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As suggested in the "I want build an EZ! Where do I start?" thread, this is my introductory post.

Skill level with auto mechanics and fabrication:
  • Auto Mechanics
I consider myself a shade-tree mechanic. Until my wife's purchase of a 2018 Subaru Impreza, I maintained and wrenched on every vehicle we owned. Biggest job to date in mechanics was replacing the engine and transmission in a 2001 Honda S2000 (cracked block in original). I also replaced the soft top on that car.

  • Fabrication
I lack the tools for fancy work, but have been fairly adept at revising the layout of my motor home, including fabricating a new dinette, overhead storage, and a Murphy bed.

  • Electronics & Electrical Systems
In addition to maintaining 3 separate electrical systems in my motor home (AC, DC house, DC chassis), I built an eBike using Luna Cycle's 3kW Cyclone motor, where I gained some experience fussing with higher DC voltage battery-based systems.

Desired range (miles/charge)
Bare minimum range would be 50 miles at highway speed (~60 mph)

What level of performance you are hoping to get
I would like the car to perform as it did new with its 1493cc ICE.

How much money you are willing to put into your project
Not counting the Spitfire itself, my spend limit is probably around $5k

What parts you've already considered, if any.
I have started researching salvage Nissan Leaf and Chevrolet Spark EV vehicles. I figure I only need ~50kW to match the sub-70HP of the Spitfire's ICE engine, but will still need to research and procure a different transmission from OEM, unless the salvage vehicle's transmission will suit.

Finally, I am in no rush on this conversion, and will likely spend several years researching, thinking, and procuring parts before I pull the ICE engine out of the Spitfire. The engine and transmission have less than 2000 miles since last overhaul, and the car is running as well as a 70s British sports car can be expected to run.

Looking forward to chatting and learning.
 

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There have been many Spitfire conversions, I believe more because there are many small convertible sports car enthusiasts, because the engines are prone to die, and because an older car is a simpler conversion target than a new one, not because the Spitfire is particularly suitable design for conversion.

I came to this forum while considering the conversion of our Spitfire 1500, and searched for other Spitfire conversions. I had a more extensive list, and will try to remember to post it later, but for now here are a couple of forum threads about Spitfire conversions:
New Mexico Spitfire
1979 Triumph Spitfire Conversion
 

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What level of performance you are hoping to get
I would like the car to perform as it did new with its 1493cc ICE.

What parts you've already considered, if any.
I have started researching salvage Nissan Leaf and Chevrolet Spark EV vehicles. I figure I only need ~50kW to match the sub-70HP of the Spitfire's ICE engine, but will still need to research and procure a different transmission from OEM, unless the salvage vehicle's transmission will suit.
That moderate performance expectation is good, because the final drive (transmission) and transmission (in case you use it) are limited in torque-handling capability, so keeping the electric motor torque down to within the capacity of those components is likely prudent.

Desired range (miles/charge)
Bare minimum range would be 50 miles at highway speed (~60 mph)
Although that seems like a modest range expectation, I think you'll find it challenging to fit in enough battery for even that without excessive weight, or taking up the trunk space, or ending up with a poor-handling car due to battery mass stuffed into the extreme ends of the car. These factors, and the realization that it would be difficult to get even enough range for the 55 km (35 mile) round-trip from my house into the nearest city, were critical in my decision not to proceed with a conversion at this time.

Finally, I am in no rush on this conversion, and will likely spend several years researching, thinking, and procuring parts before I pull the ICE engine out of the Spitfire. The engine and transmission have less than 2000 miles since last overhaul, and the car is running as well as a 70s British sports car can be expected to run.
I think that's a great plan. While still enjoying the car, you can investigate available spaces for components and be sure that you have a workable design before disabling the vehicle. :) Be prepared to learn more about the Triumph Spitfire than you ever thought you would want to... ;)
 

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I've thought about this as well. Unlike an MGB or some such, there isn't a modern motor that's at all easy to swap in...and the Spitfire engine is not exactly a legend...so it makes a good candidate in that respect.

The hard bit seems to be driving the wheels. If you can find a motor/gearbox combo that's small enough to fit in the rear, you wouldn't have to redesign the suspension, and you could ditch the transmission and diff (which frees up weight, space, and some power constraints). I'm not sure of one that's narrow enough, though. Could always bolt something up to the transmission...

Batteries are the component that are depreciating most rapidly, so it makes sense to wait on their purchase...but they determine a lot of what the rest of the system will be, so there's that.

I think there's space for batteries, but they'll fill the trunk and engine bay...Is there space behind the seats without the top? A Nissan leaf gets 60-80mi of range on 24kW, and the Spit weighs half as much. I think you might get away with half a pack or so, depending on speed, elevation changes, temperature, etc. Tesla batteries are lighter and smaller per kW, but need liquid cooling and cost more.

Interesting project.
 

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I've thought about this as well. Unlike an MGB or some such, there isn't a modern motor that's at all easy to swap in...and the Spitfire engine is not exactly a legend...so it makes a good candidate in that respect.
I agree.

The hard bit seems to be driving the wheels. If you can find a motor/gearbox combo that's small enough to fit in the rear, you wouldn't have to redesign the suspension, and you could ditch the transmission and diff (which frees up weight, space, and some power constraints). I'm not sure of one that's narrow enough, though.
It's not just the width - the Spitfire's swing-axle suspension uses the half-shafts as locating links, so the outputs of the drive unit would need to be very close together (like the original), symmetric about the vehicle centreline, and able to take the entire lateral force of the car cornering as axial load on the shafts.

I think there's space for batteries, but they'll fill the trunk and engine bay...Is there space behind the seats without the top?
Very little.

A Nissan leaf gets 60-80mi of range on 24kW, and the Spit weighs half as much. I think you might get away with half a pack or so, depending on speed, elevation changes, temperature, etc.
The Spitfire is lighter, and has less frontal area, but (despite the sporty shape) it probably has a higher coefficient of drag. To run as efficiently as a Leaf, one would need to use a comparable motor and controller... not, for instance, a salvaged forklift motor or similar aftermarket motor. Even the extra drag of the stock hypoid ring and pinion gear in the final drive (assuming that is retained or an equivalent is used) means higher energy consumption.
 

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Would it be possible to rigidly mount a Warp-9-style motor to the diff and frame, or does it move around?

The Spitfire is lighter, and has less frontal area, but (despite the sporty shape) it probably has a higher coefficient of drag.
I suspect the Spit would spend much of life around 40mph, whereas the Leaf range likely takes a lot of highway miles into account. Your mileage may vary?
 

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Would it be possible to rigidly mount a Warp-9-style motor to the diff and frame, or does it move around?
As is typical for an independent suspension, the final drive (diff) is fixed (well, mounted through rubber bushings) to the frame, so the motor could be mounted directly to it. The fixed mount of the rear spring is actually bolted to the top of the final drive housing - the whole rear of the car rides on the diff, so it can't be allowed to move much.

The problem is that ahead of the diff, where a large motor would need to sit, there is little space between the frame rails, and the seats are there. I think a motor shafted directly to the diff needs to go where the transmission does or further forward... and even then, most motors will be wider than the Spitfire transmission so it is likely to be difficult to stuff it entirely in the transmission tunnel.

The Spitfire has a semi-backbone frame: it has two frame rails, but instead of going straight back (the classic "ladder frame" of antiques and trucks) or bumping out around the passenger compartment to the rocker areas (a "perimeter frame"), the rails pinch together around the transmission, run just far enough apart to clear the propeller shaft between them, then flare out again around the final drive. It is like the worst of all worlds, with even less torsional stiffness than a ladder frame, and without the box-beam effect of a proper backbone, or the packaging and structural efficiency of a unibody. The longitudinal locating arms of the rear suspension even mount to the body - despite this being a body-on-frame car - because the silly frame is way too far inboard at that point to attach the suspension to it.

Here is a photo from one of the threads that I linked, taken from the rear of a Spitfire frame without the body. To mount to the front of the final drive (diff), the motor would be sitting where that skinny white shaft is now:


There are reasons that few companies ever built cars this way, and that nobody has for decades. Nevertheless, I am fond of our Spit. :D If only the engine still ran...


With some modification to the crossmembers behind the final drive, it might be possible to turn the final drive around (so the input faces rearward) and mount a motor directly to it, sitting in the trunk space. That would leave the entire engine compartment and transmission tunnel for battery.

I suspect the Spit would spend much of life around 40mph, whereas the Leaf range likely takes a lot of highway miles into account. Your mileage may vary?
Slower is generally better for EVs, since the energy consumption is so highly dominated by aero drag. So yes, to get close to what a modern production EV does for distance per unit of charge in highway driving, driving more slowly would be helpful.
 

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Hey, nice to see another Spitfire project!
Looking around the forums you can find half a dozen Spitfire projects here.
I converted my 1979 Spitfire a few years ago. During that time, "Moltenmetal" was also converting his 1975 Spitfire.

As with most large projects there were many issues to overcome during the conversion project. Perhaps these two build threads could also help you avoid some of the mistakes and wrong turns during our builds.

Moltenmetal's build:
https://www.diyelectriccar.com/forums/showthread.php?t=95790

And my '79 Spit: https://www.diyelectriccar.com/forums/showthread.php?t=108210

I started my conversion planning on using a Warp9 in a direct drive configuration. I changed plans and ended up using a Tremec T5/WC transmission -- which fit pretty well. I wanted more acceleration than the direct drive in my setup would have produced. My Spitfire will do 85mph without any trouble. My modeling predicts a top speed of 129 at 5000 RPM's.
 
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