EV truck conversion on the cheap, or stick with LPG?

[ChemicalChaos]

Hi all,

I'm a big alternative fuel convert, having owned LPG 4x4s for the last 4-5 years. I'm well-versed on the pros and cons of a gas setup, but I also keep a keen eye on EV developments - plan to eke my current Jeep out until I can afford a Rivian R1S in about 2022

I've recently acquired a Green Goddess fire engine which i'm going to refit as a campervan inside, and I'm at an impasse over what to do with the motive power.
Currently, it has its original Bedford 4.9 straight 6 (a bored out version of the Chevrolet Stovebolt Six lump from about 1925), complete with carburettor, points and all of 100bhp and 8mpg. This is clearly not on for something I wish to travel some distance in when finished!
In the short term, I plan to whack a very simple LPG kit on this to get the truck up and running. My friendly local LPG expert tells me £300 would get me a very nice secondhand carb vaporiser and monster sized gas tank, which sounds entirely reasonable to me. Whilst this will make it cheap(er) to run, it's still not the ideal solution.An engine swap is the long term plan, but the difficulty is in finding a suitably modern (ie 90s, 00s) big capacity straight 6 petrol engine (I do NOT want to go down the rattly diesel route when I share the cab with the engine!)
After a bit of research, it appears the Ford 4.0 "Barra" from an Aussie Falcon is not only the ideal big, lazy torquey mill with a modern yet simple management system, but it was also offered from the factory with an LPG system. Thus, we have option one.
Option two though..... I've been keeping a close eye on the recent trend of sympathetically retrofitting classic cars with EV power, either new custom builds or latterly using salvaged kit from Leafs, Teslas etc - I gather they are very popular indeed in MGBs, Minors and other hipster restomod classic cars in London. However, I'm also aware they are still ferociously expensive (compared to other power options).
As I understand it, the main cost of such a system is modern battery tech that gives a decent range (ie about 350 miles) and performance whilst still fitting in the car. Now, in a Goddess the space and weight is nothing like so much of an issue - there's a good 3ftx2ftx2ft space up inside each body sill, and of course the thing was designed to carry 3 tons of kit and water.
So, would it be a cost effective idea to use older and less energy dense battery tech to achieve a still reasonable range for much less cost? Would this still be possible, or is it the case that you can only buy the latest tech as there is no market for "obsolete" stuff any more?

Thanks,
Matt

[RobDickinson]

What do you think it will do for efficiency? i.e. miles per kwh? I would guess low, 2 or 3 at best.

So for 350 miles you would need 200kwh, not realistic at all for space or price.

Have a look at EV west for rough idea of bulk (and cost) see what you could fit in to those spaces.
https://www.evwest.com/catalog/index.php?cPath=4

Then you need inverted, charger,motor etc but thats all off the shelf probably.

[oop north]

2 or 3 miles per kWh? I’d be surprised if you could get anywhere above 1. I averaged 3.9 in my i3 over three years and only because I had to really eke it out to manage a regular 80-mile journey - in general local driving i was around 3.5. In the iPace I am averaging around 2.6. A green goddess won’t top 1 (that’s only a guess but weight and aerodynamics will be dreadful)

[RobDickinson]

I was being generous and assuming a low average speed too lol

[Chris-S]

Cost wise the petrol/lpg fuelled Barra would be an obvious winner by likely a factor of 5 or more I’d think.

Watching a RichRebuilds video the other day where he visited EV West and I’m sure the guy mentioned costs around $20,000 to put Tesla M3 motor and batteries into a conversion.

Interesting idea but far from the cheap option. Keep us posted on progress though and good luck with the project.