick search, close enough), steel is 0.122, and aluminum is 0.9.  Using 1055J as the specific heat of water (for one degree of temp change), we get some fun with half ass math:

Gear oil (~8lbs): 5,064j

Mendeola 2D is 135lbs, taking a SWAG (bolt/italic for Shitty, as I have no clue on this) at its composition, we’ll say the case weighs 40lbs, all of the steel weighs 95lbs: 

Case: 37,980J

Gears: 12,227J

Bringing the total to somewhere around 55,000J to increase the transaxle’s temperature by 1 degree, or 2-ish seconds to bring it from 70* to 71*. 200* would take a hair over 7MJ... Without ANY cooling happening...

Probably not gonna catch fire eh @socaldmax ? :bigrin 

 

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Where did you get 1055J? For what mass of water?

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13 hours ago, Supreme Air said:

I'm so confused, all what I know is I love horsepower..

The bottom line is it's well proven and understood that drivetrain loss is a % and the HP being fed into it DOES change the loss...

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

...but that's why RWHP numbers (on a properly calibrated dyno) are what's actually important if you're comparing before/after mods/tuning/etc.  If you're not making changes and tuning, then dyno numbers are just that: numbers.  Go out and run it and you'll see where you stand (as I know you well know).  

 

-TJ

 

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3 hours ago, socaldmax said:

Where did you get 1055J? For what mass of water?

https://en.m.wikipedia.org/wiki/British_thermal_unit

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Here's my delema:  I wanting a new 4 seat buggy so I can take the whole family on dune trips.  The current 2 seat buggy has a cammed LS1 than put 428hp to the ground through a 2d and 930 CVs.  I would guesstimate drivetrain losses are in the 12-15% range.  Its been very reliable, but it is harder on the CVs than I would like.  If I'm going with a new buggy, I might as well go bigger and better.  I've been watching the classifieds and seen several buggies that fit the bill.  Big LS stroker engines with S4 transmissions and 934 CVs.  The engines are being touted as having 650+hp and putting 440hp or less to the wheels.  Forty percent loss?  Whats the benefit of going bigger if the losses are really that high?  These are heavier drivetrains in heavier buggies that are going to use a lot more fuel and may or may not be any more reliable.

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2 hours ago, Kansas T said:

Here's my delema:  I wanting a new 4 seat buggy so I can take the whole family on dune trips.  The current 2 seat buggy has a cammed LS1 than put 428hp to the ground through a 2d and 930 CVs.  I would guesstimate drivetrain losses are in the 12-15% range.  Its been very reliable, but it is harder on the CVs than I would like.  If I'm going with a new buggy, I might as well go bigger and better.  I've been watching the classifieds and seen several buggies that fit the bill.  Big LS stroker engines with S4 transmissions and 934 CVs.  The engines are being touted as having 650+hp and putting 440hp or less to the wheels.  Forty percent loss?  Whats the benefit of going bigger if the losses are really that high?  These are heavier drivetrains in heavier buggies that are going to use a lot more fuel and may or may not be any more reliable.

I don’t think you’re going to double your losses to the wheels...

I think people or their builders are just inflating their numbers. You also are probably a little high on whp numbers, which really depends on who’s running the dyno and what type. 

Edited by Rockwood

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