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Insight's Powertrain Design

10K views 29 replies 18 participants last post by  elvin 
#1 ·
2019 Insight powertrain

Although specifics are still relatively limited at this this time, there are some rumors going around at what we can expect in terms of a powertrain. Power is expected to come from a 1.5-liter Atkinson-cycle engine mated to an electric motor fed by a lithium-ion battery pack. Honda has promised that the new Insight will offer class leading horsepower and fuel economy that's better than 4.7L/100 km. It's believed that the new Insight has been designed to run mostly on electric power, with engine more operating as a generator.
 
#6 ·
One thing that hasn't been discussed much with the Insight's fuel economy is the unusual design of Honda's hybrid system.

As I continue to look into this possible car purchase of mine, the combination of a series hybrid design with the direct clutch of the Insight's motor, as opposed to a traditional CVT, stands out. What you have is the Insight's motor working very efficiently as a generator, but less so when it is clutched into the drivetrain at the only possible drive ratio, so the car can't loaf along at 75 with the transmission idling the engine at 1800 to 2000 rpm like some CVTs do but instead has to rev up quite a bit. Drop just a few mph and the Insight goes entirely on the electric motor for the drivetrain except under stronger acceleration and the engine can operate at whatever rpm the system needs for power generation. This is how you come up with Consumer Reports' constant 65mph Insight test impressively registering 62mpg and Car & Driver's constant 75mph test only managing in the mid 40s while they get mid 50s on the same test with the Corolla hybrid (though I have to say I doubt that too....given their earlier Prius test I'd think the Corolla ought to get about 50 in that test, but I digress....perhaps they did both the Insight and the Prius on colder days).

In any case I think this is leading to the Insight showing a far wider range of mpg outcomes both in Youtuber and magazine testing and from people posting here than you might expect from most hybrids.

Unfortunately cleanmpg.com doesn't seem to be doing the volume of steady-state testing that it used to, so no verification on a standardized test -- which would be handy as there's a bit of a difference between C&D's I-94 loop in Michigan and CR's highways and byways of eastern Connecticut.

If anyone has managed to pull the engine RPM data e.g. through OBD of the Insight, I'd be interested to hear.
 
#10 ·
One thing that hasn't been discussed much with the Insight's fuel economy is the unusual design of Honda's hybrid system.

As I continue to look into this possible car purchase of mine, the combination of a series hybrid design with the direct clutch of the Insight's motor, as opposed to a traditional CVT, stands out. What you have is the Insight's motor working very efficiently as a generator, but less so when it is clutched into the drivetrain at the only possible drive ratio, so the car can't loaf along at 75 with the transmission idling the engine at 1800 to 2000 rpm like some CVTs do but instead has to rev up quite a bit. Drop just a few mph and the Insight goes entirely on the electric motor for the drivetrain except under stronger acceleration and the engine can operate at whatever rpm the system needs for power generation.
On flat highways at 75 mph, the Insight in Direct Drive acts much more like a traditional ICE car, until a power demand is made, the rpms stay pretty consistent, and doesn't rev high. If you mash the throttle or encounter a steep enough of a grade, the ICE goes back to generator/drive and you get electric assist.

The major difference is that at 70+ the Insight's software is perfectly fine with the ICE running the show, as it's directly in its power band and most efficient point. All a traditional transmission allows for is multiple "ideal" ICE points. Hybrids are always more popular in areas with higher gas costs, and un-ironically, the states with the highest gas costs, generally have lower average speed travelled than their counterparts.
 
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#7 ·
The Accord Hybrid uses the same hybrid design, but with larger 2.0L gas engine. At all speeds the electric motors drive the wheels in series (lower speeds) or parallel (higher speeds).

Regarding standardized testing - does cleanmpg.com test in a specialized way that's different from the EPA? Wouldn't the EPA fuel ratings/testing be the 'most' controlled way of comparing cars? https://www.gen3insight.com/forum/12564-post2.html

Here are some additional threads with info related to your questions/comments:
- Insight OBD/RPM - https://www.gen3insight.com/forum/5...s-add-ons/742-obdii-blue-tooth-adapter-2.html
- Insight eCVT - https://www.gen3insight.com/forum/153-2019-powertrain-technical-discussion/2676-ecvt-vs-cvt.html
 
#8 ·
As I understand it the guy who has been doing the test, Wayne Gerdes, has a standard loop that he has done them on that gets out into the countryside along the Illinois/Wisconsin line just on the western fringe of Chicago/Kenosha suburbia, and then only when the weather and road conditions are within certain parameters. I don't know how he is measuring it.

In other words, it's something kind of comparable to the Car&Driver I-94 loop in southern Michigan (done at a constant 75mph over 200 miles), or the circuit of roads in rural eastern Connecticut from Consumer Reports (at a constant 65 over a much shorter loop but with very precise instrumentation constantly measuring fuel flow -- not a fuel fill), but with information CR, C&D etc do not procide in the way of performance at different speeds (steady-state stretches at several different speeds; generally a 70 and a 65 -- both those would have to be on superhighways -- and then 60, 55 and 50.

The EPA test is quite different -- it's in a lab, on a dynamometer, done by the car manufacturers themselves according to EPA specs, simulating a standard, pre-programmed set of driving conditions, and the data submitted to the EPA, with about one in every six of those tests rechecked by the EPA themselves via the National Vehicles and Fuel Emissions Laboratory. The dynamometer rollers are adjusted to account for the vehicle's weight and aerodynamics. While the EPA highway cycle quite effectively simulates fast suburban driving in still weather, with stretches of 45 to 60mph driving interspersed by slowdowns and the occasional stop, it doesn't really test steady-state highway driving.
 
#12 ·
I wonder - while the engine is directly coupled to the wheels, does the energy used to charge the HV battery come from only the generator - or does it generate electricity from both the traction motor and generator? Would that be more efficient than only using the generator?
 
#18 ·
In my hopes of finding evidence that the powertrain in the Insight is nearly identical to that of the Clarity Plug-In's (and the implication that there could be a lot of performance left on the table) due to it being seemingly illogical to design and produce something significantly different for just a single model, it started to make more sense after learning that the Honda Jazz and City would be equipped with the powertrain as well.

What I had missed up until finding the Insight's press release is that the traction motor is rated for 129HP, and that the 151HP figure is the so-called "total system horsepower". Honda defines that as "Total system horsepower as measured by the peak, concurrent output of the two electric motors and gasoline engine." but in reality that's still a bit of a mystery, and there's a pretty good thread trying to make sense of it here, though it's mainly about the Clarity and Accord.

If our traction motor is rated at 129HP, then the only logical way we can have anything above that is with the engine's overdrive clutch engaged assisting the electric motor. Yet, the 151HP rating is at 6,000RPM, but that doesn't specify what's turning at 6k RPM. Presumably it means the engine, but with the clutch engaged, and an LX/EX rolling on 16" wheels with 55 sidewalls, 6k RPM equates to ~160MPH. Now, if the thread I linked to above is correct, no electric power is applied over 100MPH, then there's no way 151HP can ever be applied (never mind the fact that the car will probably never reach anywhere near 160MPH).

That makes it sound like the 151HP is some marketing BS that can realistically only be achieved in a lab.
 
#19 ·
In my hopes of finding evidence that the powertrain in the Insight is nearly identical to that of the Clarity Plug-In's (and the implication that there could be a lot of performance left on the table) due to it being seemingly illogical to design and produce something significantly different for just a single model, it started to make more sense after learning that the Honda Jazz and City would be equipped with the powertrain as well.

What I had missed up until finding the Insight's press release is that the traction motor is rated for 129HP, and that the 151HP figure is the so-called "total system horsepower". Honda defines that as "Total system horsepower as measured by the peak, concurrent output of the two electric motors and gasoline engine." but in reality that's still a bit of a mystery, and there's a pretty good thread trying to make sense of it here, though it's mainly about the Clarity and Accord.

If our traction motor is rated at 129HP, then the only logical way we can have anything above that is with the engine's overdrive clutch engaged assisting the electric motor. Yet, the 151HP rating is at 6,000RPM, but that doesn't specify what's turning at 6k RPM. Presumably it means the engine, but with the clutch engaged, and an LX/EX rolling on 16" wheels with 55 sidewalls, 6k RPM equates to ~160MPH. Now, if the thread I linked to above is correct, no electric power is applied over 100MPH, then there's no way 151HP can ever be applied (never mind the fact that the car will probably never reach anywhere near 160MPH).

That makes it sound like the 151HP is some marketing BS that can realistically only be achieved in a lab.
It doesn't say 151HP @ 6,000 RPM, it rates the engine as 107 peak HP at 6,000 RPM. In order to achieve 151 HP, the engine only has to produce an extra 22 HP as the electric motor is already producing 129HP, which is easily achievable.. Also, I have gone over 100mph and the engine and electric motor are indeed working beyond that speed (don't judge me)..
 
#20 ·
Scroll down to the powertrain table here: 2019 Honda Insight Press Kit

It does indeed specify 151HP@6k. What it doesn't specify is what's spinning at 6k. What you say would make sense if the battery could supply 129HP worth of power, but that would mean roughly 74C discharge rate for a 1.3kW/h battery pack, which is way too much to be realistic. There's also no evidence of that based on performance and system behavior.

Since it specified the traction motor's HP, and we know that's less than the 151HP figure, that means it must be rated in parallel mode (i.e. overdrive clutch engaged). Lets say that figure was based on traction motor RPM instead. Accounting for its gear ratio and final drive ratio, 6k RPM equates to roughly 54MPH. If max HP occurred at that speed, then if you mashed the "gas pedal" it wouldn't drop out of parallel mode and revert to series mode (and thus 129HP) like it does in actuality.

What's more plausible is that the engine puts out roughly 110HP @ 6k, and the battery back is capable of discharging fast enough to put out 40HP. But again, accounting for gearing, that requires the vehicle to travel at roughly 160MPH. There's just no realistic scenario I can think of where 151HP is possible given all the other information provided.
 
#26 ·
My daughter, a new driver, drove to dance class tonight. This is an 80-mile round trip with a mix of road types including interstate highway. She drove as teenagers do, a little above the speed limit, and still managed a 57mpg round trip in winter temps in New Jersey. For those seeing significantly less, I'd look into the state of your Insight. Check tire pressures, junk-in-the-trunk, and definitely check out your driving style. With an Insight in good repair, I can't fathom a way to get less than 40mpg unless one drives like Ricky Bobby or Cal Naughton, Jr. #shakeandbake
 
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