Speculation Alert - possible Harvester Engine Choices

[Chaparral]

They don't have to work that way, but that is how every Series Hybrid in existence has worked.

A 1.5L Naturally aspirated Engine can demonstrably generate 55 KW power in that application. See Chevy Bolt.

So a 3 Cyl 1.5L engine could do the job, and IMO, with some tilt could fit back there.
That was exactly my answer to what engine they should use:

https://scoutmotors.community.forum/threads/speculation-alert-possible-harvester-engine-choices.1085/page-4#post-11611

55KW is more than adequate to drive an F150 Lightning at 70 MPH down the highway.

The BMW i3 has a small generator.

For the Scout, a 1.5 L is probably still a bit too small to maintain state of charge indefinitely during normal driving. But even if it could, it definitely couldn’t fit in the available space. We’re more or less talking about the space where a 35in spare tire probably does not fit but a 32in spare does and the available depth (vertically) is probably little over a foot.

 

[Peter Hamilton]

But it IS a hybrid. It's almost certainly a series hybrid and not a parallel hybrid, but it's still a hybrid powertrain.

https://www.caranddriver.com/features/a46275944/series-hybrid-vs-parallel-hybrid-explained/

Great article thanks!

 

[Jwock]

Since we're talking VW Group here, any possibility of the Porsche flat 4 cylinder engine from Boxster?

 

[Chaparral]

What commercial product can I buy, with that engine in it?

If I can't buy a commercial product, with that engine, then it's still in the experimental stage.

It was basically only revealed as a prototype last year:

Zero Cranks Given: Is The INNengine Feasible Or Just Pure Folly?

A firm called INNengine built an engine that doesn't have valves or a crankshaft, and after slapping it into a Miata they took it for a spin.

www.enginelabs.com

And already they were caught making misleading claims about not having a Turbo, and running at atmospheric pressure. Internet Engine analyst D4A, pointed out the supercharger that they had attached:

Questions about their claims, and especially durability will take many more years to answer.

This companies “our technology” webpage only has 168 words. They have next to nothing say about how it works. That usually means they have nothing of substance.

 

[Chaparral]

Since we're talking VW Group here, any possibility of the Porsche flat 4 cylinder engine from Boxster?

Will it fit in the space available for a spare tire?

 

[oldgeeksguide]

Its totally possible that I am. I know (or thought I knew) the difference between KW (a volume of energy), and KW/H (a rate). Could you please explain what I'm missing?

But I'm fairly certain the data I have is correct in terms of consumption for the Rivian and Hummer. You can see here the reviews for the Rivian HERE, and here.

Large Pack, Dual Motor:
308.3 Miles (driven)
128.2 KWH Used
2.41 Mi/KWH

So in this case, the Rivian goes 2.41miles per KW of energy in the batteries, at 70mph. If they drove for an hour at 70mph, they'd then go 70 miles, and have used ~29KW (not KW/H) of energy (70miles/2.41 kw per mile = 29KW).

For a generator to be able to keep up with the discharge rate there, then the rate would have to be at least 29KW/H. This is the same as an engine generating ~39hp over the course of an hour.

If we assume the Scouts have less efficiency than the Rivian, but better than the Hummer, then it seems like for the same scenario it would be somewhere in the ballpark of 70 miles/1.8 miles per kw = ~39kw of energy used in an hour. And therefore a generator would need to be able to generate at least 39KW/H to keep up with the discharge rate. And that works out to ~53HP worth of output, for an hour?

That math tracks right? Or what am I doing wrong here?

I think a see a possible source of confusion here. It’s not kW/h (kilowatts per hour), it’s kWh (kilowatt * hours). Maybe another way to think of it is energy is in kilowatt hours (kWh) and power is in kilowatt hours per hour (hours cancel and you just get kW), but maybe that’s just more confusing.

 

[Chaparral]

Another data point is the fact that a Scout rep told someone at the reveal that the Harvester version will probably cost less to build than the regular BEV.

So it seems that at least someone at Scout thinks they are using an inexpensive engine.

 

[CarTechGeek]

Another data point is the fact that a Scout rep told someone at the reveal that the Harvester version will probably cost less to build than the regular BEV.

So it seems that at least someone at Scout thinks they are using an inexpensive engine.

~160 KWh battery for 350 miles.
~70 KWh battery for 150 miles.

The difference is 90 KWh.

For the price of 90 KWh of batteries, you could buy any 3 or 4 cylinder economy car engine, and have thousands of dollars left over.

 

[R1TVT]

A small buffer will need to be maintained, but in all series hybrids: Most if, not all of the power is coming from the Generator.

At minute 39 of the reveal, the Harvester is discussed by Scott, and described as follows - direct quote: "the battery will drive both of the axles"

Meaning that the RE generator will produce electricity specifically for the battery. That is why there is still a FRUNK and not a V6 sitting in it.

 

[CarTechGeek]

At minute 39 of the reveal, the Harvester is discussed by Scott, and described as follows - direct quote: "the battery will drive both of the axles"

Meaning that the RE generator will produce electricity specifically for the battery. That is why there is still a FRUNK and not a V6 sitting in it.

Speak to a lay audience and trying to make it clear there is no physical connection to the wheels.

If it literally only drew power from the batteries to power the wheels, it would be the single most ill conceived series hybrid design ever. I have more faith in their engineers.

 

[CarTechGeek]

For the Scout, a 1.5 L is probably still a bit too small to maintain state of charge indefinitely during normal driving.

Why too small? It's been demonstrated that even a naturally aspirated 1.5L can deliver 55KW in generator applications (Volt). An F150 lightning only needs about 40 KW (or less) to cruise at 70 MPH...

55KW is sufficiently larger than 40 KW, that I don't that is a serious issue. Not enough to Tow at 70 MPH, but enough to drive at 70 MPH, for certain.

But even if it could, it definitely couldn’t fit in the available space. We’re more or less talking about the space where a 35in spare tire probably does not fit but a 32in spare does and the available depth (vertically) is probably little over a foot.

Just because the RE removes the space the spare tire uses, doesn't mean that's the ONLY space it will use.

Check out this frame view. Behind the rear axle, there is a pyramid shaped structure too cover something not shaped like a spare tire. Also I would say the top of the housing is at least as tall as the top of the tires, which means reasonably tall when you have 35" tires.

 

[Bodie]

Contrary to what others have replied, you are correct, it would be relatively easy to boost power when running the gas engine to boost beyond the power output of the battery alone. You already have to be able to blend power from both system, so getting them to go beyond what the battery already provides is almost trivial.

That is precisely how the Fisker Karma, the very first plug-in series hybrid/EREV sold in the USA, operated.

0-60 in Battery only mode was about 8 seconds.
0-60 with Range extender running to boost power was about 6 seconds. Significantly faster.

The only question, is if they will want to do this, because they aren't making a sports car. Coin toss on that one.

I know, but thank you.

 

[Chaparral]

~160 KWh battery for 350 miles.
~70 KWh battery for 150 miles.

The difference is 90 KWh.

For the price of 90 KWh of batteries, you could buy any 3 or 4 cylinder economy car engine, and have thousands of dollars left over.

The pure EV range is said to be 150 miles but that might only mean that the Harvester kicks in at 150 miles not that the pack is empty.

Scout says they are only making the pack “a little bit smaller” to make room for a gas tank. You’re suggesting the pack is less than half size. That’s not “a little bit”. And it is far more than necessary to add a gas tank. The best we can do is reconcile everything they said, not pick one or two data points and ignore the others.

It might be that the pack has little less than 50% when the Harvester kicks in. Given the fact that it is shown to be a tiny engine, this makes sense, otherwise it might be too little too late to add significant range.

 

[Bodie]

Maybe this will help understand how EREV/series hybrids work. I put it in the suggestion box for desired modes. Not saying this is how the harvester WILL work but probably pretty close. If the generator is small, the lowest, safe SOC would have to be higher than the 10-15% I estimate for my car. Maybe why it’s only 150mi.

https://scoutmotors.community.forum/threads/harvester-modes.1092/

 

[Chaparral]

Why too small? It's been demonstrated that even a naturally aspirated 1.5L can deliver 55KW in generator applications (Volt). An F150 lightning only needs about 40 KW (or less) to cruise at 70 MPH...

55KW is sufficiently larger than 40 KW, that I don't that is a serious issue. Not enough to Tow at 70 MPH, but enough to drive at 70 MPH, for certain.



Just because the RE removes the space the spare tire uses, doesn't mean that's the ONLY space it will use.

Check out this frame view. Behind the rear axle, there is a pyramid shaped structure too cover something not shaped like a spare tire. Also I would say the top of the housing is at least as tall as the top of the tires, which means reasonably tall when you have 35" tires.

View attachment 3544

View attachment 3545

The engine is the orange part in the image.

That is tiny. Far smaller than a 1.5L engine ! It has to fit under the bed of the truck, basically in the space where the under-mounted spare goes.

Like I said before, even if a 1.5L could deliver the power to run the vehicle continuously (you also need to factor in the inefficiencies of converting electricity to chemical potential and back and the electric motor etc), it clearly would not fit in that tiny space.

The image also shows the battery pack extends almost all the way back. This fits with what Scout said about it only being “a little bit smaller” than the full sized battery.

 

[CarTechGeek]

The engine is the orange part in the image.

That is tiny

As noted. The top of that structure is as tall as a 35" tire. Subtract 12" for ground clearance and you have 23".

I bet a lot of economy car engines can fit in 23". Maybe a small adjustment for the oil pan, but they would fit.

 

[Bodie]

Ducati has a 209hp 89 #ft V4 motorcycle engine that I’m sure could fit. VWAG owns Ducati.

 

[speedrye]

I think I'd rather have the smaller battery and lower curb weight if the Harvester can provide enough juice to the battery. Less weight to lug around lets the electrons move the truck farther.

 

[R1TVT]

Speak to a lay audience and trying to make it clear there is no physical connection to the wheels.

If it literally only drew power from the batteries to power the wheels, it would be the single most ill conceived series hybrid design ever. I have more faith in their engineers.

I described (and quoted) what was said by the guy that is building the truck and taking my reservation. I will stick to what I heard Scott and Scout say at the reveal:

It's an EV with a small generator - batteries will be the only thing powering the electric motors, and the Harvester will help provide additional power to the battery pack (at this stage its an undetermined amount of electrons that go to the battery from the Harvester). All speculation, but since there will be a Frunk and it will not be implemented like Fisker or Ram, the Harvester is projected to be compact. This makes sense, since there is a defined range of 500 miles.

 

[Chaparral]

I think I'd rather have the smaller battery and lower curb weight if the Harvester can provide enough juice to the battery. Less weight to lug around lets the electrons move the truck farther.

The curb weight might be similar, what you save with a smaller battery size you need to add in the engine. The smaller the battery, the bigger the engine. We’ll have to wait and see if one vehicle ends up much lighter than the other.