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Discussion Starter · #1 · (Edited)
Howdy everyone!

So for starters, I'm about a year or so away from even starting this build. Second, it's going to have a gas generator and is going to be an overland 4x4 with a Land Rover Discovery II as a base. The original plan is to take something like a 2007+ Tahoe 4x4 and drop in the entire drivetrain, put in superduty axles and go up to 35 inch tires; however, I have been playing around with the following idea and I want to know your thoughts.

I have been wanting to use a Volt drivetrain in something, and I think I may have found a way to make this work in the Disco. The original thought was to mount the drive unit longitudinally, keep the transmission, transfer case and axles and weld the diff. I wanted to add a second motor to attach to the front shaft, but tapping into the Volt's charging is iffy at best, and I'm afraid I'd have to give up all of the rear seats in order to fit both the Volt's battery and the batteries required for the second motor to be doing anything. I want to at least have 4 seats.

So, I'm hoping that I can power this thing with just the first gen Volt's drivetrain. It will be a relatively slow vehicle (compared to putting in a 5.3 V8 which has 100 hp more than the original 4.6), but the biggest advantage is going to be the off-road capability which is one of the things I'm most interested in.

So here are the calculations I've done so far and I want to know what you think and if I'm possibly missing anything:

Going backwards with the numbers, the stock tire size of the Volt is 215/55R17. That means it's approximately 26 inches in diameter, which is about 770 revolutions per mile, and that comes out to right around 1300 rpm at the diff when the Volt is traveling at 100 mph (770 * 100 / 60). I'm looking to put 35 inch tires on the Disco. 315/70R17 to be a bit more exact, which is an approximate diameter of around 34.5 inches, and that comes out to around 590 revolutions per mile. Since I'm looking to keep the axles, transfer case and transmission, if the Disco is traveling at 100 mph with those tires, that gives me around 985 rpm axle shaft speed. multiplying the 985 rpm from the shafts through the diff (3.54:1) and then through the transfer case (1.21:1) while driving in 4th gear (0.73:1), the input speed of the transmission is around 3100 rpm.

To account for the discrepancy in RPM, I have contacted the folks at Northwest Fab about my project. They make a crawl box that typically acts as another gear reduction mechanism for 4x4s with a 2.73:1 ratio. I told them I'm looking to install the box backwards to basically create a 0.36:1 overdrive and negate the 2.3:1 diff reduction from the Volt's drivetrain. The maximum rpm output from the Volt would then go from 1300 rpm to around 3500 rpm, giving me the ability to easily drive at highway speeds. Northwest Fab said their units should be able to handle it, but I'll need to add a pump and radiator to cool it.

The coolest part about all of this is that for going off-road, I'm going to end up with 3 reduction gears from the transmission, low range from the transfer case, and another reduction from the backwards mounted crawl box going from "low" to direct drive. First gear in the transmission is 2.48:1, low range on the transfer case is 3.27:1 and the crawl box will be another reduction of 2.72:1 for a total reduction of 22:1 for major torque multiplication and crawl ability.

I know that this will not be an easy project. My main concerns will be getting the speed sensors from the Volt not to freak out and getting the transmission in the Disco to operate right. Now, assuming that can be accomplished (I have some theories on what could be done), is this thing going to be driveable with that little bit of power? Does my math check out?

I also know that between the weight and massive aerodynamic losses, I'm probably only going to get 10-15 miles of electric range vs the standard 30-35. Where I'm really looking to gain something here is in the off-road gears reduction and fuel economy. With the generator running and driving 65 mph, I'm hoping to get 25-30 mpg. If I hit that mileage and am able to keep the original fuel tank (24.5 gallons), that means I'll have more than 600 miles of range. On top of that, I'll be able to install a 2000 watt inverter for camping and have a massive crawl ratio to compensate for the relative lack of power.

So... Thoughts? Let me know if there's something major I'm overlooking.

Thanks!
 

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Discussion Starter · #4 ·
Weight?

No V8 but then you're keeping a generator and the tank. Adding motor and 400lbs of batteries. Not concerning to you?
Yes, most definitely concerned. That's why I mentioned in the title that I'm not sure if it will be driveable. I think worst case scenario, I should be able to go from third to fourth to get it moving. There's a good chance this thing could end up being a bit of a dog to get up to speed, but with around 275 lbs of torque, I'm really hoping that at least getting up to 50 won't be a huge ordeal. With 35 inch tires and lots of sidewall, I wouldn't really be too comfortable driving it above 65 mph. It would probably be fine, but speed is the last objective in this build.

Suspension wise, I'm not worried. I'm going to have to get in there to fit 35s, and I'm hoping to be able to keep it as close to stock ride height as possible via a ton of trimming, stretching the wheelbase by moving the axles farther out and going to airbags. That part of the build is going to happen regardless, and I'm hoping to keep some stability and economy by keeping it low.
 

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Discussion Starter · #5 ·
You would not want an overdrive

You would still want gear reduction
Since the Volt drivetrain is so complex, the diff is going to have to stay in. So that ends up being too much gear reduction. The overdrive is to cancel out the volt's diff. From there, I'll still have a 4 speed, a 1.21:1 reduction at the transfer case, plus 3.54:1 reduction at the diff.
 

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Since the Volt drivetrain is so complex, the diff is going to have to stay in. So that ends up being too much gear reduction. The overdrive is to cancel out the volt's diff. From there, I'll still have a 4 speed, a 1.21:1 reduction at the transfer case, plus 3.54:1 reduction at the diff.
The Volt stock but with the modules reprogrammed can hit 150mph

https://www.instagram.com/p/Bm6-Xb5...SzS951WsqK-E012JJDPLYzpzfq1S8IkxLi0VOUqI_aC8k

I am uncertain what speed you wish to achieve but if 50mph is fast enough it may not be an issue.

Something to consider would be using the traction controlled Volt drivetrain in its stock fwd configuration and just buying a $500 leaf motor for the rear.

Change to 15” rims and up the rubber thickness.

Another secret is that the Volt and Bolt batteries are configured in the same way with the same voltage and modules.
It may be possible to move the controllers from the Volt to the bolt pack gaining you a fully compatible but larger capacity battery option.

Ah well interesting project but remember the KISS principle
 

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Discussion Starter · #7 ·
The Volt stock but with the modules reprogrammed can hit 150mph

I am uncertain what speed you wish to achieve but if 50mph is fast enough it may not be an issue.

Something to consider would be using the traction controlled Volt drivetrain in its stock fwd configuration and just buying a $500 leaf motor for the rear.

Change to 15” rims and up the rubber thickness.

Another secret is that the Volt and Bolt batteries are configured in the same way with the same voltage and modules.
It may be possible to move the controllers from the Volt to the bolt pack gaining you a fully compatible but larger capacity battery option.

Ah well interesting project but remember the KISS principle
I'd like the ability to go 100 mph, but that's only in case of emergency.

Regarding a leaf motor in the back and volt in the front, that is something I have heavily considered. The main issue there is twofold. 1 being that I'd have to custom build independent suspension front and rear, and two would be fitting the leaf battery. I do want to do something like this in the future, but I want to keep the fabrication relatively simple. Moving solid axles around is relatively simple compared to custom building independent suspension. I originally wanted to use a Volt and Bolt drovetrains.

As far as getting them to communicate, I don't really see how it would be possible. I think I forgot to mention that I'm a former Chevy tech. I still work in service and have been studying the volt and bolt drovetrains. The volt battery has 3 modules while the Bolt has 10. Ive been trying to find a way to get a volt generator to charge a Bolt battery, but I haven't found anything that may work. I've been thinking that I could split the Volts motor 1 output... But then the problem turns into cost and risk. I could get it to work, but if I fail, that's more money than I can risk losing at the moment.

As far as rim size, I'm not completely decided yet. I do want lots of rubber, but i want this thing to be a daily driver too. So, slme sidewall firmness would be nice. I had a JK with 33s on 17s and never had an issue.

Got any sources on getting volt and bolt stuff to communicate? I'm very very interested in that.
 

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Discussion Starter · #9 · (Edited)
Do they need to communicate? You could fit two potentiometers onto the same throttle pedal assembly.
Main reason I'd want them to communicate is to only need one battery. I'd sacrifice electric range to run two motors off of a Bolt battery. Else, that's about 1600 lbs in batteries, and we're back to sacrificing the rear seats, which I don't want to do.

I do want to do this sort of setup, but it would need to be in a big vehicle. Like a small RV
 

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No one's gonna say don't do this? Have you converted an EV before?

I don't think you'll see much of a range boost from a generator vs more batteries, and it would be 10-100x simpler to just bolt a motor up to a truck with a manual transmission and gear to taste.
 

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Discussion Starter · #11 · (Edited)
No one's gonna say don't do this? Have you converted an EV before?

I don't think you'll see much of a range boost from a generator vs more batteries, and it would be 10-100x simpler to just bolt a motor up to a truck with a manual transmission and gear to taste.
I have not done an EV conversion before, but I have done EV swaps, I'm former GM tech and am Volt/Bolt certified.

EDIT: I wrote this on my phone and never saw this mistake. I meant to put in Engine swaps but my phone auto corrected and I never saw my mistake. Apologies for the confusion.

The main reason I want to go with a gas generator is for extended periods off road. I like the idea of being able to power a trailer and even a small welder if need be. The fuel efficiency gains are a big bonus too. I want this thing to be off the grid as much as possible. Solar panels would be cool, but I've done the math on what would be needed and the cost of the panels plus fabricating a setup is more than I care to do.

I think this would be simpler since the main obstacle with the conversion would be making the battery fit (cutting up the floor) and getting as many accesories from a complete donor vehicle to work as possible. If I can get it to drive and have no warning messages on the original screen, that would be the perfect goal, but if it runs and drives and everything I need to work works with a few warning messages (Thinking airbags, open doors and such), then that's still a win.

Without this conversion, the stock engine would get 11-14 mpg. The LS engine will hopefully get 18 mpg, and this setup I'm hoping will get 25 mpg plus have that 22:1 selectable reduction for doing some creepy crawling off-road.
 

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No one's gonna say don't do this? Have you converted an EV before?

I don't think you'll see much of a range boost from a generator vs more batteries, and it would be 10-100x simpler to just bolt a motor up to a truck with a manual transmission and gear to taste.
Some folks that have never done a conversion have body swapped onto an existing EV platform which is more “tedious “ than difficult.

https://www.greencarreports.com/new...up-truck-is-worlds-oldest-prius-hybrid-really


The trouble you rightly bring up is that he wants to mod an OEM drivetrain which is extraordinarily difficult .


The only 4wd “hybrid “ I’ve seen done quickly with modified OEM parts was an S10 with the stock drivetrain but the engine was replaced with an old Mercedes diesel and a portion of the prop shaft was replaced with a large 2 ended dc motor.

It had more rolling mass but would run EV or diesel but without regen and if nothing else was proficient despite being very low budget .
The designer wanted a short range EV and an EV boost when running on diesel and it did exactly that
 

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Discussion Starter · #13 ·
Some folks that have never done a conversion have body swapped onto an existing EV platform which is more “tedious “ than difficult.

https://www.greencarreports.com/new...up-truck-is-worlds-oldest-prius-hybrid-really


The trouble you rightly bring up is that he wants to mod an OEM drivetrain which is extraordinarily difficult .


The only 4wd “hybrid “ I’ve seen done quickly with modified OEM parts was an S10 with the stock drivetrain but the engine was replaced with an old Mercedes diesel and a portion of the prop shaft was replaced with a large 2 ended dc motor.

It had more rolling mass but would run EV or diesel but without regen and if nothing else was proficient despite being very low budget .
The designer wanted a short range EV and an EV boost when running on diesel and it did exactly that

Correct. What I'm trying to do is keep things "relatively" simple. I'm not looking to create an electric system. I want to take a complete donor vehicle and swap as much of it as possible into another one. The main issue still comes back to "will it be powerful enough", "does the math with the gears line up" and "is there anything major that I'm missing".

So far, on the last two parts, I don't think I am wrong with the gearing and I don't think I'm missing anything major (but that's why I'm here). I know I'm going to have issues getting ABS to work (which I'd be ok going without, but I'd much rather keep it), traction control, getting the transmission to recognize the speed without a torque converter, and basically everything that has to do with the speed sensors in general. Aside from that, I know a lot of the little things like getting the body control module to recognize things like when doors are open and such will be a bit of a pain. The goal is to get this thing to drive warning free, but I know that is a lot to ask for.

Again, the main benefits I'm looking for are the extended fuel range, electric torque availability and gear reduction for off-road use.

There were talks on getting a Bolt's electric system to communicate with a Volt. If anyone has any info on that, I am extremely interested. I have not found anything searching on my own so far.

I also want to mention that as far as experience goes, I am Bolt/Volt certified through Chevrolet and currently work in the service department at a Chevrolet dealership, though not as a technician anymore.
 
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