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Old 12-10-2020, 02:41 PM   #51
Calamity Jesus
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Quote:
Originally Posted by Snow Drift View Post
The gas engine in HSD is connected to the planetary gear in the transmission, and that power is split direct into the wheels and to MG1 (on sun gear) for charging the battery. When cruising with ICE on (always >65mph Subaru), MG1 charges the battery and can supply MG2 with electricity for added propulsion if the gas engine needs help. For EV mode, the battery supplies energy to MG2.
I did mix up the MG1 and MG2 uses in a previous post. My apologies, and thanks for the correction.

The point I was attempting (poorly) to make, is that in HV mode, the car needs MG1 to move away from a complete stop and to get up to highways speeds. There is no torque converter, so with the ICE spinning, it's the resistance against MG1 that drives the car forward. MG1 & MG2 are constantly doing work in HV mode, and they're using the battery (charging or discharging) to do so. Often, MG1 will be pulling power from the ICE while driving at constant speeds in order to send that power to the system (battery or MG2 directly). It's not just there for adding power during acceleration, it's extracting power while the engine is well within its efficiency sweet spot in order to use it later.

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Originally Posted by Snow Drift View Post
The Toyota ICE can only mechanically power the front axle, not the rear, as there's no rear driveshaft. For the rear axle, MG3, if you will, is separate, and is only powered by the battery pack. Also, the system turns off the e-rear axle above 40 mph. Thus being FWD on the highway. Now, you could argue that the MG1 is connected to the ICE and that generates electricity to recharge the battery pack, thus allowing the ICE to supply the energy used by the rear axle.
It's not an argument.. it's how it works. That's what we're all trying to get you to grasp.

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Originally Posted by Snow Drift View Post
Honda can be powered by the ICE: "Engine Drive, which uses the gas engine to deliver direct power to the front wheels. It is the only mode that can do this." https://www.detroithondadealers.com/...-system-works/
There's no transmission in the Hondas. It's only propelled by the traction motor (MG2) except under light load cruising around 50mph when the engine can be attached to MG2 (and the final drive) at a 1:1 ratio (1:3.42 final drive in the Clarity). It's usually using MG1 to charge the battery while the engine is connected (the power flow meter in the car shows a little gear when the enigine is directly connected). There's no way for hybrid Hondas to move from a stop with only a 1:1 gear. The 103hp 1.5L engine definitely gets out of it's comfort zone (ie efficiency suffers) once the EV battery is 'depleted', if you want to drive aggressively, but it still provides plenty of power to MG2 to drive the 2-ton car from 0-100mph, because there's always some battery power in reserve for HV mode.
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Old 12-11-2020, 11:53 AM   #52
Snow Drift
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It's not an argument.. it's how it works. That's what we're all trying to get you to grasp.
I hear the arguments, and on paper they work, but the roller test video (which is extreme), showed the rears couldn't push the car when the fronts lost traction. So, it's either a software limitation (don't over-exert the rear motor), or the rear motor just doesn't have the torque to move the Highlander on it's own, or in that one test the battery SoC was low and MG1 couldn't/wouldn't supply enough charge for the system to want to use the rear motor. Who knows.

I also never like the idea of the rear turning off and being FWD on the highway, but that is my personal issue.
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Old 12-11-2020, 01:05 PM   #53
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Quote:
Originally Posted by Snow Drift View Post
I hear the arguments, and on paper they work, but the roller test video (which is extreme), showed the rears couldn't push the car when the fronts lost traction. So, it's either a software limitation (don't over-exert the rear motor), or the rear motor just doesn't have the torque to move the Highlander on it's own, or in that one test the battery SoC was low and MG1 couldn't/wouldn't supply enough charge for the system to want to use the rear motor. Who knows.

I also never like the idea of the rear turning off and being FWD on the highway, but that is my personal issue.
Personally, I think it's the presence of basically zero traction messing with the traction control algorithms because a vehicle will never have zero traction in real life.

The all mechanical crosstrek couldn't move either until it twisted enough that a front wheel hit the side of the roller and pulled the car off the rollers.

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Old 12-11-2020, 01:41 PM   #54
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Originally Posted by dwf137 View Post
Personally, I think it's the presence of basically zero traction messing with the traction control algorithms because a vehicle will never have zero traction in real life.

The all mechanical crosstrek couldn't move either until it twisted enough that a front wheel hit the side of the roller and pulled the car off the rollers.

Subaru XV Crosstrek S-AWD vs Nissan Qashqai All Mode 4x4-i - 4x4 test on 3 rollers - YouTube



Driver didn't maintain center. It WAS moving. I'd like to see him keep it from hitting the side and see how it goes.
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Old 12-11-2020, 04:46 PM   #55
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Originally Posted by dwf137 View Post
Personally, I think it's the presence of basically zero traction messing with the traction control algorithms because a vehicle will never have zero traction in real life.

The all mechanical crosstrek couldn't move either until it twisted enough that a front wheel hit the side of the roller and pulled the car off the rollers.

Subaru XV Crosstrek S-AWD vs Nissan Qashqai All Mode 4x4-i - 4x4 test on 3 rollers - YouTube
In the 1st video and this last one:
  • Highlander Hybrid fails almost every attempt with front wheel slip + 1 or 2 rear grip
  • Qashqai eventually passes every test with 3 wheel slip + 1 rear grip
  • Crosstrek eventually passes every test with 3 wheel slip + 1 rear grip. Would probably perform even better if VDC was off, but they leave it on.

Last edited by Snow Drift; 12-11-2020 at 04:54 PM.
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Old 12-11-2020, 05:26 PM   #56
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Quote:
Originally Posted by Snow Drift View Post
In the 1st video and this last one:
  • Highlander Hybrid fails almost every attempt with front wheel slip + 1 or 2 rear grip
  • Qashqai eventually passes every test with 3 wheel slip + 1 rear grip
  • Crosstrek eventually passes every test with 3 wheel slip + 1 rear grip. Would probably perform even better if VDC was off, but they leave it on.
Here's a very interesting response from Honda on the performance of the CRV in roller tests:

https://www.carthrottle.com/post/att...4x4-after-all/

Quote:
Originally Posted by Honda UK
Honda***8217;s AWD system uses a compact, lightweight and fuel efficient rear differential. Due to this construction, certain torque limits are set to enable the unit to perform effectively in real world conditions, while not exceeding the overall strength of the unit.

In real world conditions, regardless of the surface, some amount of friction is available to both front and rear wheels. The AWD system allocates driving torque to the front and rear wheels in order to achieve the best possible driving force, whilst keeping within the torque limits of the rear differential.

In the roller test shown this time, the front wheels have zero friction and the rear wheels have unlimited grip, therefore if all available torque required to move the vehicle uphill was transferred to the rear differential, the torque limit of the unit would be exceeded. Because the torque is limited as described above, the vehicle will not climb the slope in this test condition.

If the vehicle is continued to operate in this condition (front wheels spinning and rear wheels stationary) after some time the system detects high slip and reduces the available torque to the rear wheels to prevent overheating and therefore the vehicle moves back down the slope.

Again, in real world conditions, this situation is highly unlikely. Normally front and rear wheels will be spinning to a similar degree, therefore front or rear slip is small and overheat protection will not be required.

Therefore our opinion is that the CR-V Realtime AWD system performance cannot be verified using this type of test and the result is as expected from the system. However as we demonstrated on 26th March 2013 at Harads together with Teknikens Vrld, the actual performance of the system in real world conditions was ***8220;very effective***8221;..

It's as if the automotive engineers at Honda agree with what I've been saying all along about roller tests not being reflective of real-world situations and just a wang measuring contest for people who don't really understand the mechanics of designing a drivetrain.
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Old 12-11-2020, 05:52 PM   #57
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Originally Posted by dwf137 View Post
Here's a very interesting response from Honda on the performance of the CRV in roller tests:

https://www.carthrottle.com/post/att...4x4-after-all/




It's as if the automotive engineers at Honda agree with what I've been saying all along about roller tests not being reflective of real-world situations and just a wang measuring contest for people who don't really understand the mechanics of designing a drivetrain.
They baby the rear diff. It gives up, or doesn't try, to prevent it from overheating. They, like almost every other automaker, sell dinky FWD-biased systems that rarely have the ability to transfer enough torque to the rear. Honda, and even Acura SH-AWD, is basically FWD until slip, then it sends torque back to the rear which has a clutch pack (differing based on which model). The rears are accuated via hydraulic pumps or electro-magnets pushing on a clutch pack.

I've driven the MDX SH-AWD for years, you can feel the fronts doing all the work on the highway, and I was able to get it stuck, in a flat parking lot (not even from a dead stop, I was tying to leave the lane), in a few inches of snow, because the fronts were slipping. I could not drive forward. I could only back up.
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Old 12-11-2020, 06:39 PM   #58
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Originally Posted by Snow Drift View Post
They baby the rear diff. It gives up, or doesn't try, to prevent it from overheating. They, like almost every other automaker, sell dinky FWD-biased systems that rarely have the ability to transfer enough torque to the rear. Honda, and even Acura SH-AWD, is basically FWD until slip, then it sends torque back to the rear which has a clutch pack (differing based on which model). The rears are accuated via hydraulic pumps or electro-magnets pushing on a clutch pack.

I've driven the MDX SH-AWD for years, you can feel the fronts doing all the work on the highway, and I was able to get it stuck, in a flat parking lot (not even from a dead stop, I was tying to leave the lane), in a few inches of snow, because the fronts were slipping. I could not drive forward. I could only back up.
If you need something that can lock up differentials, crossovers are not the market for you. Also sounds like maybe that mdx needs better tires.
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Old 12-11-2020, 06:48 PM   #59
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7:37 - forester fails on what looks like just rollers on the right side of the car.
12:00 - older gen forester fails on rollers on one side of the car
12:50 - Range Rover fails on 3 wheel roller test.
17:00 - wrx/sti fails on 3 rollers even with front wheel traction

these tests are stupid and really just need to stop.
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Old 12-12-2020, 01:59 PM   #60
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Quote:
Originally Posted by dwf137 View Post
Here's a very interesting response from Honda on the performance of the CRV in roller tests:

https://www.carthrottle.com/post/att...4x4-after-all/




It's as if the automotive engineers at Honda agree with what I've been saying all along about roller tests not being reflective of real-world situations and just a wang measuring contest for people who don't really understand the mechanics of designing a drivetrain.

I certainly agree with this. Honda has done what they needed for their customers.


Quote:
Originally Posted by dwf137 View Post
AWD sistems wars (testing) on rollers - YouTube

7:37 - forester fails on what looks like just rollers on the right side of the car.
12:00 - older gen forester fails on rollers on one side of the car
12:50 - Range Rover fails on 3 wheel roller test.
17:00 - wrx/sti fails on 3 rollers even with front wheel traction

these tests are stupid and really just need to stop.

And I can counter with this. How long did it take you to find a video of it failing from another country?

For quickness, move to the 8:30 mark


Does everyone need a "capable" AWD? Nah. I guess not. But for me, I get the itch to do this on occasion(though I haven't tried one with THIS steep an angle yet; but, not too far off) and I want my car to scratch that itch.



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Old 12-12-2020, 02:09 PM   #61
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That Forester XT was the last year of the VTD AWD (except the CVT WRX). Can the current non-turbo CVT X-mode do the same climb?
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Old 12-12-2020, 02:33 PM   #62
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That Forester XT was the last year of the VTD AWD (except the CVT WRX). Can the current non-turbo CVT X-mode do the same climb?
I would say yes maintaining momentum like in the video.


I have done that steep a climb in training on a slipperier surface. It wasn't easy standing on that plastic surface with the water on it.





I've done this at training as well.





Here's a video from another country showing a Crosstrek Hybrid(not the plug-in though) working it on one wheel.

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Old 12-12-2020, 08:58 PM   #63
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It was on the first page of a Google search... No digging.

But why does it matter? Is proving that roller tests are garbage.

If you want to test a car driving up a steep dirt covered slope, then test that. Rollers are not dirt. Show me a video of a rav4 prime failing under these same conditions...
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Old 12-13-2020, 03:37 PM   #64
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RAV4 Hybrid (not Prime, but AWD is the same)

00:17 - Stuck, with surprised driver
01:37 - Stuck in diagonal test

Besides when there is basically no snow, the car gets stuck.


Last edited by Snow Drift; 12-14-2020 at 05:44 PM.
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